/****************************************************************************
 **
 ** Copyright (C) 2016 The Qt Company Ltd.
 ** Copyright (C) 2016 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Milian Wolff <milian.wolff@kdab.com>
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtWebChannel module of the Qt Toolkit.
 **
 ** $QT_BEGIN_LICENSE:LGPL$
 ** Commercial License Usage
 ** Licensees holding valid commercial Qt licenses may use this file in
 ** accordance with the commercial license agreement provided with the
 ** Software or, alternatively, in accordance with the terms contained in
 ** a written agreement between you and The Qt Company. For licensing terms
 ** and conditions see https://www.qt.io/terms-conditions. For further
 ** information use the contact form at https://www.qt.io/contact-us.
 **
 ** GNU Lesser General Public License Usage
 ** Alternatively, this file may be used under the terms of the GNU Lesser
 ** General Public License version 3 as published by the Free Software
 ** Foundation and appearing in the file LICENSE.LGPL3 included in the
 ** packaging of this file. Please review the following information to
 ** ensure the GNU Lesser General Public License version 3 requirements
 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
 **
 ** GNU General Public License Usage
 ** Alternatively, this file may be used under the terms of the GNU
 ** General Public License version 2.0 or (at your option) the GNU General
 ** Public license version 3 or any later version approved by the KDE Free
 ** Qt Foundation. The licenses are as published by the Free Software
 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
 ** included in the packaging of this file. Please review the following
 ** information to ensure the GNU General Public License requirements will
 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and
 ** https://www.gnu.org/licenses/gpl-3.0.html.
 **
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

"use strict"

var QWebChannelMessageTypes = {
  signal: 1,
  propertyUpdate: 2,
  init: 3,
  idle: 4,
  debug: 5,
  invokeMethod: 6,
  connectToSignal: 7,
  disconnectFromSignal: 8,
  setProperty: 9,
  response: 10,
}

var QWebChannel = function (transport, initCallback) {
  if (typeof transport !== "object" || typeof transport.send !== "function") {
    console.error("The QWebChannel expects a transport object with a send function and onmessage callback property." + " Given is: transport: " + typeof transport + ", transport.send: " + typeof transport.send)
    return
  }

  var channel = this
  this.transport = transport

  this.send = function (data) {
    if (typeof data !== "string") {
      data = JSON.stringify(data)
    }
    channel.transport.send(data)
  }

  this.transport.onmessage = function (message) {
    var data = message.data
    if (typeof data === "string") {
      data = JSON.parse(data)
    }
    switch (data.type) {
      case QWebChannelMessageTypes.signal:
        channel.handleSignal(data)
        break
      case QWebChannelMessageTypes.response:
        channel.handleResponse(data)
        break
      case QWebChannelMessageTypes.propertyUpdate:
        channel.handlePropertyUpdate(data)
        break
      default:
        console.error("invalid message received:", message.data)
        break
    }
  }

  this.execCallbacks = {}
  this.execId = 0
  this.exec = function (data, callback) {
    if (!callback) {
      // if no callback is given, send directly
      channel.send(data)
      return
    }
    if (channel.execId === Number.MAX_VALUE) {
      // wrap
      channel.execId = Number.MIN_VALUE
    }
    if (data.hasOwnProperty("id")) {
      console.error("Cannot exec message with property id: " + JSON.stringify(data))
      return
    }
    data.id = channel.execId++
    channel.execCallbacks[data.id] = callback
    channel.send(data)
  }

  this.objects = {}

  this.handleSignal = function (message) {
    var object = channel.objects[message.object]
    if (object) {
      object.signalEmitted(message.signal, message.args)
    } else {
      console.warn("Unhandled signal: " + message.object + "::" + message.signal)
    }
  }

  this.handleResponse = function (message) {
    if (!message.hasOwnProperty("id")) {
      console.error("Invalid response message received: ", JSON.stringify(message))
      return
    }
    channel.execCallbacks[message.id](message.data)
    delete channel.execCallbacks[message.id]
  }

  this.handlePropertyUpdate = function (message) {
    message.data.forEach((data) => {
      var object = channel.objects[data.object]
      if (object) {
        object.propertyUpdate(data.signals, data.properties)
      } else {
        console.warn("Unhandled property update: " + data.object + "::" + data.signal)
      }
    })
    channel.exec({ type: QWebChannelMessageTypes.idle })
  }

  this.debug = function (message) {
    channel.send({ type: QWebChannelMessageTypes.debug, data: message })
  }

  channel.exec({ type: QWebChannelMessageTypes.init }, function (data) {
    for (const objectName of Object.keys(data)) {
      new QObject(objectName, data[objectName], channel)
    }

