<?php

/**
 * Implements a runnable command, like "arc diff" or "arc help".
 *
 * = Managing Conduit =
 *
 * Workflows have the builtin ability to open a Conduit connection to a
 * Phabricator installation, so methods can be invoked over the API. Workflows
 * may either not need this (e.g., "help"), or may need a Conduit but not
 * authentication (e.g., calling only public APIs), or may need a Conduit and
 * authentication (e.g., "arc diff").
 *
 * To specify that you need an //unauthenticated// conduit, override
 * @{method:requiresConduit} to return ##true##. To specify that you need an
 * //authenticated// conduit, override @{method:requiresAuthentication} to
 * return ##true##. You can also manually invoke @{method:establishConduit}
 * and/or @{method:authenticateConduit} later in a workflow to upgrade it.
 * Once a conduit is open, you can access the client by calling
 * @{method:getConduit}, which allows you to invoke methods. You can get
 * verified information about the user identity by calling @{method:getUserPHID}
 * or @{method:getUserName} after authentication occurs.
 *
 * = Scratch Files =
 *
 * Arcanist workflows can read and write 'scratch files', which are temporary
 * files stored in the project that persist across commands. They can be useful
 * if you want to save some state, or keep a copy of a long message the user
 * entered if something goes wrong.
 *
 *
 * @task  conduit   Conduit
 * @task  scratch   Scratch Files
 * @task  phabrep   Phabricator Repositories
 */
abstract class ArcanistWorkflow extends Phobject {

  const COMMIT_DISABLE = 0;
  const COMMIT_ALLOW = 1;
  const COMMIT_ENABLE = 2;

  private $commitMode = self::COMMIT_DISABLE;

  private $conduit;
  private $conduitURI;
  private $conduitCredentials;
  private $conduitAuthenticated;
  private $conduitTimeout;

  private $userPHID;
  private $userName;
  private $repositoryAPI;
  private $configurationManager;
  private $arguments = array();
  private $command;

  private $stashed;
  private $shouldAmend;

  private $projectInfo;
  private $repositoryInfo;
  private $repositoryReasons;
  private $repositoryRef;

  private $arcanistConfiguration;
  private $parentWorkflow;
  private $workingDirectory;
  private $repositoryVersion;

  private $changeCache = array();
  private $conduitEngine;

  private $toolset;
  private $runtime;
  private $configurationEngine;
  private $configurationSourceList;

  private $promptMap;

  final public function setToolset(ArcanistToolset $toolset) {
    $this->toolset = $toolset;
    return $this;
  }

  final public function getToolset() {
    return $this->toolset;
  }

  final public function setRuntime(ArcanistRuntime $runtime) {
    $this->runtime = $runtime;
    return $this;
  }

  final public function getRuntime() {
    return $this->runtime;
  }

  final public function setConfigurationEngine(
    ArcanistConfigurationEngine $engine) {
    $this->configurationEngine = $engine;
    return $this;
  }

  final public function getConfigurationEngine() {
    return $this->configurationEngine;
  }

  final public function setConfigurationSourceList(
    ArcanistConfigurationSourceList $list) {
    $this->configurationSourceList = $list;
    return $this;
  }

  final public function getConfigurationSourceList() {
    return $this->configurationSourceList;
  }

  public function newPhutilWorkflow() {
    $arguments = $this->getWorkflowArguments();
    assert_instances_of($arguments, 'ArcanistWorkflowArgument');

    $specs = mpull($arguments, 'getPhutilSpecification');

    $phutil_workflow = id(new ArcanistPhutilWorkflow())
      ->setName($this->getWorkflowName())
      ->setWorkflow($this)
      ->setArguments($specs);

    $information = $this->getWorkflowInformation();

    if ($information !== null) {
      if (!($information instanceof ArcanistWorkflowInformation)) {
        throw new Exception(
          pht(
            'Expected workflow ("%s", of class "%s") to return an '.
            '"ArcanistWorkflowInformation" object from call to '.
            '"getWorkflowInformation()", got %s.',
            $this->getWorkflowName(),
            get_class($this),
            phutil_describe_type($information)));
      }
    }

    if ($information) {
      $synopsis = $information->getSynopsis();
      if ($synopsis !== null) {
        $phutil_workflow->setSynopsis($synopsis);
      }

      $examples = $information->getExamples();
      if ($examples) {
        $examples = implode("\n", $examples);
        $phutil_workflow->setExamples($examples);
      }

      $help = $information->getHelp();
      if ($help !== null) {
        // Unwrap linebreaks in the help text so we don't get weird formatting.
        $help = preg_replace("/(?<=\S)\n(?=\S)/", ' ', $help);

        $phutil_workflow->setHelp($help);
      }
    }

    return $phutil_workflow;
  }

  final public function newLegacyPhutilWorkflow() {
    $phutil_workflow = id(new ArcanistPhutilWorkflow())
      ->setName($this->getWorkflowName());

    $arguments = $this->getArguments();

    $specs = array();
    foreach ($arguments as $key => $argument) {
      if ($key == '*') {
        $key = $argument;
        $argument = array(
          'wildcard' => true,
        );
      }

      unset($argument['paramtype']);
      unset($argument['supports']);
      unset($argument['nosupport']);
      unset($argument['passthru']);
      unset($argument['conflict']);

      $spec = array(
        'name' => $key,
      ) + $argument;

      $specs[] = $spec;
    }

    $phutil_workflow->setArguments($specs);

    $synopses = $this->getCommandSynopses();
    $phutil_workflow->setSynopsis($synopses);

    $help = $this->getCommandHelp();
    if (strlen($help)) {
      $phutil_workflow->setHelp($help);
    }

    return $phutil_workflow;
  }

  final protected function newWorkflowArgument($key) {
    return id(new ArcanistWorkflowArgument())
      ->setKey($key);
  }

  final protected function newWorkflowInformation() {
    return new ArcanistWorkflowInformation();
  }

  final public function executeWorkflow(PhutilArgumentParser $args) {
    $runtime = $this->getRuntime();

    $this->arguments = $args;
    $caught = null;

    $runtime->pushWorkflow($this);

    try {
      $err = $this->runWorkflow($args);
    } catch (Exception $ex) {
      $caught = $ex;
    }

    try {
      $this->runWorkflowCleanup();
    } catch (Exception $ex) {
      phlog($ex);
    }

    $runtime->popWorkflow();

    if ($caught) {
      throw $caught;
    }

    return $err;
  }

  final public function getLogEngine() {
    return $this->getRuntime()->getLogEngine();
  }

  protected function runWorkflowCleanup() {
    // TOOLSETS: Do we need this?
    return;
  }

  public function __construct() {}

  public function run() {
    throw new PhutilMethodNotImplementedException();
  }

  /**
   * Finalizes any cleanup operations that need to occur regardless of
   * whether the command succeeded or failed.
   */
  public function finalize() {
    $this->finalizeWorkingCopy();
  }

  /**
   * Return the command used to invoke this workflow from the command like,
   * e.g. "help" for @{class:ArcanistHelpWorkflow}.
   *
   * @return string   The command a user types to invoke this workflow.
   */
  abstract public function getWorkflowName();

  /**
   * Return console formatted string with all command synopses.
   *
   * @return string  6-space indented list of available command synopses.
   */
  public function getCommandSynopses() {
    return array();
  }

  /**
   * Return console formatted string with command help printed in `arc help`.
   *
   * @return string  10-space indented help to use the command.
   */
  public function getCommandHelp() {
    return null;
  }

  public function supportsToolset(ArcanistToolset $toolset) {
    return false;
  }


/* -(  Conduit  )------------------------------------------------------------ */


  /**
   * Set the URI which the workflow will open a conduit connection to when
   * @{method:establishConduit} is called. Arcanist makes an effort to set
   * this by default for all workflows (by reading ##.arcconfig## and/or the
   * value of ##--conduit-uri##) even if they don't need Conduit, so a workflow
   * can generally upgrade into a conduit workflow later by just calling
   * @{method:establishConduit}.
   *
   * You generally should not need to call this method unless you are
   * specifically overriding the default URI. It is normally sufficient to
   * just invoke @{method:establishConduit}.
   *
   * NOTE: You can not call this after a conduit has been established.
   *
   * @param string  The URI to open a conduit to when @{method:establishConduit}
   *                is called.
   * @return this
   * @task conduit
   */
  final public function setConduitURI($conduit_uri) {
    if ($this->conduit) {
      throw new Exception(
        pht(
          'You can not change the Conduit URI after a '.
          'conduit is already open.'));
    }
    $this->conduitURI = $conduit_uri;
    return $this;
  }

