// Filename: internal/repository/key_cache.go (最终定稿)
package repository

import (
	"context"
	"encoding/json"
	"fmt"
	"gemini-balancer/internal/models"
	"strconv"
)

// --- Redis Key 常量定义 ---
const (
	KeyGroup               = "group:%d:keys:active"
	KeyDetails             = "key:%d:details"
	KeyMapping             = "mapping:%d:%d"
	KeyGroupSequential     = "group:%d:keys:sequential"
	KeyGroupLRU            = "group:%d:keys:lru"
	KeyGroupRandomMain     = "group:%d:keys:random:main"
	KeyGroupRandomCooldown = "group:%d:keys:random:cooldown"
	BasePoolSequential     = "basepool:%s:keys:sequential"
	BasePoolLRU            = "basepool:%s:keys:lru"
	BasePoolRandomMain     = "basepool:%s:keys:random:main"
	BasePoolRandomCooldown = "basepool:%s:keys:random:cooldown"
)

// LoadAllKeysToStore 从数据库加载所有密钥和映射关系，并完整重建Redis缓存。
func (r *gormKeyRepository) LoadAllKeysToStore(ctx context.Context) error {
	r.logger.Info("Starting full cache rebuild for all keys and polling structures.")

	var allMappings []*models.GroupAPIKeyMapping
	if err := r.db.Preload("APIKey").Find(&allMappings).Error; err != nil {
		return fmt.Errorf("failed to load mappings with preloaded APIKeys: %w", err)
	}

	// 1. 批量解密所有涉及的密钥
	keyMap := make(map[uint]*models.APIKey)
	for _, m := range allMappings {
		if m.APIKey != nil {
			keyMap[m.APIKey.ID] = m.APIKey
		}
	}
	keysToDecrypt := make([]models.APIKey, 0, len(keyMap))
	for _, k := range keyMap {
		keysToDecrypt = append(keysToDecrypt, *k)
	}
	if err := r.decryptKeys(keysToDecrypt); err != nil {
		r.logger.WithError(err).Error("Batch decryption failed during cache rebuild.")
		// 即使解密失败，也继续尝试加载未加密或已解密的部分
	}
	decryptedKeyMap := make(map[uint]models.APIKey)
	for _, k := range keysToDecrypt {
		decryptedKeyMap[k.ID] = k
	}

	// 2. 清理所有分组的旧轮询结构
	pipe := r.store.Pipeline(ctx)
	var allGroups []*models.KeyGroup
	if err := r.db.Find(&allGroups).Error; err == nil {
		for _, group := range allGroups {
			pipe.Del(
				fmt.Sprintf(KeyGroup, group.ID),
				fmt.Sprintf(KeyGroupSequential, group.ID),
				fmt.Sprintf(KeyGroupLRU, group.ID),
				fmt.Sprintf(KeyGroupRandomMain, group.ID),
				fmt.Sprintf(KeyGroupRandomCooldown, group.ID),
			)
		}
	} else {
		r.logger.WithError(err).Error("Failed to get groups for cache cleanup; proceeding with rebuild.")
	}

	// 3. 准备批量更新数据
	activeKeysByGroup := make(map[uint][]*models.GroupAPIKeyMapping)
	detailsToSet := make(map[string]any)

	for _, mapping := range allMappings {
		if mapping.APIKey == nil {
			continue
		}
		decryptedKey, ok := decryptedKeyMap[mapping.APIKeyID]
		if !ok {
			continue // 跳过解密失败的密钥
		}

		// 准备 KeyDetails 和 KeyMapping 的 MSet 数据
		keyJSON, _ := json.Marshal(decryptedKey)
		detailsToSet[fmt.Sprintf(KeyDetails, decryptedKey.ID)] = keyJSON
		mappingJSON, _ := json.Marshal(mapping)
		detailsToSet[fmt.Sprintf(KeyMapping, mapping.KeyGroupID, decryptedKey.ID)] = mappingJSON

		if mapping.Status == models.StatusActive {
			activeKeysByGroup[mapping.KeyGroupID] = append(activeKeysByGroup[mapping.KeyGroupID], mapping)
		}
	}

