/**
 * @author Titus Wormer
 * @copyright 2015 Titus Wormer
 * @license MIT
 * @module remark:parse:tokenize:html-block
 * @fileoverview Tokenise block HTML.
 */

'use strict';

var openCloseTag = require('../util/html').openCloseTag;

module.exports = blockHTML;

var C_TAB = '\t';
var C_SPACE = ' ';
var C_NEWLINE = '\n';
var C_LT = '<';

/* Tokenise block HTML. */
function blockHTML(eat, value, silent) {
  var self = this;
  var blocks = self.options.blocks;
  var length = value.length;
  var index = 0;
  var next;
  var line;
  var offset;
  var character;
  var count;
  var sequence;
  var subvalue;

  var sequences = [
    [/^<(script|pre|style)(?=(\s|>|$))/i, /<\/(script|pre|style)>/i, true],
    [/^<!--/, /-->/, true],
    [/^<\?/, /\?>/, true],
    [/^<![A-Za-z]/, />/, true],
    [/^<!\[CDATA\[/, /\]\]>/, true],
    [new RegExp('^</?(' + blocks.join('|') + ')(?=(\\s|/?>|$))', 'i'), /^$/, true],
    [new RegExp(openCloseTag.source + '\\s*$'), /^$/, false]
  ];

  /* Eat initial spacing. */
  while (index < length) {
    character = value.charAt(index);

    if (character !== C_TAB && character !== C_SPACE) {
      break;
    }

    index++;
  }

  if (value.charAt(index) !== C_LT) {
    return;
  }

  next = value.indexOf(C_NEWLINE, index + 1);
  next = next === -1 ? length : next;
  line = value.slice(index, next);
  offset = -1;
  count = sequences.length;

  while (++offset < count) {
    if (sequences[offset][0].test(line)) {
      sequence = sequences[offset];
      break;
    }
  }

  if (!sequence) {
    return;
  }

  if (silent) {
    return sequence[2];
  }

  index = next;

  if (!sequence[1].test(line)) {
    while (index < length) {
      next = value.indexOf(C_NEWLINE, index + 1);
      next = next === -1 ? length : next;
      line = value.slice(index + 1, next);

      if (sequence[1].test(line)) {
        if (line) {
          index = next;
        }

        break;
      }

      index = next;
    }
  }

  subvalue = value.slice(0, index);

  return eat(subvalue)({type: 'html', value: subvalue});
}