package service

import (
	"bytes"
	"carrotskin/internal/model"
	"carrotskin/internal/repository"
	"carrotskin/pkg/database"
	"carrotskin/pkg/storage"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"fmt"
	"path/filepath"
	"strings"
	"time"

	"go.uber.org/zap"
)

// textureService TextureService的实现
type textureService struct {
	textureRepo repository.TextureRepository
	userRepo    repository.UserRepository
	storage     *storage.StorageClient
	cache       *database.CacheManager
	cacheKeys   *database.CacheKeyBuilder
	cacheInv    *database.CacheInvalidator
	logger      *zap.Logger
}

// NewTextureService 创建TextureService实例
func NewTextureService(
	textureRepo repository.TextureRepository,
	userRepo repository.UserRepository,
	storageClient *storage.StorageClient,
	cacheManager *database.CacheManager,
	logger *zap.Logger,
) TextureService {
	return &textureService{
		textureRepo: textureRepo,
		userRepo:    userRepo,
		storage:     storageClient,
		cache:       cacheManager,
		cacheKeys:   database.NewCacheKeyBuilder(""),
		cacheInv:    database.NewCacheInvalidator(cacheManager),
		logger:      logger,
	}
}

func (s *textureService) Create(ctx context.Context, uploaderID int64, name, description, textureType, url, hash string, size int, isPublic, isSlim bool) (*model.Texture, error) {
	// 验证用户存在
	user, err := s.userRepo.FindByID(ctx, uploaderID)
	if err != nil || user == nil {
		return nil, ErrUserNotFound
	}

	// 检查是否有任何用户上传过相同Hash的皮肤（复用URL，不重复保存文件）
	existingTexture, err := s.textureRepo.FindByHash(ctx, hash)
	if err != nil {
		return nil, err
	}

	// 如果已存在相同Hash的皮肤，复用已存在的URL
	finalURL := url
	if existingTexture != nil {
		finalURL = existingTexture.URL
	}

	// 转换材质类型
	textureTypeEnum, err := parseTextureTypeInternal(textureType)
	if err != nil {
		return nil, err
	}

	// 创建材质记录（即使Hash相同，也创建新的数据库记录）
	texture := &model.Texture{
		UploaderID:    uploaderID,
		Name:          name,
		Description:   description,
		Type:          textureTypeEnum,
		URL:           finalURL, // 复用已存在的URL或使用新URL
		Hash:          hash,
		Size:          size,
		IsPublic:      isPublic,
		IsSlim:        isSlim,
		Status:        1,
		DownloadCount: 0,
		FavoriteCount: 0,
	}

	if err := s.textureRepo.Create(ctx, texture); err != nil {
		return nil, err
	}

	// 清除用户的 texture 列表缓存（所有分页）
	s.cacheInv.BatchInvalidate(ctx, fmt.Sprintf("texture:user:%d:*", uploaderID))

	return texture, nil
}

func (s *textureService) GetByID(ctx context.Context, id int64) (*model.Texture, error) {
	// 尝试从缓存获取
	cacheKey := s.cacheKeys.Texture(id)
	var texture model.Texture
	if err := s.cache.Get(ctx, cacheKey, &texture); err == nil {
		if texture.Status == -1 {
			return nil, errors.New("材质已删除")
		}
		return &texture, nil
	}

	// 缓存未命中，从数据库查询
	texture2, err := s.textureRepo.FindByID(ctx, id)
	if err != nil {
		return nil, err
	}
	if texture2 == nil {
		return nil, ErrTextureNotFound
	}
	if texture2.Status == -1 {
		return nil, errors.New("材质已删除")
	}

	// 存入缓存（异步，5分钟过期）
	if texture2 != nil {
		go func() {
			_ = s.cache.Set(context.Background(), cacheKey, texture2, 5*time.Minute)
		}()
	}

	return texture2, nil
}

func (s *textureService) GetByHash(ctx context.Context, hash string) (*model.Texture, error) {
	// 尝试从缓存获取
	cacheKey := s.cacheKeys.TextureByHash(hash)
	var texture model.Texture
	if err := s.cache.Get(ctx, cacheKey, &texture); err == nil {
		if texture.Status == -1 {
			return nil, errors.New("材质已删除")
		}
		return &texture, nil
	}

	// 缓存未命中，从数据库查询
	texture2, err := s.textureRepo.FindByHash(ctx, hash)
	if err != nil {
		return nil, err
	}
	if texture2 == nil {
		return nil, ErrTextureNotFound
	}
	if texture2.Status == -1 {
		return nil, errors.New("材质已删除")
	}

