package auth

import (
	"context"
	"errors"
	"time"

	"gorm.io/gorm"

	"ws_usernode/internal/model"
	"ws_usernode/internal/pkg"
)

// 会话用户类型。
const (
	SessionUserAdmin = "admin"
	SessionUserUser  = "user"
)

// Session 为一次会话的元数据（对 model.Session 的轻量封装）。
type Session struct {
	ID       string
	UserType string
	RefID    uint
	ExpireAt time.Time
}

// ErrSessionNotFound 表示会话不存在或已过期。
var ErrSessionNotFound = errors.New("auth: session not found")

// SessionStore 为会话存储接口（DB 实现，兼容多实例）。
type SessionStore interface {
	Create(ctx context.Context, userType string, refID uint, ttl time.Duration, ip, userAgent string) (string, error)
	Get(ctx context.Context, sessionID string) (*Session, error)
	Delete(ctx context.Context, sessionID string) error
}

// DBSessionStore 基于 model.Session 的存储实现。
type DBSessionStore struct {
	db *gorm.DB
}

// NewDBSessionStore 创建会话存储。
func NewDBSessionStore(db *gorm.DB) *DBSessionStore {
	return &DBSessionStore{db: db}
}

func (s *DBSessionStore) Create(ctx context.Context, userType string, refID uint, ttl time.Duration, ip, userAgent string) (string, error) {
	id, err := pkg.RandomHex(24)
	if err != nil {
		return "", err
	}
	sess := model.Session{
		ID:        id,
		UserType:  userType,
		RefID:     refID,
		ExpireAt:  time.Now().Add(ttl),
		IP:        ip,
		UserAgent: userAgent,
	}
	if err := s.db.WithContext(ctx).Create(&sess).Error; err != nil {
		return "", err
	}
	return id, nil
}

func (s *DBSessionStore) Get(ctx context.Context, sessionID string) (*Session, error) {
	var m model.Session
	err := s.db.WithContext(ctx).First(&m, "id = ?", sessionID).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrSessionNotFound
		}
		return nil, err
	}
	if time.Now().After(m.ExpireAt) {
		return nil, ErrSessionNotFound
	}
	return &Session{ID: m.ID, UserType: m.UserType, RefID: m.RefID, ExpireAt: m.ExpireAt}, nil
}

func (s *DBSessionStore) Delete(ctx context.Context, sessionID string) error {
	return s.db.WithContext(ctx).Delete(&model.Session{}, "id = ?", sessionID).Error
}