/**
 * Module dependencies.
 */

var EventEmitter = require('events').EventEmitter;

/**
 * Module exports.
 */

var exports = module.exports = keypress;

/**
 * This module offers the internal "keypress" functionality from node-core's
 * `readline` module, for your own programs and modules to use.
 *
 * The `keypress` function accepts a readable Stream instance and makes it
 * emit "keypress" events.
 *
 * Usage:
 *
 * ``` js
 * require('keypress')(process.stdin);
 *
 * process.stdin.on('keypress', function (ch, key) {
 *   console.log(ch, key);
 *   if (key.ctrl && key.name == 'c') {
 *     process.stdin.pause();
 *   }
 * });
 * proces.stdin.resume();
 * ```
 *
 * @param {Stream} stream
 * @api public
 */

function keypress(stream) {
  if (isEmittingKeypress(stream)) return;

  var StringDecoder = require('string_decoder').StringDecoder; // lazy load
  stream._keypressDecoder = new StringDecoder('utf8');

  function onData(b) {
    if (listenerCount(stream, 'keypress') > 0) {
      var r = stream._keypressDecoder.write(b);
      if (r) emitKey(stream, r);
    } else {
      // Nobody's watching anyway
      stream.removeListener('data', onData);
      stream.on('newListener', onNewListener);
    }
  }

  function onNewListener(event) {
    if (event == 'keypress') {
      stream.on('data', onData);
      stream.removeListener('newListener', onNewListener);
    }
  }

  if (listenerCount(stream, 'keypress') > 0) {
    stream.on('data', onData);
  } else {
    stream.on('newListener', onNewListener);
  }
}

/**
 * Returns `true` if the stream is already emitting "keypress" events.
 * `false` otherwise.
 *
 * @param {Stream} stream readable stream
 * @return {Boolean} `true` if the stream is emitting "keypress" events
 * @api private
 */

function isEmittingKeypress(stream) {
  var rtn = !!stream._keypressDecoder;
  if (!rtn) {
    // XXX: for older versions of node (v0.6.x, v0.8.x) we want to remove the
    // existing "data" and "newListener" keypress events since they won't include
    // this `keypress` module extensions (like "mousepress" events).
    stream.listeners('data').slice(0).forEach(function(l) {
      if (l.name == 'onData' && /emitKey/.test(l.toString())) {
        stream.removeListener('data', l);
      }
    });
    stream.listeners('newListener').slice(0).forEach(function(l) {
      if (l.name == 'onNewListener' && /keypress/.test(l.toString())) {
        stream.removeListener('newListener', l);
      }
    });
  }
  return rtn;
}

/**
 * Enables "mousepress" events on the *input* stream. Note that `stream` must be
 * an *output* stream (i.e. a Writable Stream instance), usually `process.stdout`.
 *
 * @param {Stream} stream writable stream instance
 * @api public
 */

exports.enableMouse = function (stream) {
  stream.write('\x1b[?1000h');
};

/**
 * Disables "mousepress" events from being sent to the *input* stream.
 * Note that `stream` must be an *output* stream (i.e. a Writable Stream instance),
 * usually `process.stdout`.
 *
 * @param {Stream} stream writable stream instance
 * @api public
 */

exports.disableMouse = function (stream) {
  stream.write('\x1b[?1000l');
};

/**
 * `EventEmitter.listenerCount()` polyfill, for backwards compat.
 *
 * @param {Emitter} emitter event emitter instance
 * @param {String} event event name
 * @return {Number} number of listeners for `event`
 * @api public
 */

var listenerCount = EventEmitter.listenerCount;
if (!listenerCount) {
  listenerCount = function(emitter, event) {
    return emitter.listeners(event).length;
  };
}


///////////////////////////////////////////////////////////////////////
// Below this function is code from node-core's `readline.js` module //
///////////////////////////////////////////////////////////////////////


/*
  Some patterns seen in terminal key escape codes, derived from combos seen
  at http://www.midnight-commander.org/browser/lib/tty/key.c

  ESC letter
  ESC [ letter
  ESC [ modifier letter
  ESC [ 1 ; modifier letter
  ESC [ num char
  ESC [ num ; modifier char
  ESC O letter
  ESC O modifier letter
  ESC O 1 ; modifier letter
  ESC N letter
  ESC [ [ num ; modifier char
  ESC [ [ 1 ; modifier letter
  ESC ESC [ num char
  ESC ESC O letter

