package db

import (
	"context"
	"fmt"

	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/jacek/pamietnik/backend/internal/domain"
)

type UserStore struct {
	pool *pgxpool.Pool
}

func NewUserStore(pool *pgxpool.Pool) *UserStore {
	return &UserStore{pool: pool}
}

// SeedAdminUser creates an admin user if no users exist yet.
// Returns (true, nil) if the user was created, (false, nil) if users already exist.
func SeedAdminUser(ctx context.Context, pool *pgxpool.Pool, username, passwordHash string) (bool, error) {
	var count int
	if err := pool.QueryRow(ctx, `SELECT COUNT(*) FROM users`).Scan(&count); err != nil {
		return false, fmt.Errorf("count users: %w", err)
	}
	if count > 0 {
		return false, nil
	}
	_, err := pool.Exec(ctx,
		`INSERT INTO users (username, password_hash, is_admin) VALUES ($1, $2, true)`,
		username, passwordHash,
	)
	if err != nil {
		return false, fmt.Errorf("insert admin: %w", err)
	}
	return true, nil
}

// ListUsers returns all users ordered by created_at.
func (s *UserStore) ListUsers(ctx context.Context) ([]domain.User, error) {
	rows, err := s.pool.Query(ctx,
		`SELECT user_id, username, is_admin, created_at FROM users ORDER BY created_at`,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var users []domain.User
	for rows.Next() {
		var u domain.User
		if err := rows.Scan(&u.UserID, &u.Username, &u.IsAdmin, &u.CreatedAt); err != nil {
			return nil, err
		}
		users = append(users, u)
	}
	return users, rows.Err()
}

// DeleteUser removes a user by ID.
func (s *UserStore) DeleteUser(ctx context.Context, userID string) error {
	_, err := s.pool.Exec(ctx, `DELETE FROM users WHERE user_id = $1`, userID)
	return err
}