// Filename: internal/service/key_import_service.go
package service

import (
	"context"
	"encoding/json"
	"fmt"
	"gemini-balancer/internal/models"
	"gemini-balancer/internal/repository"
	"gemini-balancer/internal/store"
	"gemini-balancer/internal/task"
	"gemini-balancer/internal/utils"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/sirupsen/logrus"
)

const (
	TaskTypeAddKeysToGroup      = "add_keys_to_group"
	TaskTypeUnlinkKeysFromGroup = "unlink_keys_from_group"
	TaskTypeHardDeleteKeys      = "hard_delete_keys"
	TaskTypeRestoreKeys         = "restore_keys"
	chunkSize                   = 500
)

type KeyImportService struct {
	taskService   task.Reporter
	keyRepo       repository.KeyRepository
	store         store.Store
	logger        *logrus.Entry
	apiKeyService *APIKeyService
}

func NewKeyImportService(ts task.Reporter, kr repository.KeyRepository, s store.Store, as *APIKeyService, logger *logrus.Logger) *KeyImportService {
	return &KeyImportService{
		taskService:   ts,
		keyRepo:       kr,
		store:         s,
		logger:        logger.WithField("component", "KeyImportService🚀"),
		apiKeyService: as,
	}
}

func (s *KeyImportService) runTaskWithRecovery(ctx context.Context, taskID string, resourceID string, taskFunc func()) {
	defer func() {
		if r := recover(); r != nil {
			err := fmt.Errorf("panic recovered in task %s: %v", taskID, r)
			s.logger.Error(err)
			s.taskService.EndTaskByID(ctx, taskID, resourceID, nil, err)
		}
	}()
	taskFunc()
}

func (s *KeyImportService) StartAddKeysTask(ctx context.Context, groupID uint, keysText string, validateOnImport bool) (*task.Status, error) {
	keys := utils.ParseKeysFromText(keysText)
	if len(keys) == 0 {
		return nil, fmt.Errorf("no valid keys found in input text")
	}
	resourceID := fmt.Sprintf("group-%d", groupID)

	taskStatus, err := s.taskService.StartTask(ctx, uint(groupID), TaskTypeAddKeysToGroup, resourceID, len(keys), 15*time.Minute)
	if err != nil {
		return nil, err
	}
	go s.runTaskWithRecovery(context.Background(), taskStatus.ID, resourceID, func() {
		s.runAddKeysTask(context.Background(), taskStatus.ID, resourceID, groupID, keys, validateOnImport)
	})
	return taskStatus, nil
}

func (s *KeyImportService) StartUnlinkKeysTask(ctx context.Context, groupID uint, keysText string) (*task.Status, error) {
	keys := utils.ParseKeysFromText(keysText)
	if len(keys) == 0 {
		return nil, fmt.Errorf("no valid keys found")
	}
	resourceID := fmt.Sprintf("group-%d", groupID)
	taskStatus, err := s.taskService.StartTask(ctx, uint(groupID), TaskTypeUnlinkKeysFromGroup, resourceID, len(keys), time.Hour)
	if err != nil {
		return nil, err
	}
	go s.runTaskWithRecovery(context.Background(), taskStatus.ID, resourceID, func() {
		s.runUnlinkKeysTask(context.Background(), taskStatus.ID, resourceID, groupID, keys)
	})
	return taskStatus, nil
}

func (s *KeyImportService) StartHardDeleteKeysTask(ctx context.Context, keysText string) (*task.Status, error) {
	keys := utils.ParseKeysFromText(keysText)
	if len(keys) == 0 {
		return nil, fmt.Errorf("no valid keys found")
	}
	resourceID := "global_hard_delete"
	taskStatus, err := s.taskService.StartTask(ctx, 0, TaskTypeHardDeleteKeys, resourceID, len(keys), time.Hour)
	if err != nil {
		return nil, err
	}
	go s.runTaskWithRecovery(context.Background(), taskStatus.ID, resourceID, func() {
		s.runHardDeleteKeysTask(context.Background(), taskStatus.ID, resourceID, keys)
	})
	return taskStatus, nil
}

