<?php

declare(strict_types=1);

use App\App\Bootstrap;
use App\Form\FormSchema;
use App\Form\Validator;
use App\Mail\Mailer;
use App\Security\Csrf;
use App\Security\FormAccess;
use App\Storage\FileUploadStore;
use App\Storage\JsonStore;

require dirname(__DIR__) . '/src/autoload.php';
Bootstrap::init();

/** @param array<string, mixed> $app */
function resolveSubmitSuccessMessage(array $app): string
{
    $configured = Bootstrap::appMessage('submit.success');

    $contactEmail = trim((string) ($app['contact_email'] ?? ''));
    $message = str_replace(
        ['%contact_email%', '{{contact_email}}'],
        $contactEmail !== '' ? $contactEmail : 'uns',
        $configured
    );

    return trim($message);
}

function isMinorBirthdate(string $birthdate): bool
{
    $birthdate = trim($birthdate);
    if ($birthdate === '') {
        return false;
    }

    $date = DateTimeImmutable::createFromFormat('!Y-m-d', $birthdate);
    if (!$date || $date->format('Y-m-d') !== $birthdate) {
        return false;
    }

    $today = new DateTimeImmutable('today');
    if ($date > $today) {
        return false;
    }

    return $date->diff($today)->y < 18;
}

/**
 * @param array<string, string> $errors
 * @return array<int, array{key: string, label: string, message: string}>
 */
function buildValidationErrorDetails(array $errors, FormSchema $schema): array
{
    $details = [];
    $allFields = $schema->getAllFields();

    foreach ($errors as $key => $message) {
        $field = $allFields[$key] ?? [];
        $label = '';
        if (is_array($field)) {
            $label = trim((string) ($field['label'] ?? ''));
        }

        $details[] = [
            'key' => (string) $key,
            'label' => $label !== '' ? $label : (string) $key,
            'message' => (string) $message,
        ];
    }

    return $details;
}

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    Bootstrap::jsonResponse([
        'ok' => false,
        'message' => Bootstrap::appMessage('common.method_not_allowed'),
    ], 405);
}

$csrf = $_POST['csrf'] ?? '';
if (!Csrf::validate(is_string($csrf) ? $csrf : null)) {
    Bootstrap::jsonResponse([
        'ok' => false,
        'message' => Bootstrap::appMessage('common.invalid_csrf'),
    ], 419);
}

if (trim((string) ($_POST['website'] ?? '')) !== '') {
    Bootstrap::jsonResponse([
        'ok' => false,
        'message' => Bootstrap::appMessage('common.request_blocked'),
    ], 400);
}

$email = strtolower(trim((string) ($_POST['email'] ?? '')));
if (filter_var($email, FILTER_VALIDATE_EMAIL) === false) {
    Bootstrap::jsonResponse([
        'ok' => false,
        'message' => Bootstrap::appMessage('common.invalid_email'),
    ], 422);
}

$activityRaw = $_POST['last_user_activity_at'] ?? null;
$lastUserActivityAt = is_scalar($activityRaw) ? (int) $activityRaw : null;
$formAccess = new FormAccess();
$auth = $formAccess->assertVerifiedForEmail($email, $lastUserActivityAt);
if (($auth['ok'] ?? false) !== true) {
    $reason = (string) ($auth['reason'] ?? '');
    Bootstrap::jsonResponse([
        'ok' => false,
        'message' => (string) ($auth['message'] ?? 'Bitte E-Mail erneut verifizieren.'),
        'auth_required' => $reason === 'auth_required',
        'auth_expired' => $reason === 'auth_expired',
    ], (int) ($auth['status_code'] ?? 401));
}

$app = Bootstrap::config('app');

$formDataRaw = $_POST['form_data'] ?? [];
$formData = [];
if (is_array($formDataRaw)) {
    foreach ($formDataRaw as $key => $value) {
        if (!is_string($key)) {
            continue;
        }
        $formData[$key] = is_array($value) ? '' : trim((string) $value);
    }
}

$store = new JsonStore();
$schema = new FormSchema();
$uploadStore = new FileUploadStore();
$validator = new Validator($schema);

// Fast fail before upload processing to avoid writing files for known duplicates.
if ($store->hasSubmission($email)) {
    Bootstrap::jsonResponse([
        'ok' => false,
        'already_submitted' => true,
        'message' => Bootstrap::appMessage('submit.already_submitted'),
    ], 409);
}

try {
    $submitResult = $store->withEmailLock($email, static function () use ($store, $email, $formData, $validator, $uploadStore, $schema): array {
        if ($store->hasSubmission($email)) {
            return [
                'ok' => false,
                'already_submitted' => true,
                'message' => Bootstrap::appMessage('submit.already_submitted'),
            ];
        }

        $uploadResult = $uploadStore->processUploads($_FILES, $schema->getUploadFields(), $store->emailKey($email));
        if (!empty($uploadResult['errors'])) {
            return [
                'ok' => false,
                'already_submitted' => false,
                'message' => Bootstrap::appMessage('submit.upload_error'),
                'errors' => $uploadResult['errors'],
            ];
        }

        $draft = $store->getDraft($email) ?? [];

        $mergedFormData = array_merge((array) ($draft['form_data'] ?? []), $formData);
        $mergedUploads = (array) ($draft['uploads'] ?? []);
        foreach ($uploadResult['uploads'] as $field => $items) {
            $mergedUploads[$field] = array_values(array_merge((array) ($mergedUploads[$field] ?? []), $items));
        }

        $errors = $validator->validateSubmit($mergedFormData, $mergedUploads);
        if (!empty($errors)) {
            $store->saveDraft($email, [
                'step' => 4,
                'form_data' => $mergedFormData,
                'uploads' => $mergedUploads,
            ]);

            $errorFields = array_values(array_map(static fn ($key): string => (string) $key, array_keys($errors)));
            return [
                'ok' => false,
                'already_submitted' => false,
                'message' => Bootstrap::appMessage('submit.validation_error'),
                'errors' => $errors,
                'error_fields' => $errorFields,
                'error_details' => buildValidationErrorDetails($errors, $schema),
            ];
        }

        $submission = $store->saveSubmission($email, [
            'step' => 4,
            'form_data' => $mergedFormData,
            'uploads' => $mergedUploads,
            'is_minor_submission' => isMinorBirthdate((string) ($mergedFormData['geburtsdatum'] ?? '')),
        ]);

        return [
            'ok' => true,
            'submission' => $submission,
        ];
    });
} catch (Throwable $e) {
    Bootstrap::log('app', 'submit lock error: ' . $e->getMessage());
    Bootstrap::jsonResponse([
        'ok' => false,
        'message' => Bootstrap::appMessage('submit.lock_error'),
    ], 500);
}

if (($submitResult['ok'] ?? false) !== true) {
    $status = ($submitResult['already_submitted'] ?? false) ? 409 : 422;
    Bootstrap::jsonResponse([
        'ok' => false,
        'already_submitted' => (bool) ($submitResult['already_submitted'] ?? false),
        'message' => (string) ($submitResult['message'] ?? Bootstrap::appMessage('submit.failure')),
        'errors' => $submitResult['errors'] ?? [],
        'error_fields' => $submitResult['error_fields'] ?? [],
        'error_details' => $submitResult['error_details'] ?? [],
    ], $status);
}

$submission = $submitResult['submission'];
$mailer = new Mailer();
$mailer->sendSubmissionMails($submission);

Bootstrap::jsonResponse([
    'ok' => true,
    'message' => resolveSubmitSuccessMessage($app),
    'application_key' => $submission['application_key'] ?? null,
]);