// Filename: internal/service/group_manager.go (Syncer升级版)

package service

import (
	"encoding/json"
	"errors"
	"fmt"
	"gemini-balancer/internal/models"
	"gemini-balancer/internal/pkg/reflectutil"
	"gemini-balancer/internal/repository"
	"gemini-balancer/internal/settings"
	"gemini-balancer/internal/syncer"
	"gemini-balancer/internal/utils"
	"net/url"
	"path"
	"sort"
	"strings"
	"time"

	"github.com/sirupsen/logrus"
	"gorm.io/datatypes"
	"gorm.io/gorm"
)

const GroupUpdateChannel = "groups:cache_invalidation"

type GroupManagerCacheData struct {
	Groups          []*models.KeyGroup
	GroupsByName    map[string]*models.KeyGroup
	GroupsByID      map[uint]*models.KeyGroup
	KeyCounts       map[uint]int64                         // GroupID -> Total Key Count
	KeyStatusCounts map[uint]map[models.APIKeyStatus]int64 // GroupID -> Status -> Count
}

type GroupManager struct {
	db              *gorm.DB
	keyRepo         repository.KeyRepository
	groupRepo       repository.GroupRepository
	settingsManager *settings.SettingsManager
	syncer          *syncer.CacheSyncer[GroupManagerCacheData]
	logger          *logrus.Entry
}

type UpdateOrderPayload struct {
	ID    uint `json:"id" binding:"required"`
	Order int  `json:"order"`
}

func NewGroupManagerLoader(db *gorm.DB, logger *logrus.Logger) syncer.LoaderFunc[GroupManagerCacheData] {
	return func() (GroupManagerCacheData, error) {
		logger.Debugf("[GML-LOG 1/5] ---> Entering NewGroupManagerLoader...")
		var groups []*models.KeyGroup
		logger.Debugf("[GML-LOG 2/5] About to execute DB query with Preloads...")

		if err := db.Preload("AllowedUpstreams").
			Preload("AllowedModels").
			Preload("Settings").
			Preload("RequestConfig").
			Find(&groups).Error; err != nil {
			logger.Errorf("[GML-LOG] CRITICAL: DB query for groups failed: %v", err)
			return GroupManagerCacheData{}, fmt.Errorf("failed to load key groups for cache: %w", err)
		}
		logger.Debugf("[GML-LOG 2.1/5] DB query for groups finished. Found %d group records.", len(groups))

		var allMappings []*models.GroupAPIKeyMapping
		if err := db.Find(&allMappings).Error; err != nil {
			logger.Errorf("[GML-LOG] CRITICAL: DB query for mappings failed: %v", err)
			return GroupManagerCacheData{}, fmt.Errorf("failed to load key mappings for cache: %w", err)
		}
		logger.Debugf("[GML-LOG 2.2/5] DB query for mappings finished. Found %d total mapping records.", len(allMappings))

		mappingsByGroupID := make(map[uint][]*models.GroupAPIKeyMapping)
		for i := range allMappings {
			mapping := allMappings[i] // Avoid pointer issues with range
			mappingsByGroupID[mapping.KeyGroupID] = append(mappingsByGroupID[mapping.KeyGroupID], mapping)
		}

		for _, group := range groups {
			if mappings, ok := mappingsByGroupID[group.ID]; ok {
				group.Mappings = mappings
			}
		}
		logger.Debugf("[GML-LOG 3/5] Finished manually associating mappings to groups.")

