package service

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"time"

	"gorm.io/gorm"

	"github.com/sundynix/pets-be/internal/model"
)

// MockLogin 开发态登录：按昵称找回或新建用户
func (s *Service) MockLogin(nickname string) (*model.User, error) {
	autoName := nickname == ""
	if autoName {
		nickname = s.UniqueNickname()
	}
	var u model.User
	err := s.db.Where("nickname = ?", nickname).First(&u).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		u = model.User{Nickname: nickname, NicknameAuto: autoName}
		if e := s.db.Create(&u).Error; e != nil {
			return nil, e
		}
		return &u, nil
	}
	if err != nil {
		return nil, err
	}
	return &u, nil
}

// code2SessionResp 微信 jscode2session 返回
type code2SessionResp struct {
	OpenID     string `json:"openid"`
	SessionKey string `json:"session_key"`
	UnionID    string `json:"unionid"`
	ErrCode    int    `json:"errcode"`
	ErrMsg     string `json:"errmsg"`
}

// code2Session 调用微信换取 openid
func (s *Service) code2Session(code string) (*code2SessionResp, error) {
	if s.cfg.WeChat.AppID == "" || s.cfg.WeChat.AppSecret == "" {
		return nil, errors.New("微信登录未配置 app_id / app_secret")
	}
	q := url.Values{}
	q.Set("appid", s.cfg.WeChat.AppID)
	q.Set("secret", s.cfg.WeChat.AppSecret)
	q.Set("js_code", code)
	q.Set("grant_type", "authorization_code")
	endpoint := "https://api.weixin.qq.com/sns/jscode2session?" + q.Encode()

	ctx, cancel := context.WithTimeout(context.Background(), 8*time.Second)
	defer cancel()
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
	if err != nil {
		return nil, err
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var out code2SessionResp
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		return nil, err
	}
	if out.ErrCode != 0 {
		return nil, fmt.Errorf("微信登录失败(%d): %s", out.ErrCode, out.ErrMsg)
	}
	if out.OpenID == "" {
		return nil, errors.New("微信未返回 openid")
	}
	return &out, nil
}

// WechatLogin 微信小程序登录：code → openid → 找回/新建用户
func (s *Service) WechatLogin(code string) (*model.User, error) {
	sess, err := s.code2Session(code)
	if err != nil {
		return nil, err
	}
	var u model.User
	err = s.db.Where("open_id = ?", sess.OpenID).First(&u).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		u = model.User{OpenID: sess.OpenID, Nickname: s.UniqueNickname(), NicknameAuto: true}
		if e := s.db.Create(&u).Error; e != nil {
			return nil, e
		}
		return &u, nil
	}
	if err != nil {
		return nil, err
	}
	return &u, nil
}

// GetUser 取用户
func (s *Service) GetUser(userID string) (*model.User, error) {
	var u model.User
	if err := s.db.First(&u, userID).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	u.AvatarURL = s.fileURL(u.AvatarFileID)
	u.BgURL = s.fileURL(u.BgFileID)
	if !UserThemes[u.Theme] {
		u.Theme = defaultUserTheme // 老用户 theme 是空串，别让前端拿空 key 去查表
	}
	return &u, nil
}

// UpdateUser 更新用户资料（昵称/头像/手机号）
func (s *Service) UpdateUser(userID string, fields map[string]any) (*model.User, error) {
	if err := s.db.Model(&model.User{}).Where("id = ?", userID).Updates(fields).Error; err != nil {
		return nil, err
	}
	return s.GetUser(userID)
}