const {helper, assert} = require('./helper');
const {TimeoutError} = require('./Errors');
const fs = require('fs');
const util = require('util');
const readFileAsync = util.promisify(fs.readFile);

class DOMWorld {
  constructor(frame, timeoutSettings) {
    this._frame = frame;
    this._timeoutSettings = timeoutSettings;

    this._documentPromise = null;
    this._contextPromise;
    this._contextResolveCallback = null;
    this._setContext(null);

    /** @type {!Set<!WaitTask>} */
    this._waitTasks = new Set();
    this._detached = false;
  }

  frame() {
    return this._frame;
  }

  _setContext(context) {
    if (context) {
      this._contextResolveCallback.call(null, context);
      this._contextResolveCallback = null;
      for (const waitTask of this._waitTasks)
        waitTask.rerun();
    } else {
      this._documentPromise = null;
      this._contextPromise = new Promise(fulfill => {
        this._contextResolveCallback = fulfill;
      });
    }
  }

  _detach() {
    this._detached = true;
    for (const waitTask of this._waitTasks)
      waitTask.terminate(new Error('waitForFunction failed: frame got detached.'));
  }

  async executionContext() {
    if (this._detached)
      throw new Error(`Execution Context is not available in detached frame "${this.url()}" (are you trying to evaluate?)`);
    return this._contextPromise;
  }

  async evaluateHandle(pageFunction, ...args) {
    const context = await this.executionContext();
    return context.evaluateHandle(pageFunction, ...args);
  }

  async evaluate(pageFunction, ...args) {
    const context = await this.executionContext();
    return context.evaluate(pageFunction, ...args);
  }

  /**
   * @param {string} selector
   * @return {!Promise<?ElementHandle>}
   */
  async $(selector) {
    const document = await this._document();
    return document.$(selector);
  }

  _document() {
    if (!this._documentPromise)
      this._documentPromise = this.evaluateHandle('document').then(handle => handle.asElement());
    return this._documentPromise;
  }

  /**
   * @param {string} expression
   * @return {!Promise<!Array<!ElementHandle>>}
   */
  async $x(expression) {
    const document = await this._document();
    return document.$x(expression);
  }

  /**
   * @param {string} selector
   * @param {Function|String} pageFunction
   * @param {!Array<*>} args
   * @return {!Promise<(!Object|undefined)>}
   */
  async $eval(selector, pageFunction, ...args) {
    const document = await this._document();
    return document.$eval(selector, pageFunction, ...args);
  }

  /**
   * @param {string} selector
   * @param {Function|String} pageFunction
   * @param {!Array<*>} args
   * @return {!Promise<(!Object|undefined)>}
   */
  async $$eval(selector, pageFunction, ...args) {
    const document = await this._document();
    return document.$$eval(selector, pageFunction, ...args);
  }

  /**
   * @param {string} selector
   * @return {!Promise<!Array<!ElementHandle>>}
   */
  async $$(selector) {
    const document = await this._document();
    return document.$$(selector);
  }

  /**
   * @return {!Promise<String>}
   */
  async content() {
    return await this.evaluate(() => {
      let retVal = '';
      if (document.doctype)
        retVal = new XMLSerializer().serializeToString(document.doctype);
      if (document.documentElement)
        retVal += document.documentElement.outerHTML;
      return retVal;
    });
  }

  /**
   * @param {string} html
   */
  async setContent(html) {
    await this.evaluate(html => {
      document.open();
      document.write(html);
      document.close();
    }, html);
  }

  /**
   * @param {!{content?: string, path?: string, type?: string, url?: string, id?: string}} options
   * @return {!Promise<!ElementHandle>}
   */
  async addScriptTag(options) {
    const {
      type = '',
      id = ''
    } = options;

    if (typeof options.url === 'string') {
      const url = options.url;
      try {
        return (await this.evaluateHandle(addScriptUrl, url, id, type)).asElement();
      } catch (error) {
        throw new Error(`Loading script from ${url} failed`);
      }
    }

    if (typeof options.path === 'string') {
      let contents = await readFileAsync(options.path, 'utf8');
      contents += '//# sourceURL=' + options.path.replace(/\n/g, '');
      return (await this.evaluateHandle(addScriptContent, contents, id, type)).asElement();
    }

    if (typeof options.content === 'string') {
      return (await this.evaluateHandle(addScriptContent, options.content, id, type)).asElement();
    }

    throw new Error('Provide an object with a `url`, `path` or `content` property');

