'use strict';

const openBracket = '{'.charCodeAt(0);
const closeBracket = '}'.charCodeAt(0);
const openParen = '('.charCodeAt(0);
const closeParen = ')'.charCodeAt(0);
const singleQuote = '\''.charCodeAt(0);
const doubleQuote = '"'.charCodeAt(0);
const backslash = '\\'.charCodeAt(0);
const slash = '/'.charCodeAt(0);
const period = '.'.charCodeAt(0);
const comma = ','.charCodeAt(0);
const colon = ':'.charCodeAt(0);
const asterisk = '*'.charCodeAt(0);
const minus = '-'.charCodeAt(0);
const plus = '+'.charCodeAt(0);
const pound = '#'.charCodeAt(0);
const newline = '\n'.charCodeAt(0);
const space = ' '.charCodeAt(0);
const feed = '\f'.charCodeAt(0);
const tab = '\t'.charCodeAt(0);
const cr = '\r'.charCodeAt(0);
const at = '@'.charCodeAt(0);
const lowerE = 'e'.charCodeAt(0);
const upperE = 'E'.charCodeAt(0);
const digit0 = '0'.charCodeAt(0);
const digit9 = '9'.charCodeAt(0);
const lowerU = 'u'.charCodeAt(0);
const upperU = 'U'.charCodeAt(0);
const atEnd = /[ \n\t\r\{\(\)'"\\;,/]/g;
const wordEnd = /[ \n\t\r\(\)\{\}\*:;@!&'"\+\|~>,\[\]\\]|\/(?=\*)/g;
const wordEndNum = /[ \n\t\r\(\)\{\}\*:;@!&'"\-\+\|~>,\[\]\\]|\//g;
const alphaNum = /^[a-z0-9]/i;
const unicodeRange = /^[a-f0-9?\-]/i;

const util = require('util');
const TokenizeError = require('./errors/TokenizeError');

module.exports = function tokenize (input, options) {

  options = options || {};

  let tokens = [],
    css = input.valueOf(),
    length = css.length,
    offset = -1,
    line =  1,
    pos =  0,
    parentCount = 0,
    isURLArg = null,

    code, next, quote, lines, last, content, escape, nextLine, nextOffset,
    escaped, escapePos, nextChar;

  function unclosed (what) {
    let message = util.format('Unclosed %s at line: %d, column: %d, token: %d', what, line, pos - offset, pos);
    throw new TokenizeError(message);
  }

  function tokenizeError () {
    let message = util.format('Syntax error at line: %d, column: %d, token: %d', line, pos - offset, pos);
    throw new TokenizeError(message);
  }

  while (pos < length) {
    code = css.charCodeAt(pos);

    if (code === newline) {
      offset = pos;
      line  += 1;
    }

    switch (code) {
      case newline:
      case space:
      case tab:
      case cr:
      case feed:
        next = pos;
        do {
          next += 1;
          code = css.charCodeAt(next);
          if (code === newline) {
            offset = next;
            line  += 1;
          }
        } while (code === space   ||
          code === newline ||
          code === tab     ||
          code === cr      ||
          code === feed);

        tokens.push(['space', css.slice(pos, next),
          line, pos  - offset,
          line, next - offset,
          pos
        ]);

        pos = next - 1;
        break;

      case colon:
        next = pos + 1;
        tokens.push(['colon', css.slice(pos, next),
          line, pos  - offset,
          line, next - offset,
          pos
        ]);

        pos = next - 1;
        break;

      case comma:
        next = pos + 1;
        tokens.push(['comma', css.slice(pos, next),
          line, pos  - offset,
          line, next - offset,
          pos
        ]);

        pos = next - 1;
        break;

      case openBracket:
        tokens.push(['{', '{',
          line, pos  - offset,
          line, next - offset,
          pos
        ]);
        break;

      case closeBracket:
        tokens.push(['}', '}',
          line, pos  - offset,
          line, next - offset,
          pos
        ]);
        break;

      case openParen:
        parentCount++;
        isURLArg = !isURLArg && parentCount === 1 &&
          tokens.length > 0 &&
          tokens[tokens.length - 1][0] === "word" &&
          tokens[tokens.length - 1][1] === "url";
        tokens.push(['(', '(',
          line, pos  - offset,
          line, next - offset,
          pos
        ]);
        break;

      case closeParen:
        parentCount--;
        isURLArg = isURLArg && parentCount > 0;
        tokens.push([')', ')',
          line, pos  - offset,
          line, next - offset,
          pos
        ]);
        break;

      case singleQuote:
      case doubleQuote:
        quote = code === singleQuote ? '\'' : '"';
        next  = pos;
        do {
          escaped = false;
          next    = css.indexOf(quote, next + 1);
          if (next === -1) {
            unclosed('quote', quote);
          }
          escapePos = next;
          while (css.charCodeAt(escapePos - 1) === backslash) {
            escapePos -= 1;
            escaped = !escaped;
          }
        } while (escaped);