    // now unwrap properties, which might reference other registered objects
    for (const objectName of Object.keys(channel.objects)) {
      channel.objects[objectName].unwrapProperties()
    }

    if (initCallback) {
      initCallback(channel)
    }
    channel.exec({ type: QWebChannelMessageTypes.idle })
  })
}

function QObject(name, data, webChannel) {
  this.__id__ = name
  webChannel.objects[name] = this

  // List of callbacks that get invoked upon signal emission
  this.__objectSignals__ = {}

  // Cache of all properties, updated when a notify signal is emitted
  this.__propertyCache__ = {}

  var object = this

  // ----------------------------------------------------------------------

  this.unwrapQObject = function (response) {
    if (response instanceof Array) {
      // support list of objects
      return response.map((qobj) => object.unwrapQObject(qobj))
    }
    if (!(response instanceof Object)) return response

    if (!response["__QObject*__"] || response.id === undefined) {
      var jObj = {}
      for (const propName of Object.keys(response)) {
        jObj[propName] = object.unwrapQObject(response[propName])
      }
      return jObj
    }

    var objectId = response.id
    if (webChannel.objects[objectId]) return webChannel.objects[objectId]

    if (!response.data) {
      console.error("Cannot unwrap unknown QObject " + objectId + " without data.")
      return
    }

    var qObject = new QObject(objectId, response.data, webChannel)
    qObject.destroyed.connect(function () {
      if (webChannel.objects[objectId] === qObject) {
        delete webChannel.objects[objectId]
        // reset the now deleted QObject to an empty {} object
        // just assigning {} though would not have the desired effect, but the
        // below also ensures all external references will see the empty map
        // NOTE: this detour is necessary to workaround QTBUG-40021
        Object.keys(qObject).forEach((name) => delete qObject[name])
      }
    })
    // here we are already initialized, and thus must directly unwrap the properties
    qObject.unwrapProperties()
    return qObject
  }

  this.unwrapProperties = function () {
    for (const propertyIdx of Object.keys(object.__propertyCache__)) {
      object.__propertyCache__[propertyIdx] = object.unwrapQObject(object.__propertyCache__[propertyIdx])
    }
  }

  function addSignal(signalData, isPropertyNotifySignal) {
    var signalName = signalData[0]
    var signalIndex = signalData[1]
    object[signalName] = {
      connect: function (callback) {
        if (typeof callback !== "function") {
          console.error("Bad callback given to connect to signal " + signalName)
          return
        }

        object.__objectSignals__[signalIndex] = object.__objectSignals__[signalIndex] || []
        object.__objectSignals__[signalIndex].push(callback)

        // only required for "pure" signals, handled separately for properties in propertyUpdate
        if (isPropertyNotifySignal) return

        // also note that we always get notified about the destroyed signal
        if (signalName === "destroyed" || signalName === "destroyed()" || signalName === "destroyed(QObject*)") return

        // and otherwise we only need to be connected only once
        if (object.__objectSignals__[signalIndex].length == 1) {
          webChannel.exec({
            type: QWebChannelMessageTypes.connectToSignal,
            object: object.__id__,
            signal: signalIndex,
          })
        }
      },
      disconnect: function (callback) {
        if (typeof callback !== "function") {
          console.error("Bad callback given to disconnect from signal " + signalName)
          return
        }
        object.__objectSignals__[signalIndex] = object.__objectSignals__[signalIndex] || []
        var idx = object.__objectSignals__[signalIndex].indexOf(callback)
        if (idx === -1) {
          console.error("Cannot find connection of signal " + signalName + " to " + callback.name)
          return
        }
        object.__objectSignals__[signalIndex].splice(idx, 1)
        if (!isPropertyNotifySignal && object.__objectSignals__[signalIndex].length === 0) {
          // only required for "pure" signals, handled separately for properties in propertyUpdate
          webChannel.exec({
            type: QWebChannelMessageTypes.disconnectFromSignal,
            object: object.__id__,
            signal: signalIndex,
          })
        }
      },
    }
  }