    /**
     * @param {string} url
     * @param {string} id
     * @param {string} type
     * @return {!Promise<!HTMLElement>}
     */
    async function addScriptUrl(url, id, type) {
      const script = document.createElement('script');
      script.src = url;
      if (id)
        script.id = id;
      if (type)
        script.type = type;
      const promise = new Promise((res, rej) => {
        script.onload = res;
        script.onerror = rej;
      });
      document.head.appendChild(script);
      await promise;
      return script;
    }

    /**
     * @param {string} content
     * @param {string} id
     * @param {string} type
     * @return {!HTMLElement}
     */
    function addScriptContent(content, id, type = 'text/javascript') {
      const script = document.createElement('script');
      script.type = type;
      script.text = content;
      if (id)
        script.id = id;
      let error = null;
      script.onerror = e => error = e;
      document.head.appendChild(script);
      if (error)
        throw error;
      return script;
    }
  }

  /**
   * @param {!{content?: string, path?: string, url?: string}} options
   * @return {!Promise<!ElementHandle>}
   */
  async addStyleTag(options) {
    if (typeof options.url === 'string') {
      const url = options.url;
      try {
        return (await this.evaluateHandle(addStyleUrl, url)).asElement();
      } catch (error) {
        throw new Error(`Loading style from ${url} failed`);
      }
    }

    if (typeof options.path === 'string') {
      let contents = await readFileAsync(options.path, 'utf8');
      contents += '/*# sourceURL=' + options.path.replace(/\n/g, '') + '*/';
      return (await this.evaluateHandle(addStyleContent, contents)).asElement();
    }

    if (typeof options.content === 'string') {
      return (await this.evaluateHandle(addStyleContent, options.content)).asElement();
    }

    throw new Error('Provide an object with a `url`, `path` or `content` property');

    /**
     * @param {string} url
     * @return {!Promise<!HTMLElement>}
     */
    async function addStyleUrl(url) {
      const link = document.createElement('link');
      link.rel = 'stylesheet';
      link.href = url;
      const promise = new Promise((res, rej) => {
        link.onload = res;
        link.onerror = rej;
      });
      document.head.appendChild(link);
      await promise;
      return link;
    }

    /**
     * @param {string} content
     * @return {!Promise<!HTMLElement>}
     */
    async function addStyleContent(content) {
      const style = document.createElement('style');
      style.type = 'text/css';
      style.appendChild(document.createTextNode(content));
      const promise = new Promise((res, rej) => {
        style.onload = res;
        style.onerror = rej;
      });
      document.head.appendChild(style);
      await promise;
      return style;
    }
  }

  /**
   * @param {string} selector
   * @param {!{delay?: number, button?: string, clickCount?: number}=} options
   */
  async click(selector, options = {}) {
    const handle = await this.$(selector);
    assert(handle, 'No node found for selector: ' + selector);
    await handle.click(options);
    await handle.dispose();
  }

  /**
   * @param {string} selector
   */
  async focus(selector) {
    const handle = await this.$(selector);
    assert(handle, 'No node found for selector: ' + selector);
    await handle.focus();
    await handle.dispose();
  }

  /**
   * @param {string} selector
   */
  async hover(selector) {
    const handle = await this.$(selector);
    assert(handle, 'No node found for selector: ' + selector);
    await handle.hover();
    await handle.dispose();
  }

  /**
  * @param {string} selector
  * @param {!Array<string>} values
  * @return {!Promise<!Array<string>>}
  */
  select(selector, ...values) {
    for (const value of values)
      assert(helper.isString(value), 'Values must be strings. Found value "' + value + '" of type "' + (typeof value) + '"');
    return this.$eval(selector, (element, values) => {
      if (element.nodeName.toLowerCase() !== 'select')
        throw new Error('Element is not a <select> element.');

      const options = Array.from(element.options);
      element.value = undefined;
      for (const option of options) {
        option.selected = values.includes(option.value);
        if (option.selected && !element.multiple)
          break;
      }
      element.dispatchEvent(new Event('input', { 'bubbles': true }));
      element.dispatchEvent(new Event('change', { 'bubbles': true }));
      return options.filter(option => option.selected).map(option => option.value);
    }, values);
  }