        tokens.push(['string', css.slice(pos, next + 1),
          line, pos  - offset,
          line, next - offset,
          pos
        ]);
        pos = next;
        break;

      case at:
        atEnd.lastIndex = pos + 1;
        atEnd.test(css);

        if (atEnd.lastIndex === 0) {
          next = css.length - 1;
        }
        else {
          next = atEnd.lastIndex - 2;
        }

        tokens.push(['atword', css.slice(pos, next + 1),
          line, pos  - offset,
          line, next - offset,
          pos
        ]);
        pos = next;
        break;

      case backslash:
        next   = pos;
        code = css.charCodeAt(next + 1);

        if (escape && (code !== slash && code !== space &&
                        code !== newline && code !== tab &&
                        code !== cr && code !== feed)) {
          next += 1;
        }

        tokens.push(['word', css.slice(pos, next + 1),
          line, pos  - offset,
          line, next - offset,
          pos
        ]);

        pos = next;
        break;

      case plus:
      case minus:
      case asterisk:
        next = pos + 1;
        nextChar = css.slice(pos + 1, next + 1);

        let prevChar = css.slice(pos - 1, pos);

        // if the operator is immediately followed by a word character, then we
        // have a prefix of some kind, and should fall-through. eg. -webkit

        // look for --* for custom variables
        if (code === minus && nextChar.charCodeAt(0) === minus) {
          next++;

          tokens.push(['word', css.slice(pos, next),
            line, pos  - offset,
            line, next - offset,
            pos
          ]);

          pos = next - 1;
          break;
        }

        tokens.push(['operator', css.slice(pos, next),
          line, pos  - offset,
          line, next - offset,
          pos
        ]);

        pos = next - 1;
        break;

      default:
        if (code === slash && (css.charCodeAt(pos + 1) === asterisk || (options.loose && !isURLArg && css.charCodeAt(pos + 1) === slash))) {
          const isStandardComment = css.charCodeAt(pos + 1) === asterisk;

          if (isStandardComment) {
            next = css.indexOf('*/', pos + 2) + 1;
            if (next === 0) {
              unclosed('comment', '*/');
            }
          }
          else {
            const newlinePos = css.indexOf('\n', pos + 2);

            next = newlinePos !== -1 ? newlinePos - 1 : length;
          }

          content = css.slice(pos, next + 1);
          lines   = content.split('\n');
          last    = lines.length - 1;

          if (last > 0) {
            nextLine   = line + last;
            nextOffset = next - lines[last].length;
          }
          else {
            nextLine   = line;
            nextOffset = offset;
          }

          tokens.push(['comment', content,
            line,     pos  - offset,
            nextLine, next - nextOffset,
            pos
          ]);

          offset = nextOffset;
          line   = nextLine;
          pos    = next;

        }
        else if (code === pound && !alphaNum.test(css.slice(pos + 1, pos + 2))) {
          next = pos + 1;

          tokens.push(['#', css.slice(pos, next),
            line, pos  - offset,
            line, next - offset,
            pos
          ]);

          pos = next - 1;
        }
        else if ((code === lowerU || code === upperU) && css.charCodeAt(pos + 1) === plus) {
          next = pos + 2;

          do {
            next += 1;
            code = css.charCodeAt(next);
          } while (next < length && unicodeRange.test(css.slice(next, next + 1)));

          tokens.push(['unicoderange', css.slice(pos, next),
            line, pos  - offset,
            line, next - offset,
            pos
          ]);
          pos = next - 1;
        }
        // catch a regular slash, that isn't a comment
        else if (code === slash) {
          next = pos + 1;

          tokens.push(['operator', css.slice(pos, next),
            line, pos  - offset,
            line, next - offset,
            pos
          ]);

          pos = next - 1;
        }
        else {
          let regex = wordEnd;

          // we're dealing with a word that starts with a number
          // those get treated differently
          if (code >= digit0 && code <= digit9) {
            regex = wordEndNum;
          }

          regex.lastIndex = pos + 1;
          regex.test(css);

          if (regex.lastIndex === 0) {
            next = css.length - 1;
          }
          else {
            next = regex.lastIndex - 2;
          }

          // Exponential number notation with minus or plus: 1e-10, 1e+10
          if (regex === wordEndNum || code === period) {
            let ncode = css.charCodeAt(next),
              ncode1 = css.charCodeAt(next + 1),
              ncode2 = css.charCodeAt(next + 2);

            if (
              (ncode === lowerE || ncode === upperE) &&
              (ncode1 === minus || ncode1 === plus) &&
              (ncode2 >= digit0 && ncode2 <= digit9)
            ) {
              wordEndNum.lastIndex = next + 2;
              wordEndNum.test(css);

              if (wordEndNum.lastIndex === 0) {
                next = css.length - 1;
              }
              else {
                next = wordEndNum.lastIndex - 2;
              }
            }
          }

          tokens.push(['word', css.slice(pos, next + 1),
            line, pos  - offset,
            line, next - offset,
            pos
          ]);
          pos = next;
        }
        break;
    }

    pos ++;
  }

  return tokens;
};