		keyCounts := make(map[uint]int64, len(groups))
		keyStatusCounts := make(map[uint]map[models.APIKeyStatus]int64, len(groups))

		for _, group := range groups {
			keyCounts[group.ID] = int64(len(group.Mappings))
			statusCounts := make(map[models.APIKeyStatus]int64)
			for _, mapping := range group.Mappings {
				statusCounts[mapping.Status]++
			}
			keyStatusCounts[group.ID] = statusCounts
		}
		groupsByName := make(map[string]*models.KeyGroup, len(groups))
		groupsByID := make(map[uint]*models.KeyGroup, len(groups))

		logger.Debugf("[GML-LOG 4/5] Starting to process group records into maps...")
		for i, group := range groups {
			if group == nil {
				logger.Debugf("[GML] CRITICAL: Found a 'nil' group pointer at index %d! This is the most likely cause of the panic.", i)
			} else {
				groupsByName[group.Name] = group
				groupsByID[group.ID] = group
			}
		}
		logger.Debugf("[GML-LOG 5/5] Finished processing records. Building final cache data...")
		return GroupManagerCacheData{
			Groups:          groups,
			GroupsByName:    groupsByName,
			GroupsByID:      groupsByID,
			KeyCounts:       keyCounts,
			KeyStatusCounts: keyStatusCounts,
		}, nil
	}
}

func NewGroupManager(
	db *gorm.DB,
	keyRepo repository.KeyRepository,
	groupRepo repository.GroupRepository,
	sm *settings.SettingsManager,
	syncer *syncer.CacheSyncer[GroupManagerCacheData],
	logger *logrus.Logger,
) *GroupManager {
	return &GroupManager{
		db:              db,
		keyRepo:         keyRepo,
		groupRepo:       groupRepo,
		settingsManager: sm,
		syncer:          syncer,
		logger:          logger.WithField("component", "GroupManager"),
	}
}

func (gm *GroupManager) GetAllGroups() []*models.KeyGroup {
	cache := gm.syncer.Get()
	if len(cache.Groups) == 0 {
		return []*models.KeyGroup{}
	}
	groupsToOrder := cache.Groups
	sort.Slice(groupsToOrder, func(i, j int) bool {
		if groupsToOrder[i].Order != groupsToOrder[j].Order {
			return groupsToOrder[i].Order < groupsToOrder[j].Order
		}
		return groupsToOrder[i].ID < groupsToOrder[j].ID
	})
	return groupsToOrder
}

func (gm *GroupManager) GetKeyCount(groupID uint) int64 {
	cache := gm.syncer.Get()
	if len(cache.KeyCounts) == 0 {
		return 0
	}
	count := cache.KeyCounts[groupID]
	return count
}

func (gm *GroupManager) GetKeyStatusCount(groupID uint) map[models.APIKeyStatus]int64 {
	cache := gm.syncer.Get()
	if len(cache.KeyStatusCounts) == 0 {
		return make(map[models.APIKeyStatus]int64)
	}
	if counts, ok := cache.KeyStatusCounts[groupID]; ok {
		return counts
	}
	return make(map[models.APIKeyStatus]int64)
}

func (gm *GroupManager) GetGroupByName(name string) (*models.KeyGroup, bool) {
	cache := gm.syncer.Get()
	if len(cache.GroupsByName) == 0 {
		return nil, false
	}
	group, ok := cache.GroupsByName[name]
	return group, ok
}

func (gm *GroupManager) GetGroupByID(id uint) (*models.KeyGroup, bool) {
	cache := gm.syncer.Get()
	if len(cache.GroupsByID) == 0 {
		return nil, false
	}
	group, ok := cache.GroupsByID[id]
	return group, ok
}

func (gm *GroupManager) Stop() {
	gm.syncer.Stop()
}

func (gm *GroupManager) Invalidate() error {
	return gm.syncer.Invalidate()
}

// --- Write Operations ---

// CreateKeyGroup creates a new key group, including its operational settings, and invalidates the cache.
func (gm *GroupManager) CreateKeyGroup(group *models.KeyGroup, settings *models.KeyGroupSettings) error {
	if !utils.IsValidGroupName(group.Name) {
		return errors.New("invalid group name: must contain only lowercase letters, numbers, and hyphens")
	}
	err := gm.db.Transaction(func(tx *gorm.DB) error {
		// 1. Create the group itself to get an ID
		if err := tx.Create(group).Error; err != nil {
			return err
		}

