'use strict';

var util = require('./util');
var TextButton = require('./TextButton');
var config = require('./config');

function RulerHandler(viewport) {
    var _enabled = false;
    var _lines = { x: null, y: null };
    var _rect = { x: null, y: null };

    var Event = {
        /**
         * Triggers when handlebar is moved
         */
        onMove: function () {
            var axis = this.axis;
            var bounds = viewport.getBounds();
            var pos = util.assertBetween(this[axis], bounds.min[axis], bounds.max[axis]);
            this.marker[axis] = this[axis] = pos;
            var dim = (this[axis] - bounds[axis]) / (viewport.getData().ppmm * 10 * viewport.canvas.getImage().scaleX);

            if (axis === 'top') {
                dim = viewport.getData().dim.height - dim;
            }

            this.setText(Math.round(dim * 100) / 100 + ' ' + viewport.getData().dim.units);
        }
    };

    /**
     * @return {fabric.Line}
     */
    function getLine(axis) {
        var bounds = viewport.getBounds();
        return new fabric.Line([
                0, 0,
                axis === 'x' ? bounds.width : 0,
                axis === 'y' ? bounds.height : 0
            ], {
            evented: false,
            strokeDashArray: [5, 5],
            stroke: '#000',
            strokeWidth: 1,
            top: axis === 'x' ? bounds.top + bounds.height / 2 : bounds.top,
            left: axis === 'y' ? bounds.left + bounds.width / 2 : bounds.left
        });
    }

    /**
     * @return {RulerHandler}
     */
    this.clear = function () {
        [].concat(_rect.x, _rect.y, _lines.x, _lines.y).forEach(function (o) {
            viewport.canvas.remove(o);
        });
        return this;
    };

    /**
     * @param  {Boolean} enabled
     * @return {RulerHandler}
     */
    this.enable = function (enabled) {
        _enabled = enabled;
        this.clear();

        if (!_enabled) {
            viewport.canvas.renderAll();
            return;
        }

        var bounds = viewport.getBounds();

        _lines = { x: getLine('x'), y: getLine('y') };

        viewport.canvas.add(_lines.x);
        viewport.canvas.add(_lines.y);

        _rect.x = new TextButton('horizontalRuler', 'H', config.rulerHandle)
            .set(config.rulerHandle.x(_lines, bounds))
            .addTo(viewport.canvas)
            .on('moving', Event.onMove)
            .trigger('moving');

        _rect.y = new TextButton('verticalRuler', 'V', config.rulerHandle)
            .set(config.rulerHandle.y(_lines, bounds))
            .addTo(viewport.canvas)
            .on('moving', Event.onMove)
            .trigger('moving');

        viewport.canvas.renderAll();

        return this;
    };

    /**
     * @return {RulerHandler}
     */
    this.reset = function () {
        return this.enable(_enabled);
    };
}

module.exports = RulerHandler;