nagix/chartjs-plugin-datasource

'use strict';

import Chart from 'chart.js';
import datasourceHelpers from '../helpers/helpers.datasource';

var helpers = Chart.helpers;

var EXPANDO_KEY = '$datasource';

Chart.defaults.global.plugins.datasource = {};

function mergeData(target, source) {
    var sourceDatasets = source.datasets;
    var targetDatasets = target.datasets;
    var sourceLabels = source.labels;
    var targetLabels = target.labels;
    var max = 0;
    var sourceDataset, targetDataset, sourceLabel, sourceData, i, ilen;

    if (helpers.isArray(sourceDatasets)) {
        if (!helpers.isArray(targetDatasets)) {
            targetDatasets = target.datasets = [];
        }
        for (i = 0, ilen = sourceDatasets.length; i < ilen; ++i) {
            sourceDataset = sourceDatasets[i];
            targetDataset = targetDatasets[i];
            if (!datasourceHelpers.isObject(targetDataset)) {
                targetDataset = targetDatasets[i] = {};
            }
            sourceLabel = sourceDataset.label;
            if (sourceLabel !== undefined) {
                targetDataset.label = sourceLabel;
            } else if (targetDataset.label === undefined) {
                targetDataset.label = 'Dataset ' + (i + 1);
            }
            sourceData = sourceDataset.data;
            if (helpers.isArray(sourceData)) {
                targetDataset.data = sourceData;
                max = Math.max(max, sourceData.length);
            }
        }
    }
    if (helpers.isArray(sourceLabels)) {
        target.labels = sourceLabels;
    } else if (!helpers.isArray(targetLabels) || !targetLabels.length) {
        targetLabels = target.labels = [];
        for (i = 0; i < max; ++i) {
            targetLabels[i] = '' + (i + 1);
        }
    }
}

export default {
    id: 'datasource',

    beforeInit: function(chart) {
        chart[EXPANDO_KEY] = {};
    },

    beforeUpdate: function(chart, options) {
        var me = this;
        var expando = chart[EXPANDO_KEY];
        var url = options.url;
        var type = options.type || me.getType(url);
        var DataSourceClass = me.getConstructor(type);
        var datasource = expando._datasource;

        if (url && DataSourceClass && !chart[EXPANDO_KEY]._delayed) {
            if (!datasource || datasource.getType() !== type || datasource.getUrl() !== url) {
                datasource = expando._datasource = new DataSourceClass(chart, options);
            }
            datasource.request(function(response) {
                mergeData(chart.data, response.data);
                expando._delayed = true;
                chart.update();
                delete expando._delayed;
            });
            return false;
        }
    },

    constructors: {},
    extensions: {},

    register: function(type, constructor, extensions) {
        var me = this;

        me.constructors[type] = constructor;
        helpers.each(extensions, function(extension) {
            me.extensions[extension] = type;
        });
    },

    getType: function(url) {
        if (url) {
            return this.extensions[datasourceHelpers.getExtension(url)] || 'json';
        }
    },

    getConstructor: function(type) {
        if (!this.constructors.hasOwnProperty(type)) {
            throw new Error('"' + type + '" is not a data source type.');
        }
        return this.constructors[type];
    }
};