		// 2. If settings are provided, create the associated GroupSettings record
		if settings != nil {
			// Only marshal non-nil fields to keep the JSON clean
			settingsToMarshal := make(map[string]interface{})
			if settings.EnableKeyCheck != nil {
				settingsToMarshal["enable_key_check"] = settings.EnableKeyCheck
			}
			if settings.KeyCheckIntervalMinutes != nil {
				settingsToMarshal["key_check_interval_minutes"] = settings.KeyCheckIntervalMinutes
			}
			if settings.KeyBlacklistThreshold != nil {
				settingsToMarshal["key_blacklist_threshold"] = settings.KeyBlacklistThreshold
			}
			if settings.KeyCooldownMinutes != nil {
				settingsToMarshal["key_cooldown_minutes"] = settings.KeyCooldownMinutes
			}
			if settings.KeyCheckConcurrency != nil {
				settingsToMarshal["key_check_concurrency"] = settings.KeyCheckConcurrency
			}
			if settings.KeyCheckEndpoint != nil {
				settingsToMarshal["key_check_endpoint"] = settings.KeyCheckEndpoint
			}
			if settings.KeyCheckModel != nil {
				settingsToMarshal["key_check_model"] = settings.KeyCheckModel
			}
			if settings.MaxRetries != nil {
				settingsToMarshal["max_retries"] = settings.MaxRetries
			}
			if settings.EnableSmartGateway != nil {
				settingsToMarshal["enable_smart_gateway"] = settings.EnableSmartGateway
			}
			if len(settingsToMarshal) > 0 {
				settingsJSON, err := json.Marshal(settingsToMarshal)
				if err != nil {
					return fmt.Errorf("failed to marshal group settings: %w", err)
				}
				groupSettings := models.GroupSettings{
					GroupID:      group.ID,
					SettingsJSON: datatypes.JSON(settingsJSON),
				}
				if err := tx.Create(&groupSettings).Error; err != nil {
					return fmt.Errorf("failed to save group settings: %w", err)
				}
			}
		}
		return nil
	})

	if err != nil {
		return err
	}

	go gm.Invalidate()
	return nil
}

// UpdateKeyGroup updates an existing key group, its settings, and associations, then invalidates the cache.
func (gm *GroupManager) UpdateKeyGroup(group *models.KeyGroup, newSettings *models.KeyGroupSettings, upstreamURLs []string, modelNames []string) error {
	if !utils.IsValidGroupName(group.Name) {
		return fmt.Errorf("invalid group name: must contain only lowercase letters, numbers, and hyphens")
	}
	uniqueUpstreamURLs := uniqueStrings(upstreamURLs)
	uniqueModelNames := uniqueStrings(modelNames)
	err := gm.db.Transaction(func(tx *gorm.DB) error {
		// --- 1. Update AllowedUpstreams (M:N relationship) ---
		var upstreams []*models.UpstreamEndpoint
		if len(uniqueUpstreamURLs) > 0 {
			if err := tx.Where("url IN ?", uniqueUpstreamURLs).Find(&upstreams).Error; err != nil {
				return err
			}
		}
		if err := tx.Model(group).Association("AllowedUpstreams").Replace(upstreams); err != nil {
			return err
		}

		if err := tx.Model(group).Association("AllowedModels").Clear(); err != nil {
			return err
		}
		if len(uniqueModelNames) > 0 {
			var newMappings []models.GroupModelMapping
			for _, name := range uniqueModelNames {
				newMappings = append(newMappings, models.GroupModelMapping{ModelName: name})
			}
			if err := tx.Model(group).Association("AllowedModels").Append(newMappings); err != nil {
				return err
			}
		}

