package service

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

	"gitea.com/texpixel/document_ai/config"
	model "gitea.com/texpixel/document_ai/internal/model/user"
	"gitea.com/texpixel/document_ai/internal/storage/cache"
	"gitea.com/texpixel/document_ai/internal/storage/dao"
	"gitea.com/texpixel/document_ai/pkg/common"
	"gitea.com/texpixel/document_ai/pkg/log"
	"gitea.com/texpixel/document_ai/pkg/sms"
	"golang.org/x/crypto/bcrypt"
)

type UserService struct {
	userDao *dao.UserDao
}

func NewUserService() *UserService {
	return &UserService{
		userDao: dao.NewUserDao(),
	}
}

func (svc *UserService) GetSmsCode(ctx context.Context, phone string) (string, error) {
	limit, err := cache.GetUserSendSmsLimit(ctx, phone)
	if err != nil {
		log.Error(ctx, "func", "GetSmsCode", "msg", "get user send sms limit error", "error", err)
		return "", err
	}
	if limit >= cache.UserSendSmsLimitCount {
		return "", errors.New("sms code send limit reached")
	}

	user, err := svc.userDao.GetByPhone(dao.DB.WithContext(ctx), phone)
	if err != nil {
		log.Error(ctx, "func", "GetSmsCode", "msg", "get user error", "error", err)
		return "", err
	}
	if user == nil {
		user = &dao.User{Phone: phone}
		err = svc.userDao.Create(dao.DB.WithContext(ctx), user)
		if err != nil {
			log.Error(ctx, "func", "GetSmsCode", "msg", "create user error", "error", err)
			return "", err
		}
	}

	code := fmt.Sprintf("%06d", rand.Intn(1000000))
	err = sms.SendMessage(&sms.SendSmsRequest{PhoneNumbers: phone, SignName: sms.Signature, TemplateCode: sms.TemplateCode, TemplateParam: fmt.Sprintf(sms.TemplateParam, code)})
	if err != nil {
		log.Error(ctx, "func", "GetSmsCode", "msg", "send message error", "error", err)
		return "", err
	}

	cacheErr := cache.SetUserSmsCode(ctx, phone, code)
	if cacheErr != nil {
		log.Error(ctx, "func", "GetSmsCode", "msg", "set user sms code error", "error", cacheErr)
	}
	cacheErr = cache.SetUserSendSmsLimit(ctx, phone)
	if cacheErr != nil {
		log.Error(ctx, "func", "GetSmsCode", "msg", "set user send sms limit error", "error", cacheErr)
	}
	return code, nil
}

func (svc *UserService) VerifySmsCode(ctx context.Context, phone, code string) (uid int64, err error) {
	user, err := svc.userDao.GetByPhone(dao.DB.WithContext(ctx), phone)
	if err != nil {
		log.Error(ctx, "func", "VerifySmsCode", "msg", "get user error", "error", err, "phone", phone)
		return 0, err
	}
	if user == nil {
		log.Error(ctx, "func", "VerifySmsCode", "msg", "user not found", "phone", phone)
		return 0, errors.New("user not found")
	}

	storedCode, err := cache.GetUserSmsCode(ctx, phone)
	if err != nil {
		log.Error(ctx, "func", "VerifySmsCode", "msg", "get user sms code error", "error", err)
		return 0, err
	}
	if storedCode != code {
		log.Error(ctx, "func", "VerifySmsCode", "msg", "invalid sms code", "phone", phone, "code", code, "storedCode", storedCode)
		return 0, errors.New("invalid sms code")
	}

	cacheErr := cache.DeleteUserSmsCode(ctx, phone)
	if cacheErr != nil {
		log.Error(ctx, "func", "VerifySmsCode", "msg", "delete user sms code error", "error", cacheErr)
	}

	return user.ID, nil
}

func (svc *UserService) GetUserInfo(ctx context.Context, uid int64) (*dao.User, error) {
	user, err := svc.userDao.GetByID(dao.DB.WithContext(ctx), uid)
	if err != nil {
		log.Error(ctx, "func", "GetUserInfo", "msg", "get user error", "error", err)
		return nil, err
	}

	if user == nil {
		log.Warn(ctx, "func", "GetUserInfo", "msg", "user not found", "uid", uid)
		return &dao.User{}, nil
	}

	return user, nil
}

func (svc *UserService) RegisterByEmail(ctx context.Context, email, password string) (uid int64, err error) {
	existingUser, err := svc.userDao.GetByEmail(dao.DB.WithContext(ctx), email)
	if err != nil {
		log.Error(ctx, "func", "RegisterByEmail", "msg", "get user by email error", "error", err)
		return 0, err
	}
	if existingUser != nil {
		log.Warn(ctx, "func", "RegisterByEmail", "msg", "email already registered", "email", email)
		return 0, common.ErrEmailExists
	}

