<?php

declare(strict_types=1);

namespace MonetaPhpShop\protocol;

use InvalidArgumentException;
use MonetaPhpShop\Money;

/**
 * Входящий запрос сервиса на Check URL (`MNT_COMMAND=CHECK`) или Pay URL.
 */
final class CallbackNotification
{
    private const ACCOUNT_ID_MAX_LENGTH = 20;
    private const TRANSACTION_ID_MAX_LENGTH = 255;
    private const OPERATION_ID_MAX_LENGTH = 255;

    /**
     * Номер операции MONETA.RU в Pay URL — только цифры
     */
    private const PAY_OPERATION_ID = '/\A[0-9]{1,20}\z/';
    private const SUBSCRIBER_ID_MAX_LENGTH = 255;
    private const CURRENCY_LENGTH = 3;
    private const SIGNATURE_LENGTH = 32;

    /** @var string */
    private $command;

    /** @var string */
    private $accountId;

    /** @var string */
    private $transactionId;

    /** @var string */
    private $operationId;

    /** @var string */
    private $rawAmount;

    /** @var Money|null */
    private $amount;

    /** @var string */
    private $currency;

    /** @var string */
    private $subscriberId;

    /** @var string */
    private $rawTestMode;

    /** @var string */
    private $signature;

    /**
     * @param array<string, mixed> $fields параметры запроса ($_POST или $_GET — метод задаётся в настройках счёта)
     */
    public function __construct(array $fields)
    {
        $this->command = self::optional($fields, 'MNT_COMMAND', strlen(AssistantProtocol::COMMAND_CHECK));
        if (($this->command !== '') && ($this->command !== AssistantProtocol::COMMAND_CHECK)) {
            throw new InvalidArgumentException('Неизвестная команда уведомления.');
        }

        $this->accountId = self::required($fields, 'MNT_ID', self::ACCOUNT_ID_MAX_LENGTH);
        $this->transactionId = self::required($fields, 'MNT_TRANSACTION_ID', self::TRANSACTION_ID_MAX_LENGTH);
        $this->operationId = self::optional($fields, 'MNT_OPERATION_ID', self::OPERATION_ID_MAX_LENGTH);
        $this->rawAmount = self::optional($fields, 'MNT_AMOUNT', strlen(Money::MAX));
        $this->amount = $this->rawAmount === '' ? null : Money::fromDecimal($this->rawAmount);
        $this->currency = self::required($fields, 'MNT_CURRENCY_CODE', self::CURRENCY_LENGTH);
        $this->subscriberId = self::optional($fields, 'MNT_SUBSCRIBER_ID', self::SUBSCRIBER_ID_MAX_LENGTH);
        $this->rawTestMode = self::required($fields, 'MNT_TEST_MODE', 1);
        if (($this->rawTestMode !== '0') && ($this->rawTestMode !== '1')) {
            throw new InvalidArgumentException('Недопустимое значение MNT_TEST_MODE.');
        }
        $this->signature = self::required($fields, 'MNT_SIGNATURE', self::SIGNATURE_LENGTH);

        if (
            (($this->amount === null) || (preg_match(self::PAY_OPERATION_ID, $this->operationId) !== 1))
            && !$this->isCheck()
        ) {
            throw new InvalidArgumentException('Уведомлению об оплате нужны сумма и номер операции из цифр.');
        }
    }

    public function isCheck(): bool
    {
        return ($this->command === AssistantProtocol::COMMAND_CHECK);
    }

    public function getCommand(): string
    {
        return $this->command;
    }

    public function getAccountId(): string
    {
        return $this->accountId;
    }

    public function getTransactionId(): string
    {
        return $this->transactionId;
    }

    public function getOperationId(): string
    {
        return $this->operationId;
    }

    /**
     * Сумма как пришла — только для подписи; для сверки — {@see self::getAmount()}.
     */
    public function getRawAmount(): string
    {
        return $this->rawAmount;
    }

    public function getAmount(): ?Money
    {
        return $this->amount;
    }

    public function getCurrency(): string
    {
        return $this->currency;
    }

    public function getSubscriberId(): string
    {
        return $this->subscriberId;
    }

    public function getRawTestMode(): string
    {
        return $this->rawTestMode;
    }

    public function isTestMode(): bool
    {
        return $this->rawTestMode === '1';
    }

    public function isSignedBy(Signature $signature): bool
    {
        return Signature::equals($signature->forNotification($this), $this->signature);
    }

    /**
     * @param array<string, mixed> $fields
     */
    private static function required(array $fields, string $name, int $maxLength): string
    {
        $value = self::optional($fields, $name, $maxLength);
        if ($value === '') {
            throw new InvalidArgumentException("Не передано поле {$name}.");
        }

        return $value;
    }

    /**
     * @param array<string, mixed> $fields
     */
    private static function optional(array $fields, string $name, int $maxLength): string
    {
        if (!array_key_exists($name, $fields)) {
            return '';
        }

        $value = $fields[$name];
        if (!is_string($value)) {
            throw new InvalidArgumentException("Поле {$name} должно быть строкой.");
        }
        if (strlen($value) > $maxLength) {
            throw new InvalidArgumentException("Поле {$name} длиннее допустимого.");
        }

        return $value;
    }
}