<?php

declare(strict_types=1);

// Client-side backup: collecting sources, writing the archive, local retention
// and uploading to the manage server.
//
// The source list is not hardcoded: it comes from MANAGE_BACKUP_SOURCES, plus
// an optional SQL dump when MANAGE_BACKUP_DATABASE is configured.

function manageBackupDir(): string
{
    return rtrim((string) MANAGE_BACKUP_DIR, "/\\") . DIRECTORY_SEPARATOR;
}

function manageBackupIndexFile(): string
{
    return manageBackupDir() . "backup-index.json";
}

function manageBackupLockFile(): string
{
    return manageBackupDir() . ".backup.lock";
}

// ---------------------------------------------------------------------------
// Source collection
// ---------------------------------------------------------------------------

// Recursively lists readable files below $dir, mapped to $entryPrefix.
function manageBackupCollectDirectory(string $dir, string $entryPrefix, array &$files): void
{
    if (!is_dir($dir)) {
        return;
    }

    $base = rtrim($dir, "/\\") . DIRECTORY_SEPARATOR;
    $items = new RecursiveIteratorIterator(
        new RecursiveDirectoryIterator($base, FilesystemIterator::SKIP_DOTS),
        RecursiveIteratorIterator::LEAVES_ONLY,
    );

    foreach ($items as $item) {
        if (!$item->isFile() || !$item->isReadable()) {
            continue;
        }

        $path = $item->getPathname();
        if (manageIsTemporaryFile($path)) {
            continue;
        }

        $relative = ltrim(manageClientNormalizePath(substr($path, strlen($base))), "/");
        if ($relative === "" || str_contains($relative, "\0")) {
            continue;
        }

        $files[] = [
            "path" => $path,
            "name" => trim($entryPrefix . "/" . $relative, "/"),
        ];
    }
}

/**
 * Resolves MANAGE_BACKUP_SOURCES into a flat list of archive entries.
 *
 * Each source entry supports one of:
 *   "glob" => "data/*.json"      non-recursive shell glob
 *   "dir"  => "data/uploads"     recursive directory
 *   "file" => "settings.ini"     single file
 * plus an optional "as" prefix for the path inside the archive.
 */
function manageBackupCollectSources(): array
{
    $root = manageClientAppRoot();
    $sources = is_array(MANAGE_BACKUP_SOURCES) ? MANAGE_BACKUP_SOURCES : [];
    $files = [];

    foreach ($sources as $source) {
        if (!is_array($source)) {
            continue;
        }

        $prefix = trim((string) ($source["as"] ?? ""), "/");

        if (isset($source["glob"])) {
            $pattern = $root . DIRECTORY_SEPARATOR . ltrim((string) $source["glob"], "/\\");
            foreach (glob($pattern) ?: [] as $path) {
                if (!is_file($path) || !is_readable($path) || manageIsTemporaryFile($path)) {
                    continue;
                }
                $files[] = [
                    "path" => $path,
                    "name" => trim($prefix . "/" . basename($path), "/"),
                ];
            }
            continue;
        }

        if (isset($source["dir"])) {
            $dir = $root . DIRECTORY_SEPARATOR . ltrim((string) $source["dir"], "/\\");
            manageBackupCollectDirectory($dir, $prefix !== "" ? $prefix : basename($dir), $files);
            continue;
        }

        if (isset($source["file"])) {
            $path = $root . DIRECTORY_SEPARATOR . ltrim((string) $source["file"], "/\\");
            if (is_file($path) && is_readable($path)) {
                $files[] = [
                    "path" => $path,
                    "name" => trim($prefix . "/" . basename($path), "/"),
                ];
            }
        }
    }

