<?php
declare(strict_types=1);

/**
 * Sandbox smoke/reference client. Replace the two diagnostic callbacks below
 * with database transactions before production use. Never log response bodies.
 */

const BOT_API = 'https://api.integration.boringordertracker.com/v1';
const MAX_RESPONSE_BYTES = 8 * 1024 * 1024;

final class BotApiProblem extends RuntimeException
{
    public function __construct(
        public readonly int $status,
        public readonly string $problemCode,
        public readonly ?string $requestId,
        public readonly ?int $retryAfter
    ) {
        parent::__construct(sprintf(
            'BOT API HTTP %d (%s), request_id=%s',
            $status,
            $problemCode,
            $requestId ?? 'unavailable'
        ));
    }
}

function requiredEnvironment(string $name): string
{
    $value = getenv($name);
    if (!is_string($value) || $value === '') {
        throw new RuntimeException("Set {$name}.");
    }
    return $value;
}

$certificate = requiredEnvironment('BOT_CERT');
$privateKey = requiredEnvironment('BOT_KEY');
if (!is_file($certificate) || !is_file($privateKey)) {
    throw new RuntimeException('BOT_CERT and BOT_KEY must be protected PEM files.');
}
$privateKeyPassword = getenv('BOT_KEY_PASSWORD');
$privateKeyPassword = is_string($privateKeyPassword) && $privateKeyPassword !== ''
    ? $privateKeyPassword
    : null;

/** @return array{status:int,headers:array<string,string>,body:?array<string,mixed>} */
function botRequest(string $method, string $path, ?array $body = null, array $headers = []): array
{
    global $certificate, $privateKey, $privateKeyPassword;

    if (!str_starts_with($path, '/') || str_contains($path, "\r") || str_contains($path, "\n")) {
        throw new InvalidArgumentException('Invalid API path.');
    }
    $handle = curl_init(BOT_API . $path);
    if ($handle === false) {
        throw new RuntimeException('Unable to initialize cURL.');
    }

    $responseHeaders = [];
    $responseBody = '';
    $tooLarge = false;
    $requestHeaders = array_merge(['Accept: application/json'], $headers);
    if ($body !== null) {
        $encoded = json_encode($body, JSON_THROW_ON_ERROR | JSON_UNESCAPED_SLASHES);
        $requestHeaders[] = 'Content-Type: application/json';
        $requestHeaders[] = 'Content-Length: ' . strlen($encoded);
        curl_setopt($handle, CURLOPT_POSTFIELDS, $encoded);
    }

    $options = [
        CURLOPT_CUSTOMREQUEST => $method,
        CURLOPT_SSLCERT => $certificate,
        CURLOPT_SSLKEY => $privateKey,
        CURLOPT_SSL_VERIFYPEER => true,
        CURLOPT_SSL_VERIFYHOST => 2,
        CURLOPT_PROTOCOLS => CURLPROTO_HTTPS,
        CURLOPT_FOLLOWLOCATION => false,
        CURLOPT_MAXREDIRS => 0,
        CURLOPT_CONNECTTIMEOUT => 5,
        CURLOPT_TIMEOUT => 20,
        CURLOPT_HTTPHEADER => $requestHeaders,
        CURLOPT_HEADERFUNCTION => static function ($curl, string $line) use (&$responseHeaders): int {
            if (str_starts_with($line, 'HTTP/')) {
                $responseHeaders = [];
                return strlen($line);
            }
            $parts = explode(':', $line, 2);
            if (count($parts) === 2) {
                $responseHeaders[strtolower(trim($parts[0]))] = trim($parts[1]);
            }
            return strlen($line);
        },
        CURLOPT_WRITEFUNCTION => static function ($curl, string $chunk) use (&$responseBody, &$tooLarge): int {
            if (strlen($responseBody) + strlen($chunk) > MAX_RESPONSE_BYTES) {
                $tooLarge = true;
                return 0;
            }
            $responseBody .= $chunk;
            return strlen($chunk);
        },
    ];
    if ($privateKeyPassword !== null) {
        // Inject BOT_KEY_PASSWORD with the service secret manager, not a shell
        // command line, repository, image, or log.
        $options[CURLOPT_KEYPASSWD] = $privateKeyPassword;
    }
    curl_setopt_array($handle, $options);

    $ok = curl_exec($handle);
    $status = (int) curl_getinfo($handle, CURLINFO_RESPONSE_CODE);
    $curlError = curl_error($handle);
    curl_close($handle);

    if ($tooLarge) {
        throw new RuntimeException('BOT API response exceeded the local safety limit.');
    }
    if ($ok === false) {
        throw new RuntimeException('BOT API transport failed: ' . $curlError);
    }
    if ($status === 304) {
        return ['status' => 304, 'headers' => $responseHeaders, 'body' => null];
    }

