var _ = require("lodash");
var $ = require("jquery");
var EventEmitter = require('events').EventEmitter;

var utils = require("../utils.js");
var actions = require("../actions.js");
var dispatcher = require("../dispatcher.js");


function ListStore() {
    EventEmitter.call(this);
    this.reset();
}
_.extend(ListStore.prototype, EventEmitter.prototype, {
    add: function (elem) {
        if (elem.id in this._pos_map) {
            return;
        }
        this._pos_map[elem.id] = this.list.length;
        this.list.push(elem);
        this.emit("add", elem);
    },
    update: function (elem) {
        if (!(elem.id in this._pos_map)) {
            return;
        }
        this.list[this._pos_map[elem.id]] = elem;
        this.emit("update", elem);
    },
    remove: function (elem_id) {
        if (!(elem_id in this._pos_map)) {
            return;
        }
        this.list.splice(this._pos_map[elem_id], 1);
        this._build_map();
        this.emit("remove", elem_id);
    },
    reset: function (elems) {
        this.list = elems || [];
        this._build_map();
        this.emit("recalculate");
    },
    _build_map: function () {
        this._pos_map = {};
        for (var i = 0; i < this.list.length; i++) {
            var elem = this.list[i];
            this._pos_map[elem.id] = i;
        }
    },
    get: function (elem_id) {
        return this.list[this._pos_map[elem_id]];
    },
    index: function (elem_id) {
        return this._pos_map[elem_id];
    }
});


function DictStore() {
    EventEmitter.call(this);
    this.reset();
}
_.extend(DictStore.prototype, EventEmitter.prototype, {
    update: function (dict) {
        _.merge(this.dict, dict);
        this.emit("recalculate");
    },
    reset: function (dict) {
        this.dict = dict || {};
        this.emit("recalculate");
    }
});

function LiveStoreMixin(type) {
    this.type = type;

    this._updates_before_fetch = undefined;
    this._fetchxhr = false;

    this.handle = this.handle.bind(this);
    dispatcher.AppDispatcher.register(this.handle);

    // Avoid double-fetch on startup.
    if (!(window.ws && window.ws.readyState === WebSocket.CONNECTING)) {
        this.fetch();
    }
}
_.extend(LiveStoreMixin.prototype, {
    handle: function (event) {
        if (event.type === actions.ActionTypes.CONNECTION_OPEN) {
            return this.fetch();
        }
        if (event.type === this.type) {
            if (event.cmd === actions.StoreCmds.RESET) {
                this.fetch(event.data);
            } else if (this._updates_before_fetch) {
                console.log("defer update", event);
                this._updates_before_fetch.push(event);
            } else {
                this[event.cmd](event.data);
            }
        }
    },
    close: function () {
        dispatcher.AppDispatcher.unregister(this.handle);
    },
    fetch: function (data) {
        console.log("fetch " + this.type);
        if (this._fetchxhr) {
            this._fetchxhr.abort();
        }
        this._updates_before_fetch = []; // (JS: empty array is true)
        if (data) {
            this.handle_fetch(data);
        } else {
            this._fetchxhr = $.getJSON("/" + this.type)
                .done(function (message) {
                    this.handle_fetch(message.data);
                }.bind(this))
                .fail(function () {
                    EventLogActions.add_event("Could not fetch " + this.type);
                }.bind(this));
        }
    },
    handle_fetch: function (data) {
        this._fetchxhr = false;
        console.log(this.type + " fetched.", this._updates_before_fetch);
        this.reset(data);
        var updates = this._updates_before_fetch;
        this._updates_before_fetch = false;
        for (var i = 0; i < updates.length; i++) {
            this.handle(updates[i]);
        }
    },
});

function LiveListStore(type) {
    ListStore.call(this);
    LiveStoreMixin.call(this, type);
}
_.extend(LiveListStore.prototype, ListStore.prototype, LiveStoreMixin.prototype);

function LiveDictStore(type) {
    DictStore.call(this);
    LiveStoreMixin.call(this, type);
}
_.extend(LiveDictStore.prototype, DictStore.prototype, LiveStoreMixin.prototype);


function FlowStore() {
    return new LiveListStore(actions.ActionTypes.FLOW_STORE);
}

function SettingsStore() {
    return new LiveDictStore(actions.ActionTypes.SETTINGS_STORE);
}

function EventLogStore() {
    LiveListStore.call(this, actions.ActionTypes.EVENT_STORE);
}
_.extend(EventLogStore.prototype, LiveListStore.prototype, {
    fetch: function(){
        LiveListStore.prototype.fetch.apply(this, arguments);

        // Make sure to display updates even if fetching all events failed.
        // This way, we can send "fetch failed" log messages to the log.
        if(this._fetchxhr){
            this._fetchxhr.fail(function(){
                this.handle_fetch(null);
            }.bind(this));
        }
    }
});


module.exports = {
    EventLogStore: EventLogStore,
    SettingsStore: SettingsStore,
    FlowStore: FlowStore
};