  - char is usually ~ but $ and ^ also happen with rxvt
  - modifier is 1 +
                (shift     * 1) +
                (left_alt  * 2) +
                (ctrl      * 4) +
                (right_alt * 8)
  - two leading ESCs apparently mean the same as one leading ESC
*/

// Regexes used for ansi escape code splitting
var metaKeyCodeRe = /^(?:\x1b)([a-zA-Z0-9])$/;
var functionKeyCodeRe =
    /^(?:\x1b+)(O|N|\[|\[\[)(?:(\d+)(?:;(\d+))?([~^$])|(?:1;)?(\d+)?([a-zA-Z]))/;

function emitKey(stream, s) {
  var ch,
      key = {
        name: undefined,
        ctrl: false,
        meta: false,
        shift: false
      },
      parts;

  if (Buffer.isBuffer(s)) {
    if (s[0] > 127 && s[1] === undefined) {
      s[0] -= 128;
      s = '\x1b' + s.toString(stream.encoding || 'utf-8');
    } else {
      s = s.toString(stream.encoding || 'utf-8');
    }
  }

  key.sequence = s;

  if (s === '\r') {
    // carriage return
    key.name = 'return';

  } else if (s === '\n') {
    // enter, should have been called linefeed
    key.name = 'enter';

  } else if (s === '\t') {
    // tab
    key.name = 'tab';

  } else if (s === '\b' || s === '\x7f' ||
             s === '\x1b\x7f' || s === '\x1b\b') {
    // backspace or ctrl+h
    key.name = 'backspace';
    key.meta = (s.charAt(0) === '\x1b');

  } else if (s === '\x1b' || s === '\x1b\x1b') {
    // escape key
    key.name = 'escape';
    key.meta = (s.length === 2);

  } else if (s === ' ' || s === '\x1b ') {
    key.name = 'space';
    key.meta = (s.length === 2);

  } else if (s <= '\x1a') {
    // ctrl+letter
    key.name = String.fromCharCode(s.charCodeAt(0) + 'a'.charCodeAt(0) - 1);
    key.ctrl = true;

  } else if (s.length === 1 && s >= 'a' && s <= 'z') {
    // lowercase letter
    key.name = s;

  } else if (s.length === 1 && s >= 'A' && s <= 'Z') {
    // shift+letter
    key.name = s.toLowerCase();
    key.shift = true;

  } else if (parts = metaKeyCodeRe.exec(s)) {
    // meta+character key
    key.name = parts[1].toLowerCase();
    key.meta = true;
    key.shift = /^[A-Z]$/.test(parts[1]);

  } else if (parts = functionKeyCodeRe.exec(s)) {
    // ansi escape sequence

    // reassemble the key code leaving out leading \x1b's,
    // the modifier key bitflag and any meaningless "1;" sequence
    var code = (parts[1] || '') + (parts[2] || '') +
               (parts[4] || '') + (parts[6] || ''),
        modifier = (parts[3] || parts[5] || 1) - 1;

    // Parse the key modifier
    key.ctrl = !!(modifier & 4);
    key.meta = !!(modifier & 10);
    key.shift = !!(modifier & 1);
    key.code = code;

    // Parse the key itself
    switch (code) {
      /* xterm/gnome ESC O letter */
      case 'OP': key.name = 'f1'; break;
      case 'OQ': key.name = 'f2'; break;
      case 'OR': key.name = 'f3'; break;
      case 'OS': key.name = 'f4'; break;

      /* xterm/rxvt ESC [ number ~ */
      case '[11~': key.name = 'f1'; break;
      case '[12~': key.name = 'f2'; break;
      case '[13~': key.name = 'f3'; break;
      case '[14~': key.name = 'f4'; break;

      /* from Cygwin and used in libuv */
      case '[[A': key.name = 'f1'; break;
      case '[[B': key.name = 'f2'; break;
      case '[[C': key.name = 'f3'; break;
      case '[[D': key.name = 'f4'; break;
      case '[[E': key.name = 'f5'; break;

      /* common */
      case '[15~': key.name = 'f5'; break;
      case '[17~': key.name = 'f6'; break;
      case '[18~': key.name = 'f7'; break;
      case '[19~': key.name = 'f8'; break;
      case '[20~': key.name = 'f9'; break;
      case '[21~': key.name = 'f10'; break;
      case '[23~': key.name = 'f11'; break;
      case '[24~': key.name = 'f12'; break;