    $decoded = $responseBody === ''
        ? null
        : json_decode($responseBody, true, 64, JSON_THROW_ON_ERROR);
    if ($decoded !== null && !is_array($decoded)) {
        throw new RuntimeException('BOT API returned a non-object JSON response.');
    }
    if ($status >= 400) {
        $retry = $responseHeaders['retry-after'] ?? null;
        throw new BotApiProblem(
            $status,
            is_string($decoded['code'] ?? null) ? $decoded['code'] : 'unknown_problem',
            is_string($decoded['request_id'] ?? null) ? $decoded['request_id'] : null,
            is_string($retry) && preg_match('/^[0-9]+$/D', $retry) === 1 ? max(1, (int) $retry) : null
        );
    }
    if ($status < 200 || $status >= 300) {
        throw new RuntimeException("Unexpected BOT API status {$status}.");
    }
    return ['status' => $status, 'headers' => $responseHeaders, 'body' => $decoded];
}

function conditionalHeader(?string $etag): array
{
    if ($etag === null || $etag === '') {
        return [];
    }
    if (preg_match('/^(?:W\/)?"[A-Za-z0-9._~:-]{1,96}"$/D', $etag) !== 1) {
        throw new InvalidArgumentException('Refusing an invalid ETag header value.');
    }
    return ['If-None-Match: ' . $etag];
}

/**
 * @param callable(list<array<string,mixed>>,string,?string,bool):void $commitPage
 * @return array{cursor:?string,etag:?string,not_modified:bool}
 */
function synchronize(?string $cursor, ?string $etag, callable $commitPage): array
{
    while (true) {
        $query = ['limit' => '500'];
        if ($cursor !== null && $cursor !== '') {
            $query['updated_since'] = $cursor;
        }
        $response = botRequest(
            'GET',
            '/sync?' . http_build_query($query, '', '&', PHP_QUERY_RFC3986),
            null,
            conditionalHeader($etag)
        );
        if ($response['status'] === 304) {
            return ['cursor' => $cursor, 'etag' => $etag, 'not_modified' => true];
        }
        $payload = $response['body'];
        if (!is_array($payload)
            || !is_array($payload['items'] ?? null)
            || !is_string($payload['next_cursor'] ?? null)
            || !is_bool($payload['has_more'] ?? null)) {
            throw new RuntimeException('Invalid sync response contract.');
        }
        $nextCursor = $payload['next_cursor'];
        $nextEtag = is_string($response['headers']['etag'] ?? null)
            ? $response['headers']['etag']
            : null;

        // This callback must transactionally apply every item in order and
        // persist nextCursor + nextEtag. On rollback, keep the prior pair.
        $commitPage($payload['items'], $nextCursor, $nextEtag, $payload['has_more']);
        $cursor = $nextCursor;
        $etag = $nextEtag;
        if (!$payload['has_more']) {
            return ['cursor' => $cursor, 'etag' => $etag, 'not_modified' => false];
        }
    }
}

/**
 * @param callable(list<array<string,mixed>>,string,?string,bool,bool):void $commitPage
 * @return array{cursor:?string,etag:?string,not_modified:bool,history_complete:?bool}
 */
function readCompleteHistory(
    string $collection,
    string $resourceId,
    ?string $cursor,
    ?string $etag,
    callable $commitPage
): array {
    if (!in_array($collection, ['orders', 'vehicles'], true)
        || preg_match('/^[A-Za-z0-9_-]{8,80}$/D', $resourceId) !== 1) {
        throw new InvalidArgumentException('Invalid resource history target.');
    }
    while (true) {
        $query = ['limit' => '500'];
        if ($cursor !== null && $cursor !== '') {
            $query['cursor'] = $cursor;
        }
        $response = botRequest(
            'GET',
            '/' . $collection . '/' . rawurlencode($resourceId) . '/history?'
                . http_build_query($query, '', '&', PHP_QUERY_RFC3986),
            null,
            conditionalHeader($etag)
        );
        if ($response['status'] === 304) {
            return [
                'cursor' => $cursor,
                'etag' => $etag,
                'not_modified' => true,
                'history_complete' => null,
            ];
        }
        $payload = $response['body'];
        if (!is_array($payload)
            || !is_array($payload['items'] ?? null)
            || !is_string($payload['next_cursor'] ?? null)
            || !is_bool($payload['has_more'] ?? null)
            || !is_bool($payload['history_complete'] ?? null)) {
            throw new RuntimeException('Invalid history response contract.');
        }
        $nextCursor = $payload['next_cursor'];
        $nextEtag = is_string($response['headers']['etag'] ?? null)
            ? $response['headers']['etag']
            : null;
        $commitPage(
            $payload['items'],
            $nextCursor,
            $nextEtag,
            $payload['has_more'],
            $payload['history_complete']
        );
        $cursor = $nextCursor;
        $etag = $nextEtag;
        if (!$payload['has_more']) {
            return [
                'cursor' => $cursor,
                'etag' => $etag,
                'not_modified' => false,
                'history_complete' => $payload['history_complete'],
            ];
        }
    }
}