		if err := tx.Model(group).Updates(group).Error; err != nil {
			return err
		}

		var existingSettings models.GroupSettings
		if err := tx.Where("group_id = ?", group.ID).First(&existingSettings).Error; err != nil && err != gorm.ErrRecordNotFound {
			return err
		}
		var currentSettingsData models.KeyGroupSettings
		if len(existingSettings.SettingsJSON) > 0 {
			if err := json.Unmarshal(existingSettings.SettingsJSON, &currentSettingsData); err != nil {
				return fmt.Errorf("failed to unmarshal existing group settings: %w", err)
			}
		}
		if err := reflectutil.MergeNilFields(&currentSettingsData, newSettings); err != nil {
			return fmt.Errorf("failed to merge group settings: %w", err)
		}
		updatedJSON, err := json.Marshal(currentSettingsData)
		if err != nil {
			return fmt.Errorf("failed to marshal updated group settings: %w", err)
		}
		existingSettings.GroupID = group.ID
		existingSettings.SettingsJSON = datatypes.JSON(updatedJSON)
		return tx.Save(&existingSettings).Error
	})
	if err == nil {
		go gm.Invalidate()
	}
	return err
}

// DeleteKeyGroup deletes a key group and subsequently cleans up any keys that have become orphans.
func (gm *GroupManager) DeleteKeyGroup(id uint) error {
	err := gm.db.Transaction(func(tx *gorm.DB) error {
		gm.logger.Infof("Starting transaction to delete KeyGroup ID: %d", id)
		// Step 1: First, retrieve the group object we are about to delete.
		var group models.KeyGroup
		if err := tx.First(&group, id).Error; err != nil {
			if err == gorm.ErrRecordNotFound {
				gm.logger.Warnf("Attempted to delete a non-existent KeyGroup with ID: %d", id)
				return nil // Don't treat as an error, the group is already gone.
			}
			gm.logger.WithError(err).Errorf("Failed to find KeyGroup with ID: %d for deletion", id)
			return err
		}
		// Step 2: Clear all many-to-many and one-to-many associations using GORM's safe methods.
		if err := tx.Model(&group).Association("AllowedUpstreams").Clear(); err != nil {
			gm.logger.WithError(err).Errorf("Failed to clear 'AllowedUpstreams' association for KeyGroup ID: %d", id)
			return err
		}
		if err := tx.Model(&group).Association("AllowedModels").Clear(); err != nil {
			gm.logger.WithError(err).Errorf("Failed to clear 'AllowedModels' association for KeyGroup ID: %d", id)
			return err
		}
		if err := tx.Model(&group).Association("Mappings").Clear(); err != nil {
			gm.logger.WithError(err).Errorf("Failed to clear 'Mappings' (API Key associations) for KeyGroup ID: %d", id)
			return err
		}
		// Also clear settings if they exist to maintain data integrity
		if err := tx.Model(&group).Association("Settings").Delete(group.Settings); err != nil {
			gm.logger.WithError(err).Errorf("Failed to delete 'Settings' association for KeyGroup ID: %d", id)
			return err
		}
		// Step 3: Delete the KeyGroup itself.
		if err := tx.Delete(&group).Error; err != nil {
			gm.logger.WithError(err).Errorf("Failed to delete KeyGroup ID: %d", id)
			return err
		}
		gm.logger.Infof("KeyGroup ID %d associations cleared and entity deleted. Triggering orphan key cleanup.", id)
		// Step 4: Trigger the orphan key cleanup (this logic remains the same and is correct).
		deletedCount, err := gm.keyRepo.DeleteOrphanKeysTx(tx)
		if err != nil {
			gm.logger.WithError(err).Error("Failed to clean up orphan keys after deleting group.")
			return err
		}
		if deletedCount > 0 {
			gm.logger.Infof("Successfully cleaned up %d orphan keys.", deletedCount)
		}
		gm.logger.Infof("Transaction for deleting KeyGroup ID: %d completed successfully.", id)
		return nil
	})
	if err == nil {
		go gm.Invalidate()
	}
	return err
}

func (gm *GroupManager) CloneKeyGroup(id uint) (*models.KeyGroup, error) {
	var originalGroup models.KeyGroup
	if err := gm.db.
		Preload("RequestConfig").
		Preload("Mappings").
		Preload("AllowedUpstreams").
		Preload("AllowedModels").
		First(&originalGroup, id).Error; err != nil {
		return nil, fmt.Errorf("failed to find original group with id %d: %w", id, err)
	}
	newGroup := originalGroup
	timestamp := time.Now().Unix()
	newGroup.ID = 0
	newGroup.Name = fmt.Sprintf("%s-clone-%d", originalGroup.Name, timestamp)
	newGroup.DisplayName = fmt.Sprintf("%s-clone-%d", originalGroup.DisplayName, timestamp)
	newGroup.CreatedAt = time.Time{}
	newGroup.UpdatedAt = time.Time{}

