/*
FaceDetection jQuery Plugin
Copyright (c) 2016 Jay Salvat
*/

/* global $, ccv, cascade */

$.fn.faceDetection = function (settingsOrCallback) {
    "use strict";

    var time;

    var options = {
        interval: 4,
        minNeighbors: 1,
        grayscale: true,
        confidence: null,
        async: false,
        complete: function () { }, // (faces)
        error: function () { }  // (code, message)
    };

    if ($.isFunction(settingsOrCallback)) {
        options.complete = settingsOrCallback;
    } else {
        $.extend(options, settingsOrCallback);
    }

    return this.each(function () {
        var $$ = $(this),
            offset = $$.offset(),
            position = $$.position(),
            scaleX = ($$.width() / (this.naturalWidth || this.videoWidth)) || 1,
            scaleY = ($$.height() / (this.naturalHeight || this.videoHeight)) || 1;

        if (!$$.is('img, video, canvas')) {
            options.error.apply($$, [1, 'Face detection is possible on images, videos and canvas only.']);
            options.complete.apply($$, [[]]);

            return;
        }

        function detect() {
            var source, canvas;

            time = new Date().getTime();

            if ($$.is('img')) {
                source = new Image();
                source.src = $$.attr('src');
                source.crossOrigin = $$.attr('crossorigin');
                canvas = ccv.pre(source);
            } else if ($$.is('video') || $$.is('canvas')) {
                var copy, context;

                source = $$[0];

                copy = document.createElement('canvas');
                copy.setAttribute('width', source.videoWidth || source.width);
                copy.setAttribute('height', source.videoHeight || source.height);

                context = copy.getContext("2d");
                context.drawImage(source, 0, 0);

                canvas = ccv.pre(copy);
            }

            if (options.grayscale) {
                canvas = ccv.grayscale(canvas);
            }

            try {
                if (options.async && window.Worker) {
                    ccv.detect_objects({
                        "canvas": canvas,
                        "cascade": cascade,
                        "interval": options.interval,
                        "min_neighbors": options.minNeighbors,
                        "worker": 1,
                        "async": true
                    })(done);
                } else {
                    done(ccv.detect_objects({
                        "canvas": canvas,
                        "cascade": cascade,
                        "interval": options.interval,
                        "min_neighbors": options.minNeighbors
                    }));
                }
            } catch (e) {
                options.error.apply($$, [2, e.message]);
                options.complete.apply($$, [false]);
            }
        }

        function done(faces) {
            var n = faces.length,
                data = [];

            for (var i = 0; i < n; ++i) {
                if (options.confidence !== null && faces[i].confidence <= options.confidence) {
                    continue;
                }

                faces[i].positionX = position.left + faces[i].x;
                faces[i].positionY = position.top + faces[i].y;
                faces[i].offsetX = offset.left + faces[i].x;
                faces[i].offsetY = offset.top + faces[i].y;
                faces[i].scaleX = scaleX;
                faces[i].scaleY = scaleY;

                data.push(faces[i]);
            }

            data.time = new Date().getTime() - time;

            options.complete.apply($$, [data]);
        }

        return detect();
    });
};