package service

import (
	"context"
	"database/sql"
	"fmt"
	"time"

	"github.com/google/uuid"
	"github.com/ocdp/cluster-service/internal/domain/entity"
	"github.com/ocdp/cluster-service/internal/domain/repository"
)

// UserManagementService 用户管理领域服务（仅 Admin 可用）
type UserManagementService struct {
	userRepo       repository.UserRepository
	workspaceRepo  repository.WorkspaceRepository
	passwordHasher PasswordHasher
}

// NewUserManagementService 创建用户管理服务
func NewUserManagementService(
	userRepo repository.UserRepository,
	workspaceRepo repository.WorkspaceRepository,
	passwordHasher PasswordHasher,
) *UserManagementService {
	return &UserManagementService{
		userRepo:       userRepo,
		workspaceRepo:  workspaceRepo,
		passwordHasher: passwordHasher,
	}
}

// CreateUser 创建用户（Admin 操作）
func (s *UserManagementService) CreateUser(ctx context.Context, username, password, email, role string, workspaceID string) (*entity.User, error) {
	// 检查用户是否已存在
	existing, _ := s.userRepo.GetByUsername(ctx, username)
	if existing != nil {
		return nil, entity.ErrUserExists
	}

	// 验证角色
	if role != string(entity.RoleAdmin) && role != string(entity.RoleUser) {
		return nil, fmt.Errorf("invalid role: %s", role)
	}

	// 如果指定了 workspace，验证 workspace 存在
	if workspaceID != "" {
		_, err := s.workspaceRepo.GetByID(ctx, workspaceID)
		if err != nil {
			if err == entity.ErrWorkspaceNotFound {
				return nil, entity.ErrWorkspaceNotFound
			}
			return nil, err
		}
	}

	// Admin 不能分配到 workspace
	if role == string(entity.RoleAdmin) && workspaceID != "" {
		workspaceID = ""
	}

	// 哈希密码
	passwordHash, err := s.passwordHasher.Hash(password)
	if err != nil {
		return nil, err
	}

	// 生成占位邮箱
	if email == "" {
		email = username + "@local.ocdp"
	}

	// 创建用户
	user := entity.NewUser(username, passwordHash, email)
	user.ID = uuid.New().String()
	user.Role = entity.UserRole(role)
	user.WorkspaceID = workspaceID
	user.IsActive = true
	user.MustChangePassword = true // 首次登录必须修改密码

	if err := user.Validate(); err != nil {
		return nil, err
	}

	if err := s.userRepo.Create(ctx, user); err != nil {
		return nil, err
	}

	return user, nil
}

// GetUser 获取用户
func (s *UserManagementService) GetUser(ctx context.Context, id string) (*entity.User, error) {
	return s.userRepo.GetByID(ctx, id)
}

// ListUsers 列出用户（可筛选 workspace）
func (s *UserManagementService) ListUsers(ctx context.Context, workspaceID string) ([]*entity.User, error) {
	if workspaceID != "" {
		return s.userRepo.ListByWorkspace(ctx, workspaceID)
	}
	return s.userRepo.List(ctx)
}

// UpdateUser 更新用户信息
func (s *UserManagementService) UpdateUser(ctx context.Context, user *entity.User) error {
	return s.userRepo.Update(ctx, user)
}

// SetUserActive 启用/禁用用户
func (s *UserManagementService) SetUserActive(ctx context.Context, userID string, isActive bool) error {
	user, err := s.userRepo.GetByID(ctx, userID)
	if err != nil {
		return err
	}

	user.IsActive = isActive
	return s.userRepo.Update(ctx, user)
}

// ChangeUserWorkspace 分配用户到 workspace
func (s *UserManagementService) ChangeUserWorkspace(ctx context.Context, userID, workspaceID string) error {
	user, err := s.userRepo.GetByID(ctx, userID)
	if err != nil {
		return err
	}

	// Admin 不能分配到 workspace
	if user.Role == entity.RoleAdmin {
		return fmt.Errorf("admin user cannot be assigned to workspace")
	}

	// 验证 workspace 存在
	if workspaceID != "" {
		_, err := s.workspaceRepo.GetByID(ctx, workspaceID)
		if err != nil {
			if err == sql.ErrNoRows || err == entity.ErrWorkspaceNotFound {
				return entity.ErrWorkspaceNotFound
			}
			return err
		}
	}

	user.WorkspaceID = workspaceID
	return s.userRepo.Update(ctx, user)
}

// ResetPassword 重置用户密码（Admin 操作）
func (s *UserManagementService) ResetPassword(ctx context.Context, userID, newPassword string) error {
	user, err := s.userRepo.GetByID(ctx, userID)
	if err != nil {
		return err
	}