  /**
   * Returns the URI the conduit connection within the workflow uses.
   *
   * @return string
   * @task conduit
   */
  final public function getConduitURI() {
    return $this->conduitURI;
  }

  /**
   * Open a conduit channel to the server which was previously configured by
   * calling @{method:setConduitURI}. Arcanist will do this automatically if
   * the workflow returns ##true## from @{method:requiresConduit}, or you can
   * later upgrade a workflow and build a conduit by invoking it manually.
   *
   * You must establish a conduit before you can make conduit calls.
   *
   * NOTE: You must call @{method:setConduitURI} before you can call this
   * method.
   *
   * @return this
   * @task conduit
   */
  final public function establishConduit() {
    if ($this->conduit) {
      return $this;
    }

    if (!$this->conduitURI) {
      throw new Exception(
        pht(
          'You must specify a Conduit URI with %s before you can '.
          'establish a conduit.',
          'setConduitURI()'));
    }

    $this->conduit = new ConduitClient($this->conduitURI);

    if ($this->conduitTimeout) {
      $this->conduit->setTimeout($this->conduitTimeout);
    }

    return $this;
  }

  final public function getConfigFromAnySource($key) {
    $source_list = $this->getConfigurationSourceList();
    if ($source_list) {
      $value_list = $source_list->getStorageValueList($key);
      if ($value_list) {
        return last($value_list)->getValue();
      }

      return null;
    }

    return $this->configurationManager->getConfigFromAnySource($key);
  }


  /**
   * Set credentials which will be used to authenticate against Conduit. These
   * credentials can then be used to establish an authenticated connection to
   * conduit by calling @{method:authenticateConduit}. Arcanist sets some
   * defaults for all workflows regardless of whether or not they return true
   * from @{method:requireAuthentication}, based on the ##~/.arcrc## and
   * ##.arcconf## files if they are present. Thus, you can generally upgrade a
   * workflow which does not require authentication into an authenticated
   * workflow by later invoking @{method:requireAuthentication}. You should not
   * normally need to call this method unless you are specifically overriding
   * the defaults.
   *
   * NOTE: You can not call this method after calling
   * @{method:authenticateConduit}.
   *
   * @param dict  A credential dictionary, see @{method:authenticateConduit}.
   * @return this
   * @task conduit
   */
  final public function setConduitCredentials(array $credentials) {
    if ($this->isConduitAuthenticated()) {
      throw new Exception(
        pht('You may not set new credentials after authenticating conduit.'));
    }

    $this->conduitCredentials = $credentials;
    return $this;
  }


  /**
   * Get the protocol version the client should identify with.
   *
   * @return int Version the client should claim to be.
   * @task conduit
   */
  final public function getConduitVersion() {
    return 6;
  }


  /**
   * Open and authenticate a conduit connection to a Phabricator server using
   * provided credentials. Normally, Arcanist does this for you automatically
   * when you return true from @{method:requiresAuthentication}, but you can
   * also upgrade an existing workflow to one with an authenticated conduit
   * by invoking this method manually.
   *
   * You must authenticate the conduit before you can make authenticated conduit
   * calls (almost all calls require authentication).
   *
   * This method uses credentials provided via @{method:setConduitCredentials}
   * to authenticate to the server:
   *
   *    - ##user## (required) The username to authenticate with.
   *    - ##certificate## (required) The Conduit certificate to use.
   *    - ##description## (optional) Description of the invoking command.
   *
   * Successful authentication allows you to call @{method:getUserPHID} and
   * @{method:getUserName}, as well as use the client you access with
   * @{method:getConduit} to make authenticated calls.
   *
   * NOTE: You must call @{method:setConduitURI} and
   * @{method:setConduitCredentials} before you invoke this method.
   *
   * @return this
   * @task conduit
   */
  final public function authenticateConduit() {
    if ($this->isConduitAuthenticated()) {
      return $this;
    }

    $this->establishConduit();
    $credentials = $this->conduitCredentials;

    try {
      if (!$credentials) {
        throw new Exception(
          pht(
            'Set conduit credentials with %s before authenticating conduit!',
            'setConduitCredentials()'));
      }

      // If we have `token`, this server supports the simpler, new-style
      // token-based authentication. Use that instead of all the certificate
      // stuff.
      $token = idx($credentials, 'token');
      if (strlen($token)) {
        $conduit = $this->getConduit();

        $conduit->setConduitToken($token);

        try {
          $result = $this->getConduit()->callMethodSynchronous(
            'user.whoami',
            array());

          $this->userName = $result['userName'];
          $this->userPHID = $result['phid'];

          $this->conduitAuthenticated = true;

          return $this;
        } catch (Exception $ex) {
          $conduit->setConduitToken(null);
          throw $ex;
        }
      }

      if (empty($credentials['user'])) {
        throw new ConduitClientException(
          'ERR-INVALID-USER',
          pht('Empty user in credentials.'));
      }
      if (empty($credentials['certificate'])) {
        throw new ConduitClientException(
          'ERR-NO-CERTIFICATE',
          pht('Empty certificate in credentials.'));
      }

      $description = idx($credentials, 'description', '');
      $user        = $credentials['user'];
      $certificate = $credentials['certificate'];

      $connection = $this->getConduit()->callMethodSynchronous(
        'conduit.connect',
        array(
          'client'              => 'arc',
          'clientVersion'       => $this->getConduitVersion(),
          'clientDescription'   => php_uname('n').':'.$description,
          'user'                => $user,
          'certificate'         => $certificate,
          'host'                => $this->conduitURI,
        ));
    } catch (ConduitClientException $ex) {
      if ($ex->getErrorCode() == 'ERR-NO-CERTIFICATE' ||
          $ex->getErrorCode() == 'ERR-INVALID-USER' ||
          $ex->getErrorCode() == 'ERR-INVALID-AUTH') {
        $conduit_uri = $this->conduitURI;
        $message = phutil_console_format(
          "\n%s\n\n    %s\n\n%s\n%s",
          pht('YOU NEED TO __INSTALL A CERTIFICATE__ TO LOG IN'),
          pht('To do this, run: **%s**', 'arc install-certificate'),
          pht("The server '%s' rejected your request:", $conduit_uri),
          $ex->getMessage());
        throw new ArcanistUsageException($message);
      } else if ($ex->getErrorCode() == 'NEW-ARC-VERSION') {

        // Cleverly disguise this as being AWESOME!!!

        echo phutil_console_format("**%s**\n\n", pht('New Version Available!'));
        echo phutil_console_wrap($ex->getMessage());
        echo "\n\n";
        echo pht('In most cases, arc can be upgraded automatically.')."\n";

        $ok = phutil_console_confirm(
          pht('Upgrade arc now?'),
          $default_no = false);
        if (!$ok) {
          throw $ex;
        }

        $root = dirname(phutil_get_library_root('arcanist'));

        chdir($root);
        $err = phutil_passthru('%s upgrade', $root.'/bin/arc');
        if (!$err) {
          echo "\n".pht('Try running your arc command again.')."\n";
        }
        exit(1);
      } else {
        throw $ex;
      }
    }

    $this->userName = $user;
    $this->userPHID = $connection['userPHID'];

    $this->conduitAuthenticated = true;

    return $this;
  }

  /**
   * @return bool True if conduit is authenticated, false otherwise.
   * @task conduit
   */
  final protected function isConduitAuthenticated() {
    return (bool)$this->conduitAuthenticated;
  }


  /**
   * Override this to return true if your workflow requires a conduit channel.
   * Arc will build the channel for you before your workflow executes. This
   * implies that you only need an unauthenticated channel; if you need
   * authentication, override @{method:requiresAuthentication}.
   *
   * @return bool True if arc should build a conduit channel before running
   *              the workflow.
   * @task conduit
   */
  public function requiresConduit() {
    return false;
  }


  /**
   * Override this to return true if your workflow requires an authenticated
   * conduit channel. This implies that it requires a conduit. Arc will build
   * and authenticate the channel for you before the workflow executes.
   *
   * @return bool True if arc should build an authenticated conduit channel
   *              before running the workflow.
   * @task conduit
   */
  public function requiresAuthentication() {
    return false;
  }


