<?php

declare(strict_types=1);

// Extra backup destinations besides the manage server: s3, sftp and custom.
//
// There is no "managed" target type: uploading to the manage server is built
// in (manageBackupUpload) and configured through MANAGE_SERVER_URL /
// MANAGE_INSTANCE / MANAGE_TOKEN instead of a target entry.

function manageRemoteTargets(): array
{
    return is_array(MANAGE_BACKUP_REMOTE_TARGETS) ? MANAGE_BACKUP_REMOTE_TARGETS : [];
}

function manageRemoteTargetLabel(array $target, int $index): string
{
    $name = trim((string) ($target["name"] ?? ""));
    if ($name !== "") {
        return $name;
    }

    $type = trim((string) ($target["type"] ?? "target"));

    return $type . "-" . ($index + 1);
}

// Whitelist of non-secret keys, so a failure can be logged with useful context
// without ever writing an access key or password to disk.
function manageRemoteSafeContext(array $target): array
{
    $safe = [];
    $allowedKeys = [
        "name", "type", "url", "bucket", "region", "prefix", "endpoint",
        "host", "port", "username", "path", "file", "callback", "timeout",
    ];

    foreach ($allowedKeys as $key) {
        if (array_key_exists($key, $target)) {
            $safe[$key] = is_scalar($target[$key]) ? (string) $target[$key] : gettype($target[$key]);
        }
    }

    return $safe;
}

function manageRemoteResponseExcerpt($response): string
{
    if (!is_string($response) || $response === "") {
        return "";
    }

    $response = preg_replace('/\s+/', " ", trim($response));

    return is_string($response) ? substr($response, 0, 500) : "";
}

function manageRemoteLastPhpError(): string
{
    $error = error_get_last();
    if (!is_array($error)) {
        return "";
    }

    return substr(trim((string) ($error["message"] ?? "")), 0, 500);
}

// Reports which target types this installation can actually use, so the GUI can
// warn about a configured target that will always fail.
function manageRemoteCapabilities(): array
{
    $types = [];
    foreach (manageRemoteTargets() as $target) {
        if (is_array($target)) {
            $type = trim((string) ($target["type"] ?? ""));
            if ($type !== "") {
                $types[$type] = true;
            }
        }
    }

    return [
        "s3" => [
            "configured" => !empty($types["s3"]),
            "available" => function_exists("hash_hmac"),
        ],
        "sftp" => [
            "configured" => !empty($types["sftp"]),
            "available" => function_exists("ssh2_connect") && function_exists("ssh2_sftp"),
        ],
        "custom" => [
            "configured" => !empty($types["custom"]),
            "available" => true,
        ],
    ];
}

function manageRemoteUploadToS3(string $archivePath, array $metadata, array $target): array
{
    $bucket = trim((string) ($target["bucket"] ?? ""));
    $region = trim((string) ($target["region"] ?? ""));
    $accessKey = trim((string) ($target["access_key"] ?? ""));
    $secretKey = (string) ($target["secret_key"] ?? "");
    $prefix = trim((string) ($target["prefix"] ?? ""), "/");
    $endpoint = rtrim(trim((string) ($target["endpoint"] ?? "")), "/");

    if ($bucket === "" || $region === "" || $accessKey === "" || $secretKey === "") {
        throw new RuntimeException("S3-Ziel ist unvollständig konfiguriert.");
    }

    $filename = basename($archivePath);
    $key = ($prefix !== "" ? $prefix . "/" : "") . $filename;
    $host = $endpoint !== ""
        ? parse_url($endpoint, PHP_URL_HOST)
        : $bucket . ".s3." . $region . ".amazonaws.com";
    if (!is_string($host) || $host === "") {
        throw new RuntimeException("S3-Endpunkt ist ungültig.");
    }

    $url = $endpoint !== ""
        ? $endpoint . "/" . rawurlencode($bucket) . "/" . str_replace("%2F", "/", rawurlencode($key))
        : "https://" . $host . "/" . str_replace("%2F", "/", rawurlencode($key));

    // The payload must be hashed as a whole for SigV4, so a backup larger than
    // memory_limit cannot use this target.
    $payload = file_get_contents($archivePath);
    if ($payload === false) {
        throw new RuntimeException("Backup-ZIP konnte für S3 nicht gelesen werden.");
    }

