package mining

import (
	"context"
	"sync"
	"time"

	"forge.lthn.ai/Snider/Mining/pkg/logging"
)

// supervisor.RegisterTask("cleanup", func(ctx context.Context) { runCleanup(ctx) }, 30*time.Second, 10)
type TaskFunc func(ctx context.Context)

// task := &SupervisedTask{name: "stats-collector", restartDelay: 5 * time.Second, maxRestarts: -1}
type SupervisedTask struct {
	name          string
	task          TaskFunc
	restartDelay  time.Duration
	maxRestarts   int
	restartCount  int
	running       bool
	lastStartTime time.Time
	cancel        context.CancelFunc
	mutex         sync.Mutex
}

// supervisor := NewTaskSupervisor()
// supervisor.RegisterTask("stats-collector", collectStats, 5*time.Second, -1)
// supervisor.Start(); defer supervisor.Stop()
type TaskSupervisor struct {
	tasks   map[string]*SupervisedTask
	ctx     context.Context
	cancel  context.CancelFunc
	waitGroup sync.WaitGroup
	mutex   sync.RWMutex
	started bool
}

// supervisor := NewTaskSupervisor()
// supervisor.RegisterTask("stats-collector", collectStats, 5*time.Second, -1)
// supervisor.Start()
func NewTaskSupervisor() *TaskSupervisor {
	ctx, cancel := context.WithCancel(context.Background())
	return &TaskSupervisor{
		tasks:  make(map[string]*SupervisedTask),
		ctx:    ctx,
		cancel: cancel,
	}
}

// supervisor.RegisterTask("stats-collector", collectStats, 5*time.Second, -1)
// supervisor.RegisterTask("cleanup", runCleanup, 30*time.Second, 10)
func (supervisor *TaskSupervisor) RegisterTask(name string, task TaskFunc, restartDelay time.Duration, maxRestarts int) {
	supervisor.mutex.Lock()
	defer supervisor.mutex.Unlock()

	supervisor.tasks[name] = &SupervisedTask{
		name:         name,
		task:         task,
		restartDelay: restartDelay,
		maxRestarts:  maxRestarts,
	}
}

// supervisor.Start()  // begins all registered tasks; no-op if already started
func (supervisor *TaskSupervisor) Start() {
	supervisor.mutex.Lock()
	if supervisor.started {
		supervisor.mutex.Unlock()
		return
	}
	supervisor.started = true
	supervisor.mutex.Unlock()

	supervisor.mutex.RLock()
	for name, task := range supervisor.tasks {
		supervisor.startTask(name, task)
	}
	supervisor.mutex.RUnlock()
}

// supervisor.startTask("stats-collector", supervisor.tasks["stats-collector"])
func (supervisor *TaskSupervisor) startTask(name string, st *SupervisedTask) {
	st.mutex.Lock()
	if st.running {
		st.mutex.Unlock()
		return
	}
	st.running = true
	st.lastStartTime = time.Now()

	taskCtx, taskCancel := context.WithCancel(supervisor.ctx)
	st.cancel = taskCancel
	st.mutex.Unlock()

	supervisor.waitGroup.Add(1)
	go func() {
		defer supervisor.waitGroup.Done()

		for {
			select {
			case <-supervisor.ctx.Done():
				return
			default:
			}

			// Run the task with panic recovery
			func() {
				defer func() {
					if r := recover(); r != nil {
						logging.Error("supervised task panicked", logging.Fields{
							"task":  name,
							"panic": r,
						})
					}
				}()
				st.task(taskCtx)
			}()

			// Check if we should restart
			st.mutex.Lock()
			st.restartCount++
			shouldRestart := st.restartCount <= st.maxRestarts || st.maxRestarts < 0
			restartDelay := st.restartDelay
			st.mutex.Unlock()

			if !shouldRestart {
				logging.Warn("supervised task reached max restarts", logging.Fields{
					"task":       name,
					"maxRestart": st.maxRestarts,
				})
				return
			}

			select {
			case <-supervisor.ctx.Done():
				return
			case <-time.After(restartDelay):
				logging.Info("restarting supervised task", logging.Fields{
					"task":         name,
					"restartCount": st.restartCount,
				})
			}
		}
	}()

	logging.Info("started supervised task", logging.Fields{"task": name})
}

// supervisor.Stop()  // cancels all tasks and waits for clean exit
func (supervisor *TaskSupervisor) Stop() {
	supervisor.cancel()
	supervisor.waitGroup.Wait()

	supervisor.mutex.Lock()
	supervisor.started = false
	for _, task := range supervisor.tasks {
		task.mutex.Lock()
		task.running = false
		task.mutex.Unlock()
	}
	supervisor.mutex.Unlock()

	logging.Info("task supervisor stopped")
}

// running, restarts, ok := supervisor.GetTaskStatus("stats-collector")
func (supervisor *TaskSupervisor) GetTaskStatus(name string) (running bool, restartCount int, found bool) {
	supervisor.mutex.RLock()
	task, ok := supervisor.tasks[name]
	supervisor.mutex.RUnlock()

	if !ok {
		return false, 0, false
	}

	task.mutex.Lock()
	defer task.mutex.Unlock()
	return task.running, task.restartCount, true
}

// for name, status := range supervisor.GetAllTaskStatuses() { log(name, status.Running) }
func (supervisor *TaskSupervisor) GetAllTaskStatuses() map[string]TaskStatus {
	supervisor.mutex.RLock()
	defer supervisor.mutex.RUnlock()

	statuses := make(map[string]TaskStatus, len(supervisor.tasks))
	for name, task := range supervisor.tasks {
		task.mutex.Lock()
		statuses[name] = TaskStatus{
			Name:         name,
			Running:      task.running,
			RestartCount: task.restartCount,
			LastStart:    task.lastStartTime,
		}
		task.mutex.Unlock()
	}
	return statuses
}

// status := supervisor.GetAllTaskStatuses()["stats-collector"]
// if status.Running { log(status.RestartCount, status.LastStart) }
type TaskStatus struct {
	Name         string    `json:"name"`
	Running      bool      `json:"running"`
	RestartCount int       `json:"restartCount"`
	LastStart    time.Time `json:"lastStart"`
}