	// 存入缓存（异步，5分钟过期）
	go func() {
		_ = s.cache.Set(context.Background(), cacheKey, texture2, 5*time.Minute)
	}()

	return texture2, nil
}

func (s *textureService) GetByUserID(ctx context.Context, uploaderID int64, page, pageSize int) ([]*model.Texture, int64, error) {
	page, pageSize = NormalizePagination(page, pageSize)

	// 尝试从缓存获取（包含分页参数）
	cacheKey := s.cacheKeys.TextureList(uploaderID, page)
	var cachedResult struct {
		Textures []*model.Texture
		Total    int64
	}
	if err := s.cache.Get(ctx, cacheKey, &cachedResult); err == nil {
		return cachedResult.Textures, cachedResult.Total, nil
	}

	// 缓存未命中，从数据库查询
	textures, total, err := s.textureRepo.FindByUploaderID(ctx, uploaderID, page, pageSize)
	if err != nil {
		return nil, 0, err
	}

	// 存入缓存（异步，2分钟过期）
	go func() {
		result := struct {
			Textures []*model.Texture
			Total    int64
		}{Textures: textures, Total: total}
		_ = s.cache.Set(context.Background(), cacheKey, result, 2*time.Minute)
	}()

	return textures, total, nil
}

func (s *textureService) Search(ctx context.Context, keyword string, textureType model.TextureType, publicOnly bool, page, pageSize int) ([]*model.Texture, int64, error) {
	page, pageSize = NormalizePagination(page, pageSize)
	return s.textureRepo.Search(ctx, keyword, textureType, publicOnly, page, pageSize)
}

func (s *textureService) Update(ctx context.Context, textureID, uploaderID int64, name, description string, isPublic *bool) (*model.Texture, error) {
	// 获取材质并验证权限
	texture, err := s.textureRepo.FindByID(ctx, textureID)
	if err != nil {
		return nil, err
	}
	if texture == nil {
		return nil, ErrTextureNotFound
	}
	if texture.UploaderID != uploaderID {
		return nil, ErrTextureNoPermission
	}

	// 更新字段
	updates := make(map[string]interface{})
	if name != "" {
		updates["name"] = name
	}
	if description != "" {
		updates["description"] = description
	}
	if isPublic != nil {
		updates["is_public"] = *isPublic
	}

	if len(updates) > 0 {
		if err := s.textureRepo.UpdateFields(ctx, textureID, updates); err != nil {
			return nil, err
		}
	}

	// 清除 texture 缓存和用户列表缓存
	s.cacheInv.OnUpdate(ctx, s.cacheKeys.Texture(textureID))
	s.cacheInv.BatchInvalidate(ctx, fmt.Sprintf("texture:user:%d:*", uploaderID))

	return s.textureRepo.FindByID(ctx, textureID)
}

func (s *textureService) Delete(ctx context.Context, textureID, uploaderID int64) error {
	// 获取材质并验证权限
	texture, err := s.textureRepo.FindByID(ctx, textureID)
	if err != nil {
		return err
	}
	if texture == nil {
		return ErrTextureNotFound
	}
	if texture.UploaderID != uploaderID {
		return ErrTextureNoPermission
	}

	err = s.textureRepo.Delete(ctx, textureID)
	if err != nil {
		return err
	}

	// 清除 texture 缓存和用户列表缓存
	s.cacheInv.OnDelete(ctx, s.cacheKeys.Texture(textureID))
	s.cacheInv.BatchInvalidate(ctx, fmt.Sprintf("texture:user:%d:*", uploaderID))

	return nil
}

func (s *textureService) ToggleFavorite(ctx context.Context, userID, textureID int64) (bool, error) {
	// 确保材质存在
	texture, err := s.textureRepo.FindByID(ctx, textureID)
	if err != nil {
		return false, err
	}
	if texture == nil {
		return false, ErrTextureNotFound
	}

	isFavorited, err := s.textureRepo.IsFavorited(ctx, userID, textureID)
	if err != nil {
		return false, err
	}

	if isFavorited {
		// 已收藏 -> 取消收藏
		if err := s.textureRepo.RemoveFavorite(ctx, userID, textureID); err != nil {
			return false, err
		}
		if err := s.textureRepo.DecrementFavoriteCount(ctx, textureID); err != nil {
			return false, err
		}
		return false, nil
	}