func (s *KeyImportService) StartRestoreKeysTask(ctx context.Context, keysText string) (*task.Status, error) {
	keys := utils.ParseKeysFromText(keysText)
	if len(keys) == 0 {
		return nil, fmt.Errorf("no valid keys found")
	}
	resourceID := "global_restore_keys"

	taskStatus, err := s.taskService.StartTask(ctx, 0, TaskTypeRestoreKeys, resourceID, len(keys), time.Hour)
	if err != nil {
		return nil, err
	}
	go s.runTaskWithRecovery(context.Background(), taskStatus.ID, resourceID, func() {
		s.runRestoreKeysTask(context.Background(), taskStatus.ID, resourceID, keys)
	})
	return taskStatus, nil
}

func (s *KeyImportService) runAddKeysTask(ctx context.Context, taskID string, resourceID string, groupID uint, keys []string, validateOnImport bool) {
	uniqueKeysMap := make(map[string]struct{})
	var uniqueKeyStrings []string
	for _, kStr := range keys {
		if _, exists := uniqueKeysMap[kStr]; !exists {
			uniqueKeysMap[kStr] = struct{}{}
			uniqueKeyStrings = append(uniqueKeyStrings, kStr)
		}
	}
	if len(uniqueKeyStrings) == 0 {
		s.taskService.EndTaskByID(ctx, taskID, resourceID, gin.H{"newly_linked_count": 0, "already_linked_count": 0}, nil)
		return
	}
	keysToEnsure := make([]models.APIKey, len(uniqueKeyStrings))
	for i, keyStr := range uniqueKeyStrings {
		keysToEnsure[i] = models.APIKey{APIKey: keyStr}
	}
	allKeyModels, err := s.keyRepo.AddKeys(keysToEnsure)
	if err != nil {
		s.taskService.EndTaskByID(ctx, taskID, resourceID, nil, fmt.Errorf("failed to ensure keys exist: %w", err))
		return
	}
	alreadyLinkedModels, err := s.keyRepo.GetKeysByValuesAndGroupID(uniqueKeyStrings, groupID)
	if err != nil {
		s.taskService.EndTaskByID(ctx, taskID, resourceID, nil, fmt.Errorf("failed to check for already linked keys: %w", err))
		return
	}
	alreadyLinkedIDSet := make(map[uint]struct{})
	for _, key := range alreadyLinkedModels {
		alreadyLinkedIDSet[key.ID] = struct{}{}
	}
	var keysToLink []models.APIKey
	for _, key := range allKeyModels {
		if _, exists := alreadyLinkedIDSet[key.ID]; !exists {
			keysToLink = append(keysToLink, key)
		}
	}

	if err := s.taskService.UpdateTotalByID(ctx, taskID, len(keysToLink)); err != nil {
		s.logger.WithError(err).Warnf("Failed to update total for task %s", taskID)
	}
	if len(keysToLink) > 0 {
		idsToLink := make([]uint, len(keysToLink))
		for i, key := range keysToLink {
			idsToLink[i] = key.ID
		}
		for i := 0; i < len(idsToLink); i += chunkSize {
			end := i + chunkSize
			if end > len(idsToLink) {
				end = len(idsToLink)
			}
			chunk := idsToLink[i:end]
			if err := s.keyRepo.LinkKeysToGroup(ctx, groupID, chunk); err != nil {
				s.taskService.EndTaskByID(ctx, taskID, resourceID, nil, fmt.Errorf("chunk failed to link keys: %w", err))
				return
			}
			_ = s.taskService.UpdateProgressByID(ctx, taskID, i+len(chunk))
		}
	}

