module.exports = function(grunt) {

  var taskrun = {
    waiting: 'Waiting...',
    cliArgs: null,
    nameArgs: null,
    changedFiles: Object.create(null),
    startedAt: false,
  };

  // Do this when watch has completed
  taskrun.completed = function completed() {
    grunt.log.writeln('').write(String(
      'Completed in ' +
      Number((Date.now() - taskrun.startedAt) / 1000).toFixed(3) +
      's at ' +
      (new Date()).toString()
    ).cyan + ' - ' + taskrun.waiting);
    taskrun.startedAt = false;
  };

  // Do this when watch has been triggered
  taskrun.triggered = function triggered() {
    grunt.log.ok();
    Object.keys(taskrun.changedFiles).forEach(function(filepath) {
      // Log which file has changed, and how.
      grunt.log.ok('File "' + filepath + '" ' + taskrun.changedFiles[filepath] + '.');
    });
    // Reset changedFiles
    taskrun.changedFiles = Object.create(null);
  };

  // Do this when a task is interrupted
  taskrun.interrupt = function interrupt() {
    grunt.log.writeln('').write('Scheduled tasks have been interrupted...'.yellow);
    taskrun.startedAt = false;
  };

  // Keep track of spawned processes
  var spawned = Object.create(null);

  taskrun.spawn = function spawn(id, tasks, options, done) {
    // If interrupted, reset the spawned for a target
    if (options.interrupt && typeof spawned[id] === 'object') {
      taskrun.interrupt();
      spawned[id].kill('SIGINT');
      delete spawned[id];
    }

    // Only spawn one at a time unless interrupt is specified
    if (!spawned[id]) {
      taskrun.triggered();

      // Spawn the tasks as a child process
      taskrun.startedAt = Date.now();
      spawned[id] = grunt.util.spawn({
        // Spawn with the grunt bin
        grunt: true,
        // Run from current working dir and inherit stdio from process
        opts: {cwd: process.cwd(), stdio: 'inherit'},
        // Run grunt this process uses, append the task to be run and any cli options
        args: grunt.util._.union(tasks, taskrun.cliArgs)
      }, function(err, res, code) {
        // Spawn is done
        delete spawned[id];
        taskrun.completed();
      });
    }
  };

  taskrun.nospawn = function nospawn(id, tasks, options, done) {
    // If interrupted, clear the task queue and start over
    if (options.interrupt && taskrun.startedAt !== false) {
      grunt.task.clearQueue({untilMarker: true});
      taskrun.interrupt();
    }

    if (taskrun.startedAt !== false) {
      return;
    }

    taskrun.triggered();

    // Mark tasks to run and enqueue this task afterward
    taskrun.startedAt = Date.now();
    grunt.task.run(tasks).mark().run(taskrun.nameArgs);

    // Finish the task
    done();
  };

  return taskrun;
};