  /**
   * Returns the PHID for the user once they've authenticated via Conduit.
   *
   * @return phid Authenticated user PHID.
   * @task conduit
   */
  final public function getUserPHID() {
    if (!$this->userPHID) {
      $workflow = get_class($this);
      throw new Exception(
        pht(
          "This workflow ('%s') requires authentication, override ".
          "%s to return true.",
          $workflow,
          'requiresAuthentication()'));
    }
    return $this->userPHID;
  }

  /**
   * Return the username for the user once they've authenticated via Conduit.
   *
   * @return string Authenticated username.
   * @task conduit
   */
  final public function getUserName() {
    return $this->userName;
  }


  /**
   * Get the established @{class@libphutil:ConduitClient} in order to make
   * Conduit method calls. Before the client is available it must be connected,
   * either implicitly by making @{method:requireConduit} or
   * @{method:requireAuthentication} return true, or explicitly by calling
   * @{method:establishConduit} or @{method:authenticateConduit}.
   *
   * @return @{class@libphutil:ConduitClient} Live conduit client.
   * @task conduit
   */
  final public function getConduit() {
    if (!$this->conduit) {
      $workflow = get_class($this);
      throw new Exception(
        pht(
          "This workflow ('%s') requires a Conduit, override ".
          "%s to return true.",
          $workflow,
          'requiresConduit()'));
    }
    return $this->conduit;
  }


  final public function setArcanistConfiguration(
    ArcanistConfiguration $arcanist_configuration) {

    $this->arcanistConfiguration = $arcanist_configuration;
    return $this;
  }

  final public function getArcanistConfiguration() {
    return $this->arcanistConfiguration;
  }

  final public function setConfigurationManager(
    ArcanistConfigurationManager $arcanist_configuration_manager) {

    $this->configurationManager = $arcanist_configuration_manager;
    return $this;
  }

  final public function getConfigurationManager() {
    return $this->configurationManager;
  }

  public function requiresWorkingCopy() {
    return false;
  }

  public function desiresWorkingCopy() {
    return false;
  }

  public function requiresRepositoryAPI() {
    return false;
  }

  public function desiresRepositoryAPI() {
    return false;
  }

  final public function setCommand($command) {
    $this->command = $command;
    return $this;
  }

  final public function getCommand() {
    return $this->command;
  }

  public function getArguments() {
    return array();
  }

  final public function setWorkingDirectory($working_directory) {
    $this->workingDirectory = $working_directory;
    return $this;
  }

  final public function getWorkingDirectory() {
    return $this->workingDirectory;
  }

  private function setParentWorkflow($parent_workflow) {
    $this->parentWorkflow = $parent_workflow;
    return $this;
  }

  final protected function getParentWorkflow() {
    return $this->parentWorkflow;
  }

  final public function buildChildWorkflow($command, array $argv) {
    $arc_config = $this->getArcanistConfiguration();
    $workflow = $arc_config->buildWorkflow($command);
    $workflow->setParentWorkflow($this);
    $workflow->setConduitEngine($this->getConduitEngine());
    $workflow->setCommand($command);
    $workflow->setConfigurationManager($this->getConfigurationManager());

    if ($this->repositoryAPI) {
      $workflow->setRepositoryAPI($this->repositoryAPI);
    }

    if ($this->userPHID) {
      $workflow->userPHID = $this->getUserPHID();
      $workflow->userName = $this->getUserName();
    }

    if ($this->conduit) {
      $workflow->conduit = $this->conduit;
      $workflow->setConduitCredentials($this->conduitCredentials);
      $workflow->conduitAuthenticated = $this->conduitAuthenticated;
    }

    $workflow->setArcanistConfiguration($arc_config);

    $workflow->parseArguments(array_values($argv));

    return $workflow;
  }

  final public function getArgument($key, $default = null) {
    // TOOLSETS: Remove this legacy code.
    if (is_array($this->arguments)) {
      return idx($this->arguments, $key, $default);
    }

    return $this->arguments->getArg($key);
  }

  final public function getCompleteArgumentSpecification() {
    $spec = $this->getArguments();
    $arc_config = $this->getArcanistConfiguration();
    $command = $this->getCommand();
    $spec += $arc_config->getCustomArgumentsForCommand($command);

    return $spec;
  }

  final public function parseArguments(array $args) {
    $spec = $this->getCompleteArgumentSpecification();

    $dict = array();

    $more_key = null;
    if (!empty($spec['*'])) {
      $more_key = $spec['*'];
      unset($spec['*']);
      $dict[$more_key] = array();
    }

    $short_to_long_map = array();
    foreach ($spec as $long => $options) {
      if (!empty($options['short'])) {
        $short_to_long_map[$options['short']] = $long;
      }
    }

    foreach ($spec as $long => $options) {
      if (!empty($options['repeat'])) {
        $dict[$long] = array();
      }
    }

    $more = array();
    $size = count($args);
    for ($ii = 0; $ii < $size; $ii++) {
      $arg = $args[$ii];
      $arg_name = null;
      $arg_key = null;
      if ($arg == '--') {
        $more = array_merge(
          $more,
          array_slice($args, $ii + 1));
        break;
      } else if (!strncmp($arg, '--', 2)) {
        $arg_key = substr($arg, 2);
        $parts = explode('=', $arg_key, 2);
        if (count($parts) == 2) {
          list($arg_key, $val) = $parts;

          array_splice($args, $ii, 1, array('--'.$arg_key, $val));
          $size++;
        }

        if (!array_key_exists($arg_key, $spec)) {
          $corrected = PhutilArgumentSpellingCorrector::newFlagCorrector()
            ->correctSpelling($arg_key, array_keys($spec));
          if (count($corrected) == 1) {
            PhutilConsole::getConsole()->writeErr(
              pht(
                "(Assuming '%s' is the British spelling of '%s'.)",
                '--'.$arg_key,
                '--'.head($corrected))."\n");
            $arg_key = head($corrected);
          } else {
            throw new ArcanistUsageException(
              pht(
                "Unknown argument '%s'. Try '%s'.",
                $arg_key,
                'arc help'));
          }
        }
      } else if (!strncmp($arg, '-', 1)) {
        $arg_key = substr($arg, 1);
        if (empty($short_to_long_map[$arg_key])) {
          throw new ArcanistUsageException(
            pht(
              "Unknown argument '%s'. Try '%s'.",
              $arg_key,
              'arc help'));
        }
        $arg_key = $short_to_long_map[$arg_key];
      } else {
        $more[] = $arg;
        continue;
      }

      $options = $spec[$arg_key];
      if (empty($options['param'])) {
        $dict[$arg_key] = true;
      } else {
        if ($ii == $size - 1) {
          throw new ArcanistUsageException(
            pht(
              "Option '%s' requires a parameter.",
              $arg));
        }
        if (!empty($options['repeat'])) {
          $dict[$arg_key][] = $args[$ii + 1];
        } else {
          $dict[$arg_key] = $args[$ii + 1];
        }
        $ii++;
      }
    }

    if ($more) {
      if ($more_key) {
        $dict[$more_key] = $more;
      } else {
        $example = reset($more);
        throw new ArcanistUsageException(
          pht(
            "Unrecognized argument '%s'. Try '%s'.",
            $example,
            'arc help'));
      }
    }

    foreach ($dict as $key => $value) {
      if (empty($spec[$key]['conflicts'])) {
        continue;
      }
      foreach ($spec[$key]['conflicts'] as $conflict => $more) {
        if (isset($dict[$conflict])) {
          if ($more) {
            $more = ': '.$more;
          } else {
            $more = '.';
          }
          // TODO: We'll always display these as long-form, when the user might
          // have typed them as short form.
          throw new ArcanistUsageException(
            pht(
              "Arguments '%s' and '%s' are mutually exclusive",
              "--{$key}",
              "--{$conflict}").$more);
        }
      }
    }

    $this->arguments = $dict;

    $this->didParseArguments();

    return $this;
  }

  protected function didParseArguments() {
    // Override this to customize workflow argument behavior.
  }

  final public function getWorkingCopy() {
    $configuration_engine = $this->getConfigurationEngine();