    // Two sources may resolve to the same archive entry; the first one wins so
    // the ZIP can never contain a duplicate name.
    $unique = [];
    foreach ($files as $file) {
        $unique[$file["name"]] = $file;
    }
    $files = array_values($unique);

    usort($files, static function (array $left, array $right): int {
        return strcmp($left["name"], $right["name"]);
    });

    return $files;
}

// ---------------------------------------------------------------------------
// Index
// ---------------------------------------------------------------------------

function manageBackupReadIndex(): array
{
    $index = manageReadJson(manageBackupIndexFile());
    $records = isset($index["backups"]) && is_array($index["backups"])
        ? $index["backups"]
        : [];

    return ["backups" => array_values($records)];
}

function manageBackupWriteIndex(array $records): void
{
    manageWriteJson(manageBackupIndexFile(), ["backups" => array_values($records)]);
}

/**
 * Local backups, newest first. Self-healing: index records whose file is gone
 * are dropped and sizes are refreshed from disk.
 */
function manageBackupList(): array
{
    $dir = manageBackupDir();
    $existing = [];

    foreach (manageBackupReadIndex()["backups"] as $record) {
        if (!is_array($record)) {
            continue;
        }

        $filename = basename((string) ($record["filename"] ?? ""));
        if ($filename === "" || !is_file($dir . $filename)) {
            continue;
        }

        $record["filename"] = $filename;
        $record["size"] = (int) (filesize($dir . $filename) ?: ($record["size"] ?? 0));
        $existing[] = $record;
    }

    usort($existing, static function (array $left, array $right): int {
        return strcmp((string) ($right["created_at"] ?? ""), (string) ($left["created_at"] ?? ""));
    });

    return $existing;
}

function manageBackupRetentionLimit(): int
{
    return max(1, (int) MANAGE_BACKUP_LOCAL_RETENTION);
}

function manageBackupApplyRetention(): void
{
    $records = manageBackupList();
    $keep = manageBackupRetentionLimit();
    $dir = manageBackupDir();

    foreach (array_slice($records, $keep) as $record) {
        $filename = basename((string) ($record["filename"] ?? ""));
        if ($filename !== "" && is_file($dir . $filename)) {
            @unlink($dir . $filename);
        }
    }

    manageBackupWriteIndex(array_slice(manageBackupList(), 0, $keep));
}

function manageBackupPath(string $filename): string
{
    $filename = basename($filename);
    if (preg_match('/^backup-\d{8}-\d{6}(?:-\d+)?\.zip$/', $filename) !== 1) {
        throw new RuntimeException("Ungültiger Backup-Dateiname: " . $filename);
    }

    $path = manageBackupDir() . $filename;
    if (!is_file($path)) {
        throw new RuntimeException("Backup wurde nicht gefunden: " . $filename);
    }

    return $path;
}

// ---------------------------------------------------------------------------
// Upload to the manage server
// ---------------------------------------------------------------------------

function manageBackupBuildMultipartBody(
    array $fields,
    string $fileField,
    string $filePath,
    string $fileName,
    string $boundary,
): string {
    $body = "";
    foreach ($fields as $name => $value) {
        $body .= "--" . $boundary . "\r\n";
        $body .= 'Content-Disposition: form-data; name="' . addcslashes((string) $name, "\"\\") . "\"\r\n\r\n";
        $body .= (string) $value . "\r\n";
    }

    $payload = file_get_contents($filePath);
    if ($payload === false) {
        throw new RuntimeException("Backup-ZIP konnte für den Upload nicht gelesen werden.");
    }

    $body .= "--" . $boundary . "\r\n";
    $body .=
        'Content-Disposition: form-data; name="' . addcslashes($fileField, "\"\\") .
        '"; filename="' . addcslashes($fileName, "\"\\") . "\"\r\n";
    $body .= "Content-Type: application/zip\r\n\r\n";
    $body .= $payload . "\r\n";
    $body .= "--" . $boundary . "--\r\n";

    return $body;
}

/**
 * Uploads one archive to the manage server.
 *
 * @param array $meta trigger, file_count, source_bytes, sha256, app_version
 */
function manageBackupUpload(string $archivePath, array $meta = []): array
{
    manageClientRequireConfigured();

    if (!is_file($archivePath)) {
        throw new RuntimeException("Backup-Datei existiert nicht: " . $archivePath);
    }

