/**
 * @author Titus Wormer
 * @copyright 2015 Titus Wormer
 * @license MIT
 * @module remark:parse:tokenize:footnote-definition
 * @fileoverview Tokenise footnote definition.
 */

'use strict';

var whitespace = require('is-whitespace-character');
var normalize = require('../util/normalize');

module.exports = footnoteDefinition;
footnoteDefinition.notInList = true;
footnoteDefinition.notInBlock = true;

var C_BACKSLASH = '\\';
var C_NEWLINE = '\n';
var C_TAB = '\t';
var C_SPACE = ' ';
var C_BRACKET_OPEN = '[';
var C_BRACKET_CLOSE = ']';
var C_CARET = '^';
var C_COLON = ':';

var EXPRESSION_INITIAL_TAB = /^( {4}|\t)?/gm;

/* Tokenise a footnote definition. */
function footnoteDefinition(eat, value, silent) {
  var self = this;
  var offsets = self.offset;
  var index;
  var length;
  var subvalue;
  var now;
  var currentLine;
  var content;
  var queue;
  var subqueue;
  var character;
  var identifier;
  var add;
  var exit;

  if (!self.options.footnotes) {
    return;
  }

  index = 0;
  length = value.length;
  subvalue = '';
  now = eat.now();
  currentLine = now.line;

  while (index < length) {
    character = value.charAt(index);

    if (!whitespace(character)) {
      break;
    }

    subvalue += character;
    index++;
  }

  if (
    value.charAt(index) !== C_BRACKET_OPEN ||
    value.charAt(index + 1) !== C_CARET
  ) {
    return;
  }

  subvalue += C_BRACKET_OPEN + C_CARET;
  index = subvalue.length;
  queue = '';

  while (index < length) {
    character = value.charAt(index);

    if (character === C_BRACKET_CLOSE) {
      break;
    } else if (character === C_BACKSLASH) {
      queue += character;
      index++;
      character = value.charAt(index);
    }

    queue += character;
    index++;
  }

  if (
    !queue ||
    value.charAt(index) !== C_BRACKET_CLOSE ||
    value.charAt(index + 1) !== C_COLON
  ) {
    return;
  }

  if (silent) {
    return true;
  }

  identifier = normalize(queue);
  subvalue += queue + C_BRACKET_CLOSE + C_COLON;
  index = subvalue.length;

  while (index < length) {
    character = value.charAt(index);

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

    subvalue += character;
    index++;
  }

  now.column += subvalue.length;
  now.offset += subvalue.length;
  queue = '';
  content = '';
  subqueue = '';

  while (index < length) {
    character = value.charAt(index);

    if (character === C_NEWLINE) {
      subqueue = character;
      index++;

      while (index < length) {
        character = value.charAt(index);

        if (character !== C_NEWLINE) {
          break;
        }

        subqueue += character;
        index++;
      }

      queue += subqueue;
      subqueue = '';

      while (index < length) {
        character = value.charAt(index);

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

        subqueue += character;
        index++;
      }

      if (subqueue.length === 0) {
        break;
      }

      queue += subqueue;
    }

    if (queue) {
      content += queue;
      queue = '';
    }

    content += character;
    index++;
  }

  subvalue += content;

  content = content.replace(EXPRESSION_INITIAL_TAB, function (line) {
    offsets[currentLine] = (offsets[currentLine] || 0) + line.length;
    currentLine++;

    return '';
  });

  add = eat(subvalue);

  exit = self.enterBlock();
  content = self.tokenizeBlock(content, now);
  exit();

  return add({
    type: 'footnoteDefinition',
    identifier: identifier,
    children: content
  });
}