/**
 * Copyright 2017 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
const helper = require('./helper');

class ElementHandle {
  /**
   * @param {!Connection} client
   * @param {!Object} remoteObject
   * @param {!Mouse} mouse
   */
  constructor(client, remoteObject, mouse) {
    this._client = client;
    this._remoteObject = remoteObject;
    this._mouse = mouse;
    this._disposed = false;
  }

  /**
   * @return {!Promise}
   */
  async dispose() {
    if (this._disposed)
      return;
    this._disposed = true;
    await helper.releaseObject(this._client, this._remoteObject);
  }

  /**
   * @param {function()} pageFunction
   * @param {!Array<*>} args
   * @return {!Promise<(!Object|undefined)>}
   */
  async evaluate(pageFunction, ...args) {
    console.assert(!this._disposed, 'ElementHandle is disposed!');
    console.assert(typeof pageFunction === 'function', 'First argument to ElementHandle.evaluate must be a function!');

    let stringifiedArgs = ['this'];
    stringifiedArgs.push(...args.map(x => JSON.stringify(x)));
    let functionDeclaration = `function() { return (${pageFunction})(${stringifiedArgs.join(',')}) }`;
    const objectId = this._remoteObject.objectId;
    let { exceptionDetails, result: remoteObject } = await this._client.send('Runtime.callFunctionOn', { objectId, functionDeclaration, returnByValue: false, awaitPromise: true});
    if (exceptionDetails)
      throw new Error('Evaluation failed: ' + helper.getExceptionMessage(exceptionDetails));
    return await helper.serializeRemoteObject(this._client, remoteObject);
  }

  /**
   * @return {!Promise<{x: number, y: number}>}
   */
  async _visibleCenter() {
    let center = await this.evaluate(element => {
      if (!element.ownerDocument.contains(element))
        return null;
      element.scrollIntoViewIfNeeded();
      let rect = element.getBoundingClientRect();
      return {
        x: (Math.max(rect.left, 0) + Math.min(rect.right, window.innerWidth)) / 2,
        y: (Math.max(rect.top, 0) + Math.min(rect.bottom, window.innerHeight)) / 2
      };
    });
    if (!center)
      throw new Error('No node found for selector: ' + selector);
    return center;
  }

  /**
   * @return {!Promise}
   */
  async hover() {
    let {x, y} = await this._visibleCenter();
    await this._mouse.move(x, y);
  }

  /**
   * @param {!Object=} options
   * @return {!Promise}
   */
  async click(options) {
    let {x, y} = await this._visibleCenter();
    await this._mouse.click(x, y, options);
  }
}

module.exports = ElementHandle;
helper.tracePublicAPI(ElementHandle);