    $filename = basename($archivePath);
    $sha256 = strtolower(trim((string) ($meta["sha256"] ?? "")));
    if (preg_match('/^[a-f0-9]{64}$/', $sha256) !== 1) {
        $sha256 = strtolower(hash_file("sha256", $archivePath) ?: "");
    }
    if (preg_match('/^[a-f0-9]{64}$/', $sha256) !== 1) {
        throw new RuntimeException("Prüfsumme des Backups konnte nicht berechnet werden.");
    }

    $metaPayload = json_encode([
        "trigger" => (string) ($meta["trigger"] ?? "manual"),
        "file_count" => (int) ($meta["file_count"] ?? 0),
        "source_bytes" => (int) ($meta["source_bytes"] ?? 0),
        "app_version" => manageClientVersion(),
    ], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);

    $boundary = "----manage-client-" . bin2hex(random_bytes(12));
    $body = manageBackupBuildMultipartBody(
        [
            "filename" => $filename,
            "sha256" => $sha256,
            "meta" => $metaPayload === false ? "{}" : $metaPayload,
        ],
        "backup",
        $archivePath,
        $filename,
        $boundary,
    );

    $response = manageClientRequest(
        "POST",
        "backup.php",
        $body,
        "multipart/form-data; boundary=" . $boundary,
        (int) MANAGE_HTTP_TIMEOUT_LONG,
    );

    if ($response["status"] < 200 || $response["status"] >= 300) {
        throw new ManageRemoteUploadException(
            manageClientErrorMessage($response["status"], $response["body"]),
            [
                "http_status" => $response["status"],
                "response_excerpt" => manageRemoteResponseExcerpt($response["body"]),
                "filename" => $filename,
            ],
        );
    }

    $decoded = json_decode($response["body"], true);
    if (!is_array($decoded) || empty($decoded["success"])) {
        $error = is_array($decoded) ? trim((string) ($decoded["error"] ?? "")) : "";
        throw new ManageRemoteUploadException(
            "Der Manage-Server hat das Backup abgelehnt" . ($error !== "" ? ": " . $error : "."),
            [
                "http_status" => $response["status"],
                "response_excerpt" => manageRemoteResponseExcerpt($response["body"]),
                "filename" => $filename,
            ],
        );
    }

    return [
        "target" => "Manage-Server",
        "type" => "manage",
        "success" => true,
        "uploaded_at" => date(DATE_ATOM),
        "server_filename" => (string) ($decoded["filename"] ?? ""),
        "remote_path" => manageClientEndpoint("backup.php"),
    ];
}

// ---------------------------------------------------------------------------
// Creating a backup
// ---------------------------------------------------------------------------

/**
 * Creates a local archive and, unless disabled, uploads it.
 *
 * A failed upload never invalidates the local archive: the error is stored in
 * the index record and logged, exactly like the extra remote targets.
 *
 * @param string $trigger manual | automatic | cron | update
 */
function manageBackupCreate(string $trigger = "manual"): array
{
    $dir = manageBackupDir();
    manageEnsureDir($dir);

    $lockHandle = fopen(manageBackupLockFile(), "c+");
    if ($lockHandle === false) {
        throw new RuntimeException("Backup-Sperrdatei konnte nicht geöffnet werden.");
    }

    if (!flock($lockHandle, LOCK_EX | LOCK_NB)) {
        fclose($lockHandle);
        throw new RuntimeException("Es läuft bereits ein Backup.");
    }

    $dumpFile = null;

    try {
        $baseName = "backup-" . date("Ymd-His");
        $filename = $baseName . ".zip";
        $counter = 2;
        while (file_exists($dir . $filename)) {
            $filename = $baseName . "-" . $counter . ".zip";
            $counter++;
        }

        $tmpFile = $dir . "." . $filename . ".tmp";
        $archivePath = $dir . $filename;
        $createdAt = date(DATE_ATOM);

        $files = manageBackupCollectSources();
        $database = null;

        if (manageDatabaseConfigured()) {
            $dumpFile = rtrim((string) MANAGE_WORK_DIR, "/\\") . DIRECTORY_SEPARATOR .
                "dump-" . date("Ymd-His") . "-" . bin2hex(random_bytes(4)) . ".sql";
            $database = manageDatabaseDump($dumpFile);
            $files[] = [
                "path" => $dumpFile,
                "name" => "database/" . $database["database"] . ".sql",
            ];
        }