  /**
   * @param {string} selector
   */
  async tap(selector) {
    const handle = await this.$(selector);
    assert(handle, 'No node found for selector: ' + selector);
    await handle.tap();
    await handle.dispose();
  }

  /**
   * @param {string} selector
   * @param {string} text
   * @param {{delay: (number|undefined)}=} options
   */
  async type(selector, text, options) {
    const handle = await this.$(selector);
    assert(handle, 'No node found for selector: ' + selector);
    await handle.type(text, options);
    await handle.dispose();
  }

  /**
   * @param {string} selector
   * @param {!{timeout?: number, visible?: boolean, hidden?: boolean}=} options
   * @return {!Promise<!ElementHandle>}
   */
  waitForSelector(selector, options) {
    return this._waitForSelectorOrXPath(selector, false, options);
  }

  /**
   * @param {string} xpath
   * @param {!{timeout?: number, visible?: boolean, hidden?: boolean}=} options
   * @return {!Promise<!ElementHandle>}
   */
  waitForXPath(xpath, options) {
    return this._waitForSelectorOrXPath(xpath, true, options);
  }

  /**
   * @param {Function|string} pageFunction
   * @param {!{polling?: string|number, timeout?: number}=} options
   * @return {!Promise<!JSHandle>}
   */
  waitForFunction(pageFunction, options = {}, ...args) {
    const {
      polling = 'raf',
      timeout = this._timeoutSettings.timeout(),
    } = options;
    return new WaitTask(this, pageFunction, 'function', polling, timeout, ...args).promise;
  }

  /**
   * @return {!Promise<string>}
   */
  async title() {
    return this.evaluate(() => document.title);
  }

  /**
   * @param {string} selectorOrXPath
   * @param {boolean} isXPath
   * @param {!{timeout?: number, visible?: boolean, hidden?: boolean}=} options
   * @return {!Promise<!ElementHandle>}
   */
  async _waitForSelectorOrXPath(selectorOrXPath, isXPath, options = {}) {
    const {
      visible: waitForVisible = false,
      hidden: waitForHidden = false,
      timeout = this._timeoutSettings.timeout(),
    } = options;
    const polling = waitForVisible || waitForHidden ? 'raf' : 'mutation';
    const title = `${isXPath ? 'XPath' : 'selector'} "${selectorOrXPath}"${waitForHidden ? ' to be hidden' : ''}`;
    const waitTask = new WaitTask(this, predicate, title, polling, timeout, selectorOrXPath, isXPath, waitForVisible, waitForHidden);
    const handle = await waitTask.promise;
    if (!handle.asElement()) {
      await handle.dispose();
      return null;
    }
    return handle.asElement();

    /**
     * @param {string} selectorOrXPath
     * @param {boolean} isXPath
     * @param {boolean} waitForVisible
     * @param {boolean} waitForHidden
     * @return {?Node|boolean}
     */
    function predicate(selectorOrXPath, isXPath, waitForVisible, waitForHidden) {
      const node = isXPath
        ? document.evaluate(selectorOrXPath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue
        : document.querySelector(selectorOrXPath);
      if (!node)
        return waitForHidden;
      if (!waitForVisible && !waitForHidden)
        return node;
      const element = /** @type {Element} */ (node.nodeType === Node.TEXT_NODE ? node.parentElement : node);

      const style = window.getComputedStyle(element);
      const isVisible = style && style.visibility !== 'hidden' && hasVisibleBoundingBox();
      const success = (waitForVisible === isVisible || waitForHidden === !isVisible);
      return success ? node : null;

      /**
       * @return {boolean}
       */
      function hasVisibleBoundingBox() {
        const rect = element.getBoundingClientRect();
        return !!(rect.top || rect.bottom || rect.width || rect.height);
      }
    }
  }
}

