package repository

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

	"gorm.io/gorm"
)

type userRoleRepository struct {
	db *gorm.DB
}

// NewUserRoleRepository 建立使用者角色 Repository
func NewUserRoleRepository(db *gorm.DB) repository.UserRoleRepository {
	return &userRoleRepository{db: db}
}

func (r *userRoleRepository) Create(ctx context.Context, userRole *entity.UserRole) error {
	if err := userRole.Validate(); err != nil {
		return errors.Wrap(errors.ErrCodeInvalidInput, "invalid user role data", err)
	}

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

	return nil
}

func (r *userRoleRepository) Update(ctx context.Context, uid, roleID string) (*entity.UserRole, error) {
	var userRole entity.UserRole

	result := r.db.WithContext(ctx).
		Model(&userRole).
		Where("uid = ? AND status != ?", uid, entity.StatusDeleted).
		Update("role_id", roleID)

	if result.Error != nil {
		return nil, errors.Wrap(errors.ErrCodeDBQuery, "failed to update user role", result.Error)
	}

	if result.RowsAffected == 0 {
		return nil, errors.ErrUserRoleNotFound
	}

	// 重新查詢更新後的資料
	if err := r.db.WithContext(ctx).Where("uid = ?", uid).First(&userRole).Error; err != nil {
		return nil, errors.Wrap(errors.ErrCodeDBQuery, "failed to get updated user role", err)
	}

	return &userRole, nil
}

func (r *userRoleRepository) Delete(ctx context.Context, uid string) error {
	result := r.db.WithContext(ctx).
		Model(&entity.UserRole{}).
		Where("uid = ?", uid).
		Update("status", entity.StatusDeleted)

	if result.Error != nil {
		return errors.Wrap(errors.ErrCodeDBQuery, "failed to delete user role", result.Error)
	}

	if result.RowsAffected == 0 {
		return errors.ErrUserRoleNotFound
	}

	return nil
}

func (r *userRoleRepository) Get(ctx context.Context, uid string) (*entity.UserRole, error) {
	var userRole entity.UserRole
	err := r.db.WithContext(ctx).
		Where("uid = ? AND status != ?", uid, entity.StatusDeleted).
		First(&userRole).Error

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

	return &userRole, nil
}

func (r *userRoleRepository) GetByRoleID(ctx context.Context, roleID string) ([]*entity.UserRole, error) {
	var userRoles []*entity.UserRole
	err := r.db.WithContext(ctx).
		Where("role_id = ? AND status != ?", roleID, entity.StatusDeleted).
		Find(&userRoles).Error

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

	return userRoles, nil
}

func (r *userRoleRepository) List(ctx context.Context, filter repository.UserRoleFilter) ([]*entity.UserRole, error) {
	query := r.buildQuery(ctx, filter)

	var userRoles []*entity.UserRole
	if err := query.Find(&userRoles).Error; err != nil {
		return nil, errors.Wrap(errors.ErrCodeDBQuery, "failed to list user roles", err)
	}

	return userRoles, nil
}

// CountByRoleID 統計每個角色的使用者數量 (批量查詢，避免 N+1)
func (r *userRoleRepository) CountByRoleID(ctx context.Context, roleIDs []string) (map[string]int, error) {
	if len(roleIDs) == 0 {
		return make(map[string]int), nil
	}

	var counts []entity.RoleUserCount
	err := r.db.WithContext(ctx).
		Model(&entity.UserRole{}).
		Select("role_id, COUNT(*) as count").
		Where("role_id IN ? AND status != ?", roleIDs, entity.StatusDeleted).
		Group("role_id").
		Find(&counts).Error

	if err != nil {
		return nil, errors.Wrap(errors.ErrCodeDBQuery, "failed to count users by role id", err)
	}

	result := make(map[string]int)
	for _, c := range counts {
		result[c.RoleID] = c.Count
	}

	return result, nil
}

func (r *userRoleRepository) Exists(ctx context.Context, uid string) (bool, error) {
	var count int64
	err := r.db.WithContext(ctx).
		Model(&entity.UserRole{}).
		Where("uid = ? AND status != ?", uid, entity.StatusDeleted).
		Count(&count).Error

	if err != nil {
		return false, errors.Wrap(errors.ErrCodeDBQuery, "failed to check user role exists", err)
	}

	return count > 0, nil
}

func (r *userRoleRepository) buildQuery(ctx context.Context, filter repository.UserRoleFilter) *gorm.DB {
	query := r.db.WithContext(ctx).
		Model(&entity.UserRole{}).
		Where("status != ?", entity.StatusDeleted)

	if filter.Brand != "" {
		query = query.Where("brand = ?", filter.Brand)
	}

	if filter.RoleID != "" {
		query = query.Where("role_id = ?", filter.RoleID)
	}

	if filter.Status != nil {
		query = query.Where("status = ?", *filter.Status)
	}

	return query
}