package service

import (
	"electricity_bill_calc/cache"
	"electricity_bill_calc/config"
	"electricity_bill_calc/exceptions"
	"electricity_bill_calc/global"
	"electricity_bill_calc/model"
	"electricity_bill_calc/tools"
	"fmt"
	"strconv"
	"time"

	"github.com/fufuok/utils"
	"github.com/google/uuid"
	"xorm.io/builder"
)

type _UserService struct{}

var UserService _UserService

func (u _UserService) ProcessEnterpriseUserLogin(username, password string) (*model.Session, error) {
	user, err := u.findUserWithCredentialsByUsername(username)

	if err != nil {
		return nil, err
	}
	if user == nil {
		return nil, exceptions.NewAuthenticationError(404, "用户不存在。")
	}
	if user.Type != 0 {
		return nil, exceptions.NewAuthenticationError(400, "用户类型不正确。")
	}
	if !user.Enabled {
		return nil, exceptions.NewAuthenticationError(403, "用户已被禁用。")
	}
	hashedPassword := utils.Sha512Hex(password)
	if hashedPassword != user.Password {
		return nil, exceptions.NewAuthenticationError(402, "用户凭据不正确。")
	}
	if user.ResetNeeded {
		authErr := exceptions.NewAuthenticationError(401, "用户凭据已失效。")
		authErr.NeedReset = true
		return nil, authErr
	}
	userDetial, _ := u.retreiveUserDetail(user.Id)
	if userDetial.ServiceExpiration.Before(time.Now()) {
		return nil, exceptions.NewAuthenticationError(406, "用户服务期限已过。")
	}
	session := &model.Session{
		Token:     uuid.New().String(),
		Uid:       user.Id,
		Type:      user.Type,
		Name:      user.Username,
		ExpiresAt: time.Now().Add(config.ServiceSettings.MaxSessionLife),
	}
	if userDetial != nil {
		session.Name = *userDetial.Name
	}
	cache.CacheSession(session)
	return session, nil
}

func (u _UserService) ProcessManagementUserLogin(username, password string) (*model.Session, error) {
	user, err := u.findUserWithCredentialsByUsername(username)

	if err != nil {
		return nil, err
	}
	if user == nil {
		return nil, exceptions.NewAuthenticationError(404, "用户不存在。")
	}
	if user.Type != 1 && user.Type != 2 {
		return nil, exceptions.NewAuthenticationError(401, "用户类型不正确。")
	}
	if !user.Enabled {
		return nil, exceptions.NewAuthenticationError(401, "用户已被禁用。")
	}
	hashedPassword := utils.Sha512Hex(password)
	if hashedPassword != user.Password {
		return nil, exceptions.NewAuthenticationError(401, "用户凭据不正确。")
	}
	if user.ResetNeeded {
		authErr := exceptions.NewAuthenticationError(401, "用户凭据已失效。")
		authErr.NeedReset = true
		return nil, authErr
	}
	session := &model.Session{
		Token:     uuid.New().String(),
		Uid:       user.Id,
		Type:      user.Type,
		Name:      user.Username,
		ExpiresAt: time.Now().Add(config.ServiceSettings.MaxSessionLife),
	}
	userDetial, _ := u.retreiveUserDetail(user.Id)
	if userDetial != nil {
		session.Name = *userDetial.Name
	}
	cache.CacheSession(session)
	return session, nil
}

func (u _UserService) InvalidUserPassword(uid string) (string, error) {
	user, err := u.findUserByID(uid)
	if user == nil && err != nil {
		return "", exceptions.NewNotFoundError("指定的用户不存在。")
	}
	verifyCode := tools.RandStr(10)
	user.Password = utils.Sha512Hex(verifyCode)
	user.ResetNeeded = true
	affected, err := global.DBConn.ID(uid).Cols("password", "reset_needed").Update(user)
	if err != nil {
		return "", err
	}
	if affected > 0 {
		// ! 同一个用户在缓存中有两个键。
		cache.AbolishRelation(fmt.Sprintf("user_%s", uid))
		cache.AbolishRelation("user")
		return verifyCode, nil
	} else {
		return "", exceptions.NewUnsuccessfulOperationError()
	}
}

func (u _UserService) VerifyUserPassword(username, verifyCode string) (bool, error) {
	user, err := u.findUserByUsername(username)
	if user == nil || err != nil {
		return false, exceptions.NewNotFoundError("指定的用户不存在。")
	}
	hashedVerifyCode := utils.Sha512Hex(verifyCode)
	if hashedVerifyCode != user.Password {
		return false, nil
	} else {
		return true, nil
	}
}