    // TOOLSETS: Remove this once all workflows are toolset workflows.
    if (!$configuration_engine) {
      throw new Exception(
        pht(
          'This workflow has not yet been updated to Toolsets and can '.
          'not retrieve a modern WorkingCopy object. Use '.
          '"getWorkingCopyIdentity()" to retrieve a previous-generation '.
          'object.'));
    }

    return $configuration_engine->getWorkingCopy();
  }


  final public function getWorkingCopyIdentity() {
    $configuration_engine = $this->getConfigurationEngine();
    if ($configuration_engine) {
      $working_copy = $configuration_engine->getWorkingCopy();
      $working_path = $working_copy->getWorkingDirectory();

      return ArcanistWorkingCopyIdentity::newFromPath($working_path);
    }

    $working_copy = $this->getConfigurationManager()->getWorkingCopyIdentity();
    if (!$working_copy) {
      $workflow = get_class($this);
      throw new Exception(
        pht(
          "This workflow ('%s') requires a working copy, override ".
          "%s to return true.",
          $workflow,
          'requiresWorkingCopy()'));
    }
    return $working_copy;
  }

  final public function setRepositoryAPI($api) {
    $this->repositoryAPI = $api;
    return $this;
  }

  final public function hasRepositoryAPI() {
    try {
      return (bool)$this->getRepositoryAPI();
    } catch (Exception $ex) {
      return false;
    }
  }

  final public function getRepositoryAPI() {
    $configuration_engine = $this->getConfigurationEngine();
    if ($configuration_engine) {
      $working_copy = $configuration_engine->getWorkingCopy();
      return $working_copy->getRepositoryAPI();
    }

    if (!$this->repositoryAPI) {
      $workflow = get_class($this);
      throw new Exception(
        pht(
          "This workflow ('%s') requires a Repository API, override ".
          "%s to return true.",
          $workflow,
          'requiresRepositoryAPI()'));
    }
    return $this->repositoryAPI;
  }

  final protected function shouldRequireCleanUntrackedFiles() {
    return empty($this->arguments['allow-untracked']);
  }

  final public function setCommitMode($mode) {
    $this->commitMode = $mode;
    return $this;
  }

  final public function finalizeWorkingCopy() {
    if ($this->stashed) {
      $api = $this->getRepositoryAPI();
      $api->unstashChanges();
      echo pht('Restored stashed changes to the working directory.')."\n";
    }
  }

  final public function requireCleanWorkingCopy() {
    $api = $this->getRepositoryAPI();

    $must_commit = array();

    $working_copy_desc = phutil_console_format(
      "  %s: __%s__\n\n",
      pht('Working copy'),
      $api->getPath());

    // NOTE: this is a subversion-only concept.
    $incomplete = $api->getIncompleteChanges();
    if ($incomplete) {
      throw new ArcanistUsageException(
        sprintf(
          "%s\n\n%s  %s\n    %s\n\n%s",
          pht(
            "You have incompletely checked out directories in this working ".
            "copy. Fix them before proceeding.'"),
          $working_copy_desc,
          pht('Incomplete directories in working copy:'),
          implode("\n    ", $incomplete),
          pht(
            "You can fix these paths by running '%s' on them.",
            'svn update')));
    }

    $conflicts = $api->getMergeConflicts();
    if ($conflicts) {
      throw new ArcanistUsageException(
        sprintf(
          "%s\n\n%s  %s\n    %s",
          pht(
            'You have merge conflicts in this working copy. Resolve merge '.
            'conflicts before proceeding.'),
          $working_copy_desc,
          pht('Conflicts in working copy:'),
          implode("\n    ", $conflicts)));
    }

    $missing = $api->getMissingChanges();
    if ($missing) {
      throw new ArcanistUsageException(
        sprintf(
          "%s\n\n%s  %s\n    %s\n",
          pht(
            'You have missing files in this working copy. Revert or formally '.
            'remove them (with `%s`) before proceeding.',
            'svn rm'),
          $working_copy_desc,
          pht('Missing files in working copy:'),
          implode("\n    ", $missing)));
    }

    $externals = $api->getDirtyExternalChanges();

    // TODO: This state can exist in Subversion, but it is currently handled
    // elsewhere. It should probably be handled here, eventually.
    if ($api instanceof ArcanistSubversionAPI) {
      $externals = array();
    }

    if ($externals) {
      $message = pht(
        '%s submodule(s) have uncommitted or untracked changes:',
        new PhutilNumber(count($externals)));

      $prompt = pht(
        'Ignore the changes to these %s submodule(s) and continue?',
        new PhutilNumber(count($externals)));

      $list = id(new PhutilConsoleList())
        ->setWrap(false)
        ->addItems($externals);

      id(new PhutilConsoleBlock())
        ->addParagraph($message)
        ->addList($list)
        ->draw();

      $ok = phutil_console_confirm($prompt, $default_no = false);
      if (!$ok) {
        throw new ArcanistUserAbortException();
      }
    }

    $uncommitted = $api->getUncommittedChanges();
    $unstaged = $api->getUnstagedChanges();

    // We already dealt with externals.
    $unstaged = array_diff($unstaged, $externals);

    // We only want files which are purely uncommitted.
    $uncommitted = array_diff($uncommitted, $unstaged);
    $uncommitted = array_diff($uncommitted, $externals);

    $untracked = $api->getUntrackedChanges();
    if (!$this->shouldRequireCleanUntrackedFiles()) {
      $untracked = array();
    }

    if ($untracked) {
      echo sprintf(
        "%s\n\n%s",
        pht('You have untracked files in this working copy.'),
        $working_copy_desc);

      if ($api instanceof ArcanistGitAPI) {
        $hint = pht(
          '(To ignore these %s change(s), add them to "%s".)',
          phutil_count($untracked),
          '.git/info/exclude');
      } else if ($api instanceof ArcanistSubversionAPI) {
        $hint = pht(
          '(To ignore these %s change(s), add them to "%s".)',
          phutil_count($untracked),
          'svn:ignore');
      } else if ($api instanceof ArcanistMercurialAPI) {
        $hint = pht(
          '(To ignore these %s change(s), add them to "%s".)',
          phutil_count($untracked),
          '.hgignore');
      }

      $untracked_list = "    ".implode("\n    ", $untracked);
      echo sprintf(
        "  %s\n  %s\n%s",
        pht('Untracked changes in working copy:'),
        $hint,
        $untracked_list);

      $prompt = pht(
        'Ignore these %s untracked file(s) and continue?',
        phutil_count($untracked));

      if (!phutil_console_confirm($prompt)) {
        throw new ArcanistUserAbortException();
      }
    }


    $should_commit = false;
    if ($unstaged || $uncommitted) {

      // NOTE: We're running this because it builds a cache and can take a
      // perceptible amount of time to arrive at an answer, but we don't want
      // to pause in the middle of printing the output below.
      $this->getShouldAmend();

      echo sprintf(
        "%s\n\n%s",
        pht('You have uncommitted changes in this working copy.'),
        $working_copy_desc);

      $lists = array();

      if ($unstaged) {
        $unstaged_list = "    ".implode("\n    ", $unstaged);
        $lists[] = sprintf(
          "  %s\n%s",
          pht('Unstaged changes in working copy:'),
          $unstaged_list);
      }

      if ($uncommitted) {
        $uncommitted_list = "    ".implode("\n    ", $uncommitted);
        $lists[] = sprintf(
          "%s\n%s",
          pht('Uncommitted changes in working copy:'),
          $uncommitted_list);
      }

      echo implode("\n\n", $lists)."\n";

      $all_uncommitted = array_merge($unstaged, $uncommitted);
      if ($this->askForAdd($all_uncommitted)) {
        if ($unstaged) {
          $api->addToCommit($unstaged);
        }
        $should_commit = true;
      } else {
        $permit_autostash = $this->getConfigFromAnySource('arc.autostash');
        if ($permit_autostash && $api->canStashChanges()) {
           echo pht(
            'Stashing uncommitted changes. (You can restore them with `%s`).',
            'git stash pop')."\n";
          $api->stashChanges();
          $this->stashed = true;
        } else {
          throw new ArcanistUsageException(
            pht(
              'You can not continue with uncommitted changes. '.
              'Commit or discard them before proceeding.'));
        }
      }
    }

    if ($should_commit) {
      if ($this->getShouldAmend()) {
        $commit = head($api->getLocalCommitInformation());
        $api->amendCommit($commit['message']);
      } else if ($api->supportsLocalCommits()) {
        $template = sprintf(
          "\n\n# %s\n#\n# %s\n#\n",
          pht('Enter a commit message.'),
          pht('Changes:'));

