package service

import (
	"strings"

	"github.com/freefire/jiang13-bbs/model"
)

// 权限码：后台功能点。路由通过 RequirePerm 声明，
// 板块管理员的板块范围由 Actor.BoardIDs 在业务层二次校验。
const (
	PermUsers         = "users"         // 用户与权限管理（超管/站长）
	PermAnnouncements = "announcements" // 公告管理（管理员及以上）
	PermSettings      = "settings"      // 站点外观设置（超管/站长）
	PermModeration    = "moderation"    // 内容审核（任意管理角色，板块范围受限）
	PermMessages      = "messages"      // 后台消息管理（站长/超管/站点消息 flag；群管另有业务层放行）
	PermBoards        = "boards"        // 板块管理（仅站长）
)

// Actor 当前请求操作者的实时权限快照（每次后台请求从 DB 现取，
// 不依赖 JWT 内的 role claim，角色/授权变更立即生效）
type Actor struct {
	ID                uint
	Username          string
	Role              model.Role
	BoardIDs          []uint // 板块管理员被授权的板块；其他角色为空
	CanManageMessages bool   // 站点级消息管理 flag（站长授予）；站长/超管不必依赖此字段
}

// IsStaff 是否管理团队成员
func (a *Actor) IsStaff() bool {
	return a != nil && model.IsStaff(a.Role)
}

// HasPerm 是否拥有某后台功能点
func (a *Actor) HasPerm(p string) bool {
	if a == nil {
		return false
	}
	switch p {
	case PermBoards:
		return a.Role == model.RoleOwner
	case PermUsers, PermSettings:
		return a.Role == model.RoleSuperAdmin || a.Role == model.RoleOwner
	case PermAnnouncements:
		return model.RoleLevel(a.Role) >= model.RoleLevel(model.RoleAdmin)
	case PermModeration:
		return a.IsStaff()
	case PermMessages:
		return a.HasSiteMessagePerm()
	}
	return false
}

// HasSiteMessagePerm 站点级消息管理：站长/超管固有，或被授予 CanManageMessages
func (a *Actor) HasSiteMessagePerm() bool {
	if a == nil {
		return false
	}
	if a.Role == model.RoleOwner || a.Role == model.RoleSuperAdmin {
		return true
	}
	return a.CanManageMessages
}

// CanPurgeContent 彻底删除帖/评：仅站长
func (a *Actor) CanPurgeContent() bool {
	return a != nil && a.Role == model.RoleOwner
}

// CanModerateBoard 是否可管理指定板块的内容：
// 管理员及以上不限板块；板块管理员仅限被授权板块
func (a *Actor) CanModerateBoard(boardID uint) bool {
	if a == nil {
		return false
	}
	if model.RoleLevel(a.Role) >= model.RoleLevel(model.RoleAdmin) {
		return true
	}
	if a.Role != model.RoleBoardAdmin {
		return false
	}
	for _, id := range a.BoardIDs {
		if id == boardID {
			return true
		}
	}
	return false
}

// CanModerateAuthor 板管不可软删/恢复管理员及以上作者的内容；其他角色不受此限
func (a *Actor) CanModerateAuthor(authorRole model.Role) bool {
	if a == nil {
		return false
	}
	if a.Role == model.RoleBoardAdmin {
		return model.RoleLevel(authorRole) < model.RoleLevel(model.RoleAdmin)
	}
	return true
}

// CanAssignRole 操作者能否把他人设置为目标角色（站长不可被授予，仅站长可授予超管）
func (a *Actor) CanAssignRole(target model.Role) bool {
	if a == nil {
		return false
	}
	if target == model.RoleOwner {
		return false // 站长身份不通过授权产生
	}
	if target == model.RoleSuperAdmin {
		return a.Role == model.RoleOwner
	}
	return a.HasPerm(PermUsers)
}

// LoadActor 读取用户实时角色与板块授权
func (s *AuthService) LoadActor(id uint) (*Actor, error) {
	var u model.User
	if err := s.db.Select("id", "username", "role", "can_manage_messages").First(&u, id).Error; err != nil {
		return nil, err
	}
	actor := &Actor{
		ID: u.ID, Username: u.Username, Role: u.Role, BoardIDs: []uint{},
		CanManageMessages: u.CanManageMessages,
	}
	if u.Role == model.RoleBoardAdmin {
		var ids []uint
		if err := s.db.Model(&model.UserBoard{}).
			Where("user_id = ?", id).
			Order("board_id ASC").
			Pluck("board_id", &ids).Error; err != nil {
			return nil, err
		}
		actor.BoardIDs = ids
	}
	return actor, nil
}

// GetUserRole 读取用户角色（内容作者保护用）；用户不存在返回 user
func (s *AuthService) GetUserRole(id uint) (model.Role, error) {
	var u model.User
	if err := s.db.Select("role").First(&u, id).Error; err != nil {
		return model.RoleUser, err
	}
	return u.Role, nil
}

// GetUserBoardIDs 读取用户被授权的板块 ID（供 /me 等场景）
func (s *AuthService) GetUserBoardIDs(id uint) ([]uint, error) {
	var ids []uint
	err := s.db.Model(&model.UserBoard{}).
		Where("user_id = ?", id).Order("board_id ASC").Pluck("board_id", &ids).Error
	return ids, err
}

// GetUserIDByUsername 按用户名查 ID（登录失败审计用），用户不存在返回 0
func (s *AuthService) GetUserIDByUsername(username string) uint {
	username = strings.TrimSpace(username)
	if username == "" {
		return 0
	}
	var u model.User
	if err := s.db.Select("id").Where("username = ?", username).First(&u).Error; err != nil {
		return 0
	}
	return u.ID
}

// ListBoardModeratorIDs 可审核指定板块的用户 ID：
// 站长/超管/全站管理员 + 被授权该板的板块管理员（未封禁、未删除）
func (s *AuthService) ListBoardModeratorIDs(boardID uint) ([]uint, error) {
	var ids []uint
	// 全站可审：admin / super_admin / owner
	if err := s.db.Model(&model.User{}).
		Where("deleted_at IS NULL AND banned = ? AND role IN ?", false,
			[]string{string(model.RoleAdmin), string(model.RoleSuperAdmin), string(model.RoleOwner)}).
		Pluck("id", &ids).Error; err != nil {
		return nil, err
	}
	// 板块管理员（授权该板）
	var boardAdminIDs []uint
	if err := s.db.Model(&model.UserBoard{}).
		Select("user_boards.user_id").
		Joins("JOIN users ON users.id = user_boards.user_id").
		Where("user_boards.board_id = ? AND users.deleted_at IS NULL AND users.banned = ? AND users.role = ?",
			boardID, false, string(model.RoleBoardAdmin)).
		Pluck("user_boards.user_id", &boardAdminIDs).Error; err != nil {
		return nil, err
	}
	seen := make(map[uint]struct{}, len(ids)+len(boardAdminIDs))
	out := make([]uint, 0, len(ids)+len(boardAdminIDs))
	for _, id := range ids {
		if _, ok := seen[id]; ok {
			continue
		}
		seen[id] = struct{}{}
		out = append(out, id)
	}
	for _, id := range boardAdminIDs {
		if _, ok := seen[id]; ok {
			continue
		}
		seen[id] = struct{}{}
		out = append(out, id)
	}
	return out, nil
}