/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2016 Klar채lvdalens 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
	};
}