        $paths = array_merge($uncommitted, $unstaged);
        $paths = array_unique($paths);
        sort($paths);

        foreach ($paths as $path) {
          $template .= "#     ".$path."\n";
        }

        $commit_message = $this->newInteractiveEditor($template)
          ->setName(pht('commit-message'))
          ->setTaskMessage(pht(
            'Supply commit message for uncommitted changes, then save and '.
            'exit.'))
          ->editInteractively();

        if ($commit_message === $template) {
          throw new ArcanistUsageException(
            pht('You must provide a commit message.'));
        }

        $commit_message = ArcanistCommentRemover::removeComments(
          $commit_message);

        if (!strlen($commit_message)) {
          throw new ArcanistUsageException(
            pht('You must provide a nonempty commit message.'));
        }

        $api->doCommit($commit_message);
      }
    }
  }

  private function getShouldAmend() {
    if ($this->shouldAmend === null) {
      $this->shouldAmend = $this->calculateShouldAmend();
    }
    return $this->shouldAmend;
  }

  private function calculateShouldAmend() {
    $api = $this->getRepositoryAPI();

    if ($this->isHistoryImmutable() || !$api->supportsAmend()) {
      return false;
    }

    $commits = $api->getLocalCommitInformation();
    if (!$commits) {
      return false;
    }

    $commit = reset($commits);
    $message = ArcanistDifferentialCommitMessage::newFromRawCorpus(
      $commit['message']);

    if ($message->getGitSVNBaseRevision()) {
      return false;
    }

    if ($api->getAuthor() != $commit['author']) {
      return false;
    }

    if ($message->getRevisionID() && $this->getArgument('create')) {
      return false;
    }

    // TODO: Check commits since tracking branch. If empty then return false.

    // Don't amend the current commit if it has already been published.
    $repository = $this->loadProjectRepository();
    if ($repository) {
      $repo_id = $repository['id'];
      $commit_hash = $commit['commit'];
      $callsign =  idx($repository, 'callsign');
      if ($callsign) {
        // The server might be too old to support the new style commit names,
        // so prefer the old way
        $commit_name = "r{$callsign}{$commit_hash}";
      } else {
        $commit_name = "R{$repo_id}:{$commit_hash}";
      }

      $result = $this->getConduit()->callMethodSynchronous(
        'diffusion.querycommits',
        array('names' => array($commit_name)));
      $known_commit = idx($result['identifierMap'], $commit_name);
      if ($known_commit) {
        return false;
      }
    }

    if (!$message->getRevisionID()) {
      return true;
    }

    $in_working_copy = $api->loadWorkingCopyDifferentialRevisions(
      $this->getConduit(),
      array(
        'authors' => array($this->getUserPHID()),
        'status' => 'status-open',
      ));
    if ($in_working_copy) {
      return true;
    }

    return false;
  }

  private function askForAdd(array $files) {
    if ($this->commitMode == self::COMMIT_DISABLE) {
      return false;
    }
    if ($this->commitMode == self::COMMIT_ENABLE) {
      return true;
    }
    $prompt = $this->getAskForAddPrompt($files);
    return phutil_console_confirm($prompt);
  }

  private function getAskForAddPrompt(array $files) {
    if ($this->getShouldAmend()) {
      $prompt = pht(
        'Do you want to amend these %s change(s) to the current commit?',
        phutil_count($files));
    } else {
      $prompt = pht(
        'Do you want to create a new commit with these %s change(s)?',
        phutil_count($files));
    }
    return $prompt;
  }

  final protected function loadDiffBundleFromConduit(
    ConduitClient $conduit,
    $diff_id) {

    return $this->loadBundleFromConduit(
      $conduit,
      array(
      'ids' => array($diff_id),
    ));
  }

  final protected function loadRevisionBundleFromConduit(
    ConduitClient $conduit,
    $revision_id) {

    return $this->loadBundleFromConduit(
      $conduit,
      array(
      'revisionIDs' => array($revision_id),
    ));
  }

  private function loadBundleFromConduit(
    ConduitClient $conduit,
    $params) {

    $future = $conduit->callMethod('differential.querydiffs', $params);
    $diff = head($future->resolve());

    if ($diff == null) {
      throw new Exception(
        phutil_console_wrap(
          pht("The diff or revision you specified is either invalid or you ".
          "don't have permission to view it."))
      );
    }

    $changes = array();
    foreach ($diff['changes'] as $changedict) {
      $changes[] = ArcanistDiffChange::newFromDictionary($changedict);
    }
    $bundle = ArcanistBundle::newFromChanges($changes);
    $bundle->setConduit($conduit);
    // since the conduit method has changes, assume that these fields
    // could be unset
    $bundle->setBaseRevision(idx($diff, 'sourceControlBaseRevision'));
    $bundle->setRevisionID(idx($diff, 'revisionID'));
    $bundle->setAuthorName(idx($diff, 'authorName'));
    $bundle->setAuthorEmail(idx($diff, 'authorEmail'));
    return $bundle;
  }

  /**
   * Return a list of lines changed by the current diff, or ##null## if the
   * change list is meaningless (for example, because the path is a directory
   * or binary file).
   *
   * @param string      Path within the repository.
   * @param string      Change selection mode (see ArcanistDiffHunk).
   * @return list|null  List of changed line numbers, or null to indicate that
   *                    the path is not a line-oriented text file.
   */
  final protected function getChangedLines($path, $mode) {
    $repository_api = $this->getRepositoryAPI();
    $full_path = $repository_api->getPath($path);
    if (is_dir($full_path)) {
      return null;
    }

    if (!file_exists($full_path)) {
      return null;
    }

    $change = $this->getChange($path);

    if ($change->getFileType() !== ArcanistDiffChangeType::FILE_TEXT) {
      return null;
    }

    $lines = $change->getChangedLines($mode);
    return array_keys($lines);
  }

  final protected function getChange($path) {
    $repository_api = $this->getRepositoryAPI();

    // TODO: Very gross
    $is_git = ($repository_api instanceof ArcanistGitAPI);
    $is_hg = ($repository_api instanceof ArcanistMercurialAPI);
    $is_svn = ($repository_api instanceof ArcanistSubversionAPI);

    if ($is_svn) {
      // NOTE: In SVN, we don't currently support a "get all local changes"
      // operation, so special case it.
      if (empty($this->changeCache[$path])) {
        $diff = $repository_api->getRawDiffText($path);
        $parser = $this->newDiffParser();
        $changes = $parser->parseDiff($diff);
        if (count($changes) != 1) {
          throw new Exception(pht('Expected exactly one change.'));
        }
        $this->changeCache[$path] = reset($changes);
      }
    } else if ($is_git || $is_hg) {
      if (empty($this->changeCache)) {
        $changes = $repository_api->getAllLocalChanges();
        foreach ($changes as $change) {
          $this->changeCache[$change->getCurrentPath()] = $change;
        }
      }
    } else {
      throw new Exception(pht('Missing VCS support.'));
    }

    if (empty($this->changeCache[$path])) {
      if ($is_git || $is_hg) {
        // This can legitimately occur under git/hg if you make a change,
        // "git/hg commit" it, and then revert the change in the working copy
        // and run "arc lint".
        $change = new ArcanistDiffChange();
        $change->setCurrentPath($path);
        return $change;
      } else {
        throw new Exception(
          pht(
            "Trying to get change for unchanged path '%s'!",
            $path));
      }
    }

    return $this->changeCache[$path];
  }

  final public function willRunWorkflow() {
    $spec = $this->getCompleteArgumentSpecification();
    foreach ($this->arguments as $arg => $value) {
      if (empty($spec[$arg])) {
        continue;
      }
      $options = $spec[$arg];
      if (!empty($options['supports'])) {
        $system_name = $this->getRepositoryAPI()->getSourceControlSystemName();
        if (!in_array($system_name, $options['supports'])) {
          $extended_info = null;
          if (!empty($options['nosupport'][$system_name])) {
            $extended_info = ' '.$options['nosupport'][$system_name];
          }
          throw new ArcanistUsageException(
            pht(
              "Option '%s' is not supported under %s.",
              "--{$arg}",
              $system_name).
            $extended_info);
        }
      }
    }
  }

  final protected function normalizeRevisionID($revision_id) {
    return preg_replace('/^D/i', '', $revision_id);
  }

  protected function shouldShellComplete() {
    return true;
  }

  protected function getShellCompletions(array $argv) {
    return array();
  }

  public function getSupportedRevisionControlSystems() {
    return array('git', 'hg', 'svn');
  }

  final protected function getPassthruArgumentsAsMap($command) {
    $map = array();
    foreach ($this->getCompleteArgumentSpecification() as $key => $spec) {
      if (!empty($spec['passthru'][$command])) {
        if (isset($this->arguments[$key])) {
          $map[$key] = $this->arguments[$key];
        }
      }
    }
    return $map;
  }

  final protected function getPassthruArgumentsAsArgv($command) {
    $spec = $this->getCompleteArgumentSpecification();
    $map = $this->getPassthruArgumentsAsMap($command);
    $argv = array();
    foreach ($map as $key => $value) {
      $argv[] = '--'.$key;
      if (!empty($spec[$key]['param'])) {
        $argv[] = $value;
      }
    }
    return $argv;
  }

