package user

import (
	"context"
	"database/sql"
	"errors"
	"strings"
	"time"
)

var ErrUserAlreadyExists = errors.New("user already exists")

type User struct {
	ID           int64
	Username     string
	PasswordHash string
	CreatedAt    time.Time
}

type UserRepo struct {
	db *sql.DB
}

func NewUserRepo(db *sql.DB) *UserRepo {
	return &UserRepo{db: db}
}

func (r *UserRepo) Create(ctx context.Context, username string, passwordHash string) error {
	// sqlite 不同版本/驱动对 unique 冲突错误信息不完全一致，用字符串兜底识别。
	_, err := r.db.ExecContext(ctx,
		`INSERT INTO users(username, password_hash) VALUES(?, ?)`,
		username, passwordHash,
	)
	if err != nil {
		msg := strings.ToLower(err.Error())
		if strings.Contains(msg, "unique") || strings.Contains(msg, "constraint failed") {
			return ErrUserAlreadyExists
		}
		return err
	}
	return nil
}

func (r *UserRepo) GetByUsername(ctx context.Context, username string) (*User, error) {
	var u User
	row := r.db.QueryRowContext(ctx,
		`SELECT id, username, password_hash, created_at FROM users WHERE username = ?`,
		username,
	)
	if err := row.Scan(&u.ID, &u.Username, &u.PasswordHash, &u.CreatedAt); err != nil {
		return nil, err
	}
	return &u, nil
}