func (u _UserService) ResetUserPassword(username, password string) (bool, error) {
	user, err := u.findUserByUsername(username)
	if user == nil || err != nil {
		return false, exceptions.NewNotFoundError("指定的用户不存在。")
	}
	user.Password = utils.Sha512Hex(password)
	user.ResetNeeded = false
	affected, err := global.DBConn.ID(user.Id).Cols("password", "reset_needed").Update(user)
	if err != nil {
		return false, err
	}
	if affected > 0 {
		cache.AbolishRelation(fmt.Sprintf("user_%s", user.Id))
		cache.AbolishRelation("user")
		return true, nil
	} else {
		return false, nil
	}
}

func (_UserService) IsUserExists(uid string) (bool, error) {
	if has, _ := cache.CheckExists("user", uid); has {
		return has, nil
	}
	has, err := global.DBConn.ID(uid).Exist(&model.User{})
	if has {
		cache.CacheExists([]string{fmt.Sprintf("user_%s", uid)}, "user", uid)
	}
	return has, err
}

func (_UserService) IsUsernameExists(username string) (bool, error) {
	if has, _ := cache.CheckExists("user", username); has {
		return has, nil
	}
	has, err := global.DBConn.Where(builder.Eq{"username": username}).Exist(&model.User{})
	if has {
		cache.CacheExists([]string{"user"}, "user", username)
	}
	return has, err
}

func (u _UserService) CreateUser(user *model.User, detail *model.UserDetail) (string, error) {
	if len(user.Id) == 0 {
		user.Id = uuid.New().String()
	}
	exists, err := u.IsUserExists(user.Id)
	if exists {
		return "", exceptions.NewNotFoundError("user already exists")
	}
	if err != nil {
		return "", nil
	}
	detail.Id = user.Id

	verifyCode := tools.RandStr(10)
	user.Password = utils.Sha512Hex(verifyCode)
	user.ResetNeeded = true

	if detail.Name != nil {
		finalAbbr := tools.PinyinAbbr(*detail.Name)
		detail.Abbr = &finalAbbr
	}

	tx := global.DBConn.NewSession()
	defer tx.Close()
	if err := tx.Begin(); err != nil {
		return "", err
	}
	_, err = tx.Insert(user)
	if err != nil {
		tx.Rollback()
		return "", fmt.Errorf("user create failed: %w", err)
	}
	_, err = tx.Insert(detail)
	if err != nil {
		tx.Rollback()
		return "", fmt.Errorf("user Detail create failed: %w", err)
	}
	err = tx.Commit()
	if err != nil {
		tx.Rollback()
		return "", fmt.Errorf("transaction commit unsuccessful: %w", err)
	}
	cache.AbolishRelation("user")
	return verifyCode, nil
}

func (u _UserService) SwitchUserState(uid string, enabled bool) error {
	exists, err := u.IsUserExists(uid)
	if !exists {
		return exceptions.NewNotFoundError("user not exists")
	}
	if err != nil {
		return err
	}
	newStateUser := new(model.User)
	newStateUser.Enabled = enabled
	_, err = global.DBConn.ID(uid).Cols("enabled").Update(newStateUser)
	if err != nil {
		cache.AbolishRelation("user")
		cache.AbolishRelation(fmt.Sprintf("user_%s", uid))
	}
	return err
}

func (_UserService) SearchLimitUsers(keyword string, limit int) ([]model.JoinedUserDetail, error) {
	if cachedUsers, _ := cache.RetreiveSearch[[]model.JoinedUserDetail]("join_user_detail", keyword, strconv.Itoa(limit)); cachedUsers != nil {
		return *cachedUsers, nil
	}
	var users = make([]model.JoinedUserDetail, 0)
	err := global.DBConn.
		Table("user_detail").Alias("d").
		Join("INNER", []string{"user", "u"}, "d.id=u.id").
		Where(
			builder.NewCond().
				Or(builder.Like{"u.username", keyword}).
				Or(builder.Like{"d.name", keyword}).
				Or(builder.Like{"d.abbr", keyword})).
		And(builder.Eq{"u.type": 0}).
		Asc("u.created_at").
		Limit(limit, 0).
		Find(&users)
	if err != nil {
		return make([]model.JoinedUserDetail, 0), err
	}
	cache.CacheSearch(users, []string{"user"}, "join_user_detail", keyword, strconv.Itoa(limit))
	return users, nil
}

func (_UserService) findUserWithCredentialsByUsername(username string) (*model.UserWithCredentials, error) {
	if cachedUser, _ := cache.RetreiveSearch[model.UserWithCredentials]("user_with_credentials", username); cachedUser != nil {
		return cachedUser, nil
	}
	user := new(model.UserWithCredentials)
	has, err := global.DBConn.Where(builder.Eq{"username": username}).NoAutoCondition().Get(user)
	if has {
		cache.CacheSearch(*user, []string{"user"}, "user_with_credentials", username)
	}
	return _postProcessSingle(user, has, err)
}