	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		log.Error(ctx, "func", "RegisterByEmail", "msg", "hash password error", "error", err)
		return 0, err
	}

	user := &dao.User{
		Email:    email,
		Password: string(hashedPassword),
	}
	err = svc.userDao.Create(dao.DB.WithContext(ctx), user)
	if err != nil {
		log.Error(ctx, "func", "RegisterByEmail", "msg", "create user error", "error", err)
		return 0, err
	}

	return user.ID, nil
}

func (svc *UserService) LoginByEmail(ctx context.Context, email, password string) (uid int64, err error) {
	user, err := svc.userDao.GetByEmail(dao.DB.WithContext(ctx), email)
	if err != nil {
		log.Error(ctx, "func", "LoginByEmail", "msg", "get user by email error", "error", err)
		return 0, err
	}
	if user == nil {
		log.Warn(ctx, "func", "LoginByEmail", "msg", "user not found", "email", email)
		return 0, common.ErrEmailNotFound
	}

	err = bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(password))
	if err != nil {
		log.Warn(ctx, "func", "LoginByEmail", "msg", "password mismatch", "email", email)
		return 0, common.ErrPasswordMismatch
	}

	return user.ID, nil
}

type googleTokenResponse struct {
	AccessToken string `json:"access_token"`
	IDToken     string `json:"id_token"`
	ExpiresIn   int    `json:"expires_in"`
	TokenType   string `json:"token_type"`
}

func (svc *UserService) googleHTTPClient() *http.Client {
	if config.GlobalConfig.Google.Proxy == "" {
		return &http.Client{}
	}
	proxyURL, err := url.Parse(config.GlobalConfig.Google.Proxy)
	if err != nil {
		return &http.Client{}
	}
	return &http.Client{Transport: &http.Transport{Proxy: http.ProxyURL(proxyURL)}}
}

func (svc *UserService) ExchangeGoogleCodeAndGetUserInfo(ctx context.Context, clientID, clientSecret, code, redirectURI string) (*model.GoogleUserInfo, error) {
	tokenURL := "https://oauth2.googleapis.com/token"
	formData := url.Values{
		"client_id":     {clientID},
		"client_secret": {clientSecret},
		"code":          {code},
		"grant_type":    {"authorization_code"},
		"redirect_uri":  {redirectURI},
	}

	client := svc.googleHTTPClient()
	resp, err := client.PostForm(tokenURL, formData)
	if err != nil {
		log.Error(ctx, "func", "ExchangeGoogleCodeAndGetUserInfo", "msg", "exchange code failed", "error", err)
		return nil, err
	}
	defer resp.Body.Close()

	var tokenResp googleTokenResponse
	if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
		log.Error(ctx, "func", "ExchangeGoogleCodeAndGetUserInfo", "msg", "decode token response failed", "error", err)
		return nil, err
	}

	if tokenResp.AccessToken == "" {
		log.Error(ctx, "func", "ExchangeGoogleCodeAndGetUserInfo", "msg", "no access token in response")
		return nil, errors.New("no access token in response")
	}

	userInfo, err := svc.getGoogleUserInfo(ctx, tokenResp.AccessToken)
	if err != nil {
		log.Error(ctx, "func", "ExchangeGoogleCodeAndGetUserInfo", "msg", "get user info failed", "error", err)
		return nil, err
	}

	return &model.GoogleUserInfo{
		ID:    userInfo.ID,
		Email: userInfo.Email,
		Name:  userInfo.Name,
	}, nil
}

func (svc *UserService) getGoogleUserInfo(ctx context.Context, accessToken string) (*model.GoogleUserInfo, error) {
	req, err := http.NewRequestWithContext(ctx, "GET", "https://www.googleapis.com/oauth2/v2/userinfo", nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Authorization", "Bearer "+accessToken)

	client := svc.googleHTTPClient()
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var userInfo model.GoogleUserInfo
	if err := json.NewDecoder(resp.Body).Decode(&userInfo); err != nil {
		return nil, err
	}

	return &userInfo, nil
}

func (svc *UserService) FindOrCreateGoogleUser(ctx context.Context, userInfo *model.GoogleUserInfo) (uid int64, err error) {
	existingUser, err := svc.userDao.GetByGoogleID(dao.DB.WithContext(ctx), userInfo.ID)
	if err != nil {
		log.Error(ctx, "func", "FindOrCreateGoogleUser", "msg", "get user by google id error", "error", err)
		return 0, err
	}

	if existingUser != nil {
		return existingUser.ID, nil
	}

	existingUser, err = svc.userDao.GetByEmail(dao.DB.WithContext(ctx), userInfo.Email)
	if err != nil {
		log.Error(ctx, "func", "FindOrCreateGoogleUser", "msg", "get user by email error", "error", err)
		return 0, err
	}

	if existingUser != nil {
		existingUser.GoogleID = userInfo.ID
		err = svc.userDao.Update(dao.DB.WithContext(ctx), existingUser)
		if err != nil {
			log.Error(ctx, "func", "FindOrCreateGoogleUser", "msg", "update user google id error", "error", err)
			return 0, err
		}
		return existingUser.ID, nil
	}

	user := &dao.User{
		Email:    userInfo.Email,
		GoogleID: userInfo.ID,
		Username: userInfo.Name,
	}
	err = svc.userDao.Create(dao.DB.WithContext(ctx), user)
	if err != nil {
		log.Error(ctx, "func", "FindOrCreateGoogleUser", "msg", "create user error", "error", err)
		return 0, err
	}

	return user.ID, nil
}