  /**
   * Write a message to stderr so that '--json' flags or stdout which is meant
   * to be piped somewhere aren't disrupted.
   *
   * @param string  Message to write to stderr.
   * @return void
   */
  final protected function writeStatusMessage($msg) {
    PhutilSystem::writeStderr($msg);
  }

  final public function writeInfo($title, $message) {
    $this->writeStatusMessage(
      phutil_console_format(
        "<bg:blue>** %s **</bg> %s\n",
        $title,
        $message));
  }

  final public function writeWarn($title, $message) {
    $this->writeStatusMessage(
      phutil_console_format(
        "<bg:yellow>** %s **</bg> %s\n",
        $title,
        $message));
  }

  final public function writeOkay($title, $message) {
    $this->writeStatusMessage(
      phutil_console_format(
        "<bg:green>** %s **</bg> %s\n",
        $title,
        $message));
  }

  final protected function isHistoryImmutable() {
    $repository_api = $this->getRepositoryAPI();

    $config = $this->getConfigFromAnySource('history.immutable');
    if ($config !== null) {
      return $config;
    }

    return $repository_api->isHistoryDefaultImmutable();
  }

  /**
   * Workflows like 'lint' and 'unit' operate on a list of working copy paths.
   * The user can either specify the paths explicitly ("a.js b.php"), or by
   * specifying a revision ("--rev a3f10f1f") to select all paths modified
   * since that revision, or by omitting both and letting arc choose the
   * default relative revision.
   *
   * This method takes the user's selections and returns the paths that the
   * workflow should act upon.
   *
   * @param   list          List of explicitly provided paths.
   * @param   string|null   Revision name, if provided.
   * @param   mask          Mask of ArcanistRepositoryAPI flags to exclude.
   *                        Defaults to ArcanistRepositoryAPI::FLAG_UNTRACKED.
   * @return  list          List of paths the workflow should act on.
   */
  final protected function selectPathsForWorkflow(
    array $paths,
    $rev,
    $omit_mask = null) {

    if ($omit_mask === null) {
      $omit_mask = ArcanistRepositoryAPI::FLAG_UNTRACKED;
    }

    if ($paths) {
      $working_copy = $this->getWorkingCopyIdentity();
      foreach ($paths as $key => $path) {
        $full_path = Filesystem::resolvePath($path);
        if (!Filesystem::pathExists($full_path)) {
          throw new ArcanistUsageException(
            pht(
              "Path '%s' does not exist!",
              $path));
        }
        $relative_path = Filesystem::readablePath(
          $full_path,
          $working_copy->getProjectRoot());
        $paths[$key] = $relative_path;
      }
    } else {
      $repository_api = $this->getRepositoryAPI();

      if ($rev) {
        $this->parseBaseCommitArgument(array($rev));
      }

      $paths = $repository_api->getWorkingCopyStatus();
      foreach ($paths as $path => $flags) {
        if ($flags & $omit_mask) {
          unset($paths[$path]);
        }
      }
      $paths = array_keys($paths);
    }

    return array_values($paths);
  }

  final protected function renderRevisionList(array $revisions) {
    $list = array();
    foreach ($revisions as $revision) {
      $list[] = '     - D'.$revision['id'].': '.$revision['title']."\n";
    }
    return implode('', $list);
  }


/* -(  Scratch Files  )------------------------------------------------------ */


  /**
   * Try to read a scratch file, if it exists and is readable.
   *
   * @param string Scratch file name.
   * @return mixed String for file contents, or false for failure.
   * @task scratch
   */
  final protected function readScratchFile($path) {
    if (!$this->repositoryAPI) {
      return false;
    }
    return $this->getRepositoryAPI()->readScratchFile($path);
  }


  /**
   * Try to read a scratch JSON file, if it exists and is readable.
   *
   * @param string Scratch file name.
   * @return array Empty array for failure.
   * @task scratch
   */
  final protected function readScratchJSONFile($path) {
    $file = $this->readScratchFile($path);
    if (!$file) {
      return array();
    }
    return phutil_json_decode($file);
  }


  /**
   * Try to write a scratch file, if there's somewhere to put it and we can
   * write there.
   *
   * @param  string Scratch file name to write.
   * @param  string Data to write.
   * @return bool   True on success, false on failure.
   * @task scratch
   */
  final protected function writeScratchFile($path, $data) {
    if (!$this->repositoryAPI) {
      return false;
    }
    return $this->getRepositoryAPI()->writeScratchFile($path, $data);
  }


  /**
   * Try to write a scratch JSON file, if there's somewhere to put it and we can
   * write there.
   *
   * @param  string Scratch file name to write.
   * @param  array Data to write.
   * @return bool   True on success, false on failure.
   * @task scratch
   */
  final protected function writeScratchJSONFile($path, array $data) {
    return $this->writeScratchFile($path, json_encode($data));
  }


  /**
   * Try to remove a scratch file.
   *
   * @param   string  Scratch file name to remove.
   * @return  bool    True if the file was removed successfully.
   * @task scratch
   */
  final protected function removeScratchFile($path) {
    if (!$this->repositoryAPI) {
      return false;
    }
    return $this->getRepositoryAPI()->removeScratchFile($path);
  }


  /**
   * Get a human-readable description of the scratch file location.
   *
   * @param string  Scratch file name.
   * @return mixed  String, or false on failure.
   * @task scratch
   */
  final protected function getReadableScratchFilePath($path) {
    if (!$this->repositoryAPI) {
      return false;
    }
    return $this->getRepositoryAPI()->getReadableScratchFilePath($path);
  }


  /**
   * Get the path to a scratch file, if possible.
   *
   * @param string  Scratch file name.
   * @return mixed  File path, or false on failure.
   * @task scratch
   */
  final protected function getScratchFilePath($path) {
    if (!$this->repositoryAPI) {
      return false;
    }
    return $this->getRepositoryAPI()->getScratchFilePath($path);
  }

  final protected function getRepositoryEncoding() {
    return nonempty(
      idx($this->loadProjectRepository(), 'encoding'),
      'UTF-8');
  }

  final protected function loadProjectRepository() {
    list($info, $reasons) = $this->loadRepositoryInformation();
    return coalesce($info, array());
  }

  final protected function newInteractiveEditor($text) {
    $editor = new PhutilInteractiveEditor($text);

    $preferred = $this->getConfigFromAnySource('editor');
    if ($preferred) {
      $editor->setPreferredEditor($preferred);
    }

    return $editor;
  }

  final protected function newDiffParser() {
    $parser = new ArcanistDiffParser();
    if ($this->repositoryAPI) {
      $parser->setRepositoryAPI($this->getRepositoryAPI());
    }
    $parser->setWriteDiffOnFailure(true);
    return $parser;
  }

  final protected function dispatchEvent($type, array $data) {
    $data += array(
      'workflow' => $this,
    );

    $event = new PhutilEvent($type, $data);
    PhutilEventEngine::dispatchEvent($event);

    return $event;
  }

  final public function parseBaseCommitArgument(array $argv) {
    if (!count($argv)) {
      return;
    }

    $api = $this->getRepositoryAPI();
    if (!$api->supportsCommitRanges()) {
      throw new ArcanistUsageException(
        pht('This version control system does not support commit ranges.'));
    }

    if (count($argv) > 1) {
      throw new ArcanistUsageException(
        pht(
          'Specify exactly one base commit. The end of the commit range is '.
          'always the working copy state.'));
    }

