package command

import (
	"bytes"
	"encoding/gob"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/hashicorp/nomad/api"
	"github.com/hashicorp/nomad/jobspec"
	"github.com/hashicorp/nomad/nomad/structs"
)

var (
	// enforceIndexRegex is a regular expression which extracts the enforcement error
	enforceIndexRegex = regexp.MustCompile(`\((Enforcing job modify index.*)\)`)
)

type RunCommand struct {
	Meta

	// The fields below can be overwritten for tests
	testStdin io.Reader
}

func (c *RunCommand) Help() string {
	helpText := `
Usage: nomad run [options] <path>

  Starts running a new job or updates an existing job using
  the specification located at <path>. This is the main command
  used to interact with Nomad.

  If the supplied path is "-", the jobfile is read from stdin. Otherwise
  it is read from the file at the supplied path.

  Upon successful job submission, this command will immediately
  enter an interactive monitor. This is useful to watch Nomad's
  internals make scheduling decisions and place the submitted work
  onto nodes. The monitor will end once job placement is done. It
  is safe to exit the monitor early using ctrl+c.

  On successful job submission and scheduling, exit code 0 will be
  returned. If there are job placement issues encountered
  (unsatisfiable constraints, resource exhaustion, etc), then the
  exit code will be 2. Any other errors, including client connection
  issues or internal errors, are indicated by exit code 1.

  If the job has specified the region, the -region flag and NOMAD_REGION
  environment variable are overridden and the the job's region is used.

General Options:

  ` + generalOptionsUsage() + `

Run Options:

  -check-index
	If set, the job is only registered or updated if the the passed
	job modify index matches the server side version. If a check-index value of
	zero is passed, the job is only registered if it does not yet exist. If a
	non-zero value is passed, it ensures that the job is being updated from a
	known state. The use of this flag is most common in conjunction with plan
	command.

  -detach
	Return immediately instead of entering monitor mode. After job submission,
	the evaluation ID will be printed to the screen, which can be used to
	examine the evaluation using the eval-status command.

  -verbose
    Display full information.

  -output
    Output the JSON that would be submitted to the HTTP API without submitting
    the job.
`
	return strings.TrimSpace(helpText)
}

func (c *RunCommand) Synopsis() string {
	return "Run a new job or update an existing job"
}

func (c *RunCommand) Run(args []string) int {
	var detach, verbose, output bool
	var checkIndexStr string

	flags := c.Meta.FlagSet("run", FlagSetClient)
	flags.Usage = func() { c.Ui.Output(c.Help()) }
	flags.BoolVar(&detach, "detach", false, "")
	flags.BoolVar(&verbose, "verbose", false, "")
	flags.BoolVar(&output, "output", false, "")
	flags.StringVar(&checkIndexStr, "check-index", "", "")

	if err := flags.Parse(args); err != nil {
		return 1
	}

	// Truncate the id unless full length is requested
	length := shortId
	if verbose {
		length = fullId
	}

	// Check that we got exactly one node
	args = flags.Args()
	if len(args) != 1 {
		c.Ui.Error(c.Help())
		return 1
	}

	// Read the Jobfile
	path := args[0]

	var f io.Reader
	switch path {
	case "-":
		if c.testStdin != nil {
			f = c.testStdin
		} else {
			f = os.Stdin
		}
	default:
		file, err := os.Open(path)
		defer file.Close()
		if err != nil {
			c.Ui.Error(fmt.Sprintf("Error opening file %q: %v", path, err))
			return 1
		}
		f = file
	}

	// Parse the JobFile
	job, err := jobspec.Parse(f)
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error parsing job file %s: %v", f, err))
		return 1
	}

	// Initialize any fields that need to be.
	job.InitFields()

	// Check that the job is valid
	if err := job.Validate(); err != nil {
		c.Ui.Error(fmt.Sprintf("Error validating job: %v", err))
		return 1
	}

	// Check if the job is periodic.
	periodic := job.IsPeriodic()

	// Convert it to something we can use
	apiJob, err := convertStructJob(job)
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error converting job: %s", err))
		return 1
	}

	if output {
		req := api.RegisterJobRequest{Job: apiJob}
		buf, err := json.MarshalIndent(req, "", "    ")
		if err != nil {
			c.Ui.Error(fmt.Sprintf("Error converting job: %s", err))
			return 1
		}

		c.Ui.Output(string(buf))
		return 0
	}

	// Get the HTTP client
	client, err := c.Meta.Client()
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error initializing client: %s", err))
		return 1
	}

	// Force the region to be that of the job.
	if r := job.Region; r != "" {
		client.SetRegion(r)
	}

	// Parse the check-index
	checkIndex, enforce, err := parseCheckIndex(checkIndexStr)
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error parsing check-index value %q: %v", checkIndexStr, err))
		return 1
	}

	// Submit the job
	var evalID string
	if enforce {
		evalID, _, err = client.Jobs().EnforceRegister(apiJob, checkIndex, nil)
	} else {
		evalID, _, err = client.Jobs().Register(apiJob, nil)
	}
	if err != nil {
		if strings.Contains(err.Error(), api.RegisterEnforceIndexErrPrefix) {
			// Format the error specially if the error is due to index
			// enforcement
			matches := enforceIndexRegex.FindStringSubmatch(err.Error())
			if len(matches) == 2 {
				c.Ui.Error(matches[1]) // The matched group
				c.Ui.Error("Job not updated")
				return 1
			}
		}

		c.Ui.Error(fmt.Sprintf("Error submitting job: %s", err))
		return 1
	}

	// Check if we should enter monitor mode
	if detach || periodic {
		c.Ui.Output("Job registration successful")
		if periodic {
			now := time.Now().UTC()
			next := job.Periodic.Next(now)
			c.Ui.Output(fmt.Sprintf("Approximate next launch time: %s (%s from now)",
				formatTime(next), formatTimeDifference(now, next, time.Second)))
		} else {
			c.Ui.Output("Evaluation ID: " + evalID)
		}

		return 0
	}

	// Detach was not specified, so start monitoring
	mon := newMonitor(c.Ui, client, length)
	return mon.monitor(evalID, false)

}

// parseCheckIndex parses the check-index flag and returns the index, whether it
// was set and potentially an error during parsing.
func parseCheckIndex(input string) (uint64, bool, error) {
	if input == "" {
		return 0, false, nil
	}

	u, err := strconv.ParseUint(input, 10, 64)
	return u, true, err
}

// convertStructJob is used to take a *structs.Job and convert it to an *api.Job.
// This function is just a hammer and probably needs to be revisited.
func convertStructJob(in *structs.Job) (*api.Job, error) {
	gob.Register([]map[string]interface{}{})
	gob.Register([]interface{}{})
	var apiJob *api.Job
	buf := new(bytes.Buffer)
	if err := gob.NewEncoder(buf).Encode(in); err != nil {
		return nil, err
	}
	if err := gob.NewDecoder(buf).Decode(&apiJob); err != nil {
		return nil, err
	}
	return apiJob, nil
}
