package flash

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"visiona-local/server/internal/device"
	"visiona-local/server/internal/driver"
	"visiona-local/server/internal/model"
)

func isCompatible(modelHardware []string, deviceType string) bool {
	dt := strings.ToUpper(deviceType)
	for _, hw := range modelHardware {
		if strings.ToUpper(hw) == dt || strings.Contains(dt, strings.ToUpper(hw)) {
			return true
		}
	}
	return false
}

func resolveModelPath(filePath string, deviceType string) string {
	if filePath == "" {
		return filePath
	}

	targetChip := ""
	if strings.Contains(strings.ToLower(deviceType), "kl720") {
		targetChip = "kl720"
	} else if strings.Contains(strings.ToLower(deviceType), "kl520") {
		targetChip = "kl520"
	}
	if targetChip == "" {
		return filePath
	}

	if strings.Contains(filePath, "/"+targetChip+"/") {
		return filePath
	}

	dir := filepath.Dir(filePath)
	base := filepath.Base(filePath)

	sourceChip := ""
	if strings.Contains(dir, "kl520") {
		sourceChip = "kl520"
	} else if strings.Contains(dir, "kl720") {
		sourceChip = "kl720"
	}

	if sourceChip != "" && sourceChip != targetChip {
		newDir := strings.Replace(dir, sourceChip, targetChip, 1)
		newBase := strings.Replace(base, sourceChip, targetChip, 1)
		candidate := filepath.Join(newDir, newBase)
		if _, err := os.Stat(candidate); err == nil {
			return candidate
		}
	}

	return filePath
}

type Service struct {
	deviceMgr *device.Manager
	modelRepo *model.Repository
	tracker   *ProgressTracker
}

func NewService(deviceMgr *device.Manager, modelRepo *model.Repository) *Service {
	return &Service{
		deviceMgr: deviceMgr,
		modelRepo: modelRepo,
		tracker:   NewProgressTracker(),
	}
}

// CleanupTask 清除已完成的 flash task（由 handler goroutine 在讀取完 progressCh 後呼叫）。
func (s *Service) CleanupTask(taskID string) {
	s.tracker.Remove(taskID)
}

func (s *Service) StartFlash(deviceID, modelID string) (string, <-chan driver.FlashProgress, error) {
	session, err := s.deviceMgr.GetDevice(deviceID)
	if err != nil {
		return "", nil, fmt.Errorf("device not found: %w", err)
	}
	if !session.Driver.IsConnected() {
		return "", nil, fmt.Errorf("device not connected")
	}

	m, err := s.modelRepo.GetByID(modelID)
	if err != nil {
		return "", nil, fmt.Errorf("model not found: %w", err)
	}

	deviceInfo := session.Driver.Info()
	if !isCompatible(m.SupportedHardware, deviceInfo.Type) {
		return "", nil, fmt.Errorf("model not compatible with device type %s", deviceInfo.Type)
	}

	modelPath := m.FilePath
	if modelPath == "" {
		return "", nil, fmt.Errorf("model %s has no .nef file path", modelID)
	}

	modelPath = resolveModelPath(modelPath, deviceInfo.Type)

	taskID := fmt.Sprintf("flash-%s-%s", deviceID, modelID)

	// M3 fix: 防止同裝置同模型重複 flash
	task := s.tracker.Create(taskID, deviceID, modelID)
	if task == nil {
		return "", nil, fmt.Errorf("flash already in progress for device %s model %s", deviceID, modelID)
	}

	go func() {
		// M1 fix: 先跑 driver.Flash，收集 error，最後才寫 error message + close channel。
		// driver.Flash 內部會多次寫入 task.ProgressCh（進度更新），我們不能在它還在寫的時候 close。
		// driver.Flash 返回時保證不會再寫入 progressCh。

		time.Sleep(500 * time.Millisecond)

		flashErr := session.Driver.Flash(modelPath, task.ProgressCh)

		// Flash 完成或失敗後，driver 不會再寫 progressCh，安全地寫 error 訊息然後 close。
		if flashErr != nil {
			task.ProgressCh <- driver.FlashProgress{
				Percent: -1,
				Stage:   "error",
				Error:   flashErr.Error(),
			}
		}

		task.Done = true
		close(task.ProgressCh)
		// M2 note: 不在這裡 Remove — 讓 handler 讀完 progressCh 後呼叫 CleanupTask
	}()

	return taskID, task.ProgressCh, nil
}