	result := gin.H{
		"newly_linked_count":   len(keysToLink),
		"already_linked_count": len(alreadyLinkedIDSet),
		"total_linked_count":   len(allKeyModels),
	}
	if len(keysToLink) > 0 {
		idsToLink := make([]uint, len(keysToLink))
		for i, key := range keysToLink {
			idsToLink[i] = key.ID
		}
		if validateOnImport {
			s.publishImportGroupCompletedEvent(ctx, groupID, idsToLink)
			for _, keyID := range idsToLink {
				s.publishSingleKeyChangeEvent(ctx, groupID, keyID, "", models.StatusPendingValidation, "key_linked")
			}
		} else {
			for _, keyID := range idsToLink {
				if _, err := s.apiKeyService.UpdateMappingStatus(ctx, groupID, keyID, models.StatusActive); err != nil {
					s.logger.Errorf("Failed to directly activate key ID %d in group %d: %v", keyID, groupID, err)
				}
			}
		}
	}
	s.taskService.EndTaskByID(ctx, taskID, resourceID, result, nil)
}

func (s *KeyImportService) runUnlinkKeysTask(ctx context.Context, taskID, resourceID string, groupID uint, keys []string) {
	uniqueKeysMap := make(map[string]struct{})
	var uniqueKeys []string
	for _, kStr := range keys {
		if _, exists := uniqueKeysMap[kStr]; !exists {
			uniqueKeysMap[kStr] = struct{}{}
			uniqueKeys = append(uniqueKeys, kStr)
		}
	}
	keysToUnlink, err := s.keyRepo.GetKeysByValuesAndGroupID(uniqueKeys, groupID)
	if err != nil {
		s.taskService.EndTaskByID(ctx, taskID, resourceID, nil, fmt.Errorf("failed to find keys to unlink: %w", err))
		return
	}

	if len(keysToUnlink) == 0 {
		result := gin.H{"unlinked_count": 0, "hard_deleted_count": 0, "not_found_count": len(uniqueKeys)}
		s.taskService.EndTaskByID(ctx, taskID, resourceID, result, nil)
		return
	}
	idsToUnlink := make([]uint, len(keysToUnlink))
	for i, key := range keysToUnlink {
		idsToUnlink[i] = key.ID
	}

	if err := s.taskService.UpdateTotalByID(ctx, taskID, len(idsToUnlink)); err != nil {
		s.logger.WithError(err).Warnf("Failed to update total for task %s", taskID)
	}
	var totalUnlinked int64
	for i := 0; i < len(idsToUnlink); i += chunkSize {
		end := i + chunkSize
		if end > len(idsToUnlink) {
			end = len(idsToUnlink)
		}
		chunk := idsToUnlink[i:end]
		unlinked, err := s.keyRepo.UnlinkKeysFromGroup(ctx, groupID, chunk)
		if err != nil {
			s.taskService.EndTaskByID(ctx, taskID, resourceID, nil, fmt.Errorf("chunk failed: could not unlink keys: %w", err))
			return
		}
		totalUnlinked += unlinked
		for _, keyID := range chunk {
			s.publishSingleKeyChangeEvent(ctx, groupID, keyID, models.StatusActive, "", "key_unlinked")
		}
		_ = s.taskService.UpdateProgressByID(ctx, taskID, i+len(chunk))
	}

	totalDeleted, err := s.keyRepo.DeleteOrphanKeys()
	if err != nil {
		s.logger.WithError(err).Warn("Orphan key cleanup failed after unlink task.")
	}
	result := gin.H{
		"unlinked_count":     totalUnlinked,
		"hard_deleted_count": totalDeleted,
		"not_found_count":    len(uniqueKeys) - int(totalUnlinked),
	}
	s.taskService.EndTaskByID(ctx, taskID, resourceID, result, nil)
}

func (s *KeyImportService) runHardDeleteKeysTask(ctx context.Context, taskID, resourceID string, keys []string) {
	var totalDeleted int64
	for i := 0; i < len(keys); i += chunkSize {
		end := i + chunkSize
		if end > len(keys) {
			end = len(keys)
		}
		chunk := keys[i:end]

		deleted, err := s.keyRepo.HardDeleteByValues(chunk)
		if err != nil {
			s.taskService.EndTaskByID(ctx, taskID, resourceID, nil, fmt.Errorf("failed to hard delete chunk: %w", err))
			return
		}
		totalDeleted += deleted
		_ = s.taskService.UpdateProgressByID(ctx, taskID, i+len(chunk))
	}
	result := gin.H{
		"hard_deleted_count": totalDeleted,
		"not_found_count":    int64(len(keys)) - totalDeleted,
	}
	s.taskService.EndTaskByID(ctx, taskID, resourceID, result, nil)
	s.publishChangeEvent(ctx, 0, "keys_hard_deleted")
}