  /**
   * Invokes all callbacks for the given signalname. Also works for property notify callbacks.
   */
  function invokeSignalCallbacks(signalName, signalArgs) {
    var connections = object.__objectSignals__[signalName]
    if (connections) {
      connections.forEach(function (callback) {
        callback.apply(callback, signalArgs)
      })
    }
  }

  this.propertyUpdate = function (signals, propertyMap) {
    // update property cache
    for (const propertyIndex of Object.keys(propertyMap)) {
      var propertyValue = propertyMap[propertyIndex]
      object.__propertyCache__[propertyIndex] = this.unwrapQObject(propertyValue)
    }

    for (const signalName of Object.keys(signals)) {
      // Invoke all callbacks, as signalEmitted() does not. This ensures the
      // property cache is updated before the callbacks are invoked.
      invokeSignalCallbacks(signalName, signals[signalName])
    }
  }

  this.signalEmitted = function (signalName, signalArgs) {
    invokeSignalCallbacks(signalName, this.unwrapQObject(signalArgs))
  }

  function addMethod(methodData) {
    var methodName = methodData[0]
    var methodIdx = methodData[1]

    // Fully specified methods are invoked by id, others by name for host-side overload resolution
    var invokedMethod = methodName[methodName.length - 1] === ")" ? methodIdx : methodName

    object[methodName] = function () {
      var args = []
      var callback
      var errCallback
      for (var i = 0; i < arguments.length; ++i) {
        var argument = arguments[i]
        if (typeof argument === "function") callback = argument
        else if (argument instanceof QObject && webChannel.objects[argument.__id__] !== undefined)
          args.push({
            id: argument.__id__,
          })
        else args.push(argument)
      }

      var result
      // during test, webChannel.exec synchronously calls the callback
      // therefore, the promise must be constucted before calling
      // webChannel.exec to ensure the callback is set up
      if (!callback && typeof Promise === "function") {
        result = new Promise(function (resolve, reject) {
          callback = resolve
          errCallback = reject
        })
      }

      webChannel.exec(
        {
          type: QWebChannelMessageTypes.invokeMethod,
          object: object.__id__,
          method: invokedMethod,
          args: args,
        },
        function (response) {
          if (response !== undefined) {
            var result = object.unwrapQObject(response)
            if (callback) {
              callback(result)
            }
          } else if (errCallback) {
            errCallback()
          }
        },
      )

      return result
    }
  }

  function bindGetterSetter(propertyInfo) {
    var propertyIndex = propertyInfo[0]
    var propertyName = propertyInfo[1]
    var notifySignalData = propertyInfo[2]
    // initialize property cache with current value
    // NOTE: if this is an object, it is not directly unwrapped as it might
    // reference other QObject that we do not know yet
    object.__propertyCache__[propertyIndex] = propertyInfo[3]

    if (notifySignalData) {
      if (notifySignalData[0] === 1) {
        // signal name is optimized away, reconstruct the actual name
        notifySignalData[0] = propertyName + "Changed"
      }
      addSignal(notifySignalData, true)
    }

    Object.defineProperty(object, propertyName, {
      configurable: true,
      get: function () {
        var propertyValue = object.__propertyCache__[propertyIndex]
        if (propertyValue === undefined) {
          // This shouldn't happen
          console.warn('Undefined value in property cache for property "' + propertyName + '" in object ' + object.__id__)
        }

        return propertyValue
      },
      set: function (value) {
        if (value === undefined) {
          console.warn("Property setter for " + propertyName + " called with undefined value!")
          return
        }
        object.__propertyCache__[propertyIndex] = value
        var valueToSend = value
        if (valueToSend instanceof QObject && webChannel.objects[valueToSend.__id__] !== undefined) valueToSend = { id: valueToSend.__id__ }
        webChannel.exec({
          type: QWebChannelMessageTypes.setProperty,
          object: object.__id__,
          property: propertyIndex,
          value: valueToSend,
        })
      },
    })
  }

  // ----------------------------------------------------------------------

  data.methods.forEach(addMethod)

  data.properties.forEach(bindGetterSetter)

  data.signals.forEach(function (signal) {
    addSignal(signal, false)
  })

  Object.assign(object, data.enums)
}

//required for use with nodejs
if (typeof module === "object") {
  module.exports = {
    QWebChannel: QWebChannel,
  }
}