/**
 * CDN static file resolvers.
 *
 * @example
 *     <%- cdn(package, version, filename) %>
 *     <%- fontcdn(fontName) %>
 *     <%- iconcdn() %>
 */
const cdn_providers = {
    cdnjs: 'https://cdnjs.cloudflare.com/ajax/libs/${ package }/${ version }/${ filename }',
    jsdelivr: 'https://cdn.jsdelivr.net/npm/${ package }@${ version }/${ filename }',
    unpkg: 'https://unpkg.com/${ package }@${ version }/${ filename }'
};

const font_providers = {
    google: 'https://fonts.googleapis.com/${ type }?family=${ fontname }'
};

const icon_providers = {
    fontawesome: 'https://use.fontawesome.com/releases/v5.4.1/css/all.css'
};

module.exports = function(hexo) {
    hexo.extend.helper.register('cdn', function(_package, version, filename) {
        let provider = this.config.provider && 'cdn' in this.config.provider ? this.config.provider.cdn : 'jsdelivr';

        // cdn.js does not follow a GitHub npm style like jsdeliver and unpkg do. Patch it!
        if (provider === 'cdnjs' || provider.startsWith('[cdnjs]')) {
            if (provider.startsWith('[cdnjs]')) {
                provider = provider.substr(7);
            }
            if (filename.startsWith('dist/')) {
                filename = filename.substr(5);
            }
            if (_package === 'moment') {
                _package = 'moment.js';
                filename = filename.startsWith('min/') ? filename.substr(4) : filename;
            }
            if (_package === 'outdatedbrowser') {
                _package = 'outdated-browser';
                filename = filename.startsWith('outdatedbrowser/') ? filename.substr(16) : filename;
            }
            if (_package === 'highlight.js') {
                filename = filename.endsWith('.css') && filename.indexOf('.min.') === -1
                    ? filename.substr(0, filename.length - 4) + '.min.css' : filename;
            }
            if (_package === 'mathjax') {
                filename = filename.startsWith('unpacked/') ? filename.substr(9) : filename;
            }
            if (_package === 'pace-js') {
                _package = 'pace';
            }
            if (_package === 'clipboard') {
                _package = 'clipboard.js';
            }
            if (_package === 'disqusjs') {
                provider = 'jsdelivr';
            }
            if (_package === 'katex') {
                _package = 'KaTeX.js';
            }
        }
        if (provider !== null && provider in cdn_providers) {
            provider = cdn_providers[provider];
        }
        return provider.replace(/\${\s*package\s*}/gi, _package)
            .replace(/\${\s*version\s*}/gi, version)
            .replace(/\${\s*filename\s*}/gi, filename);
    });

    hexo.extend.helper.register('fontcdn', function(fontName, type = 'css') {
        let provider = this.config.provider && 'fontcdn' in this.config.provider ? this.config.provider.fontcdn : 'google';
        if (provider !== null && provider in font_providers) {
            provider = font_providers[provider];
        }
        return provider.replace(/\${\s*fontname\s*}/gi, fontName)
            .replace(/\${\s*type\s*}/gi, type);
    });

    hexo.extend.helper.register('iconcdn', function(provider = null) {
        if (provider !== null && provider in icon_providers) {
            provider = icon_providers[provider];
        } else {
            provider = this.config.provider && 'iconcdn' in this.config.provider ? this.config.provider.iconcdn : 'fontawesome';
            if (provider !== null && provider in icon_providers) {
                provider = icon_providers[provider];
            }
        }
        return provider;
    });
};