	// 未收藏 -> 添加收藏
	if err := s.textureRepo.AddFavorite(ctx, userID, textureID); err != nil {
		return false, err
	}
	if err := s.textureRepo.IncrementFavoriteCount(ctx, textureID); err != nil {
		return false, err
	}
	return true, nil
}

func (s *textureService) GetUserFavorites(ctx context.Context, userID int64, page, pageSize int) ([]*model.Texture, int64, error) {
	page, pageSize = NormalizePagination(page, pageSize)
	return s.textureRepo.GetUserFavorites(ctx, userID, page, pageSize)
}

func (s *textureService) CheckUploadLimit(ctx context.Context, uploaderID int64, maxTextures int) error {
	count, err := s.textureRepo.CountByUploaderID(ctx, uploaderID)
	if err != nil {
		return err
	}

	if count >= int64(maxTextures) {
		return fmt.Errorf("已达到最大上传数量限制(%d)", maxTextures)
	}

	return nil
}

// UploadTexture 直接上传材质文件
func (s *textureService) UploadTexture(ctx context.Context, uploaderID int64, name, description, textureType string, fileData []byte, fileName string, isPublic, isSlim bool) (*model.Texture, error) {
	// 验证用户存在
	user, err := s.userRepo.FindByID(ctx, uploaderID)
	if err != nil || user == nil {
		return nil, ErrUserNotFound
	}

	// 验证文件大小和扩展名
	fileSize := len(fileData)
	const minSize = 512              // 512B
	const maxSize = 10 * 1024 * 1024 // 10MB
	if int64(fileSize) < minSize || int64(fileSize) > maxSize {
		return nil, fmt.Errorf("文件大小必须在 %d 到 %d 字节之间", minSize, maxSize)
	}

	// 验证文件扩展名（只支持PNG）
	ext := strings.ToLower(filepath.Ext(fileName))
	if ext != ".png" {
		return nil, fmt.Errorf("不支持的文件格式: %s，仅支持PNG格式", ext)
	}

	// 验证材质类型
	if textureType != "SKIN" && textureType != "CAPE" {
		return nil, errors.New("无效的材质类型")
	}

	// 计算文件SHA256哈希
	hashBytes := sha256.Sum256(fileData)
	hash := hex.EncodeToString(hashBytes[:])

	// 检查是否有任何用户上传过相同Hash的皮肤（复用URL，不重复保存文件）
	existingTexture, err := s.textureRepo.FindByHash(ctx, hash)
	if err != nil {
		return nil, err
	}

	var finalURL string
	if existingTexture != nil {
		// 如果已存在相同Hash的皮肤，复用已存在的URL，不重复上传
		finalURL = existingTexture.URL
		s.logger.Info("复用已存在的材质文件",
			zap.String("hash", hash),
			zap.String("url", finalURL),
		)
	} else {
		// 如果不存在，上传到对象存储
		if s.storage == nil {
			return nil, errors.New("存储服务不可用")
		}

		// 获取存储桶名称
		bucketName, err := s.storage.GetBucket("textures")
		if err != nil {
			return nil, fmt.Errorf("获取存储桶失败: %w", err)
		}

		// 生成对象名称（路径）
		// 格式: hash/{hash[:2]}/{hash[2:4]}/{hash}.png
		// 使用哈希值作为路径，避免重复存储相同文件
		textureTypeFolder := strings.ToLower(textureType)
		objectName := fmt.Sprintf("%s/%s/%s/%s/%s%s", textureTypeFolder, hash[:2], hash[2:4], hash, hash, ext)

		// 上传文件
		reader := bytes.NewReader(fileData)
		contentType := "image/png"
		if err := s.storage.UploadObject(ctx, bucketName, objectName, reader, int64(fileSize), contentType); err != nil {
			return nil, fmt.Errorf("上传文件失败: %w", err)
		}

		// 构建文件URL
		finalURL = s.storage.BuildFileURL(bucketName, objectName)
		s.logger.Info("上传新的材质文件",
			zap.String("hash", hash),
			zap.String("url", finalURL),
		)
	}

	// 转换材质类型
	textureTypeEnum, err := parseTextureTypeInternal(textureType)
	if err != nil {
		return nil, err
	}

	// 创建材质记录（即使Hash相同，也创建新的数据库记录）
	texture := &model.Texture{
		UploaderID:    uploaderID,
		Name:          name,
		Description:   description,
		Type:          textureTypeEnum,
		URL:           finalURL,
		Hash:          hash,
		Size:          fileSize,
		IsPublic:      isPublic,
		IsSlim:        isSlim,
		Status:        1,
		DownloadCount: 0,
		FavoriteCount: 0,
	}

	if err := s.textureRepo.Create(ctx, texture); err != nil {
		return nil, err
	}

	// 清除用户的 texture 列表缓存（所有分页）
	s.cacheInv.BatchInvalidate(ctx, fmt.Sprintf("texture:user:%d:*", uploaderID))

	return texture, nil
}

// parseTextureTypeInternal 解析材质类型
func parseTextureTypeInternal(textureType string) (model.TextureType, error) {
	switch textureType {
	case "SKIN":
		return model.TextureTypeSkin, nil
	case "CAPE":
		return model.TextureTypeCape, nil
	default:
		return "", errors.New("无效的材质类型")
	}
}