var Montage = require("./core").Montage;
var UUID = require("./uuid");
var Promise = require("./promise").Promise;
var PromiseQueue = require("./promise-queue").PromiseQueue;
var CacheMap = require("./shim/structures").CacheMap;
var logger = require("./logger").logger("promise-connections");
var rootId = "";

exports.connect = connect;
function connect(port, local, options) {
    return PromiseConnection.create().init(port, local, options);
}

var PromiseConnection =
exports.PromiseConnection = Montage.create(Montage, {

    init: {
        value: function (port, local, options) {
            options = options || {};
            // sigil for debug message prefix
            this.sigil = Math.random().toString(36).toUpperCase().slice(2, 4);
            this.makeId = options.makeId || UUID.generate;
            this.locals = CacheMap(options.max);
            this.port = Adapter.adapt(port, options.origin);
            this.port.forEach(function (message) {
                this.log("receive:", message);
                message = JSON.parse(message);
                if (!this.receivers[message.type])
                    return;
                if (!this.locals.has(message.to))
                    return;
                this.receivers[message.type].call(this, message);
            }, this);
            this.makeLocal(rootId);
            this.resolveLocal(rootId, local);
            return this.makeRemote(rootId);
        }
    },

    log: {
        value: function (/*...args*/) {
            logger.debug.apply(logger, ["Connection:", this.sigil].concat(Array.prototype.slice.call(arguments)))
        }
    },

    encode: {
        value: function (object) {
            if (Promise.isPromise(object)) {
                var id = this.makeId();
                this.makeLocal(id);
                this.resolveLocal(id, object);
                return {"@": id};
            } else if (Array.isArray(object)) {
                return object.map(this.encode, this);
            } else if (typeof object === "object") {
                var newObject = {};
                if (has.call(object, key)) {
                    var newKey = key;
                    if (/^[!@]$/.exec(key))
                        newKey = key + key;
                    newObject[newKey] = this.encode(object[key]);
                }
                return newObject;
            } else {
                return object;
            }
        }
    },

    decode: {
        value: function (object) {
            if (!object) {
                return object;
            } else if (object['!']) {
                return Promise.reject(object['!']);
            } else if (object['@']) {
                return this.makeRemote(object['@']);
            } else if (Array.isArray(object)) {
                return object.map(this.decode, this);
            } else if (typeof object === 'object') {
                var newObject = {};
                for (var key in object) {
                    if (has.call(object, key)) {
                        var newKey = key;
                        if (/^(@@|!!)$/.exec(key))
                            newKey = key.substring(1);
                        newObject[newKey] = this.decode(object[key]);
                    }
                }
                return newObject;
            } else {
                return object;
            }
        }
    },

    makeLocal: {
        value: function (id) {
            if (!this.locals.has(id)) {
                this.locals.set(id, Promise.defer());
            }
            return this.locals.get(id).promise;
        }
    },

    resolveLocal: {
        value: function (id, value) {
            this.log('resolve:', 'L' + JSON.stringify(id), JSON.stringify(value));
            this.locals.get(id).resolve(value);
        }
    },

    makeRemote: {
        value: function (id) {
            return RemotePromise.create().init(this, id);
        }
    },

    receivers: {
        value: Object.create(null, {

            resolve: {
                value: function (message) {
                    if (this.locals.has(message.to)) {
                        this.resolveLocal(message.to, this.decode(message.resolution));
                    }
                }
            },

            send: {
                value: function (message) {
                    var connection = this;
                    this.locals.get(message.to).promise
                    .send(message.op, this.decode(message.args))
                    .then(function (resolution) {
                        return Promise.call(function () {
                            return JSON.stringify({
                                type: 'resolve',
                                to: message.from,
                                resolution: connection.encode(resolution)
                            })
                        })
                        .fail(function (error) {
                            console.log('XXX:', error);
                            return JSON.stringify({
                                type: 'resolve',
                                to: message.from,
                                resolution: null
                            });
                        })
                    }, function (reason, error, rejection) {
                        return Promise.call(function () {
                            return JSON.stringify({
                                type: 'resolve',
                                to: message.from,
                                resolution: {'!': connection.encode(reason)}
                            })
                        })
                        .fail(function () {
                            return JSON.stringify({
                                type: 'resolve',
                                to: message.from,
                                resolution: {'!': null}
                            });
                        })
                    })
                    .then(function (envelope) {
                        connection.port.put(envelope);
                    })
                    .end();
                }
            }

        })
    }

});

var RemotePromise = Montage.create(Promise.AbstractPromise, {
    init: {
        value: function (connection, id) {
            this._connection = connection;
            this._id = id;
            this.Promise = Promise;
            return this;
        }
    },
    _handlers: {
        value: {}
    },
    _fallback: {
        value: function (resolve, op /*...args*/) {
            var localId = this._connection.makeId();
            var response = this._connection.makeLocal(localId);
            var args = Array.prototype.slice.call(arguments, 2);
            this._connection.log('sending:', 'R' + JSON.stringify(this._id), JSON.stringify(op), JSON.stringify(args));
            this._connection.port.put(JSON.stringify({
                type: 'send',
                to: this._id,
                from: localId,
                op: op,
                args: this._connection.encode(args)
            }));
            return response;
        }
    }
});

var Adapter =
exports.Adapter = Montage.create(Montage, {
    adapt: {
        value: function (port, origin) {
            return this.create().init(port, origin);
        }
    },
    init: {
        value: function (port, origin) {
            if (port.postMessage) {
                // MessagePorts
                this._send = function (message) {
                    // some message ports require an "origin"
                    port.postMessage(message, origin);
                };
            } else if (port.send) {
                // WebSockets have a "send" method, indicating
                // that we cannot send until the connection has
                // opened.  We change the send method into a
                // promise for the send method, resolved after
                // the connection opens, rejected if it closes
                // before it opens.
                var deferred = Promise.defer();
                this._send = deferred.promise;
                port.addEventListener("open", function () {
                    deferred.resolve(port.send);
                });
                port.addEventListener("close", function () {
                    queue.close();
                    deferred.reject("Connection closed.");
                });
            } else if (port.get && port.put) {
                return port;
            } else {
                throw new Error("An adaptable message port required");
            }
            // Message ports have a start method; call it to make sure
            // that messages get sent.
            port.start && port.start();
            var queue = this._queue = PromiseQueue.create().init();
            function onmessage(event) {
                queue.put(event.data);
            }
            if (port.addEventListener) {
                port.addEventListener("message", onmessage, false);
            } else {
                // onmessage is one thing common between WebSocket and
                // WebWorker message ports.
                port.onmessage = onmessage;
            }
            this._port = port;
            this.closed = queue.closed;
            return this;
        }
    },
    get: {
        value: function () {
            return this._queue.get();
        }
    },
    put: {
        value: function (value) {
            return Promise.invoke(this._send, "call", this._port, value);
        }
    },
    forEach: {
        value: PromiseQueue.forEach
    },
    close: {
        value: function (reason, error, rejection) {
            this._port.close && this._port.close();
            return this._queue.close();
        }
    }
});