'use strict';


function escapeHTML(str) {
  return str.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
}

var MD_UNESCAPE_RE = /\\([!"#$%&\'()*+,.\/:;<=>?@[\\\]^_`{|}~-])/g;

function unescapeMD(str) {
  return str.replace(MD_UNESCAPE_RE, '$1');
}

function joinLines(state, begin, end) {
 return state.src.slice(
    state.bMarks[begin],
    end < state.lineMax ? state.bMarks[end] : state.src.length
  );
}

var rules = {};


rules.blockquote_open = function (state, token) {
  state.result += '<blockquote>';
};
rules.blockquote_close = function (state, token) {
  state.result += '</blockquote>\n';
};


rules.code = function (state, token) {
  var content = joinLines(state, token.startLine, token.endLine).replace(/^ {4}/gm, '');

  state.result += '<pre><code>' + escapeHTML(content) + '</code></pre>\n';
};


rules.fence = function (state, token) {
  var content = joinLines(state, token.startLine, token.endLine);
  var langMark = '';

  if (token.params.length) {
    langMark = ' class="language-' + escapeHTML(token.params[0]) + '"';
  }

  state.result += '<pre><code' + langMark + '>' + escapeHTML(content) + '</code></pre>\n';
};


rules.heading_open = function (state, token) {
  state.result += '<h' + token.level + '>';
};
rules.heading_close = function (state, token) {
  state.result += '</h' + token.level + '>\n';
};


rules.hr = function (state, token) {
  state.result += '<hr>\n';
};


rules.paragraph_open = function (state, token) {
  state.result += '<p>';
};
rules.paragraph_close = function (state, token) {
  state.result += '</p>\n';
};


rules.text = function (state, token) {
  state.result += escapeHTML(unescapeMD(state.src.slice(token.begin, token.end)));
};


// TODO: Stub. Do extendable.
function Renderer() {
}

Renderer.prototype.render = function (state) {
  var i, len, rule,
      tokens = state.tokens;

  for (i = 0, len = tokens.length; i < len; i++) {
    rule = rules[tokens[i].type];

    // TODO: temporary check
    if (!rule) {
      throw Error('Renderer error: unknown token ' + tokens[i].type);
    }

    rule(state, tokens[i]);
  }

  return state.result;
};

module.exports = Renderer;