/*****************************************************************
** Author: Asvin Goel, goel@telematique.eu
** Fixed for Reveal4: kotborealis@awooo.ru
**
** A plugin for reveal.js allowing to integrate Chart.js
**
** Version: 1.3.1
**
** License: MIT license (see LICENSE.md)
**
******************************************************************/

/**
 * Reveal Plugin
 * https://revealjs.com/creating-plugins/
 */
window.RevealChart = window.RevealChart || {
    id: 'RevealChart',
    init: function (deck) {
        initChart(deck);
    },
    update: function (canvas, idx, data) { update(canvas, idx, data); },
};

const initChart = function (Reveal) {
    function parseJSON(str) {
        var json;
        try {
            json = JSON.parse(str);
        } catch (e) {
            return null;
        }
        return json;
    }

    /*
    * Recursively merge properties of two objects
    */
    function mergeRecursive(obj1, obj2) {

        for (var p in obj2) {
            try {
                // Property in destination object set; update its value.
                if (obj1[p] !== null && typeof obj1[p] === 'object' && typeof obj2[p] === 'object') {
                    obj1[p] = mergeRecursive(obj1[p], obj2[p]);
                }
                else {
                    obj1[p] = obj2[p];
                }
            } catch (e) {
                // Property in destination object not set; create it and set its value.
                obj1[p] = obj2[p];
            }
        }

        return obj1;
    }


    function createChart(canvas, CSV, comments) {
        canvas.chart = null;
        var ctx = canvas.getContext("2d");
        var chartOptions = { responsive: true, maintainAspectRatio: false };
        var chartData = { labels: null, datasets: [] };
        if (comments !== null) for (var j = 0; j < comments.length; j++) {
            comments[j] = comments[j].replace(/<!--/, '');
            comments[j] = comments[j].replace(/-->/, '');
            var config = parseJSON(comments[j]);
            if (config) {
                if (config.data) {
                    mergeRecursive(chartData, config.data);
                }
                if (config.options) {
                    mergeRecursive(chartOptions, config.options);
                }
            }
        }

        var lines = CSV.split('\n').filter(function (v) { return v !== '' });
        // if labels are not defined, get them from first line
        if (chartData.labels === null && lines.length > 0) {
            chartData.labels = lines[0].split(',');
            chartData.labels.shift();
            lines.shift();
        }
        // get data values
        for (var j = 0; j < lines.length; j++) {
            if (chartData.datasets.length <= j) chartData.datasets[j] = {};
            chartData.datasets[j].data = lines[j].split(','); //.filter(function(v){return v!==''});
            chartData.datasets[j].label = chartData.datasets[j].data[0];
            chartData.datasets[j].data.shift();
            for (var k = 0; k < chartData.datasets[j].data.length; k++) {
                chartData.datasets[j].data[k] = Number(chartData.datasets[j].data[k]);
            }
        }

        // add chart options
        var config = chartConfig[canvas.getAttribute("data-chart")];
        if (config) {
            for (var j = 0; j < chartData.datasets.length; j++) {
                for (var attrname in config) {
                    if (!chartData.datasets[j][attrname]) {
                        chartData.datasets[j][attrname] = config[attrname][j % config[attrname].length];
                    }
                }
            }
        }

        canvas.chart = new Chart(ctx, { type: canvas.getAttribute("data-chart"), data: chartData, options: chartOptions });

    }

    function updateChart(canvas, idx, data) {
        canvas.chart.data.datasets[idx].data = data;
        recreateChart(canvas);
    }

    var initializeCharts = function () {
        // Get all canvases
        var canvases = document.querySelectorAll("canvas");
        for (var i = 0; i < canvases.length; i++) {
            // check if canvas has data-chart attribute
            if (canvases[i].hasAttribute("data-chart")) {
                var CSV = canvases[i].innerHTML.trim();
                var comments = CSV.match(/<!--[\s\S]*?-->/g);
                CSV = CSV.replace(/<!--[\s\S]*?-->/g, '').replace(/^\s*\n/gm, "")
                if (!canvases[i].hasAttribute("data-chart-src")) {
                    createChart(canvases[i], CSV, comments);
                }
                else {
                    var canvas = canvases[i];
                    var xhr = new XMLHttpRequest();
                    xhr.onload = function () {
                        if (xhr.readyState === 4) {
                            createChart(canvas, xhr.responseText, comments);
                        }
                        else {
                            console.warn('Failed to get file ' + canvas.getAttribute("data-chart-src") + ". ReadyState: " + xhr.readyState + ", Status: " + xhr.status);
                        }
                    };

                    xhr.open('GET', canvas.getAttribute("data-chart-src"), false);
                    try {
                        xhr.send();
                    }
                    catch (error) {
                        console.warn('Failed to get file ' + canvas.getAttribute("data-chart-src") + '. Make sure that the presentation and the file are served by a HTTP server and the file can be found there. ' + error);
                    }
                }

            }
        }
    }

    function recreateChart(canvas) {
        // clear data to redraw animation
        var data = canvas.chart.data.datasets;
        canvas.chart.data.datasets = [];
        canvas.chart.update();
        canvas.style.visibility = "hidden";
        setTimeout(function (canvas, data) {
            canvas.chart.data.datasets = data;
            canvas.style.visibility = "visible";
            canvas.chart.update();
        }, 500, canvas, data); // wait for slide transition to re-add data and animation
        /*
                var config = canvas.chart.config;
                canvas.chart.destroy();
                setTimeout( function() { canvas.chart = new Chart(canvas, config);}, 500); // wait for slide transition
        */
    }

    // check if chart option is given or not
    var chartConfig = Reveal.getConfig().chart || {};

    // set global chart options
    var config = chartConfig.defaults;
    if (config) {
        mergeRecursive(Chart.defaults, config);
    }

    Reveal.addEventListener('ready', function () {
        initializeCharts();
        Reveal.addEventListener('slidechanged', function () {
            var canvases = Reveal.getCurrentSlide().querySelectorAll("canvas[data-chart]");
            for (var i = 0; i < canvases.length; i++) {
                if (canvases[i].chart && canvases[i].chart.config.options.animation !== false) {
                    recreateChart(canvases[i]);
                }
            }

        });
    });

    this.update = updateChart;

    return this;
};