/* 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 b64ToUint6 (nChr) {

  return nChr > 64 && nChr < 91 ?
      nChr - 65
    : nChr > 96 && nChr < 123 ?
      nChr - 71
    : nChr > 47 && nChr < 58 ?
      nChr + 4
    : nChr === 43 ?
      62
    : nChr === 47 ?
      63
    :
      0;

}

function base64DecToArr (sBase64, nBlocksSize) {
  var
    sB64Enc = sBase64.replace(/[^A-Za-z0-9\+\/]/g, ""), nInLen = sB64Enc.length,
    nOutLen = nBlocksSize ? Math.ceil((nInLen * 3 + 1 >> 2) / nBlocksSize) * nBlocksSize : nInLen * 3 + 1 >> 2;
var aBBytes = new ArrayBuffer(nOutLen);
var taBytes = new Uint8Array(aBBytes);

  for (var nMod3, nMod4, nUint24 = 0, nOutIdx = 0, nInIdx = 0; nInIdx < nInLen; nInIdx++) {
    nMod4 = nInIdx & 3;
    nUint24 |= b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << 18 - 6 * nMod4;
    if (nMod4 === 3 || nInLen - nInIdx === 1) {
      for (nMod3 = 0; nMod3 < 3 && nOutIdx < nOutLen; nMod3++, nOutIdx++) {
        taBytes[nOutIdx] = nUint24 >>> (16 >>> nMod3 & 24) & 255;
      }
      nUint24 = 0;
    }
  }
  return aBBytes;
}

/* Base64 string to array encoding */

function uint6ToB64 (nUint6) {

  return nUint6 < 26 ?
      nUint6 + 65
    : nUint6 < 52 ?
      nUint6 + 71
    : nUint6 < 62 ?
      nUint6 - 4
    : nUint6 === 62 ?
      43
    : nUint6 === 63 ?
      47
    :
      65;

}

function base64EncArr (aBytes) {

  var nMod3, sB64Enc = "";

  for (var nLen = aBytes.length, nUint24 = 0, nIdx = 0; nIdx < nLen; nIdx++) {
    nMod3 = nIdx % 3;
    //if (nIdx > 0 && (nIdx * 4 / 3) % 76 === 0) { sB64Enc += "\r\n"; }
    nUint24 |= aBytes[nIdx] << (16 >>> nMod3 & 24);
    if (nMod3 === 2 || aBytes.length - nIdx === 1) {
      sB64Enc += String.fromCharCode(uint6ToB64(nUint24 >>> 18 & 63), uint6ToB64(nUint24 >>> 12 & 63), uint6ToB64(nUint24 >>> 6 & 63), uint6ToB64(nUint24 & 63));
      nUint24 = 0;
    }
  }

  return sB64Enc.replace(/A(?=A$|$)/g, "=");

}


window.textsecure = window.textsecure || {};

/*********************************
 *** Type conversion utilities ***
 *********************************/
// Strings/arrays
//TODO: Throw all this shit in favor of consistent types
//TODO: Namespace
var StaticByteBufferProto = new dcodeIO.ByteBuffer().__proto__;
var StaticArrayBufferProto = new ArrayBuffer().__proto__;
var StaticUint8ArrayProto = new Uint8Array().__proto__;
function getString(thing) {
    if (thing === Object(thing)) {
        if (thing.__proto__ == StaticUint8ArrayProto)
            return String.fromCharCode.apply(null, thing);
        if (thing.__proto__ == StaticArrayBufferProto)
            return getString(new Uint8Array(thing));
        if (thing.__proto__ == StaticByteBufferProto)
            return thing.toString("binary");
    }
    return thing;
}

function getStringable(thing) {
    return (typeof thing == "string" || typeof thing == "number" || typeof thing == "boolean" ||
            (thing === Object(thing) &&
                (thing.__proto__ == StaticArrayBufferProto ||
                thing.__proto__ == StaticUint8ArrayProto ||
                thing.__proto__ == StaticByteBufferProto)));
}

function isEqual(a, b, mayBeShort) {
    // TODO: Special-case arraybuffers, etc
    if (a === undefined || b === undefined)
        return false;
    a = getString(a);
    b = getString(b);
    var maxLength = mayBeShort ? Math.min(a.length, b.length) : Math.max(a.length, b.length);
    if (maxLength < 5)
        throw new Error("a/b compare too short");
    return a.substring(0, Math.min(maxLength, a.length)) == b.substring(0, Math.min(maxLength, b.length));
}

function toArrayBuffer(thing) {
    //TODO: Optimize this for specific cases
    if (thing === undefined)
        return undefined;
    if (thing === Object(thing) && thing.__proto__ == StaticArrayBufferProto)
        return thing;

    if (thing instanceof Array) {
        // Assuming Uint16Array from curve25519
        var res = new ArrayBuffer(thing.length * 2);
        var uint = new Uint16Array(res);
        for (var i = 0; i < thing.length; i++)
            uint[i] = thing[i];
        return res;
    }

    if (!getStringable(thing))
        throw new Error("Tried to convert a non-stringable thing of type " + typeof thing + " to an array buffer");
    var str = getString(thing);
    var res = new ArrayBuffer(str.length);
    var uint = new Uint8Array(res);
    for (var i = 0; i < str.length; i++)
        uint[i] = str.charCodeAt(i);
    return res;
}

