package ingest

import (
	"sync"
	"time"
)

// WorkerStatus 描述日志后台 worker 的当前运行状态。
type WorkerStatus struct {
	Name            string    `json:"name"`
	Running         bool      `json:"running"`
	LastStartedAt   time.Time `json:"last_started_at,omitempty"`
	LastSucceededAt time.Time `json:"last_succeeded_at,omitempty"`
	LastErrorAt     time.Time `json:"last_error_at,omitempty"`
	LastError       string    `json:"last_error,omitempty"`
	QueueDepth      *int64    `json:"queue_depth,omitempty"`
}

func markWorkerQueueDepth(name string, depth int64) {
	lifecycle.Lock()
	status := lifecycle.workers[name]
	status.Name = name
	status.QueueDepth = new(int64)
	*status.QueueDepth = depth
	lifecycle.workers[name] = status
	lifecycle.Unlock()
}

var lifecycle = struct {
	sync.RWMutex
	wg      sync.WaitGroup
	workers map[string]WorkerStatus
}{workers: make(map[string]WorkerStatus)}

func startWorker(name string, run func() error) {
	lifecycle.Lock()
	lifecycle.workers[name] = WorkerStatus{Name: name, Running: true, LastStartedAt: time.Now().UTC()}
	lifecycle.wg.Add(1)
	lifecycle.Unlock()
	go func() {
		defer lifecycle.wg.Done()
		err := run()
		lifecycle.Lock()
		status := lifecycle.workers[name]
		status.Running = false
		if err != nil {
			status.LastErrorAt = time.Now().UTC()
			status.LastError = err.Error()
		}
		lifecycle.workers[name] = status
		lifecycle.Unlock()
	}()
}

func markWorkerSucceeded(name string) {
	lifecycle.Lock()
	status := lifecycle.workers[name]
	status.Name = name
	status.LastSucceededAt = time.Now().UTC()
	status.LastError = ""
	lifecycle.workers[name] = status
	lifecycle.Unlock()
}

func markWorkerError(name string, err error) {
	if err == nil {
		return
	}
	lifecycle.Lock()
	status := lifecycle.workers[name]
	status.Name = name
	status.LastErrorAt = time.Now().UTC()
	status.LastError = err.Error()
	lifecycle.workers[name] = status
	lifecycle.Unlock()
}

// WorkerStatuses 返回状态快照。
func WorkerStatuses() []WorkerStatus {
	lifecycle.RLock()
	defer lifecycle.RUnlock()
	result := make([]WorkerStatus, 0, len(lifecycle.workers))
	for _, status := range lifecycle.workers {
		if status.QueueDepth != nil {
			depth := *status.QueueDepth
			status.QueueDepth = &depth
		}
		result = append(result, status)
	}
	return result
}

// Wait 等待后台 worker 退出，返回是否在超时内完成。
func Wait(timeout time.Duration) bool {
	done := make(chan struct{})
	go func() {
		lifecycle.wg.Wait()
		close(done)
	}()
	select {
	case <-done:
		return true
	case <-time.After(timeout):
		return false
	}
}