// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-

const Lang = imports.lang;
const Signals = imports.signals;
const Clutter = imports.gi.Clutter;
const Params = imports.misc.params;

var DEFAULT_LIMIT = 512;

var HistoryManager = new Lang.Class({
    Name: 'HistoryManager',

    _init(params) {
        params = Params.parse(params, { gsettingsKey: null,
                                        limit: DEFAULT_LIMIT,
                                        entry: null });

        this._key = params.gsettingsKey;
        this._limit = params.limit;

        this._historyIndex = 0;
        if (this._key) {
            this._history = global.settings.get_strv(this._key);
            global.settings.connect('changed::' + this._key,
                                    this._historyChanged.bind(this));

        } else {
            this._history = [];
        }

        this._entry = params.entry;

        if (this._entry) {
            this._entry.connect('key-press-event', 
                                this._onEntryKeyPress.bind(this));
        }
    },

    _historyChanged() {
        this._history = global.settings.get_strv(this._key);
        this._historyIndex = this._history.length;
    },

    _setPrevItem(text) {
        if (this._historyIndex <= 0)
            return false;

        if (text)
            this._history[this._historyIndex] = text;
        this._historyIndex--;
        this._indexChanged();
        return true;
    },

    _setNextItem(text) {
        if (this._historyIndex >= this._history.length)
            return false;

        if (text)
            this._history[this._historyIndex] = text;
        this._historyIndex++;
        this._indexChanged();
        return true;
    },

    lastItem() {
        if (this._historyIndex != this._history.length) {
            this._historyIndex = this._history.length;
            this._indexChanged();
        }

        return this._historyIndex ? this._history[this._historyIndex -1] : null;
    },

    addItem(input) {
        if (this._history.length == 0 ||
            this._history[this._history.length - 1] != input) {

            this._history = this._history.filter(entry => entry != input);
            this._history.push(input);
            this._save();
        }
        this._historyIndex = this._history.length;
    },

    _onEntryKeyPress(entry, event) {
        let symbol = event.get_key_symbol();
        if (symbol == Clutter.KEY_Up) {
            return this._setPrevItem(entry.get_text());
        } else if (symbol == Clutter.KEY_Down) {
            return this._setNextItem(entry.get_text());
        }
        return Clutter.EVENT_PROPAGATE;
    },

    _indexChanged() {
        let current = this._history[this._historyIndex] || '';
        this.emit('changed', current);

        if (this._entry)
            this._entry.set_text(current);
    },

    _save() {
        if (this._history.length > this._limit)
            this._history.splice(0, this._history.length - this._limit);

        if (this._key)
            global.settings.set_strv(this._key, this._history);
    }
});
Signals.addSignalMethods(HistoryManager.prototype);