function acknowledgeDeletion(string $revocationId): array
{
    if (preg_match('/^[A-Za-z0-9_-]{8,80}$/D', $revocationId) !== 1) {
        throw new InvalidArgumentException('Invalid revocation ID.');
    }
    return botRequest(
        'POST',
        '/revocations/' . rawurlencode($revocationId) . '/ack',
        ['deletion_completed' => true],
        ['Idempotency-Key: ack-' . $revocationId]
    );
}

try {
    $expectedEnvironment = getenv('BOT_EXPECTED_ENVIRONMENT') ?: 'sandbox';
    if (!in_array($expectedEnvironment, ['sandbox', 'production'], true)) {
        throw new RuntimeException('BOT_EXPECTED_ENVIRONMENT must be sandbox or production.');
    }
    $capabilities = botRequest('GET', '/capabilities')['body'];
    if (!is_array($capabilities) || ($capabilities['environment'] ?? null) !== $expectedEnvironment) {
        throw new RuntimeException('Certificate is bound to the wrong environment.');
    }
    if ($expectedEnvironment === 'production'
        && (($capabilities['integration_status'] ?? null) !== 'active'
            || ($capabilities['production_data_enabled'] ?? null) !== true)) {
        throw new RuntimeException('Production is not active/data-enabled; stopping safely.');
    }
    printf(
        "Authenticated to %s; %d scope(s).\n",
        $expectedEnvironment,
        is_array($capabilities['scopes'] ?? null) ? count($capabilities['scopes']) : 0
    );

    $syncCursor = getenv('BOT_SYNC_CURSOR') ?: null;
    $syncEtag = getenv('BOT_SYNC_ETAG') ?: null;
    synchronize(
        $syncCursor,
        $syncEtag,
        static function (array $items, string $nextCursor, ?string $nextEtag, bool $hasMore): void {
            // SANDBOX DIAGNOSTIC ONLY. Production must replace this body with
            // one DB transaction: apply upserts/deletes in order and persist
            // nextCursor + nextEtag only when the transaction commits.
            $deletions = count(array_filter(
                $items,
                static fn (array $item): bool => ($item['operation'] ?? null) === 'delete'
            ));
            printf("Sync page: %d item(s), %d deletion(s), has_more=%s.\n",
                count($items), $deletions, $hasMore ? 'true' : 'false');
        }
    );

    $resourceId = getenv('BOT_RESOURCE_ID');
    $collection = getenv('BOT_RESOURCE_COLLECTION');
    if (is_string($resourceId) && $resourceId !== '' && is_string($collection) && $collection !== '') {
        readCompleteHistory(
            $collection,
            $resourceId,
            getenv('BOT_HISTORY_CURSOR') ?: null,
            getenv('BOT_HISTORY_ETAG') ?: null,
            static function (
                array $items,
                string $nextCursor,
                ?string $nextEtag,
                bool $hasMore,
                bool $historyComplete
            ): void {
                // SANDBOX DIAGNOSTIC ONLY. Persist events and state in one DB
                // transaction. Never label the prefix complete while false.
                printf("History page: %d event(s), complete=%s, has_more=%s.\n",
                    count($items), $historyComplete ? 'true' : 'false', $hasMore ? 'true' : 'false');
            }
        );
    }

    $revocationId = getenv('BOT_REVOCATION_ID');
    if (is_string($revocationId) && $revocationId !== '') {
        if (getenv('BOT_DELETION_COMPLETED') !== '1') {
            throw new RuntimeException(
                'Refusing revocation ACK: set BOT_DELETION_COMPLETED=1 only after all copies are deleted.'
            );
        }
        acknowledgeDeletion($revocationId);
        echo "Deletion acknowledgement accepted.\n";
    }
} catch (BotApiProblem $problem) {
    if ($problem->status === 429 && $problem->retryAfter !== null) {
        fwrite(STDERR, "Rate limited; retry no earlier than {$problem->retryAfter} seconds.\n");
        exit(75);
    }
    fwrite(STDERR, $problem->getMessage() . "\n");
    exit(1);
} catch (Throwable $error) {
    fwrite(STDERR, $error->getMessage() . "\n");
    exit(1);
}