    $now = gmdate("Ymd\THis\Z");
    $date = substr($now, 0, 8);
    $payloadHash = hash("sha256", $payload);
    $canonicalUri = parse_url($url, PHP_URL_PATH);
    $canonicalUri = is_string($canonicalUri) && $canonicalUri !== "" ? $canonicalUri : "/";
    $signedHeaders = "content-type;host;x-amz-content-sha256;x-amz-date";
    $canonicalHeaders =
        "content-type:application/zip\n" .
        "host:" . $host . "\n" .
        "x-amz-content-sha256:" . $payloadHash . "\n" .
        "x-amz-date:" . $now . "\n";
    $canonicalRequest =
        "PUT\n" . $canonicalUri . "\n\n" . $canonicalHeaders . "\n" . $signedHeaders . "\n" . $payloadHash;
    $scope = $date . "/" . $region . "/s3/aws4_request";
    $stringToSign =
        "AWS4-HMAC-SHA256\n" . $now . "\n" . $scope . "\n" . hash("sha256", $canonicalRequest);
    $kDate = hash_hmac("sha256", $date, "AWS4" . $secretKey, true);
    $kRegion = hash_hmac("sha256", $region, $kDate, true);
    $kService = hash_hmac("sha256", "s3", $kRegion, true);
    $kSigning = hash_hmac("sha256", "aws4_request", $kService, true);
    $signature = hash_hmac("sha256", $stringToSign, $kSigning);
    $authorization =
        "AWS4-HMAC-SHA256 Credential=" . $accessKey . "/" . $scope .
        ", SignedHeaders=" . $signedHeaders . ", Signature=" . $signature;

    $context = stream_context_create([
        "http" => [
            "method" => "PUT",
            "timeout" => (int) ($target["timeout"] ?? 120),
            "ignore_errors" => true,
            "follow_location" => 0,
            "header" =>
                "Content-Type: application/zip\r\n" .
                "Content-Length: " . strlen($payload) . "\r\n" .
                "Host: " . $host . "\r\n" .
                "X-Amz-Date: " . $now . "\r\n" .
                "X-Amz-Content-Sha256: " . $payloadHash . "\r\n" .
                "Authorization: " . $authorization . "\r\n" .
                "User-Agent: " . manageClientUserAgent() . "\r\n",
            "content" => $payload,
        ],
    ]);

    $response = @file_get_contents($url, false, $context);
    $phpError = $response === false ? manageRemoteLastPhpError() : "";
    $headers = manageClientResponseHeaders($http_response_header ?? null);
    $status = manageClientStatusFromHeaders($headers);

    if ($response === false || $status < 200 || $status >= 300) {
        throw new ManageRemoteUploadException(
            "S3-Upload fehlgeschlagen" . ($status > 0 ? " (HTTP " . $status . ")" : "") . ".",
            [
                "http_status" => $status,
                "response_excerpt" => manageRemoteResponseExcerpt($response),
                "php_error" => $phpError,
                "bucket" => $bucket,
                "region" => $region,
                "key" => $key,
                "endpoint" => $endpoint,
            ],
        );
    }

    return ["remote_path" => "s3://" . $bucket . "/" . $key];
}

function manageRemoteUploadToSftp(string $archivePath, array $metadata, array $target): array
{
    if (!function_exists("ssh2_connect") || !function_exists("ssh2_sftp")) {
        throw new RuntimeException("Die PHP-SSH2-Erweiterung ist nicht verfügbar.");
    }

    $host = trim((string) ($target["host"] ?? ""));
    $username = trim((string) ($target["username"] ?? ""));
    $password = (string) ($target["password"] ?? "");
    $remoteDir = rtrim((string) ($target["path"] ?? ""), "/");
    $port = (int) ($target["port"] ?? 22);

    if ($host === "" || $username === "" || $remoteDir === "") {
        throw new RuntimeException("SFTP-Ziel ist unvollständig konfiguriert.");
    }

    $connection = @ssh2_connect($host, $port > 0 ? $port : 22);
    if ($connection === false) {
        throw new RuntimeException("SFTP-Verbindung konnte nicht hergestellt werden.");
    }

    $authenticated = false;
    $privateKey = trim((string) ($target["private_key"] ?? ""));
    $publicKey = trim((string) ($target["public_key"] ?? ""));
    if ($privateKey !== "" && $publicKey !== "" && function_exists("ssh2_auth_pubkey_file")) {
        $authenticated = @ssh2_auth_pubkey_file(
            $connection,
            $username,
            $publicKey,
            $privateKey,
            $password !== "" ? $password : null,
        );
    } elseif (function_exists("ssh2_auth_password")) {
        $authenticated = @ssh2_auth_password($connection, $username, $password);
    }

    if (!$authenticated) {
        throw new RuntimeException("SFTP-Anmeldung fehlgeschlagen.");
    }

