package director

import (
	"sync"

	"code.google.com/p/go.net/context"
	"github.com/drone/drone/server/worker"
	"github.com/drone/drone/server/worker/pool"
)

// Director manages workloads and delegates to workers.
type Director struct {
	sync.Mutex

	pending map[*worker.Work]bool
	started map[*worker.Work]worker.Worker
}

func New() *Director {
	return &Director{
		pending: make(map[*worker.Work]bool),
		started: make(map[*worker.Work]worker.Worker),
	}
}

// Do processes the work request async.
func (d *Director) Do(c context.Context, work *worker.Work) {
	defer func() {
		recover()
	}()

	d.do(c, work)
}

// do is a blocking function that waits for an
// available worker to process work.
func (d *Director) do(c context.Context, work *worker.Work) {
	d.markPending(work)
	var pool = pool.FromContext(c)
	var worker = <-pool.Reserve()

	//	var worker worker.Worker
	//
	//	// waits for an available worker. This is a blocking
	//	// operation and will reject any nil workers to avoid
	//	// a potential panic.
	//	select {
	//	case worker = <-pool.Reserve():
	//		if worker != nil {
	//			break
	//		}
	//	}

	d.markStarted(work, worker)
	worker.Do(c, work)
	d.markComplete(work)
	pool.Release(worker)
}

// GetStarted returns a list of all jobs that
// are assigned and being worked on.
func (d *Director) GetStarted() []*worker.Work {
	d.Lock()
	defer d.Unlock()
	started := []*worker.Work{}
	for work, _ := range d.started {
		started = append(started, work)
	}
	return started
}

// GetPending returns a list of all work that
// is pending assignment to a worker.
func (d *Director) GetPending() []*worker.Work {
	d.Lock()
	defer d.Unlock()
	pending := []*worker.Work{}
	for work, _ := range d.pending {
		pending = append(pending, work)
	}
	return pending
}

// GetAssignments returns a list of assignments. The
// assignment type is a structure that stores the
// work being performed and the assigned worker.
func (d *Director) GetAssignemnts() []*worker.Assignment {
	d.Lock()
	defer d.Unlock()
	assignments := []*worker.Assignment{}
	for work, _worker := range d.started {
		assignment := &worker.Assignment{Work: work, Worker: _worker}
		assignments = append(assignments, assignment)
	}
	return assignments
}

func (d *Director) markPending(work *worker.Work) {
	d.Lock()
	defer d.Unlock()
	delete(d.started, work)
	d.pending[work] = true
}

func (d *Director) markStarted(work *worker.Work, worker worker.Worker) {
	d.Lock()
	defer d.Unlock()
	delete(d.pending, work)
	d.started[work] = worker
}

func (d *Director) markComplete(work *worker.Work) {
	d.Lock()
	defer d.Unlock()
	delete(d.pending, work)
	delete(d.started, work)
}