	// 4. 使用 MSet 批量写入详情和映射缓存
	if len(detailsToSet) > 0 {
		if err := r.store.MSet(ctx, detailsToSet); err != nil {
			r.logger.WithError(err).Error("Failed to MSet key details and mappings during cache rebuild.")
		}
	}

	// 5. 在Pipeline中重建所有分组的轮询结构
	for groupID, activeMappings := range activeKeysByGroup {
		if len(activeMappings) == 0 {
			continue
		}
		var activeKeyIDs []interface{}
		lruMembers := make(map[string]float64)
		for _, mapping := range activeMappings {
			keyIDStr := strconv.FormatUint(uint64(mapping.APIKeyID), 10)
			activeKeyIDs = append(activeKeyIDs, keyIDStr)
			var score float64
			if mapping.LastUsedAt != nil {
				score = float64(mapping.LastUsedAt.UnixMilli())
			}
			lruMembers[keyIDStr] = score
		}
		pipe.SAdd(fmt.Sprintf(KeyGroup, groupID), activeKeyIDs...)
		pipe.LPush(fmt.Sprintf(KeyGroupSequential, groupID), activeKeyIDs...)
		pipe.SAdd(fmt.Sprintf(KeyGroupRandomMain, groupID), activeKeyIDs...)
		pipe.ZAdd(fmt.Sprintf(KeyGroupLRU, groupID), lruMembers)
	}

	// 6. 执行Pipeline
	if err := pipe.Exec(); err != nil {
		return fmt.Errorf("pipeline execution for polling structures failed: %w", err)
	}

	r.logger.Info("Full cache rebuild completed successfully.")
	return nil
}

// updateStoreCacheForKey 更新单个APIKey的详情缓存 (K-V)。
func (r *gormKeyRepository) updateStoreCacheForKey(key *models.APIKey) error {
	if err := r.decryptKey(key); err != nil {
		return fmt.Errorf("failed to decrypt key %d for cache update: %w", key.ID, err)
	}
	keyJSON, err := json.Marshal(key)
	if err != nil {
		return fmt.Errorf("failed to marshal key %d for cache update: %w", key.ID, err)
	}
	return r.store.Set(context.Background(), fmt.Sprintf(KeyDetails, key.ID), keyJSON, 0)
}

// removeStoreCacheForKey 从所有缓存结构中彻底移除一个APIKey。
func (r *gormKeyRepository) removeStoreCacheForKey(ctx context.Context, key *models.APIKey) error {
	groupIDs, err := r.GetGroupsForKey(ctx, key.ID)
	if err != nil {
		r.logger.WithError(err).Warnf("Failed to get groups for key %d during cache removal, cleanup may be partial.", key.ID)
	}

	pipe := r.store.Pipeline(ctx)
	pipe.Del(fmt.Sprintf(KeyDetails, key.ID))

	keyIDStr := strconv.FormatUint(uint64(key.ID), 10)
	for _, groupID := range groupIDs {
		pipe.Del(fmt.Sprintf(KeyMapping, groupID, key.ID))
		pipe.SRem(fmt.Sprintf(KeyGroup, groupID), keyIDStr)
		pipe.LRem(fmt.Sprintf(KeyGroupSequential, groupID), 0, keyIDStr)
		pipe.SRem(fmt.Sprintf(KeyGroupRandomMain, groupID), keyIDStr)
		pipe.SRem(fmt.Sprintf(KeyGroupRandomCooldown, groupID), keyIDStr)
		pipe.ZRem(fmt.Sprintf(KeyGroupLRU, groupID), keyIDStr)
	}

	return pipe.Exec()
}

// updateStoreCacheForMapping 根据单个映射关系的状态，原子性地更新所有相关的缓存结构。
func (r *gormKeyRepository) updateStoreCacheForMapping(mapping *models.GroupAPIKeyMapping) error {
	keyIDStr := strconv.FormatUint(uint64(mapping.APIKeyID), 10)
	groupID := mapping.KeyGroupID
	ctx := context.Background()

	pipe := r.store.Pipeline(ctx)