	newGroup.RequestConfigID = nil
	newGroup.RequestConfig = nil
	newGroup.Mappings = nil
	newGroup.AllowedUpstreams = nil
	newGroup.AllowedModels = nil
	err := gm.db.Transaction(func(tx *gorm.DB) error {

		if err := tx.Create(&newGroup).Error; err != nil {
			return err
		}

		if originalGroup.RequestConfig != nil {
			newRequestConfig := *originalGroup.RequestConfig
			newRequestConfig.ID = 0 // Mark as new record

			if err := tx.Create(&newRequestConfig).Error; err != nil {
				return fmt.Errorf("failed to clone request config: %w", err)
			}

			if err := tx.Model(&newGroup).Update("request_config_id", newRequestConfig.ID).Error; err != nil {
				return fmt.Errorf("failed to link new group to cloned request config: %w", err)
			}
		}

		var originalSettings models.GroupSettings
		err := tx.Where("group_id = ?", originalGroup.ID).First(&originalSettings).Error
		if err == nil && len(originalSettings.SettingsJSON) > 0 {
			newSettings := models.GroupSettings{
				GroupID:      newGroup.ID,
				SettingsJSON: originalSettings.SettingsJSON,
			}
			if err := tx.Create(&newSettings).Error; err != nil {
				return fmt.Errorf("failed to clone group settings: %w", err)
			}
		} else if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
			return fmt.Errorf("failed to query original group settings: %w", err)
		}

		if len(originalGroup.Mappings) > 0 {
			newMappings := make([]models.GroupAPIKeyMapping, len(originalGroup.Mappings))
			for i, oldMapping := range originalGroup.Mappings {
				newMappings[i] = models.GroupAPIKeyMapping{
					KeyGroupID:            newGroup.ID,
					APIKeyID:              oldMapping.APIKeyID,
					Status:                oldMapping.Status,
					LastError:             oldMapping.LastError,
					ConsecutiveErrorCount: oldMapping.ConsecutiveErrorCount,
					LastUsedAt:            oldMapping.LastUsedAt,
					CooldownUntil:         oldMapping.CooldownUntil,
				}
			}
			if err := tx.Create(&newMappings).Error; err != nil {
				return fmt.Errorf("failed to clone key group mappings: %w", err)
			}
		}
		if len(originalGroup.AllowedUpstreams) > 0 {
			if err := tx.Model(&newGroup).Association("AllowedUpstreams").Append(originalGroup.AllowedUpstreams); err != nil {
				return err
			}
		}
		if len(originalGroup.AllowedModels) > 0 {
			if err := tx.Model(&newGroup).Association("AllowedModels").Append(originalGroup.AllowedModels); err != nil {
				return err
			}
		}
		return nil
	})

	if err != nil {
		return nil, err
	}

	go gm.Invalidate()

	var finalClonedGroup models.KeyGroup
	if err := gm.db.
		Preload("RequestConfig").
		Preload("Mappings").
		Preload("AllowedUpstreams").
		Preload("AllowedModels").
		First(&finalClonedGroup, newGroup.ID).Error; err != nil {
		return nil, err
	}
	return &finalClonedGroup, nil
}

func (gm *GroupManager) BuildOperationalConfig(group *models.KeyGroup) (*models.KeyGroupSettings, error) {
	globalSettings := gm.settingsManager.GetSettings()
	s := "gemini-1.5-flash" // Per user feedback for default model
	opConfig := &models.KeyGroupSettings{
		EnableKeyCheck:          &globalSettings.EnableBaseKeyCheck,
		KeyCheckConcurrency:     &globalSettings.BaseKeyCheckConcurrency,
		KeyCheckIntervalMinutes: &globalSettings.BaseKeyCheckIntervalMinutes,
		KeyCheckEndpoint:        &globalSettings.DefaultUpstreamURL,
		KeyBlacklistThreshold:   &globalSettings.BlacklistThreshold,
		KeyCooldownMinutes:      &globalSettings.KeyCooldownMinutes,
		KeyCheckModel:           &s,
		MaxRetries:              &globalSettings.MaxRetries,
		EnableSmartGateway:      &globalSettings.EnableSmartGateway,
	}

