"use strict";

var Class = require("./class");

var Subscribable = Class.inherit({
    "className": "Subscribable",
    "constructor": function() {
        Class.fn.constructor.call(this);

        this._events = Object.create(null);
    },
    "destructor": function() {
        this.off();
        Class.fn.destructor.call(this);
    },

    "on": function(name, handler, context) {
        var handlers = this._events[name];

        if (typeof name !== "string") {
            throw new Error("Name of event is mandatory");
        }

        if (!(handler instanceof Function)) {
            throw new Error("Handler of event is mandatory");
        }

        if (!handlers) {
            handlers = [];
            this._events[name] = handlers;
        }

        handlers.push({
            handler: handler,
            context: context || this,
            once: false
        });
    },
    "one": function(name) {
        Subscribable.fn.on.apply(this, arguments);
        this._events[name][this._events[name].length - 1].once = true;
    },
    "off": function(name, handler, context) {

        if (typeof name === "string") {
            if (this._events[name]) {
                if (handler instanceof Function) {
                    var handlers = this._events[name];
                    for (var i = handlers.length - 1; i >= 0 ; --i) {
                        if (handlers[i].handler === handler) {
                            if (context) {
                                if (handlers[i].context === context) {
                                    handlers.splice(i, 1);
                                }
                            } else {
                                handlers.splice(i, 1);
                            }
                        }
                    }
                } else {
                    delete this._events[name];
                }
            }
        } else {
            this._events = Object.create(null);
        }
    },
    "trigger": function() {
        var args = [].slice.call(arguments);
        if (args.length === 0) {
            throw new Error("Name of event is mandatory");
        }
        var answer = false;
        var name = args.shift();
        var handlers = this._events[name];
        if (handlers) {
            for (var i = 0; i < handlers.length; ++i) {
                var handle = handlers[i];
                answer = handle.handler.apply(handle.context, args);
                if (handle.once) {
                    handlers.splice(i, 1);
                    --i;
                }

                if (answer === false) {
                    return false;
                }
            }
        }
        return answer;
    }
});

module.exports = Subscribable;