// Number formatting utils
window.textsecure.utils = function() {
    var self = {};
    self.unencodeNumber = function(number) {
        return number.split(".");
    };

    /**************************
     *** JSON'ing Utilities ***
     **************************/
    function ensureStringed(thing) {
        if (getStringable(thing))
            return getString(thing);
        else if (thing instanceof Array) {
            var res = [];
            for (var i = 0; i < thing.length; i++)
                res[i] = ensureStringed(thing[i]);
            return res;
        } else if (thing === Object(thing)) {
            var res = {};
            for (var key in thing)
                res[key] = ensureStringed(thing[key]);
            return res;
        }
        throw new Error("unsure of how to jsonify object of type " + typeof thing);

    }

    self.jsonThing = function(thing) {
        return JSON.stringify(ensureStringed(thing));
    }

    return self;
}();

window.textsecure.throwHumanError = function(error, type, humanError) {
    var e = new Error(error);
    if (type !== undefined)
        e.name = type;
    e.humanError = humanError;
    throw e;
}

window.textsecure.replay = function() {
    var self = {};

    self.REPLAY_FUNCS = {
        SEND_MESSAGE: 1,
        INIT_SESSION: 2,
    }

    var functions = {};

    self.registerReplayFunction = function(func, functionCode) {
        functions[functionCode] = func;
    }

    self.replayError = function(replayData) {
        var args = Array.prototype.slice.call(arguments);
        args.shift();
        args = replayData.args.concat(args);
        functions[replayData.replayFunction].apply(window, args);
    }

    self.createReplayableError = function(shortMsg, longMsg, replayFunction, args) {
        var e = new Error(shortMsg);
        e.name = "ReplayableError";
        e.humanError = e.longMessage = longMsg;
        e.replayData = { replayFunction: replayFunction, args: args };
        e.replay = function() {
            self.replayError(e.replayData);
        }
        return e;
    }

    return self;
}();

// message_callback({message: decryptedMessage, pushMessage: server-providedPushMessage})
window.textsecure.subscribeToPush = function(message_callback) {
    var socket = textsecure.api.getMessageWebsocket();

    socket.onmessage = function(message) {
        textsecure.protocol.decryptWebsocketMessage(message.body).then(function(plaintext) {
            var proto = textsecure.protobuf.IncomingPushMessageSignal.decode(plaintext);
            // After this point, a) decoding errors are not the server's fault, and
            // b) we should handle them gracefully and tell the user they received an invalid message
            console.log("Successfully decoded message with id: " + message.id);

            socket.send(
                new textsecure.protobuf.WebSocketMessage({
                    response: { id: message.id, message: 'OK', status: 200 },
                    type: textsecure.protobuf.WebSocketMessage.Type.RESPONSE
                }).encode().toArrayBuffer()
            );

            return textsecure.protocol.handleIncomingPushMessageProto(proto).then(function(decrypted) {
                // Delivery receipt
                if (decrypted === null)
                    //TODO: Pass to UI
                    return;

                // Now that its decrypted, validate the message and clean it up for consumer processing
                // Note that messages may (generally) only perform one action and we ignore remaining fields
                // after the first action.

                if (decrypted.flags == null)
                    decrypted.flags = 0;

                if ((decrypted.flags & textsecure.protobuf.PushMessageContent.Flags.END_SESSION)
                            == textsecure.protobuf.PushMessageContent.Flags.END_SESSION)
                    return;
                if (decrypted.flags != 0)
                    throw new Error("Unknown flags in message");

                var handleAttachment = function(attachment) {
                    return textsecure.api.getAttachment(attachment.id.toString()).then(function(encryptedBin) {
                        return textsecure.protocol.decryptAttachment(encryptedBin, attachment.key.toArrayBuffer()).then(function(decryptedBin) {
                            attachment.data = decryptedBin;
                        });
                    });
                };

                var promises = [];

                if (decrypted.group !== null) {
                    decrypted.group.id = getString(decrypted.group.id);
                    var existingGroup = textsecure.storage.groups.getNumbers(decrypted.group.id);
                    if (existingGroup === undefined) {
                        if (decrypted.group.type != textsecure.protobuf.PushMessageContent.GroupContext.Type.UPDATE)
                            throw new Error("Got message for unknown group");
                        textsecure.storage.groups.createNewGroup(decrypted.group.members, decrypted.group.id);
                    } else {
                        var fromIndex = existingGroup.indexOf(proto.source);

                        if (fromIndex < 0) //TODO: This could be indication of a race...
                            throw new Error("Sender was not a member of the group they were sending from");