	// 统一、无条件地从所有轮询结构中移除，确保状态清洁
	pipe.SRem(fmt.Sprintf(KeyGroup, groupID), keyIDStr)
	pipe.LRem(fmt.Sprintf(KeyGroupSequential, groupID), 0, keyIDStr)
	pipe.SRem(fmt.Sprintf(KeyGroupRandomMain, groupID), keyIDStr)
	pipe.SRem(fmt.Sprintf(KeyGroupRandomCooldown, groupID), keyIDStr)
	pipe.ZRem(fmt.Sprintf(KeyGroupLRU, groupID), keyIDStr)

	// 如果新状态是 Active，则重新添加到所有轮询结构中
	if mapping.Status == models.StatusActive {
		pipe.SAdd(fmt.Sprintf(KeyGroup, groupID), keyIDStr)
		pipe.LPush(fmt.Sprintf(KeyGroupSequential, groupID), keyIDStr)
		pipe.SAdd(fmt.Sprintf(KeyGroupRandomMain, groupID), keyIDStr)

		var score float64
		if mapping.LastUsedAt != nil {
			score = float64(mapping.LastUsedAt.UnixMilli())
		}
		pipe.ZAdd(fmt.Sprintf(KeyGroupLRU, groupID), map[string]float64{keyIDStr: score})
	}

	// 无论状态如何，都更新映射详情的 K-V 缓存
	mappingJSON, err := json.Marshal(mapping)
	if err != nil {
		return fmt.Errorf("failed to marshal mapping: %w", err)
	}
	pipe.Set(fmt.Sprintf(KeyMapping, groupID, mapping.APIKeyID), mappingJSON, 0)

	return pipe.Exec()
}

// HandleCacheUpdateEventBatch 批量、原子性地更新多个映射关系的缓存。
func (r *gormKeyRepository) HandleCacheUpdateEventBatch(ctx context.Context, mappings []*models.GroupAPIKeyMapping) error {
	if len(mappings) == 0 {
		return nil
	}

	pipe := r.store.Pipeline(ctx)

	for _, mapping := range mappings {
		keyIDStr := strconv.FormatUint(uint64(mapping.APIKeyID), 10)
		groupID := mapping.KeyGroupID

		// 对于批处理中的每一个mapping，都执行完整的、正确的“先删后增”逻辑
		pipe.SRem(fmt.Sprintf(KeyGroup, groupID), keyIDStr)
		pipe.LRem(fmt.Sprintf(KeyGroupSequential, groupID), 0, keyIDStr)
		pipe.SRem(fmt.Sprintf(KeyGroupRandomMain, groupID), keyIDStr)
		pipe.SRem(fmt.Sprintf(KeyGroupRandomCooldown, groupID), keyIDStr)
		pipe.ZRem(fmt.Sprintf(KeyGroupLRU, groupID), keyIDStr)

		if mapping.Status == models.StatusActive {
			pipe.SAdd(fmt.Sprintf(KeyGroup, groupID), keyIDStr)
			pipe.LPush(fmt.Sprintf(KeyGroupSequential, groupID), keyIDStr)
			pipe.SAdd(fmt.Sprintf(KeyGroupRandomMain, groupID), keyIDStr)

			var score float64
			if mapping.LastUsedAt != nil {
				score = float64(mapping.LastUsedAt.UnixMilli())
			}
			pipe.ZAdd(fmt.Sprintf(KeyGroupLRU, groupID), map[string]float64{keyIDStr: score})
		}

		mappingJSON, _ := json.Marshal(mapping) // 在批处理中忽略单个marshal错误，以保证大部分更新成功
		pipe.Set(fmt.Sprintf(KeyMapping, groupID, mapping.APIKeyID), mappingJSON, 0)
	}

	return pipe.Exec()
}