func (s *KeyImportService) runRestoreKeysTask(ctx context.Context, taskID, resourceID string, keys []string) {
	var restoredCount int64
	for i := 0; i < len(keys); i += chunkSize {
		end := i + chunkSize
		if end > len(keys) {
			end = len(keys)
		}
		chunk := keys[i:end]

		count, err := s.keyRepo.UpdateMasterStatusByValues(chunk, models.MasterStatusActive)
		if err != nil {
			s.taskService.EndTaskByID(ctx, taskID, resourceID, nil, fmt.Errorf("failed to restore chunk: %w", err))
			return
		}
		restoredCount += count
		_ = s.taskService.UpdateProgressByID(ctx, taskID, i+len(chunk))
	}
	result := gin.H{
		"restored_count":  restoredCount,
		"not_found_count": int64(len(keys)) - restoredCount,
	}
	s.taskService.EndTaskByID(ctx, taskID, resourceID, result, nil)
	s.publishChangeEvent(ctx, 0, "keys_bulk_restored")
}

func (s *KeyImportService) publishSingleKeyChangeEvent(ctx context.Context, groupID, keyID uint, oldStatus, newStatus models.APIKeyStatus, reason string) {
	event := models.KeyStatusChangedEvent{
		GroupID:      groupID,
		KeyID:        keyID,
		OldStatus:    oldStatus,
		NewStatus:    newStatus,
		ChangeReason: reason,
		ChangedAt:    time.Now(),
	}
	eventData, _ := json.Marshal(event)
	if err := s.store.Publish(ctx, models.TopicKeyStatusChanged, eventData); err != nil {
		s.logger.WithError(err).WithFields(logrus.Fields{
			"group_id": groupID,
			"key_id":   keyID,
			"reason":   reason,
		}).Error("Failed to publish single key change event.")
	}
}

func (s *KeyImportService) publishChangeEvent(ctx context.Context, groupID uint, reason string) {
	event := models.KeyStatusChangedEvent{
		GroupID:      groupID,
		ChangeReason: reason,
	}
	eventData, _ := json.Marshal(event)
	_ = s.store.Publish(ctx, models.TopicKeyStatusChanged, eventData)
}

func (s *KeyImportService) publishImportGroupCompletedEvent(ctx context.Context, groupID uint, keyIDs []uint) {
	if len(keyIDs) == 0 {
		return
	}
	event := models.ImportGroupCompletedEvent{
		GroupID:     groupID,
		KeyIDs:      keyIDs,
		CompletedAt: time.Now(),
	}
	eventData, err := json.Marshal(event)
	if err != nil {
		s.logger.WithError(err).Error("Failed to marshal ImportGroupCompletedEvent.")
		return
	}
	if err := s.store.Publish(ctx, models.TopicImportGroupCompleted, eventData); err != nil {
		s.logger.WithError(err).Error("Failed to publish ImportGroupCompletedEvent.")
	} else {
		s.logger.Infof("Published ImportGroupCompletedEvent for group %d with %d keys.", groupID, len(keyIDs))
	}
}

func (s *KeyImportService) StartUnlinkKeysByFilterTask(ctx context.Context, groupID uint, statuses []string) (*task.Status, error) {
	s.logger.Infof("Starting unlink task for group %d with status filter: %v", groupID, statuses)
	keyValues, err := s.keyRepo.FindKeyValuesByStatus(groupID, statuses)
	if err != nil {
		return nil, fmt.Errorf("failed to find keys by filter: %w", err)
	}
	if len(keyValues) == 0 {
		return nil, fmt.Errorf("no keys found matching the provided filter")
	}
	keysAsText := strings.Join(keyValues, "\n")
	s.logger.Infof("Found %d keys to unlink for group %d.", len(keyValues), groupID)
	return s.StartUnlinkKeysTask(ctx, groupID, keysAsText)
}