    $api->setBaseCommit(head($argv));

    return $this;
  }

  final protected function getRepositoryVersion() {
    if (!$this->repositoryVersion) {
      $api = $this->getRepositoryAPI();
      $commit = $api->getSourceControlBaseRevision();
      $versions = array('' => $commit);
      foreach ($api->getChangedFiles($commit) as $path => $mask) {
        $versions[$path] = (Filesystem::pathExists($path)
          ? md5_file($path)
          : '');
      }
      $this->repositoryVersion = md5(json_encode($versions));
    }
    return $this->repositoryVersion;
  }


/* -(  Phabricator Repositories  )------------------------------------------- */


  /**
   * Get the PHID of the Phabricator repository this working copy corresponds
   * to. Returns `null` if no repository can be identified.
   *
   * @return phid|null  Repository PHID, or null if no repository can be
   *                    identified.
   *
   * @task phabrep
   */
  final protected function getRepositoryPHID() {
    return idx($this->getRepositoryInformation(), 'phid');
  }

  /**
   * Get the name of the Phabricator repository this working copy
   * corresponds to. Returns `null` if no repository can be identified.
   *
   * @return string|null  Repository name, or null if no repository can be
   *                      identified.
   *
   * @task phabrep
   */
  final protected function getRepositoryName() {
    return idx($this->getRepositoryInformation(), 'name');
  }


  /**
   * Get the URI of the Phabricator repository this working copy
   * corresponds to. Returns `null` if no repository can be identified.
   *
   * @return string|null  Repository URI, or null if no repository can be
   *                      identified.
   *
   * @task phabrep
   */
  final protected function getRepositoryURI() {
    return idx($this->getRepositoryInformation(), 'uri');
  }


  final protected function getRepositoryStagingConfiguration() {
    return idx($this->getRepositoryInformation(), 'staging');
  }


  /**
   * Get human-readable reasoning explaining how `arc` evaluated which
   * Phabricator repository corresponds to this working copy. Used by
   * `arc which` to explain the process to users.
   *
   * @return list<string> Human-readable explanation of the repository
   *                      association process.
   *
   * @task phabrep
   */
  final protected function getRepositoryReasons() {
    $this->getRepositoryInformation();
    return $this->repositoryReasons;
  }


  /**
   * @task phabrep
   */
  private function getRepositoryInformation() {
    if ($this->repositoryInfo === null) {
      list($info, $reasons) = $this->loadRepositoryInformation();
      $this->repositoryInfo = nonempty($info, array());
      $this->repositoryReasons = $reasons;
    }

    return $this->repositoryInfo;
  }


  /**
   * @task phabrep
   */
  private function loadRepositoryInformation() {
    list($query, $reasons) = $this->getRepositoryQuery();
    if (!$query) {
      return array(null, $reasons);
    }

    try {
      $method = 'repository.query';
      $results = $this->getConduitEngine()
        ->newFuture($method, $query)
        ->resolve();
    } catch (ConduitClientException $ex) {
      if ($ex->getErrorCode() == 'ERR-CONDUIT-CALL') {
        $reasons[] = pht(
          'This software version on the server you are connecting to is out '.
          'of date and does not have support for identifying repositories '.
          'by callsign or URI. Update the server sofwware to enable these '.
          'features.');
        return array(null, $reasons);
      }
      throw $ex;
    }

    $result = null;
    if (!$results) {
      $reasons[] = pht(
        'No repositories matched the query. Check that your configuration '.
        'is correct, or use "%s" to select a repository explicitly.',
        'repository.callsign');
    } else if (count($results) > 1) {
      $reasons[] = pht(
        'Multiple repostories (%s) matched the query. You can use the '.
        '"%s" configuration to select the one you want.',
        implode(', ', ipull($results, 'callsign')),
        'repository.callsign');
    } else {
      $result = head($results);
      $reasons[] = pht('Found a unique matching repository.');
    }

    return array($result, $reasons);
  }


  /**
   * @task phabrep
   */
  private function getRepositoryQuery() {
    $reasons = array();

    $callsign = $this->getConfigFromAnySource('repository.callsign');
    if ($callsign) {
      $query = array(
        'callsigns' => array($callsign),
      );
      $reasons[] = pht(
        'Configuration value "%s" is set to "%s".',
        'repository.callsign',
        $callsign);
      return array($query, $reasons);
    } else {
      $reasons[] = pht(
        'Configuration value "%s" is empty.',
        'repository.callsign');
    }

    $uuid = $this->getRepositoryAPI()->getRepositoryUUID();
    if ($uuid !== null) {
      $query = array(
        'uuids' => array($uuid),
      );
      $reasons[] = pht(
        'The UUID for this working copy is "%s".',
        $uuid);
      return array($query, $reasons);
    } else {
      $reasons[] = pht(
        'This repository has no VCS UUID (this is normal for git/hg).');
    }

    // TODO: Swap this for a RemoteRefQuery.

    $remote_uri = $this->getRepositoryAPI()->getRemoteURI();
    if ($remote_uri !== null) {
      $query = array(
        'remoteURIs' => array($remote_uri),
      );
      $reasons[] = pht(
        'The remote URI for this working copy is "%s".',
        $remote_uri);
      return array($query, $reasons);
    } else {
      $reasons[] = pht(
        'Unable to determine the remote URI for this repository.');
    }

    return array(null, $reasons);
  }


  /**
   * Build a new lint engine for the current working copy.
   *
   * Optionally, you can pass an explicit engine class name to build an engine
   * of a particular class. Normally this is used to implement an `--engine`
   * flag from the CLI.
   *
   * @param string Optional explicit engine class name.
   * @return ArcanistLintEngine Constructed engine.
   */
  protected function newLintEngine($engine_class = null) {
    $working_copy = $this->getWorkingCopyIdentity();
    $config = $this->getConfigurationManager();

    if (!$engine_class) {
      $engine_class = $config->getConfigFromAnySource('lint.engine');
    }

    if (!$engine_class) {
      if (Filesystem::pathExists($working_copy->getProjectPath('.arclint'))) {
        $engine_class = 'ArcanistConfigurationDrivenLintEngine';
      }
    }

    if (!$engine_class) {
      throw new ArcanistNoEngineException(
        pht(
          "No lint engine is configured for this project. Create an '%s' ".
          "file, or configure an advanced engine with '%s' in '%s'.",
          '.arclint',
          'lint.engine',
          '.arcconfig'));
    }

    $base_class = 'ArcanistLintEngine';
    if (!class_exists($engine_class) ||
        !is_subclass_of($engine_class, $base_class)) {
      throw new ArcanistUsageException(
        pht(
          'Configured lint engine "%s" is not a subclass of "%s", but must be.',
          $engine_class,
          $base_class));
    }

    $engine = newv($engine_class, array())
      ->setWorkingCopy($working_copy)
      ->setConfigurationManager($config);

    return $engine;
  }

  /**
   * Build a new unit test engine for the current working copy.
   *
   * Optionally, you can pass an explicit engine class name to build an engine
   * of a particular class. Normally this is used to implement an `--engine`
   * flag from the CLI.
   *
   * @param string Optional explicit engine class name.
   * @return ArcanistUnitTestEngine Constructed engine.
   */
  protected function newUnitTestEngine($engine_class = null) {
    $working_copy = $this->getWorkingCopyIdentity();
    $config = $this->getConfigurationManager();

    if (!$engine_class) {
      $engine_class = $config->getConfigFromAnySource('unit.engine');
    }

    if (!$engine_class) {
      if (Filesystem::pathExists($working_copy->getProjectPath('.arcunit'))) {
        $engine_class = 'ArcanistConfigurationDrivenUnitTestEngine';
      }
    }

    if (!$engine_class) {
      throw new ArcanistNoEngineException(
        pht(
          "No unit test engine is configured for this project. Create an ".
          "'%s' file, or configure an advanced engine with '%s' in '%s'.",
          '.arcunit',
          'unit.engine',
          '.arcconfig'));
    }

    $base_class = 'ArcanistUnitTestEngine';
    if (!class_exists($engine_class) ||
        !is_subclass_of($engine_class, $base_class)) {
      throw new ArcanistUsageException(
        pht(
          'Configured unit test engine "%s" is not a subclass of "%s", '.
          'but must be.',
          $engine_class,
          $base_class));
    }

