/* shterm.js: browser-side JavaScript to handle I/O for termemu.js when it 
 * is running a shell via the webtty.js server.
 */

var isalive = false; // Whether the session is currently active.
var conn = null; // WebSocket

function writeData(hexstr) {
  var codenum;
  var codes = [];
  var nc;
  var u8wait = 0; /* Stores bits from previous bytes of multibyte sequences. */
  var expect = 0; /* The number of 10------ bytes expected. */
  /* UTF-8 translation. */
  for (var i = 0; i < hexstr.length; i += 2) {
    nc = Number("0x" + hexstr.substr(i, 2));
    if (nc < 0x7F) {
      /* 0------- */
      codes.push(nc);
      /* Any incomplete sequence will be discarded. */
      u8wait = 0;
      expect = 0;
    }
    else if (nc < 0xC0) {
      /* 10------ : part of a multibyte sequence */
      if (expect > 0) {
        u8wait <<= 6;
        u8wait += (nc & 0x3F);
        expect--;
        if (expect == 0) {
          codes.push(u8wait);
          u8wait = 0;
        }
      }
      else {
        /* Assume an initial byte was missed. */
        u8wait = 0;
      }
    }
    /* These will all discard any incomplete sequence. */
    else if (nc < 0xE0) {
      /* 110----- : introduces 2-byte sequence */
      u8wait = (nc & 0x1F);
      expect = 1;
    }
    else if (nc < 0xF0) {
      /* 1110---- : introduces 3-byte sequence */
      u8wait = (nc & 0x0F);
      expect = 2;
    }
    else if (nc < 0xF8) {
      /* 11110--- : introduces 4-byte sequence */
      u8wait = (nc & 0x07);
      expect = 3;
    }
    else if (nc < 0xFC) {
      /* 111110-- : introduces 5-byte sequence */
      u8wait = (nc & 0x03);
      expect = 4;
    }
    else if (nc < 0xFE) {
      /* 1111110- : introduces 6-byte sequence */
      u8wait = (nc & 0x01);
      expect = 5;
    }
    else {
      /* 1111111- : should never appear */
      u8wait = 0;
      expect = 0;
    }
    /* Supporting all 31 bits is probably overkill... */
  }
  termemu.write(codes);
  return;
}

function sendback(str) {
  /* For responding to terminal queries. */
  if (conn) {
    var msgObj = {"t": "d", "d": str};
    conn.send(JSON.stringify(msgObj));
  }
  else {
    debug(1, "No connection: cannot send " + str);
  }
  return;
}

function sendkey(ev) {
  if (!isalive)
    return;
  var keynum = ev.keyCode;
  var code;
  if (keynum >= 65 && keynum <= 90) {
    /* Letters. */
    if (ev.ctrlKey)
      keynum -= 64;
    else if (!ev.shiftKey)
      keynum += 32;
    code = keynum.toString(16);
    if (code.length < 2)
      code = "0" + code;
  }
  else if (keynum >= 48 && keynum <= 57) {
    /* The number row. */
    if (ev.shiftKey) {
      code = numShifts[keynum - 48].toString(16);
    }
    else {
      code = keynum.toString(16);
    }
  }
  else if (keynum in keyHexCodes) {
    if (ev.shiftKey)
      code = keyHexCodes[keynum][1];
    else
      code = keyHexCodes[keynum][0];
  }
  else if (keynum >= 16 && keynum <= 20) {
    return;
  }
  else {
    debug(1, "Ignoring keycode " + keynum);
    return;
  }
  ev.preventDefault();
  var msgObj = {"t": "d", "d": code};
  conn.send(JSON.stringify(msgObj));
  //dkey(code);
  return;
}

var charshifts = { '-': "5f", '=': "2b", '[': "7b", ']': "7d", '\\': "7c",
  ';': "3a", '\'': "22", ',': "3c", '.': "3e", '/': "3f", '`': "7e"
}

var kpkeys = { "KP1": "1b4f46", "KP2": "1b4f42", "KP3": "1b5b367e", 
               "KP4": "1b4f44", "KP5": "1b5b45", "KP6": "1b4f43", 
               "KP7": "1b4f48", "KP8": "1b4f41", "KP9": "1b5b357e" };

