/* vim: ts=4:sw=4:expandtab
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

;(function () {
    'use strict';
    window.textsecure = window.textsecure || {};

    function MessageReceiver(eventTarget) {
        if (eventTarget instanceof EventTarget) {
            this.target = eventTarget;
        } else {
            throw new TypeError('MessageReceiver expected an EventTarget');
        }
    }

    MessageReceiver.prototype = {
        constructor: MessageReceiver,
        connect: function() {
            // initialize the socket and start listening for messages
            this.socket = TextSecureServer.getMessageWebsocket();

            new WebSocketResource(this.socket, this.handleRequest.bind(this));
        },
        handleRequest: function(request) {
            // TODO: handle different types of requests. for now we only expect
            // PUT /messages <encrypted IncomingPushMessageSignal>
            textsecure.crypto.decryptWebsocketMessage(request.body).then(function(plaintext) {
                var envelope = textsecure.protobuf.Envelope.decode(plaintext);
                // After this point, decoding errors are not the server's
                // fault, and we should handle them gracefully and tell the
                // user they received an invalid message
                request.respond(200, 'OK');

                if (envelope.type === textsecure.protobuf.Envelope.Type.RECEIPT) {
                    this.onDeliveryReceipt(envelope);
                } else if (envelope.content) {
                    this.handleContentMessage(envelope);
                } else if (envelope.legacyMessage) {
                    this.handleLegacyMessage(envelope);
                } else {
                    throw new Error('Received message with no content and no legacyMessage');
                }

            }.bind(this)).catch(function(e) {
                request.respond(500, 'Bad encrypted websocket message');
                console.log("Error handling incoming message:", e);
                var ev = new Event('error');
                ev.error = e;
                this.target.dispatchEvent(ev);
            }.bind(this));
        },
        getStatus: function() {
            if (this.socket) {
                return this.socket.getStatus();
            } else {
                return -1;
            }
        },
        onDeliveryReceipt: function (envelope) {
            var ev = new Event('receipt');
            ev.proto = envelope;
            this.target.dispatchEvent(ev);
        },
        decrypt: function(envelope, ciphertext) {
            return textsecure.protocol_wrapper.decrypt(
                envelope.source,
                envelope.sourceDevice,
                envelope.type,
                ciphertext
            ).catch(function(error) {
                var ev = new Event('error');
                ev.error = error;
                ev.proto = envelope;
                this.target.dispatchEvent(ev);
            }.bind(this));
        },
        handleSentMessage: function(destination, timestamp, message) {
            var source = textsecure.storage.user.getNumber();
            return processDecrypted(message, source).then(function(message) {
                var ev = new Event('sent');
                ev.data = {
                    destination : destination,
                    timestamp   : timestamp.toNumber(),
                    message     : message
                };
                this.target.dispatchEvent(ev);
            }.bind(this));
        },
        handleDataMessage: function(envelope, message, close_session) {
            if ((message.flags & textsecure.protobuf.DataMessage.Flags.END_SESSION)
                == textsecure.protobuf.DataMessage.Flags.END_SESSION ) {
                close_session();
            }
            return processDecrypted(message, envelope.source).then(function(message) {
                var ev = new Event('message');
                ev.data = {
                    source    : envelope.source,
                    timestamp : envelope.timestamp.toNumber(),
                    message   : message
                };
                this.target.dispatchEvent(ev);
            }.bind(this));
        },
        handleLegacyMessage: function (envelope) {
            return this.decrypt(envelope, envelope.legacyMessage).then(function(result) {
                var plaintext = result[0]; // array buffer
                var close_session = result[1]; // function
                var message = textsecure.protobuf.DataMessage.decode(plaintext);
                return this.handleDataMessage(envelope, message, close_session);
            }.bind(this));
        },
        handleContentMessage: function (envelope) {
            return this.decrypt(envelope, envelope.content).then(function(result) {
                var plaintext = result[0]; // array buffer
                var close_session = result[1]; // function
                var content = textsecure.protobuf.Content.decode(plaintext);
                if (content.syncMessage) {
                    return this.handleSyncMessage(envelope, content.syncMessage);
                } else if (content.dataMessage) {
                    return this.handleDataMessage(envelope, content.dataMessage, close_session);
                } else {
                    throw new Error('Got Content message with no dataMessage and no syncMessage');
                }
            }.bind(this));
        },
        handleSyncMessage: function(envelope, syncMessage) {
            if (envelope.source !== textsecure.storage.user.getNumber()) {
                throw new Error('Received sync message from another number');
            }
            if (envelope.sourceDevice == textsecure.storage.user.getDeviceId()) {
                throw new Error('Received sync message from our own device');
            }
            if (syncMessage.sent) {
                var sentMessage = syncMessage.sent;
                return this.handleSentMessage(
                        sentMessage.destination,
                        sentMessage.timestamp,
                        sentMessage.message
                );
            } else if (syncMessage.contacts) {
                this.handleContacts(syncMessage.contacts);
            } else if (syncMessage.group) {
                this.handleGroup(syncMessage.group);
            } else {
                throw new Error('Got SyncMessage with no sent, contacts, or group');
            }
        },
        handleContacts: function(contacts) {
            var eventTarget = this.target;
            var attachmentPointer = contacts.blob;
            return handleAttachment(attachmentPointer).then(function() {
                var contactBuffer = new ContactBuffer(attachmentPointer.data);
                var contactInfo = contactBuffer.readContact();
                while (contactInfo !== undefined) {
                    var ev = new Event('contact');
                    ev.contactInfo = contactInfo;
                    eventTarget.dispatchEvent(ev);
                    contactInfo = contactBuffer.readContact();
                }
            });
        },
        handleGroup: function(envelope) {
            var ev = new Event('group');
            ev.group = envelope.group;
            this.target.dispatchEvent(ev);
        }
    };

    textsecure.MessageReceiver = MessageReceiver;


}());