'use strict';

const React = require('react');
const hljs = require('highlight.js')
const Markdown = require('remarkable');
const toSlug = require("./toSlug.js");

const CWD = process.cwd();

/**
 * The anchors plugin adds GFM-style anchors to headings.
 */
function anchors(md) {
  md.renderer.rules.heading_open = function(tokens, idx /*, options, env */) {
    return '<h' + tokens[idx].hLevel + '>' + '<a class="anchor" name="' + toSlug(tokens[idx+1].content) + '"></a>';
  };
  md.renderer.rules.heading_close = function(tokens, idx /*, options, env */) {
    return ' <a class="hash-link" href="#' + toSlug(tokens[idx-1].content) + '">#</a>' + '</h' + tokens[idx].hLevel + '>\n';
  };
}

class Remarkable extends React.Component {

  render() {
    var Container = this.props.container;

    return (
      <Container>
        {this.content()}
      </Container>
    );
  }

  componentWillUpdate(nextProps, nextState) {
    if (nextProps.options !== this.props.options) {
      this.md = new Markdown(nextProps.options);
    }
  }

  content() {
    if (this.props.source) {
      return <span dangerouslySetInnerHTML={{ __html: this.renderMarkdown(this.props.source) }} />;
    }
    else {
      return React.Children.map(this.props.children, child => {
        if (typeof child === 'string') {
          return <span dangerouslySetInnerHTML={{ __html: this.renderMarkdown(child) }} />;
        }
        else {
          return child;
        }
      });
    }
  }

  renderMarkdown(source) {
    if (!this.md) {
      this.md = new Markdown({
        // Highlight.js expects hljs css classes on the code element.
        // This results in <pre><code class="hljs css javascript">
        langPrefix: 'hljs css ',
        highlight: function (str, lang) {
          if (lang && hljs.getLanguage(lang)) {
            try {
              return hljs.highlight(lang, str).value;
            } catch (err) {}
          }
      
          try {
            return hljs.highlightAuto(str).value;
          } catch (err) {}
      
          return '';
        }
      });

      // Register anchors plugin
      this.md.use(anchors);

      // Allow client sites to register their own plugins
      const siteConfig = require(CWD + "/siteConfig.js");
      if (siteConfig.markdownPlugins) {
        siteConfig.markdownPlugins.forEach(function(plugin) {
          this.md.use(plugin);
        }, this);
      }

    }

    // Ensure fenced code blocks use Highlight.js hljs class
    // https://github.com/jonschlinkert/remarkable/issues/224
    return this.md.render(source).replace('<pre><code>','<pre><code class="hljs">');
  }
}

Remarkable.defaultProps = {
  container: 'div',
  options: {},
};

module.exports = Remarkable;