package repository

import (
	"context"
	"permission/reborn/domain/entity"
	"permission/reborn/domain/errors"
	"permission/reborn/domain/repository"

	"gorm.io/gorm"
)

type rolePermissionRepository struct {
	db *gorm.DB
}

// NewRolePermissionRepository 建立角色權限 Repository
func NewRolePermissionRepository(db *gorm.DB) repository.RolePermissionRepository {
	return &rolePermissionRepository{db: db}
}

func (r *rolePermissionRepository) Create(ctx context.Context, roleID int64, permissionIDs []int64) error {
	if len(permissionIDs) == 0 {
		return nil
	}

	rolePerms := make([]*entity.RolePermission, 0, len(permissionIDs))
	for _, permID := range permissionIDs {
		rolePerms = append(rolePerms, &entity.RolePermission{
			RoleID:       roleID,
			PermissionID: permID,
		})
	}

	if err := r.db.WithContext(ctx).Create(&rolePerms).Error; err != nil {
		return errors.Wrap(errors.ErrCodeDBQuery, "failed to create role permissions", err)
	}

	return nil
}

func (r *rolePermissionRepository) Update(ctx context.Context, roleID int64, permissionIDs []int64) error {
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		// 刪除舊的權限關聯
		if err := tx.Where("role_id = ?", roleID).Delete(&entity.RolePermission{}).Error; err != nil {
			return errors.Wrap(errors.ErrCodeDBTransaction, "failed to delete old role permissions", err)
		}

		// 建立新的權限關聯
		if len(permissionIDs) > 0 {
			rolePerms := make([]*entity.RolePermission, 0, len(permissionIDs))
			for _, permID := range permissionIDs {
				rolePerms = append(rolePerms, &entity.RolePermission{
					RoleID:       roleID,
					PermissionID: permID,
				})
			}

			if err := tx.Create(&rolePerms).Error; err != nil {
				return errors.Wrap(errors.ErrCodeDBTransaction, "failed to create new role permissions", err)
			}
		}

		return nil
	})
}

func (r *rolePermissionRepository) Delete(ctx context.Context, roleID int64) error {
	if err := r.db.WithContext(ctx).Where("role_id = ?", roleID).Delete(&entity.RolePermission{}).Error; err != nil {
		return errors.Wrap(errors.ErrCodeDBQuery, "failed to delete role permissions", err)
	}
	return nil
}

func (r *rolePermissionRepository) GetByRoleID(ctx context.Context, roleID int64) ([]*entity.RolePermission, error) {
	var rolePerms []*entity.RolePermission
	err := r.db.WithContext(ctx).
		Where("role_id = ?", roleID).
		Find(&rolePerms).Error

	if err != nil {
		return nil, errors.Wrap(errors.ErrCodeDBQuery, "failed to get role permissions", err)
	}

	return rolePerms, nil
}

// GetByRoleIDs 批量取得多個角色的權限關聯 (解決 N+1 查詢問題)
func (r *rolePermissionRepository) GetByRoleIDs(ctx context.Context, roleIDs []int64) (map[int64][]*entity.RolePermission, error) {
	if len(roleIDs) == 0 {
		return make(map[int64][]*entity.RolePermission), nil
	}

	var rolePerms []*entity.RolePermission
	err := r.db.WithContext(ctx).
		Where("role_id IN ?", roleIDs).
		Find(&rolePerms).Error

	if err != nil {
		return nil, errors.Wrap(errors.ErrCodeDBQuery, "failed to get role permissions by role ids", err)
	}

	// 按 role_id 分組
	result := make(map[int64][]*entity.RolePermission)
	for _, rp := range rolePerms {
		result[rp.RoleID] = append(result[rp.RoleID], rp)
	}

	return result, nil
}

func (r *rolePermissionRepository) GetByPermissionIDs(ctx context.Context, permissionIDs []int64) ([]*entity.RolePermission, error) {
	if len(permissionIDs) == 0 {
		return []*entity.RolePermission{}, nil
	}

	var rolePerms []*entity.RolePermission
	err := r.db.WithContext(ctx).
		Where("permission_id IN ?", permissionIDs).
		Find(&rolePerms).Error

	if err != nil {
		return nil, errors.Wrap(errors.ErrCodeDBQuery, "failed to get role permissions by permission ids", err)
	}

	return rolePerms, nil
}

func (r *rolePermissionRepository) GetRolesByPermission(ctx context.Context, permissionID int64) ([]int64, error) {
	var roleIDs []int64
	err := r.db.WithContext(ctx).
		Model(&entity.RolePermission{}).
		Where("permission_id = ?", permissionID).
		Pluck("role_id", &roleIDs).Error

	if err != nil {
		return nil, errors.Wrap(errors.ErrCodeDBQuery, "failed to get roles by permission", err)
	}

	return roleIDs, nil
}