var once = require('once');

var noop = function () {};

var isRequest = function (stream) {
  return stream.setHeader && typeof stream.abort === 'function';
};

var isChildProcess = function (stream) {
  return (
    stream.stdio && Array.isArray(stream.stdio) && stream.stdio.length === 3
  );
};

var eos = function (stream, opts, callback) {
  if (typeof opts === 'function') return eos(stream, null, opts);
  if (!opts) opts = {};

  callback = once(callback || noop);

  var ws = stream._writableState;
  var rs = stream._readableState;
  var readable = opts.readable || (opts.readable !== false && stream.readable);
  var writable = opts.writable || (opts.writable !== false && stream.writable);
  var cancelled = false;

  var onlegacyfinish = function () {
    if (!stream.writable) onfinish();
  };

  var onfinish = function () {
    writable = false;
    if (!readable) callback.call(stream);
  };

  var onend = function () {
    readable = false;
    if (!writable) callback.call(stream);
  };

  var onexit = function (exitCode) {
    callback.call(
      stream,
      exitCode ? new Error('exited with error code: ' + exitCode) : null
    );
  };

  var onerror = function (err) {
    callback.call(stream, err);
  };

  var onclose = function () {
    process.nextTick(onclosenexttick);
  };

  var onclosenexttick = function () {
    if (cancelled) return;
    if (readable && !(rs && rs.ended && !rs.destroyed))
      return callback.call(stream, new Error('premature close'));
    if (writable && !(ws && ws.ended && !ws.destroyed))
      return callback.call(stream, new Error('premature close'));
  };

  var onrequest = function () {
    stream.req.on('finish', onfinish);
  };

  if (isRequest(stream)) {
    stream.on('complete', onfinish);
    stream.on('abort', onclose);
    if (stream.req) onrequest();
    else stream.on('request', onrequest);
  } else if (writable && !ws) {
    // legacy streams
    stream.on('end', onlegacyfinish);
    stream.on('close', onlegacyfinish);
  }

  if (isChildProcess(stream)) stream.on('exit', onexit);

  stream.on('end', onend);
  stream.on('finish', onfinish);
  if (opts.error !== false) stream.on('error', onerror);
  stream.on('close', onclose);

  return function () {
    cancelled = true;
    stream.removeListener('complete', onfinish);
    stream.removeListener('abort', onclose);
    stream.removeListener('request', onrequest);
    if (stream.req) stream.req.removeListener('finish', onfinish);
    stream.removeListener('end', onlegacyfinish);
    stream.removeListener('close', onlegacyfinish);
    stream.removeListener('finish', onfinish);
    stream.removeListener('exit', onexit);
    stream.removeListener('end', onend);
    stream.removeListener('error', onerror);
    stream.removeListener('close', onclose);
  };
};

module.exports = eos;