package service

import (
	"crypto/sha512"
	"electricity_bill_calc/cache"
	"electricity_bill_calc/config"
	"electricity_bill_calc/exceptions"
	"electricity_bill_calc/global"
	"electricity_bill_calc/model"
	"electricity_bill_calc/repository"
	"electricity_bill_calc/utils"
	"fmt"
	"time"

	"github.com/google/uuid"
)

type _UserService struct{}

var UserService _UserService

func (_UserService) ProcessEnterpriseUserLogin(username, password string) (*model.Session, error) {
	user, err := repository.UserRepo.FindUserByUsername(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(401, "用户类型不正确。")
	}
	if !user.Enabled {
		return nil, exceptions.NewAuthenticationError(401, "用户已被禁用。")
	}
	hash := sha512.New512_256()
	hash.Write([]byte(password))
	hashedPassword := fmt.Sprintf("%x", hash.Sum(nil))
	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, _ := repository.UserRepo.RetreiveUserDetail(user.Id)
	if userDetial != nil {
		session.Name = *userDetial.Name
	}
	cache.CacheSession(session)
	return session, nil
}

func (_UserService) ProcessManagementUserLogin(username, password string) (*model.Session, error) {
	user, err := repository.UserRepo.FindUserByUsername(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。")
	}
	hash := sha512.New512_256()
	hash.Write([]byte(password))
	hashedPassword := fmt.Sprintf("%x", hash.Sum(nil))
	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, _ := repository.UserRepo.RetreiveUserDetail(user.Id)
	if userDetial != nil {
		session.Name = *userDetial.Name
	}
	cache.CacheSession(session)
	return session, nil
}

func (_UserService) InvalidUserPassword(uid string) (string, error) {
	user, err := repository.UserRepo.FindUserByID(uid)
	if user == nil && err != nil {
		return "", exceptions.NewNotFoundError("指定的用户不存在。")
	}
	verifyCode := utils.RandStr(10)
	hash := sha512.New512_256()
	hash.Write([]byte(verifyCode))
	user.Password = string(hash.Sum(nil))
	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.AbolishCacheData("user", user.Id)
		cache.AbolishCacheData("user", user.Username)
		return verifyCode, nil
	} else {
		return "", exceptions.NewUnsuccessfulOperationError()
	}
}

func (_UserService) VerifyUserPassword(username, verifyCode string) (bool, error) {
	user, err := repository.UserRepo.FindUserByUsername(username)
	if user == nil || err != nil {
		return false, exceptions.NewNotFoundError("指定的用户不存在。")
	}
	hash := sha512.New512_256()
	hash.Write([]byte(verifyCode))
	hashedVerifyCode := string(hash.Sum(nil))
	if hashedVerifyCode != user.Password {
		return false, nil
	} else {
		return true, nil
	}
}

func (_UserService) ResetUserPassword(username, password string) (bool, error) {
	user, err := repository.UserRepo.FindUserByUsername(username)
	if user == nil || err != nil {
		return false, exceptions.NewNotFoundError("指定的用户不存在。")
	}
	hash := sha512.New512_256()
	hash.Write([]byte(password))
	user.Password = string(hash.Sum(nil))
	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.AbolishCacheData("user", user.Id)
		cache.AbolishCacheData("user", user.Username)
		return true, nil
	} else {
		return false, nil
	}
}