	// 哈希新密码
	passwordHash, err := s.passwordHasher.Hash(newPassword)
	if err != nil {
		return err
	}

	// 更新密码并设置必须修改密码标志
	user.PasswordHash = passwordHash
	user.MustChangePassword = true
	user.RevokeAllTokens() // 强制登出所有会话

	return s.userRepo.Update(ctx, user)
}

// DeleteUser 删除用户
func (s *UserManagementService) DeleteUser(ctx context.Context, id string) error {
	return s.userRepo.Delete(ctx, id)
}

// GetUserWithWorkspace 获取用户及其 workspace 信息
type UserWithWorkspace struct {
	User      *entity.User
	Workspace *entity.Workspace
}

// GetUserWithWorkspace 获取用户及其 workspace 信息
func (s *UserManagementService) GetUserWithWorkspace(ctx context.Context, userID string) (*UserWithWorkspace, error) {
	user, err := s.userRepo.GetByID(ctx, userID)
	if err != nil {
		return nil, err
	}

	result := &UserWithWorkspace{
		User: user,
	}

	if user.WorkspaceID != "" {
		workspace, _ := s.workspaceRepo.GetByID(ctx, user.WorkspaceID)
		result.Workspace = workspace
	}

	return result, nil
}

// ListUsersWithWorkspace 列出用户及其 workspace 信息
func (s *UserManagementService) ListUsersWithWorkspace(ctx context.Context) ([]*UserWithWorkspace, error) {
	users, err := s.userRepo.List(ctx)
	if err != nil {
		return nil, err
	}

	// 预加载所有 workspace
	workspaces, err := s.workspaceRepo.List(ctx)
	if err != nil {
		return nil, err
	}

	workspaceMap := make(map[string]*entity.Workspace)
	for _, w := range workspaces {
		workspaceMap[w.ID] = w
	}

	result := make([]*UserWithWorkspace, len(users))
	for i, user := range users {
		result[i] = &UserWithWorkspace{
			User: user,
		}
		if user.WorkspaceID != "" {
			result[i].Workspace = workspaceMap[user.WorkspaceID]
		}
	}

	return result, nil
}

// EnsureAdminExists 确保存在一个 Admin 用户
func (s *UserManagementService) EnsureAdminExists(ctx context.Context, defaultPassword string) error {
	users, err := s.userRepo.List(ctx)
	if err != nil {
		return err
	}

	// 检查是否已有 admin
	for _, u := range users {
		if u.Role == entity.RoleAdmin {
			return nil
		}
	}

	// 创建默认 admin 用户
	_, err = s.CreateUser(ctx, "admin", defaultPassword, "", string(entity.RoleAdmin), "")
	return err
}

// CreateInitialUser 创建初始用户（首次启动时调用）
func (s *UserManagementService) CreateInitialUser(ctx context.Context, username, password, role string) (*entity.User, error) {
	// 检查是否已有用户
	users, err := s.userRepo.List(ctx)
	if err != nil {
		return nil, err
	}

	if len(users) > 0 {
		return nil, fmt.Errorf("initial user already exists")
	}

	// 验证角色
	if role != string(entity.RoleAdmin) && role != string(entity.RoleUser) {
		return nil, fmt.Errorf("invalid role: %s", role)
	}

	// 哈希密码
	passwordHash, err := s.passwordHasher.Hash(password)
	if err != nil {
		return nil, err
	}

	// 生成占位邮箱
	email := username + "@local.ocdp"

	// 创建用户
	user := entity.NewUser(username, passwordHash, email)
	user.ID = uuid.New().String()
	user.Role = entity.UserRole(role)
	// workspace_id 为 NULL（admin）或空（首个普通用户）
	user.IsActive = true
	user.MustChangePassword = false // 初始用户不需要强制修改密码

	if err := user.Validate(); err != nil {
		return nil, err
	}

	// 设置创建时间和更新时间
	now := time.Now()
	user.CreatedAt = now
	user.UpdatedAt = now

	if err := s.userRepo.Create(ctx, user); err != nil {
		return nil, err
	}

	return user, nil
}