/**
 * @internal
 */
class WaitTask {
  /**
   * @param {!DOMWorld} domWorld
   * @param {Function|string} predicateBody
   * @param {string|number} polling
   * @param {number} timeout
   * @param {!Array<*>} args
   */
  constructor(domWorld, predicateBody, title, polling, timeout, ...args) {
    if (helper.isString(polling))
      assert(polling === 'raf' || polling === 'mutation', 'Unknown polling option: ' + polling);
    else if (helper.isNumber(polling))
      assert(polling > 0, 'Cannot poll with non-positive interval: ' + polling);
    else
      throw new Error('Unknown polling options: ' + polling);

    this._domWorld = domWorld;
    this._polling = polling;
    this._timeout = timeout;
    this._predicateBody = helper.isString(predicateBody) ? 'return (' + predicateBody + ')' : 'return (' + predicateBody + ')(...args)';
    this._args = args;
    this._runCount = 0;
    domWorld._waitTasks.add(this);
    this.promise = new Promise((resolve, reject) => {
      this._resolve = resolve;
      this._reject = reject;
    });
    // Since page navigation requires us to re-install the pageScript, we should track
    // timeout on our end.
    if (timeout) {
      const timeoutError = new TimeoutError(`waiting for ${title} failed: timeout ${timeout}ms exceeded`);
      this._timeoutTimer = setTimeout(() => this.terminate(timeoutError), timeout);
    }
    this.rerun();
  }

  /**
   * @param {!Error} error
   */
  terminate(error) {
    this._terminated = true;
    this._reject(error);
    this._cleanup();
  }

  async rerun() {
    const runCount = ++this._runCount;
    /** @type {?JSHandle} */
    let success = null;
    let error = null;
    try {
      success = await this._domWorld.evaluateHandle(waitForPredicatePageFunction, this._predicateBody, this._polling, this._timeout, ...this._args);
    } catch (e) {
      error = e;
    }

    if (this._terminated || runCount !== this._runCount) {
      if (success)
        await success.dispose();
      return;
    }

    // Ignore timeouts in pageScript - we track timeouts ourselves.
    // If the frame's execution context has already changed, `frame.evaluate` will
    // throw an error - ignore this predicate run altogether.
    if (!error && await this._domWorld.evaluate(s => !s, success).catch(e => true)) {
      await success.dispose();
      return;
    }

    // When the page is navigated, the promise is rejected.
    // Try again right away.
    if (error && error.message.includes('Execution context was destroyed')) {
      this.rerun();
      return;
    }

    if (error)
      this._reject(error);
    else
      this._resolve(success);

    this._cleanup();
  }

  _cleanup() {
    clearTimeout(this._timeoutTimer);
    this._domWorld._waitTasks.delete(this);
    this._runningTask = null;
  }
}

/**
 * @param {string} predicateBody
 * @param {string} polling
 * @param {number} timeout
 * @return {!Promise<*>}
 */
async function waitForPredicatePageFunction(predicateBody, polling, timeout, ...args) {
  const predicate = new Function('...args', predicateBody);
  let timedOut = false;
  if (timeout)
    setTimeout(() => timedOut = true, timeout);
  if (polling === 'raf')
    return await pollRaf();
  if (polling === 'mutation')
    return await pollMutation();
  if (typeof polling === 'number')
    return await pollInterval(polling);

  /**
   * @return {!Promise<*>}
   */
  function pollMutation() {
    const success = predicate.apply(null, args);
    if (success)
      return Promise.resolve(success);

    let fulfill;
    const result = new Promise(x => fulfill = x);
    const observer = new MutationObserver(mutations => {
      if (timedOut) {
        observer.disconnect();
        fulfill();
      }
      const success = predicate.apply(null, args);
      if (success) {
        observer.disconnect();
        fulfill(success);
      }
    });
    observer.observe(document, {
      childList: true,
      subtree: true,
      attributes: true
    });
    return result;
  }

  /**
   * @return {!Promise<*>}
   */
  function pollRaf() {
    let fulfill;
    const result = new Promise(x => fulfill = x);
    onRaf();
    return result;

    function onRaf() {
      if (timedOut) {
        fulfill();
        return;
      }
      const success = predicate.apply(null, args);
      if (success)
        fulfill(success);
      else
        requestAnimationFrame(onRaf);
    }
  }

  /**
   * @param {number} pollInterval
   * @return {!Promise<*>}
   */
  function pollInterval(pollInterval) {
    let fulfill;
    const result = new Promise(x => fulfill = x);
    onTimeout();
    return result;

    function onTimeout() {
      if (timedOut) {
        fulfill();
        return;
      }
      const success = predicate.apply(null, args);
      if (success)
        fulfill(success);
      else
        setTimeout(onTimeout, pollInterval);
    }
  }
}

module.exports = {DOMWorld};
