package service

import (
	"context"
	"errors"
	"fmt"

	"giter.top/smart/internal/iam/entity"
	"giter.top/smart/internal/iam/repository"
	"giter.top/smart/pkg/utils/id"
)

// RoleService 角色
type RoleService interface {
	Create(ctx context.Context, tenantID string, req *CreateRoleRequest, grantorUserID *string) (*entity.Role, error)
	Update(ctx context.Context, tenantID string, rid string, req *UpdateRoleRequest, grantorUserID *string) (*entity.Role, error)
	Delete(ctx context.Context, tenantID string, ids []string) error
	Get(ctx context.Context, tenantID string, rid string) (*entity.Role, error)
	List(ctx context.Context, tenantID string, name, code string, page, pageSize int) (*RoleListResponse, error)
	AssignMenus(ctx context.Context, tenantID string, roleID string, menuIDs []string, grantorUserID *string) error
}

type CreateRoleRequest struct {
	RoleCode    string   `json:"role_code" binding:"required,max=64"`
	RoleName    string   `json:"role_name" binding:"required,max=128"`
	DataScope   int16    `json:"data_scope" binding:"required"`
	Description string   `json:"description"`
	MenuIDs     []string `json:"menu_ids"`
}

type UpdateRoleRequest struct {
	RoleName    *string  `json:"role_name"`
	DataScope   *int16   `json:"data_scope"`
	Description *string  `json:"description"`
	MenuIDs     []string `json:"menu_ids"`
}

type RoleListResponse struct {
	Items      []entity.Role `json:"items"`
	Total      int64         `json:"total"`
	Page       int           `json:"page"`
	PageSize   int           `json:"page_size"`
	TotalPages int           `json:"total_pages"`
}

type roleService struct {
	roles repository.RoleRepository
	users repository.UserRepository
	menus repository.MenuRepository
}

func NewRoleService(roles repository.RoleRepository, users repository.UserRepository, menus repository.MenuRepository) RoleService {
	return &roleService{roles: roles, users: users, menus: menus}
}

func (s *roleService) grantorMenuSet(ctx context.Context, grantorUserID string) (map[string]struct{}, error) {
	rids, err := s.users.ListRoleIDs(ctx, grantorUserID)
	if err != nil {
		return nil, err
	}
	ids, err := s.roles.ListMenuIDsByRoles(ctx, rids)
	if err != nil {
		return nil, err
	}
	m := make(map[string]struct{}, len(ids))
	for _, mid := range ids {
		m[mid] = struct{}{}
	}
	return m, nil
}

func (s *roleService) assertMenuSubset(ctx context.Context, grantorUserID *string, menuIDs []string) error {
	if grantorUserID == nil || *grantorUserID == "" {
		return nil
	}
	allowed, err := s.grantorMenuSet(ctx, *grantorUserID)
	if err != nil {
		return err
	}
	for _, mid := range menuIDs {
		if _, ok := allowed[mid]; !ok {
			return fmt.Errorf("防越权: 不能分配自身未拥有的菜单权限 (menu_id=%s)", mid)
		}
	}
	return nil
}

func (s *roleService) Create(ctx context.Context, tenantID string, req *CreateRoleRequest, grantorUserID *string) (*entity.Role, error) {
	ok, err := s.roles.ExistsCode(ctx, tenantID, req.RoleCode, "")
	if err != nil {
		return nil, err
	}
	if ok {
		return nil, fmt.Errorf("角色编码已存在")
	}
	if err := s.assertMenuSubset(ctx, grantorUserID, req.MenuIDs); err != nil {
		return nil, err
	}
	r := &entity.Role{
		ID:          id.New(),
		TenantID:    tenantID,
		RoleCode:    req.RoleCode,
		RoleName:    req.RoleName,
		DataScope:   req.DataScope,
		Description: req.Description,
		Status:      1,
	}
	if err := s.roles.Create(ctx, r); err != nil {
		return nil, err
	}
	if len(req.MenuIDs) > 0 {
		if err := s.roles.ReplaceRoleMenus(ctx, r.ID, req.MenuIDs); err != nil {
			return nil, err
		}
	}
	return r, nil
}

func (s *roleService) Update(ctx context.Context, tenantID string, rid string, req *UpdateRoleRequest, grantorUserID *string) (*entity.Role, error) {
	r, err := s.roles.GetByID(ctx, rid)
	if err != nil {
		if errors.Is(err, repository.ErrNotFound) {
			return nil, fmt.Errorf("角色不存在")
		}
		return nil, err
	}
	if r.TenantID != tenantID {
		return nil, fmt.Errorf("角色不属于当前租户")
	}
	if r.IsBuiltin {
		// 内置角色仅允许改部分字段（MVP：允许改名称与数据范围与菜单需业务再定）
	}
	if req.RoleName != nil {
		r.RoleName = *req.RoleName
	}
	if req.DataScope != nil {
		r.DataScope = *req.DataScope
	}
	if req.Description != nil {
		r.Description = *req.Description
	}
	if err := s.roles.Update(ctx, r); err != nil {
		return nil, err
	}
	if req.MenuIDs != nil {
		if err := s.assertMenuSubset(ctx, grantorUserID, req.MenuIDs); err != nil {
			return nil, err
		}
		if err := s.roles.ReplaceRoleMenus(ctx, r.ID, req.MenuIDs); err != nil {
			return nil, err
		}
	}
	return r, nil
}

func (s *roleService) Delete(ctx context.Context, tenantID string, ids []string) error {
	for _, rid := range ids {
		r, err := s.roles.GetByID(ctx, rid)
		if err != nil {
			return err
		}
		if r.TenantID != tenantID {
			return fmt.Errorf("角色 %s 不属于当前租户", rid)
		}
		if r.IsBuiltin {
			return fmt.Errorf("内置角色不可删除")
		}
		n, err := s.roles.CountUsers(ctx, rid)
		if err != nil {
			return err
		}
		if n > 0 {
			return fmt.Errorf("角色仍被用户使用")
		}
		if err := s.roles.Delete(ctx, rid); err != nil {
			return err
		}
	}
	return nil
}

func (s *roleService) Get(ctx context.Context, tenantID string, rid string) (*entity.Role, error) {
	r, err := s.roles.GetByID(ctx, rid)
	if err != nil {
		return nil, err
	}
	if r.TenantID != tenantID {
		return nil, fmt.Errorf("角色不属于当前租户")
	}
	return r, nil
}

func (s *roleService) List(ctx context.Context, tenantID string, name, code string, page, pageSize int) (*RoleListResponse, error) {
	if page <= 0 {
		page = 1
	}
	if pageSize <= 0 {
		pageSize = 10
	}
	rows, total, err := s.roles.List(ctx, tenantID, name, code, page, pageSize)
	if err != nil {
		return nil, err
	}
	tp := int(total) / pageSize
	if int(total)%pageSize != 0 {
		tp++
	}
	return &RoleListResponse{Items: rows, Total: total, Page: page, PageSize: pageSize, TotalPages: tp}, nil
}

func (s *roleService) AssignMenus(ctx context.Context, tenantID string, roleID string, menuIDs []string, grantorUserID *string) error {
	r, err := s.roles.GetByID(ctx, roleID)
	if err != nil {
		return err
	}
	if r.TenantID != tenantID {
		return fmt.Errorf("角色不属于当前租户")
	}
	if err := s.assertMenuSubset(ctx, grantorUserID, menuIDs); err != nil {
		return err
	}
	return s.roles.ReplaceRoleMenus(ctx, roleID, menuIDs)
}