      /* xterm ESC [ letter */
      case '[A': key.name = 'up'; break;
      case '[B': key.name = 'down'; break;
      case '[C': key.name = 'right'; break;
      case '[D': key.name = 'left'; break;
      case '[E': key.name = 'clear'; break;
      case '[F': key.name = 'end'; break;
      case '[H': key.name = 'home'; break;

      /* xterm/gnome ESC O letter */
      case 'OA': key.name = 'up'; break;
      case 'OB': key.name = 'down'; break;
      case 'OC': key.name = 'right'; break;
      case 'OD': key.name = 'left'; break;
      case 'OE': key.name = 'clear'; break;
      case 'OF': key.name = 'end'; break;
      case 'OH': key.name = 'home'; break;

      /* xterm/rxvt ESC [ number ~ */
      case '[1~': key.name = 'home'; break;
      case '[2~': key.name = 'insert'; break;
      case '[3~': key.name = 'delete'; break;
      case '[4~': key.name = 'end'; break;
      case '[5~': key.name = 'pageup'; break;
      case '[6~': key.name = 'pagedown'; break;

      /* putty */
      case '[[5~': key.name = 'pageup'; break;
      case '[[6~': key.name = 'pagedown'; break;

      /* rxvt */
      case '[7~': key.name = 'home'; break;
      case '[8~': key.name = 'end'; break;

      /* rxvt keys with modifiers */
      case '[a': key.name = 'up'; key.shift = true; break;
      case '[b': key.name = 'down'; key.shift = true; break;
      case '[c': key.name = 'right'; key.shift = true; break;
      case '[d': key.name = 'left'; key.shift = true; break;
      case '[e': key.name = 'clear'; key.shift = true; break;

      case '[2$': key.name = 'insert'; key.shift = true; break;
      case '[3$': key.name = 'delete'; key.shift = true; break;
      case '[5$': key.name = 'pageup'; key.shift = true; break;
      case '[6$': key.name = 'pagedown'; key.shift = true; break;
      case '[7$': key.name = 'home'; key.shift = true; break;
      case '[8$': key.name = 'end'; key.shift = true; break;

      case 'Oa': key.name = 'up'; key.ctrl = true; break;
      case 'Ob': key.name = 'down'; key.ctrl = true; break;
      case 'Oc': key.name = 'right'; key.ctrl = true; break;
      case 'Od': key.name = 'left'; key.ctrl = true; break;
      case 'Oe': key.name = 'clear'; key.ctrl = true; break;

      case '[2^': key.name = 'insert'; key.ctrl = true; break;
      case '[3^': key.name = 'delete'; key.ctrl = true; break;
      case '[5^': key.name = 'pageup'; key.ctrl = true; break;
      case '[6^': key.name = 'pagedown'; key.ctrl = true; break;
      case '[7^': key.name = 'home'; key.ctrl = true; break;
      case '[8^': key.name = 'end'; key.ctrl = true; break;

      /* misc. */
      case '[Z': key.name = 'tab'; key.shift = true; break;
      default: key.name = 'undefined'; break;

    }
  } else if (s.length > 1 && s[0] !== '\x1b') {
    // Got a longer-than-one string of characters.
    // Probably a paste, since it wasn't a control sequence.
    Array.prototype.forEach.call(s, function(c) {
      emitKey(stream, c);
    });
    return;
  }

  // XXX: this "mouse" parsing code is NOT part of the node-core standard
  // `readline.js` module, and is a `keypress` module non-standard extension.
  if (key.code == '[M') {
    key.name = 'mouse';
    var s = key.sequence;
    var b = s.charCodeAt(3);
    key.x = s.charCodeAt(4) - 040;
    key.y = s.charCodeAt(5) - 040;

    key.scroll = 0;

    key.ctrl  = !!(1<<4 & b);
    key.meta  = !!(1<<3 & b);
    key.shift = !!(1<<2 & b);

    key.release = (3 & b) === 3;

    if (1<<6 & b) { //scroll
      key.scroll = 1 & b ? 1 : -1;
    }

    if (!key.release && !key.scroll) {
      key.button = b & 3;
    }
  }

  // Don't emit a key if no name was found
  if (key.name === undefined) {
    key = undefined;
  }

  if (s.length === 1) {
    ch = s;
  }

  if (key && key.name == 'mouse') {
    stream.emit('mousepress', key);
  } else if (key || ch) {
    stream.emit('keypress', ch, key);
  }
}