    $sftp = @ssh2_sftp($connection);
    if ($sftp === false) {
        throw new RuntimeException("SFTP-Subsystem konnte nicht gestartet werden.");
    }

    $remotePath = $remoteDir . "/" . basename($archivePath);
    $targetStream = @fopen("ssh2.sftp://" . intval($sftp) . $remotePath, "wb");
    if ($targetStream === false) {
        throw new RuntimeException("SFTP-Zieldatei konnte nicht geöffnet werden. Existiert das Verzeichnis?");
    }

    $source = fopen($archivePath, "rb");
    if ($source === false) {
        fclose($targetStream);
        throw new RuntimeException("Backup-ZIP konnte für SFTP nicht gelesen werden.");
    }

    $copied = stream_copy_to_stream($source, $targetStream);
    fclose($source);
    fclose($targetStream);

    if ($copied === false) {
        throw new RuntimeException("SFTP-Upload fehlgeschlagen.");
    }

    return ["remote_path" => "sftp://" . $host . $remotePath];
}

function manageRemoteUploadToCustom(string $archivePath, array $metadata, array $target): array
{
    $file = trim((string) ($target["file"] ?? ""));
    $callback = $target["callback"] ?? null;

    if ($file !== "") {
        if (!is_file($file)) {
            throw new RuntimeException("Custom-Uploader-Datei wurde nicht gefunden: " . $file);
        }
        require_once $file;
    }

    if (!is_callable($callback)) {
        throw new RuntimeException("Custom-Uploader ist nicht aufrufbar.");
    }

    $result = call_user_func($callback, $archivePath, $metadata, $target);
    if ($result === true) {
        return [];
    }
    if (is_array($result) && ($result["success"] ?? true) !== false) {
        return $result;
    }
    if (is_array($result)) {
        throw new RuntimeException(trim((string) ($result["error"] ?? "Custom-Uploader meldet einen Fehler.")));
    }

    throw new RuntimeException("Custom-Uploader meldet einen Fehler.");
}

/**
 * Runs every configured extra target. Each is attempted independently and a
 * failure never invalidates the local backup: the error is recorded in the
 * backup index and logged.
 */
function manageRemoteUploadAll(string $archivePath, array $metadata): array
{
    $results = [];

    foreach (manageRemoteTargets() as $index => $target) {
        if (!is_array($target)) {
            continue;
        }

        $type = trim((string) ($target["type"] ?? ""));
        $label = manageRemoteTargetLabel($target, (int) $index);
        $startedAt = date(DATE_ATOM);

        try {
            if ($type === "s3") {
                $extra = manageRemoteUploadToS3($archivePath, $metadata, $target);
            } elseif ($type === "sftp") {
                $extra = manageRemoteUploadToSftp($archivePath, $metadata, $target);
            } elseif ($type === "custom") {
                $extra = manageRemoteUploadToCustom($archivePath, $metadata, $target);
            } else {
                throw new RuntimeException("Unbekannter Backup-Zieltyp: " . ($type !== "" ? $type : "(leer)"));
            }

            $results[] = array_merge([
                "target" => $label,
                "type" => $type,
                "success" => true,
                "started_at" => $startedAt,
                "uploaded_at" => date(DATE_ATOM),
            ], $extra);

            manageClientLog("INFO", "Remote upload succeeded", [
                "target" => $label,
                "type" => $type,
                "filename" => $metadata["filename"] ?? basename($archivePath),
            ]);
        } catch (Throwable $exception) {
            $debugContext = $exception instanceof ManageRemoteUploadException
                ? $exception->getDebugContext()
                : [];

            $result = [
                "target" => $label,
                "type" => $type !== "" ? $type : "unknown",
                "success" => false,
                "started_at" => $startedAt,
                "error" => $exception->getMessage(),
            ];
            if ($debugContext !== []) {
                $result["debug"] = $debugContext;
            }
            $results[] = $result;

            manageClientLog("ERROR", "Remote upload failed", [
                "target" => $label,
                "type" => $type !== "" ? $type : "unknown",
                "target_config" => manageRemoteSafeContext($target),
                "filename" => $metadata["filename"] ?? basename($archivePath),
                "error" => $exception->getMessage(),
                "debug" => $debugContext,
            ]);
        }
    }

    return $results;
}