        $zipStats = manageZipWrite($tmpFile, $files);

        if (!rename($tmpFile, $archivePath)) {
            @unlink($tmpFile);
            throw new RuntimeException("Backup-ZIP konnte nicht finalisiert werden.");
        }
        @chmod($archivePath, 0660);

        $metadata = [
            "filename" => $filename,
            "created_at" => $createdAt,
            "trigger" => $trigger,
            "sha256" => $zipStats["sha256"],
            "file_count" => $zipStats["file_count"],
            "source_bytes" => $zipStats["source_bytes"],
        ];

        $uploads = [];
        if (MANAGE_BACKUP_UPLOAD === true && manageClientConfigured()) {
            try {
                $uploads[] = manageBackupUpload($archivePath, $metadata);
            } catch (Throwable $exception) {
                $debugContext = $exception instanceof ManageRemoteUploadException
                    ? $exception->getDebugContext()
                    : [];
                $uploads[] = [
                    "target" => "Manage-Server",
                    "type" => "manage",
                    "success" => false,
                    "error" => $exception->getMessage(),
                    "debug" => $debugContext,
                ];
                manageClientLog("ERROR", "Backup upload to manage server failed", [
                    "filename" => $filename,
                    "error" => $exception->getMessage(),
                    "debug" => $debugContext,
                ]);
            }
        }

        $uploads = array_merge($uploads, manageRemoteUploadAll($archivePath, $metadata));

        $record = [
            "filename" => $filename,
            "created_at" => $createdAt,
            "trigger" => $trigger,
            "size" => (int) (filesize($archivePath) ?: $zipStats["archive_bytes"]),
            "file_count" => $zipStats["file_count"],
            "source_bytes" => $zipStats["source_bytes"],
            "sha256" => $zipStats["sha256"],
            "app_version" => manageClientVersion(),
            "database" => $database,
            "remote_uploads" => $uploads,
        ];

        $records = manageBackupList();
        array_unshift($records, $record);
        manageBackupWriteIndex($records);
        manageBackupApplyRetention();

        manageClientLog("INFO", "Backup created", [
            "filename" => $filename,
            "trigger" => $trigger,
            "file_count" => $record["file_count"],
            "size" => $record["size"],
        ]);

        return $record;
    } catch (Throwable $exception) {
        manageClientLog("ERROR", "Backup failed", [
            "trigger" => $trigger,
            "error" => $exception->getMessage(),
        ]);
        throw $exception;
    } finally {
        if ($dumpFile !== null && is_file($dumpFile)) {
            @unlink($dumpFile);
        }
        flock($lockHandle, LOCK_UN);
        fclose($lockHandle);
    }
}

// ---------------------------------------------------------------------------
// Automatic scheduling for hosts without cron
// ---------------------------------------------------------------------------

function manageBackupLastAutomaticAt(): int
{
    foreach (manageBackupList() as $record) {
        $trigger = (string) ($record["trigger"] ?? "");
        if ($trigger !== "automatic" && $trigger !== "cron") {
            continue;
        }

        $timestamp = strtotime((string) ($record["created_at"] ?? ""));
        if ($timestamp !== false) {
            return $timestamp;
        }
    }

    return 0;
}

function manageBackupIsAutomaticDue(): bool
{
    $interval = (int) MANAGE_BACKUP_AUTO_INTERVAL_SECONDS;
    if ($interval < 1) {
        return false;
    }

    return time() - manageBackupLastAutomaticAt() >= $interval;
}

/**
 * Creates an automatic backup when the interval has elapsed. Meant to be called
 * from an admin page the host application loads regularly. Returns null when
 * nothing was due.
 */
function manageBackupCreateAutomaticIfDue(): ?array
{
    if (!manageBackupIsAutomaticDue()) {
        return null;
    }

    return manageBackupCreate("automatic");
}