    $engine = newv($engine_class, array())
      ->setWorkingCopy($working_copy)
      ->setConfigurationManager($config);

    return $engine;
  }


  protected function openURIsInBrowser(array $uris) {
    $browser = $this->getBrowserCommand();

    // The "browser" may actually be a list of arguments.
    if (!is_array($browser)) {
      $browser = array($browser);
    }

    foreach ($uris as $uri) {
      $err = phutil_passthru('%LR %R', $browser, $uri);
      if ($err) {
        throw new ArcanistUsageException(
          pht(
            'Failed to open URI "%s" in browser ("%s"). '.
            'Check your "browser" config option.',
            $uri,
            implode(' ', $browser)));
      }
    }
  }

  private function getBrowserCommand() {
    $config = $this->getConfigFromAnySource('browser');
    if ($config) {
      return $config;
    }

    if (phutil_is_windows()) {
      // See T13504. We now use "bypass_shell", so "start" alone is no longer
      // a valid binary to invoke directly.
      return array(
        'cmd',
        '/c',
        'start',
      );
    }

    $candidates = array(
      'sensible-browser' => array('sensible-browser'),
      'xdg-open' => array('xdg-open'),
      'open' => array('open', '--'),
    );

    // NOTE: The "open" command works well on OS X, but on many Linuxes "open"
    // exists and is not a browser. For now, we're just looking for other
    // commands first, but we might want to be smarter about selecting "open"
    // only on OS X.

    foreach ($candidates as $cmd => $argv) {
      if (Filesystem::binaryExists($cmd)) {
        return $argv;
      }
    }

    throw new ArcanistUsageException(
      pht(
        'Unable to find a browser command to run. Set "browser" in your '.
        'configuration to specify a command to use.'));
  }


  /**
   * Ask Phabricator to update the current repository as soon as possible.
   *
   * Calling this method after pushing commits allows Phabricator to discover
   * the commits more quickly, so the system overall is more responsive.
   *
   * @return void
   */
  protected function askForRepositoryUpdate() {
    // If we know which repository we're in, try to tell Phabricator that we
    // pushed commits to it so it can update. This hint can help pull updates
    // more quickly, especially in rarely-used repositories.
    if ($this->getRepositoryPHID()) {
      try {
        $this->getConduit()->callMethodSynchronous(
          'diffusion.looksoon',
          array(
            'repositories' => array($this->getRepositoryPHID()),
          ));
      } catch (ConduitClientException $ex) {
        // If we hit an exception, just ignore it. Likely, we are running
        // against a Phabricator which is too old to support this method.
        // Since this hint is purely advisory, it doesn't matter if it has
        // no effect.
      }
    }
  }

  protected function getModernLintDictionary(array $map) {
    $map = $this->getModernCommonDictionary($map);
    return $map;
  }

  protected function getModernUnitDictionary(array $map) {
    $map = $this->getModernCommonDictionary($map);

    $details = idx($map, 'userData');
    if (strlen($details)) {
      $map['details'] = (string)$details;
    }
    unset($map['userData']);

    return $map;
  }

  private function getModernCommonDictionary(array $map) {
    foreach ($map as $key => $value) {
      if ($value === null) {
        unset($map[$key]);
      }
    }
    return $map;
  }

  final public function setConduitEngine(
    ArcanistConduitEngine $conduit_engine) {
    $this->conduitEngine = $conduit_engine;
    return $this;
  }

  final public function getConduitEngine() {
    return $this->conduitEngine;
  }

  final public function getRepositoryRef() {
    $configuration_engine = $this->getConfigurationEngine();
    if ($configuration_engine) {
      // This is a toolset workflow and can always build a repository ref.
    } else {
      if (!$this->getConfigurationManager()->getWorkingCopyIdentity()) {
        return null;
      }

      if (!$this->repositoryAPI) {
        return null;
      }
    }

    if (!$this->repositoryRef) {
      $ref = id(new ArcanistRepositoryRef())
        ->setPHID($this->getRepositoryPHID())
        ->setBrowseURI($this->getRepositoryURI());

      $this->repositoryRef = $ref;
    }

    return $this->repositoryRef;
  }

  final public function getToolsetKey() {
    return $this->getToolset()->getToolsetKey();
  }

  final public function getConfig($key) {
    return $this->getConfigurationSourceList()->getConfig($key);
  }

  public function canHandleSignal($signo) {
    return false;
  }

  public function handleSignal($signo) {
    return;
  }

  final public function newCommand(PhutilExecutableFuture $future) {
    return id(new ArcanistCommand())
      ->setLogEngine($this->getLogEngine())
      ->setExecutableFuture($future);
  }

  final public function loadHardpoints(
    $objects,
    $requests) {
    return $this->getRuntime()->loadHardpoints($objects, $requests);
  }

  protected function newPrompts() {
    return array();
  }

  protected function newPrompt($key) {
    return id(new ArcanistPrompt())
      ->setWorkflow($this)
      ->setKey($key);
  }

  public function hasPrompt($key) {
    $map = $this->getPromptMap();
    return isset($map[$key]);
  }

  public function getPromptMap() {
    if ($this->promptMap === null) {
      $prompts = $this->newPrompts();
      assert_instances_of($prompts, 'ArcanistPrompt');

      // TODO: Move this somewhere modular.

      $prompts[] = $this->newPrompt('arc.state.stash')
        ->setDescription(
          pht(
            'Prompts the user to stash changes and continue when the '.
            'working copy has untracked, uncommitted, or unstaged '.
            'changes.'));

      // TODO: Swap to ArrayCheck?

      $map = array();
      foreach ($prompts as $prompt) {
        $key = $prompt->getKey();

        if (isset($map[$key])) {
          throw new Exception(
            pht(
              'Workflow ("%s") generates two prompts with the same '.
              'key ("%s"). Each prompt a workflow generates must have a '.
              'unique key.',
              get_class($this),
              $key));
        }

        $map[$key] = $prompt;
      }

      $this->promptMap = $map;
    }

    return $this->promptMap;
  }

  final public function getPrompt($key) {
    $map = $this->getPromptMap();

    $prompt = idx($map, $key);
    if (!$prompt) {
      throw new Exception(
        pht(
          'Workflow ("%s") is requesting a prompt ("%s") but it did not '.
          'generate any prompt with that name in "newPrompts()".',
          get_class($this),
          $key));
    }

    return clone $prompt;
  }

  final protected function getSymbolEngine() {
    return $this->getRuntime()->getSymbolEngine();
  }

  final protected function getViewer() {
    return $this->getRuntime()->getViewer();
  }

  final protected function readStdin() {
    $log = $this->getLogEngine();
    $log->writeWaitingForInput();

    // NOTE: We can't just "file_get_contents()" here because signals don't
    // interrupt it. If the user types "^C", we want to interrupt the read.

    $raw_handle = fopen('php://stdin', 'rb');
    $stdin = new PhutilSocketChannel($raw_handle);

    while ($stdin->update()) {
      PhutilChannel::waitForAny(array($stdin));
    }

    return $stdin->read();
  }

  final public function getAbsoluteURI($raw_uri) {
    // TODO: "ArcanistRevisionRef", at least, may return a relative URI.
    // If we get a relative URI, guess the correct absolute URI based on
    // the Conduit URI. This might not be correct for Conduit over SSH.

    $raw_uri = new PhutilURI($raw_uri);
    if (!strlen($raw_uri->getDomain())) {
      $base_uri = $this->getConduitEngine()
        ->getConduitURI();

      $raw_uri = id(new PhutilURI($base_uri))
        ->setPath($raw_uri->getPath());
    }

    $raw_uri = phutil_string_cast($raw_uri);

    return $raw_uri;
  }

  final public function writeToPager($corpus) {
    $is_tty = (function_exists('posix_isatty') && posix_isatty(STDOUT));

    if (!$is_tty) {
      echo $corpus;
    } else {
      $pager = $this->getConfig('pager');

      if (!$pager) {
        $pager = array('less', '-R', '--');
      }

      // Try to show the content through a pager.
      $err = id(new PhutilExecPassthru('%Ls', $pager))
        ->write($corpus)
        ->resolve();

      // If the pager exits with an error, print the content normally.
      if ($err) {
        echo $corpus;
      }
    }

    return $this;
  }

}