function vkey(c) {
  if (!isalive)
    return;
  var keystr;
  if (c.match(/^[a-z]$/)) {
    if (termemu.ctrlp()) {
      var n = c.charCodeAt(0) - 96;
      keystr = n.toString(16);
      if (keystr.length < 2)
        keystr = "0" + keystr;
    }
    else if (termemu.shiftp())
      keystr = c.toUpperCase().charCodeAt(0).toString(16);
    else
      keystr = c.charCodeAt(0).toString(16);
  }
  else if (c.match(/^[0-9]$/)) {
    if (termemu.shiftp())
      keystr = numShifts[c.charCodeAt(0) - 48].toString(16);
    else
      keystr = c.charCodeAt(0).toString(16);
  }
  else if (c == '\n')
    keystr = "0a";
  else if (c == '\t')
    keystr = "09";
  else if (c == '\b')
    keystr = "08";
  else if (c == ' ')
    keystr = "20";
  else if (c in charshifts) {
    if (termemu.shiftp())
      keystr = charshifts[c];
    else
      keystr = c.charCodeAt(0).toString(16);
  }
  else if (c in kpkeys) {
    keystr = kpkeys[c];
  }
  else
    return;
  //writeData("Sending " + keystr);
  var msgObj = {"t": "d", "d": keystr};
  conn.send(JSON.stringify(msgObj));
  return;
}

function setup() {
  keyHexCodes.init();
  termemu.init("termwrap", 24, 80);
  setTitle("Not connected.");
  return;
}

function toggleshift() {
  termemu.toggleshift();
  keydiv = document.getElementById("shiftkey");
  if (termemu.shiftp())
    keydiv.className = "keysel";
  else
    keydiv.className = "key";
  return;
}

function togglectrl() {
  termemu.togglectrl();
  keydiv = document.getElementById("ctrlkey");
  if (termemu.ctrlp())
    keydiv.className = "keysel";
  else
    keydiv.className = "key";
  return;
}

function login(h, w) {
  if (conn)
    return;
  if (!(window.WebSocket)) {
    debug(1, "Cannot connect: WebSockets not supported");
    return;
  }
  var sockurl = "ws://" + window.location.host + "/sock?w=" + w + "&h=" + h;
  conn = new WebSocket(sockurl);
  conn.onopen = function (event) {
    isalive = true;
    setTitle("Logged in");
    debug(1, "Logged in via WebSocket");
  }
  conn.onmessage = function (event) {
    var msgObj = JSON.parse(event.data);
    if (msgObj.t == 'l') {
      termemu.resize(msgObj.h, msgObj.w);
    }
    else if (msgObj.t == 'd') {
      debug(0, msgObj.d);
      writeData(msgObj.d);
    }
    else if (msgObj.t == 'q') {
      debug(0, "Quit message!");
      conn.close();
    }
  }
  conn.onclose = function (event) {
    conn = null;
    isalive = false;
    debug(1, "WebSocket connection closed.");
    setTitle("Not connected.");
  }
}

function stop() {
  if (conn) {
    conn.close();
  }
  else {
    debug(1, "Cannot stop: connection already closed");
  }
  return;
}

function setTitle(tstr) {
  var titlespan = document.getElementById("ttitle");
  var tnode = document.createTextNode(tstr);
  if (titlespan.childNodes.length == 0)
    titlespan.appendChild(tnode);
  else
    titlespan.replaceChild(tnode, titlespan.childNodes[0]);
  return;
}

function debug(level, msg) {
  if (level < debugSuppress)
    return;
  var msgdiv = document.createElement("div");
  var msgtext = document.createTextNode(msg);
  msgdiv.appendChild(msgtext);
  document.getElementById("debug").appendChild(msgdiv);
  return;
}

/* This should be a termemu method. */
function textsize(larger) {
  var cssSize = document.getElementById("term").style.fontSize;
  if (!cssSize)
    return;
  var match = cssSize.match(/\d*/);
  if (!match)
    return;
  var csize = Number(match[0]);
  var nsize;
  if (larger) {
    if (csize >= 48)
      nsize = 48;
    else if (csize >= 20)
      nsize = csize + 4;
    else if (csize >= 12)
      nsize = csize + 2;
    else if (csize >= 8)
      nsize = csize + 1;
    else
      nsize = 8;
  }
  else {
    if (csize <= 8)
      nsize = 8;
    else if (csize <= 12)
      nsize = csize - 1;
    else if (csize <= 20)
      nsize = csize - 2;
    else if (csize <= 48)
      nsize = csize - 4;
    else
      nsize = 48;
  }
  document.getElementById("term").style.fontSize = nsize.toString() + "px";
  termemu.fixsize();
  debug(1, "Changing font size to " + nsize.toString());
  return;
}

function bell(on) {
  var imgnode = document.getElementById("bell");
  if (on) {
    imgnode.style.visibility = "visible";
    window.setTimeout(bell, 1500, false);
  }
  else
    imgnode.style.visibility = "hidden";
  return;
}

function dkey(codestr) {
  var dstr = "Keystring: ";
  for (var i = 0; i < codestr.length; i += 2) {
    code = Number("0x" + codestr.substr(i, 2));
    if (code < 32 || (code >= 127 && code < 160))
      dstr += "\\x" + code.toString(16);
    else
      dstr += String.fromCharCode(code);
  }
  debug(1, dstr);
  return;
}