package account

import (
	"context"
	"errors"
	"feedsystem_video_go/internal/auth"
	"fmt"
	"log"
	"time"

	rediscache "feedsystem_video_go/internal/redis"

	"github.com/go-sql-driver/mysql"
	"golang.org/x/crypto/bcrypt"
	"gorm.io/gorm"
)

type AccountService struct {
	accountRepository *AccountRepository
	cache             *rediscache.Client
}

var (
	ErrUsernameTaken       = errors.New("username already exists")
	ErrNewUsernameRequired = errors.New("new_username is required")
)

func NewAccountService(accountRepository *AccountRepository, cache *rediscache.Client) *AccountService {
	return &AccountService{accountRepository: accountRepository, cache: cache}
}

func (as *AccountService) CreateAccount(ctx context.Context, account *Account) error {
	passwordHash, err := bcrypt.GenerateFromPassword([]byte(account.Password), bcrypt.DefaultCost)
	if err != nil {
		return err
	}
	account.Password = string(passwordHash)
	if err := as.accountRepository.CreateAccount(ctx, account); err != nil {
		return err
	}
	return nil
}

func (as *AccountService) Rename(ctx context.Context, accountID uint, newUsername string) (string, error) {
	if newUsername == "" {
		return "", ErrNewUsernameRequired
	}

	token, err := auth.GenerateToken(accountID, newUsername)
	if err != nil {
		return "", err
	}

	if err := as.accountRepository.RenameWithToken(ctx, accountID, newUsername, token); err != nil {
		var mysqlErr *mysql.MySQLError
		if errors.As(err, &mysqlErr) && mysqlErr.Number == 1062 {
			return "", ErrUsernameTaken
		}
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return "", err
		}
		return "", err
	}
	if as.cache != nil {
		cacheCtx, cancel := context.WithTimeout(ctx, 50*time.Millisecond)
		defer cancel()

		if err := as.cache.SetBytes(cacheCtx, fmt.Sprintf("account:%d", accountID), []byte(token), 24*time.Hour); err != nil {
			log.Printf("failed to set cache: %v", err)
		}
	}
	return token, nil
}

func (as *AccountService) ChangePassword(ctx context.Context, username, oldPassword, newPassword string) error {
	account, err := as.FindByUsername(ctx, username)
	if err != nil {
		return err
	}
	if err := bcrypt.CompareHashAndPassword([]byte(account.Password), []byte(oldPassword)); err != nil {
		return err
	}
	passwordHash, err := bcrypt.GenerateFromPassword([]byte(newPassword), bcrypt.DefaultCost)
	if err != nil {
		return err
	}
	if err := as.accountRepository.ChangePassword(ctx, account.ID, string(passwordHash)); err != nil {
		return err
	}
	if err := as.Logout(ctx, account.ID); err != nil {
		return err
	}
	return nil
}

func (as *AccountService) FindByID(ctx context.Context, id uint) (*Account, error) {
	if account, err := as.accountRepository.FindByID(ctx, id); err != nil {
		return nil, err
	} else {
		return account, nil
	}
}

func (as *AccountService) FindByUsername(ctx context.Context, username string) (*Account, error) {
	if account, err := as.accountRepository.FindByUsername(ctx, username); err != nil {
		return nil, err
	} else {
		return account, nil
	}
}

func (as *AccountService) Login(ctx context.Context, username, password string) (string, error) {
	account, err := as.FindByUsername(ctx, username)
	if err != nil {
		return "", err
	}
	if err := bcrypt.CompareHashAndPassword([]byte(account.Password), []byte(password)); err != nil {
		return "", err
	}
	// generate token
	token, err := auth.GenerateToken(account.ID, account.Username)
	if err != nil {
		return "", err
	}
	if err := as.accountRepository.Login(ctx, account.ID, token); err != nil {
		return "", err
	}
	if as.cache != nil {
		cacheCtx, cancel := context.WithTimeout(ctx, 50*time.Millisecond)
		defer cancel()

		if err := as.cache.SetBytes(cacheCtx, fmt.Sprintf("account:%d", account.ID), []byte(token), 24*time.Hour); err != nil {
			log.Printf("failed to set cache: %v", err)
		}
	}
	return token, nil
}

func (as *AccountService) Logout(ctx context.Context, accountID uint) error {
	account, err := as.FindByID(ctx, accountID)
	if err != nil {
		return err
	}
	if account.Token == "" {
		return nil
	}
	if as.cache != nil {
		cacheCtx, cancel := context.WithTimeout(ctx, 50*time.Millisecond)
		defer cancel()

		if err := as.cache.Del(cacheCtx, fmt.Sprintf("account:%d", account.ID)); err != nil {
			log.Printf("failed to del cache: %v", err)
		}
	}
	return as.accountRepository.Logout(ctx, account.ID)
}