                        switch(decrypted.group.type) {
                        case textsecure.protobuf.PushMessageContent.GroupContext.Type.UPDATE:
                            if (decrypted.group.avatar !== null)
                                promises.push(handleAttachment(decrypted.group.avatar));

                            if (existingGroup.filter(function(number) { decrypted.group.members.indexOf(number) < 0 }).length != 0)
                                throw new Error("Attempted to remove numbers from group with an UPDATE");
                            decrypted.group.added = decrypted.group.members.filter(function(number) { return existingGroup.indexOf(number) < 0; });

                            var newGroup = textsecure.storage.groups.addNumbers(decrypted.group.id, decrypted.group.added);
                            if (newGroup.length != decrypted.group.members.length ||
                                        newGroup.filter(function(number) { return decrypted.group.members.indexOf(number) < 0; }).length != 0)
                                throw new Error("Error calculating group member difference");

                            //TODO: Also follow this path if avatar + name haven't changed (ie we should start storing those)
                            if (decrypted.group.avatar === null && decrypted.group.added.length == 0 && decrypted.group.name === null)
                                return;

                            //TODO: Strictly verify all numbers (ie dont let verifyNumber do any user-magic tweaking)

                            decrypted.body = null;
                            decrypted.attachments = [];

                            break;
                        case textsecure.protobuf.PushMessageContent.GroupContext.Type.QUIT:
                            textsecure.storage.groups.removeNumber(decrypted.group.id, proto.source);

                            decrypted.body = null;
                            decrypted.attachments = [];
                        case textsecure.protobuf.PushMessageContent.GroupContext.Type.DELIVER:
                            decrypted.group.name = null;
                            decrypted.group.members = [];
                            decrypted.group.avatar = null;

                            break;
                        default:
                            throw new Error("Unknown group message type");
                        }
                    }
                }

                for (var i in decrypted.attachments)
                    promises.push(handleAttachment(decrypted.attachments[i]));
                return Promise.all(promises).then(function() {
                    message_callback({pushMessage: proto, message: decrypted});
                });
            })
        }).catch(function(e) {
            // TODO: Show "Invalid message" messages?
            console.log("Error handling incoming message: ");
            console.log(e);
        });
    };
};

window.textsecure.registerSingleDevice = function(number, verificationCode, stepDone) {
    var signalingKey = textsecure.crypto.getRandomBytes(32 + 20);
    textsecure.storage.putEncrypted('signaling_key', signalingKey);

    var password = btoa(getString(textsecure.crypto.getRandomBytes(16)));
    password = password.substring(0, password.length - 2);
    textsecure.storage.putEncrypted("password", password);

    var registrationId = new Uint16Array(textsecure.crypto.getRandomBytes(2))[0];
    registrationId = registrationId & 0x3fff;
    textsecure.storage.putUnencrypted("registrationId", registrationId);

    return textsecure.api.confirmCode(number, verificationCode, password, signalingKey, registrationId, true).then(function() {
        var numberId = number + ".1";
        textsecure.storage.putUnencrypted("number_id", numberId);
        textsecure.storage.putUnencrypted("regionCode", libphonenumber.util.getRegionCodeForNumber(number));
        stepDone(1);

        return textsecure.protocol.generateKeys().then(function(keys) {
            stepDone(2);
            return textsecure.api.registerKeys(keys).then(function() {
                stepDone(3);
            });
        });
    });
}

window.textsecure.registerSecondDevice = function(encodedDeviceInit, cryptoInfo, stepDone) {
    var deviceInit = textsecure.protobuf.DeviceInit.decode(encodedDeviceInit, 'binary');
    return cryptoInfo.decryptAndHandleDeviceInit(deviceInit).then(function(identityKey) {
        if (identityKey.server != textsecure.api.relay)
            throw new Error("Unknown relay used by master");
        var number = identityKey.phoneNumber;

        stepDone(1);

        var signalingKey = textsecure.crypto.getRandomBytes(32 + 20);
        textsecure.storage.putEncrypted('signaling_key', signalingKey);

        var password = btoa(getString(textsecure.crypto.getRandomBytes(16)));
        password = password.substring(0, password.length - 2);
        textsecure.storage.putEncrypted("password", password);

        var registrationId = new Uint16Array(textsecure.crypto.getRandomBytes(2))[0];
        registrationId = registrationId & 0x3fff;
        textsecure.storage.putUnencrypted("registrationId", registrationId);

        return textsecure.api.confirmCode(number, identityKey.provisioningCode, password, signalingKey, registrationId, false).then(function(result) {
            var numberId = number + "." + result;
            textsecure.storage.putUnencrypted("number_id", numberId);
            textsecure.storage.putUnencrypted("regionCode", libphonenumber.util.getRegion(number));
            stepDone(2);

            return textsecure.protocol.generateKeys().then(function(keys) {
                stepDone(3);
                return textsecure.api.registerKeys(keys).then(function() {
                    stepDone(4);
                    //TODO: Send DeviceControl.NEW_DEVICE_REGISTERED to all other devices
                });
            });
        });
    });
};