/*!
 * split-string <https://github.com/jonschlinkert/split-string>
 *
 * Copyright (c) 2015-2017, Jon Schlinkert.
 * Released under the MIT License.
 */

'use strict';

var extend = require('extend-shallow');

module.exports = function(str, options, fn) {
  if (typeof str !== 'string') {
    throw new TypeError('expected a string');
  }

  if (typeof options === 'function') {
    fn = options;
    options = null;
  }

  // allow separator to be defined as a string
  if (typeof options === 'string') {
    options = { sep: options };
  }

  var opts = extend({sep: '.'}, options);
  var quotes = opts.quotes || ['"', "'", '`'];
  var brackets;

  if (opts.brackets === true) {
    brackets = {
      '<': '>',
      '(': ')',
      '[': ']',
      '{': '}'
    };
  } else if (opts.brackets) {
    brackets = opts.brackets;
  }

  var tokens = [];
  var stack = [];
  var arr = [''];
  var sep = opts.sep;
  var len = str.length;
  var idx = -1;
  var closeIdx;

  function expected() {
    if (brackets && stack.length) {
      return brackets[stack[stack.length - 1]];
    }
  }

  while (++idx < len) {
    var ch = str[idx];
    var next = str[idx + 1];
    var tok = { val: ch, idx: idx, arr: arr, str: str };
    tokens.push(tok);

    if (ch === '\\') {
      tok.val = keepEscaping(opts, str, idx) === true ? (ch + next) : next;
      tok.escaped = true;
      if (typeof fn === 'function') {
        fn(tok);
      }
      arr[arr.length - 1] += tok.val;
      idx++;
      continue;
    }

    if (brackets && brackets[ch]) {
      stack.push(ch);
      var e = expected();
      var i = idx + 1;

      if (str.indexOf(e, i + 1) !== -1) {
        while (stack.length && i < len) {
          var s = str[++i];
          if (s === '\\') {
            s++;
            continue;
          }

          if (quotes.indexOf(s) !== -1) {
            i = getClosingQuote(str, s, i + 1);
            continue;
          }

          e = expected();
          if (stack.length && str.indexOf(e, i + 1) === -1) {
            break;
          }

          if (brackets[s]) {
            stack.push(s);
            continue;
          }

          if (e === s) {
            stack.pop();
          }
        }
      }

      closeIdx = i;
      if (closeIdx === -1) {
        arr[arr.length - 1] += ch;
        continue;
      }

      ch = str.slice(idx, closeIdx + 1);
      tok.val = ch;
      tok.idx = idx = closeIdx;
    }

    if (quotes.indexOf(ch) !== -1) {
      closeIdx = getClosingQuote(str, ch, idx + 1);
      if (closeIdx === -1) {
        arr[arr.length - 1] += ch;
        continue;
      }

      if (keepQuotes(ch, opts) === true) {
        ch = str.slice(idx, closeIdx + 1);
      } else {
        ch = str.slice(idx + 1, closeIdx);
      }

      tok.val = ch;
      tok.idx = idx = closeIdx;
    }

    if (typeof fn === 'function') {
      fn(tok, tokens);
      ch = tok.val;
      idx = tok.idx;
    }

    if (tok.val === sep && tok.split !== false) {
      arr.push('');
      continue;
    }

    arr[arr.length - 1] += tok.val;
  }

  return arr;
};

function getClosingQuote(str, ch, i, brackets) {
  var idx = str.indexOf(ch, i);
  if (str.charAt(idx - 1) === '\\') {
    return getClosingQuote(str, ch, idx + 1);
  }
  return idx;
}

function keepQuotes(ch, opts) {
  if (opts.keepDoubleQuotes === true && ch === '"') return true;
  if (opts.keepSingleQuotes === true && ch === "'") return true;
  return opts.keepQuotes;
}

function keepEscaping(opts, str, idx) {
  if (typeof opts.keepEscaping === 'function') {
    return opts.keepEscaping(str, idx);
  }
  return opts.keepEscaping === true || str[idx + 1] === '\\';
}