import _ from 'lodash';
import xml from 'xml';
import moment from 'moment';
import url from 'url';
import path from 'path';

import * as utils from './utils';

const XMLNS_DECLS = {
    _attr: {
        xmlns: `http://www.sitemaps.org/schemas/sitemap/0.9`
    }
};

export default class SiteMapIndexGenerator {
    constructor(options) {
        options = options || {};
        this.types = options.types;
    }

    getXml(options) {
        const urlElements = this.generateSiteMapUrlElements(options);
        const data = {
            // Concat the elements to the _attr declaration
            sitemapindex: [XMLNS_DECLS].concat(urlElements)
        };

        // Return the xml
        return utils.sitemapsUtils.getDeclarations(options) + xml(data);
    }

    generateSiteMapUrlElements({sources, siteUrl, pathPrefix, resourcesOutput}) {
        return _.map(sources, (source) => {
            const filePath = resourcesOutput.replace(/:resource/, source.name).replace(/^\//, ``);
            const siteMapUrl = source.url ? source.url : url.resolve(siteUrl, path.join(pathPrefix, filePath));
            const lastModified = source.url ? moment(new Date(), moment.ISO_8601).toISOString()
                : this.types[source.sitemap].lastModified || moment(new Date(), moment.ISO_8601).toISOString();

            return {
                sitemap: [
                    {loc: siteMapUrl},
                    {lastmod: moment(lastModified).toISOString()}
                ]
            };
        });
    }
}