const fs = require("fs")
    , util = require("util")
    , EventEmitter = require("events").EventEmitter
    , {eviocgrab, eviocgid} = require("bindings")("ioctl.node")
    , events = require("./events");

const arch = (process.arch.indexOf("64")>=0)?64:32;

function Device(path) {
  this.grabbed = false;
  if (path) this.open(path);
}

util.inherits(Device, EventEmitter);

Device.prototype.open = function(path) {
  this.stream = fs
    .createReadStream(path, {flags: "r", autoClose: true})
    .on("error", e => this.emit("error", e))
    .on("open", fd => { this.fd = fd;
      try { this.id = eviocgid(fd); }
      catch(e) { this.emit("error",
        new Error("Reader eviocgid error:"+e)); }
      if (this.grabbed) eviocgrab(this.fd, 1);
      this.emit("open", fd); })
    .on("data", buf => {
      var i, j, chunk = (arch===64)?24:16;
      for (i=0, j=buf.length; i<j; i+=chunk) {
        const e = parse(buf.slice(i, i+chunk));
        this.emit("event", e);
        this.emit(e.type, e);
      }});
};

Device.prototype.close = function() {
  this.grabbed = false;
  this.stream.close();
  delete this.stream;
  delete this.fd;
  delete this.id;
};

Device.prototype.grab = function() {
  if (this.grabbed) return; this.grabbed = true;
  if (this.fd) eviocgrab(this.fd, 1);
};

Device.prototype.ungrab = function() {
  if (!this.grabbed) return; this.grabbed = false;
  if (this.fd) eviocgrab(this.fd, 0);
};

// struct input_event {
//   struct timeval {
//     long tv_sec;  // s32/64 (arch)
//     long tv_usec; // LE (always?)
//   } time;
//   __u16 type;
//   __u16 code;
//   __s32 value;
// };
function parse(buf) {
  var e = {time: {sec: null, usec: null},
    type: null, code: null, value: null};

  var offset;
  if (arch === 64) { offset = 16;
    e.time.sec  = buf.readBigInt64LE(0);
    e.time.usec = buf.readBigInt64LE(8);
  } else { offset = 8;
    e.time.sec  = buf.readInt32LE(0);
    e.time.usec = buf.readInt32LE(4);
  }

  e.type = buf.readUInt16LE(offset);
  e.code = buf.readUInt16LE(offset + 2);
  e.value = buf.readInt32LE(offset + 4);

  if (events.types[e.type])
    e.type = events.types[e.type];
  if (events[e.type] && events[e.type][e.code])
    e.code = events[e.type][e.code];

  return e;
};

module.exports = Device;