package store

import (
	"context"
	"errors"

	"github.com/jackc/pgconn"
	"github.com/jackc/pgerrcode"
	"github.com/jackc/pgx/v5"
)

// CreateUser inserts a new user returning the created record or ErrDuplicate on conflict.
func (s *Store) CreateUser(ctx context.Context, username, displayName, passwordHash string) (*User, error) {
	var u User
	err := s.pool.QueryRow(ctx, `
       INSERT INTO users(username, display_name, password_hash)
       VALUES($1, $2, $3)
       RETURNING id, username, display_name, password_hash, avatar, created_at
   `, username, displayName, passwordHash).Scan(
		&u.ID, &u.Username, &u.DisplayName, &u.PasswordHash, &u.Avatar, &u.CreatedAt,
	)
	if err != nil {
		var pgErr *pgconn.PgError
		if errors.As(err, &pgErr) && pgErr.Code == pgerrcode.UniqueViolation {
			return nil, ErrDuplicate
		}
		return nil, err
	}
	return &u, nil
}

// GetUserByUsername retrieves a user by username or returns ErrNotFound.
func (s *Store) GetUserByUsername(ctx context.Context, username string) (*User, error) {
	var u User
	err := s.pool.QueryRow(ctx, `
       SELECT id, username, display_name, password_hash, avatar, created_at
       FROM users WHERE username=$1
   `, username).Scan(
		&u.ID, &u.Username, &u.DisplayName, &u.PasswordHash, &u.Avatar, &u.CreatedAt,
	)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	return &u, nil
}

// GetUserByID retrieves a user by ID or returns ErrNotFound.
func (s *Store) GetUserByID(ctx context.Context, id int64) (*User, error) {
	var u User
	err := s.pool.QueryRow(ctx, `
       SELECT id, username, display_name, password_hash, avatar, created_at
       FROM users WHERE id=$1
   `, id).Scan(
		&u.ID, &u.Username, &u.DisplayName, &u.PasswordHash, &u.Avatar, &u.CreatedAt,
	)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	return &u, nil
}

// SearchUsers returns users matching query in username or display_name via ILIKE.
// Empty query returns an empty slice.
func (s *Store) SearchUsers(ctx context.Context, query string, limit int) ([]User, error) {
	if query == "" {
		return []User{}, nil
	}
	pattern := "%" + query + "%"
	rows, err := s.pool.Query(ctx, `
       SELECT id, username, display_name, password_hash, avatar, created_at
       FROM users
       WHERE username ILIKE $1 OR display_name ILIKE $1
       ORDER BY username
       LIMIT $2
   `, pattern, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var users []User
	for rows.Next() {
		var u User
		if err := rows.Scan(
			&u.ID, &u.Username, &u.DisplayName, &u.PasswordHash, &u.Avatar, &u.CreatedAt,
		); err != nil {
			return nil, err
		}
		users = append(users, u)
	}
	return users, nil
}