	if group == nil {
		return opConfig, nil
	}

	var groupSettingsRecord models.GroupSettings
	err := gm.db.Where("group_id = ?", group.ID).First(&groupSettingsRecord).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return opConfig, nil
		}

		gm.logger.WithError(err).Errorf("Failed to query group settings for group ID %d", group.ID)
		return nil, err
	}

	if len(groupSettingsRecord.SettingsJSON) == 0 {
		return opConfig, nil
	}

	var groupSpecificSettings models.KeyGroupSettings
	if err := json.Unmarshal(groupSettingsRecord.SettingsJSON, &groupSpecificSettings); err != nil {
		gm.logger.WithError(err).WithField("group_id", group.ID).Warn("Failed to unmarshal group settings JSON.")
		return opConfig, err
	}

	if err := reflectutil.MergeNilFields(opConfig, &groupSpecificSettings); err != nil {
		gm.logger.WithError(err).WithField("group_id", group.ID).Error("Failed to merge group-specific settings over defaults.")
		return opConfig, nil
	}

	return opConfig, nil
}

func (gm *GroupManager) BuildKeyCheckEndpoint(groupID uint) (string, error) {
	group, ok := gm.GetGroupByID(groupID)
	if !ok {
		return "", fmt.Errorf("group with id %d not found", groupID)
	}
	opConfig, err := gm.BuildOperationalConfig(group)
	if err != nil {
		return "", fmt.Errorf("failed to build operational config for group %d: %w", groupID, err)
	}
	globalSettings := gm.settingsManager.GetSettings()
	baseURL := globalSettings.DefaultUpstreamURL
	if opConfig.KeyCheckEndpoint != nil && *opConfig.KeyCheckEndpoint != "" {
		baseURL = *opConfig.KeyCheckEndpoint
	}
	if baseURL == "" {
		return "", fmt.Errorf("no key check endpoint or default upstream URL is configured for group %d", groupID)
	}
	modelName := globalSettings.BaseKeyCheckModel
	if opConfig.KeyCheckModel != nil && *opConfig.KeyCheckModel != "" {
		modelName = *opConfig.KeyCheckModel
	}
	parsedURL, err := url.Parse(baseURL)
	if err != nil {
		return "", fmt.Errorf("failed to parse base URL '%s': %w", baseURL, err)
	}
	cleanedPath := parsedURL.Path
	cleanedPath = strings.TrimSuffix(cleanedPath, "/")
	cleanedPath = strings.TrimSuffix(cleanedPath, "/v1beta")
	parsedURL.Path = path.Join(cleanedPath, "v1beta", "models", modelName)
	finalEndpoint := parsedURL.String()
	return finalEndpoint, nil
}

func (gm *GroupManager) UpdateOrder(payload []UpdateOrderPayload) error {
	ordersMap := make(map[uint]int, len(payload))
	for _, item := range payload {
		ordersMap[item.ID] = item.Order
	}
	if err := gm.groupRepo.UpdateOrderInTransaction(ordersMap); err != nil {
		gm.logger.WithError(err).Error("Failed to update group order in transaction")
		return fmt.Errorf("database transaction failed: %w", err)
	}
	gm.logger.Info("Group order updated successfully, invalidating cache...")
	go gm.Invalidate()
	return nil
}

func uniqueStrings(slice []string) []string {
	keys := make(map[string]struct{})
	list := []string{}
	for _, entry := range slice {
		if _, value := keys[entry]; !value {
			keys[entry] = struct{}{}
			list = append(list, entry)
		}
	}
	return list
}