func (_UserService) findUserByUsername(username string) (*model.User, error) {
	if cachedUser, _ := cache.RetreiveSearch[model.User]("user", username); cachedUser != nil {
		return cachedUser, nil
	}
	user := new(model.User)
	has, err := global.DBConn.Where(builder.Eq{"username": username}).NoAutoCondition().Get(user)
	if has {
		cache.CacheSearch(*user, []string{"user"}, "user", username)
	}
	return _postProcessSingle(user, has, err)
}

func (_UserService) retreiveUserDetail(uid string) (*model.UserDetail, error) {
	if cachedUser, _ := cache.RetreiveEntity[model.UserDetail]("user_detail", uid); cachedUser != nil {
		return cachedUser, nil
	}
	user := new(model.UserDetail)
	has, err := global.DBConn.ID(uid).NoAutoCondition().Get(user)
	if has {
		cache.CacheEntity(*user, []string{fmt.Sprintf("user_%s", uid)}, "user_detail", uid)
	}
	return _postProcessSingle(user, has, err)
}

func (_UserService) findUserByID(uid string) (*model.User, error) {
	cachedUser, _ := cache.RetreiveEntity[model.User]("user", uid)
	if cachedUser != nil {
		return cachedUser, nil
	}
	user := new(model.User)
	has, err := global.DBConn.ID(uid).NoAutoCondition().Get(user)
	if has {
		cache.CacheEntity(*user, []string{fmt.Sprintf("user_%s", uid)}, "user", uid)
	}
	return _postProcessSingle(user, has, err)
}

func (_UserService) ListUserDetail(keyword string, userType int, userState *bool, page int) ([]model.JoinedUserDetail, int64, error) {
	var (
		cond            = builder.NewCond()
		cacheConditions = make([]string, 0)
	)
	cacheConditions = append(cacheConditions, strconv.Itoa(page))
	cond = cond.And(builder.Neq{"d.id": "000"})
	if len(keyword) != 0 {
		keywordCond := builder.NewCond().
			Or(builder.Like{"u.username", keyword}).
			Or(builder.Like{"d.name", keyword})
		cond = cond.And(keywordCond)
		cacheConditions = append(cacheConditions, keyword)
	}
	if userType != -1 {
		cond = cond.And(builder.Eq{"u.type": userType})
		cacheConditions = append(cacheConditions, strconv.Itoa(userType))
	}
	if userState != nil {
		cond = cond.And(builder.Eq{"u.enabled": *userState})
		cacheConditions = append(cacheConditions, strconv.FormatBool(*userState))
	}
	startItem := (page - 1) * config.ServiceSettings.ItemsPageSize
	var (
		total int64
		err   error
	)
	if cacheCounts, err := cache.RetreiveCount("join_user_detail", cacheConditions...); cacheCounts != -1 && err == nil {
		total = cacheCounts
	} else {
		total, err = global.DBConn.
			Table("user_detail").Alias("d").
			Join("INNER", []string{"user", "u"}, "d.id=u.id").
			Where(cond).
			Count(&model.User{})
		if err != nil {
			return nil, -1, err
		}
		cache.CacheCount([]string{"user"}, "join_user_detail", total, cacheConditions...)
	}
	users := make([]model.JoinedUserDetail, 0)
	if cachedUsers, _ := cache.RetreiveSearch[[]model.JoinedUserDetail]("join_user_detail", cacheConditions...); cachedUsers != nil {
		return *cachedUsers, total, nil
	}
	err = global.DBConn.
		Table("user_detail").Alias("d").
		Join("INNER", []string{"user", "u"}, "d.id=u.id").
		Where(cond).
		Limit(config.ServiceSettings.ItemsPageSize, startItem).
		Find(&users)
	cache.CacheSearch(users, []string{"user"}, "join_user_detail", cacheConditions...)
	return users, total, err
}

func (_UserService) FetchUserDetail(uid string) (*model.FullJoinedUserDetail, error) {
	if cachedUser, _ := cache.RetreiveEntity[model.FullJoinedUserDetail]("full_join_user_detail", uid); cachedUser != nil {
		return cachedUser, nil
	}
	user := &model.FullJoinedUserDetail{}
	has, err := global.DBConn.
		Table("user_detail").Alias("d").
		Join("INNER", []string{"user", "u"}, "d.id=u.id").
		Where(builder.Eq{"d.id": uid}).
		NoAutoCondition().
		Get(user)
	if has {
		cache.CacheEntity(*user, []string{fmt.Sprintf("user_%s", uid)}, "full_join_user_detail", uid)
		return user, nil
	}
	return nil, err
}