package usecase

import (
	"context"
	"permission/reborn/config"
	"permission/reborn/domain/entity"
	"permission/reborn/domain/errors"
	"permission/reborn/domain/repository"
	"permission/reborn/domain/usecase"
)

type rolePermissionUseCase struct {
	permRepo     repository.PermissionRepository
	rolePermRepo repository.RolePermissionRepository
	roleRepo     repository.RoleRepository
	userRoleRepo repository.UserRoleRepository
	permUseCase  usecase.PermissionUseCase
	cache        repository.CacheRepository
	config       config.RoleConfig
}

// NewRolePermissionUseCase 建立角色權限 UseCase
func NewRolePermissionUseCase(
	permRepo repository.PermissionRepository,
	rolePermRepo repository.RolePermissionRepository,
	roleRepo repository.RoleRepository,
	userRoleRepo repository.UserRoleRepository,
	permUseCase usecase.PermissionUseCase,
	cache repository.CacheRepository,
	cfg config.RoleConfig,
) usecase.RolePermissionUseCase {
	return &rolePermissionUseCase{
		permRepo:     permRepo,
		rolePermRepo: rolePermRepo,
		roleRepo:     roleRepo,
		userRoleRepo: userRoleRepo,
		permUseCase:  permUseCase,
		cache:        cache,
		config:       cfg,
	}
}

func (uc *rolePermissionUseCase) GetByRoleUID(ctx context.Context, roleUID string) (entity.Permissions, error) {
	// 檢查是否為管理員
	if roleUID == uc.config.AdminRoleUID {
		return uc.getAllPermissions(ctx)
	}

	// 嘗試從快取取得
	if uc.cache != nil {
		var permissions entity.Permissions
		cacheKey := repository.CacheKeyRolePermission(roleUID)
		err := uc.cache.GetObject(ctx, cacheKey, &permissions)
		if err == nil && len(permissions) > 0 {
			return permissions, nil
		}
	}

	// 取得角色
	role, err := uc.roleRepo.GetByUID(ctx, roleUID)
	if err != nil {
		return nil, err
	}

	// 取得角色權限關聯
	rolePerms, err := uc.rolePermRepo.GetByRoleID(ctx, role.ID)
	if err != nil {
		return nil, err
	}

	if len(rolePerms) == 0 {
		return make(entity.Permissions), nil
	}

	// 取得權限樹並建立權限集合
	perms, err := uc.permRepo.ListActive(ctx)
	if err != nil {
		return nil, err
	}

	tree := NewPermissionTree(perms)

	// 取得權限 ID 列表
	permIDs := make([]int64, len(rolePerms))
	for i, rp := range rolePerms {
		permIDs[i] = rp.PermissionID
	}

	// 建立權限集合 (包含父權限)
	permissions := tree.BuildPermissionsFromIDs(permIDs)

	// 存入快取
	if uc.cache != nil {
		cacheKey := repository.CacheKeyRolePermission(roleUID)
		_ = uc.cache.SetObject(ctx, cacheKey, permissions, 0)
	}

	return permissions, nil
}

func (uc *rolePermissionUseCase) GetByUserUID(ctx context.Context, userUID string) (*usecase.UserPermissionResponse, error) {
	// 嘗試從快取取得
	if uc.cache != nil {
		var resp usecase.UserPermissionResponse
		cacheKey := repository.CacheKeyUserPermission(userUID)
		err := uc.cache.GetObject(ctx, cacheKey, &resp)
		if err == nil && resp.RoleUID != "" {
			return &resp, nil
		}
	}

	// 取得使用者角色
	userRole, err := uc.userRoleRepo.Get(ctx, userUID)
	if err != nil {
		return nil, err
	}

	// 取得角色
	role, err := uc.roleRepo.GetByUID(ctx, userRole.RoleID)
	if err != nil {
		return nil, err
	}

	// 取得角色權限
	permissions, err := uc.GetByRoleUID(ctx, userRole.RoleID)
	if err != nil {
		return nil, err
	}

	resp := &usecase.UserPermissionResponse{
		UserUID:     userUID,
		RoleUID:     role.UID,
		RoleName:    role.Name,
		Permissions: permissions,
	}

	// 存入快取
	if uc.cache != nil {
		cacheKey := repository.CacheKeyUserPermission(userUID)
		_ = uc.cache.SetObject(ctx, cacheKey, resp, 0)
	}

	return resp, nil
}

func (uc *rolePermissionUseCase) UpdateRolePermissions(ctx context.Context, roleUID string, permissions entity.Permissions) error {
	// 取得角色
	role, err := uc.roleRepo.GetByUID(ctx, roleUID)
	if err != nil {
		return err
	}

	// 展開權限 (包含父權限)
	expandedPerms, err := uc.permUseCase.ExpandPermissions(ctx, permissions)
	if err != nil {
		return err
	}

	// 取得權限樹並轉換為 ID
	perms, err := uc.permRepo.ListActive(ctx)
	if err != nil {
		return err
	}

	tree := NewPermissionTree(perms)
	permIDs, err := tree.GetPermissionIDs(expandedPerms)
	if err != nil {
		return err
	}

	// 更新角色權限
	if err := uc.rolePermRepo.Update(ctx, role.ID, permIDs); err != nil {
		return err
	}

	// 清除快取
	if uc.cache != nil {
		// 清除角色權限快取
		_ = uc.cache.Delete(ctx, repository.CacheKeyRolePermission(roleUID))

		// 清除所有使用此角色的使用者權限快取
		userRoles, _ := uc.userRoleRepo.GetByRoleID(ctx, roleUID)
		for _, ur := range userRoles {
			_ = uc.cache.Delete(ctx, repository.CacheKeyUserPermission(ur.UID))
		}
	}

	return nil
}

func (uc *rolePermissionUseCase) CheckPermission(ctx context.Context, roleUID, path, method string) (*usecase.PermissionCheckResponse, error) {
	// 檢查是否為管理員
	if roleUID == uc.config.AdminRoleUID {
		return &usecase.PermissionCheckResponse{
			Allowed:   true,
			PlainCode: true,
		}, nil
	}

	// 取得角色權限
	permissions, err := uc.GetByRoleUID(ctx, roleUID)
	if err != nil {
		return nil, err
	}

	// 取得 API 權限
	perm, err := uc.permRepo.GetByHTTP(ctx, path, method)
	if err != nil {
		if errors.Is(err, errors.ErrPermissionNotFound) {
			// 如果找不到對應的權限定義，預設拒絕
			return &usecase.PermissionCheckResponse{
				Allowed: false,
			}, nil
		}
		return nil, err
	}

	// 檢查是否有權限
	allowed := permissions.HasPermission(perm.Name)

	resp := &usecase.PermissionCheckResponse{
		Allowed:        allowed,
		PermissionName: perm.Name,
		PlainCode:      false,
	}

	// 檢查是否有 plain_code 權限 (特殊邏輯)
	if allowed && method == "GET" {
		plainCodePermName := perm.Name + ".plain_code"
		resp.PlainCode = permissions.HasPermission(plainCodePermName)
	}

	return resp, nil
}

// getAllPermissions 取得所有權限 (管理員用)
func (uc *rolePermissionUseCase) getAllPermissions(ctx context.Context) (entity.Permissions, error) {
	perms, err := uc.permRepo.ListActive(ctx)
	if err != nil {
		return nil, err
	}

	permissions := make(entity.Permissions)
	for _, perm := range perms {
		permissions.AddPermission(perm.Name)
	}

	return permissions, nil
}