<?php

declare(strict_types=1);

// Update pipeline: check, download, verify, extract, deploy, post-update hook.
//
// Everything host-specific is configurable:
//   - the version file (for example includes/version.php with APP_VERSION)
//   - the protected paths (for example config.php, data/, .git/)
//   - the package sanity marker (for example index.php / admin/ / includes/)
//
// Deployment is an overlay copy: every file in the package is written over the
// application root, with each overwritten file copied aside first. Files that
// disappeared between releases are NOT removed, and there is no restore path —
// the aside copies exist for manual recovery only.

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

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

// ---------------------------------------------------------------------------
// Manifest
// ---------------------------------------------------------------------------

/**
 * Fetches and strictly validates the manifest.
 *
 * Every field is re-checked here because the response decides which code the
 * instance will execute next.
 */
function manageUpdateFetchManifest(): array
{
    $decoded = manageClientRequestJson("GET", "manifest.php", null, (int) MANAGE_HTTP_TIMEOUT);

    $version = trim((string) ($decoded["version"] ?? $decoded["latest"] ?? ""));
    $packageUrl = trim((string) ($decoded["package_url"] ?? ""));
    $sha256 = strtolower(trim((string) ($decoded["sha256"] ?? "")));
    $size = isset($decoded["size"]) ? (int) $decoded["size"] : 0;
    $publishedAt = trim((string) ($decoded["published_at"] ?? ""));

    if (!manageIsVersionString($version)) {
        throw new RuntimeException("Version im Manifest ist ungültig.");
    }
    if (!filter_var($packageUrl, FILTER_VALIDATE_URL)) {
        throw new RuntimeException("Paket-URL im Manifest ist ungültig.");
    }
    if (preg_match('/^[a-f0-9]{64}$/', $sha256) !== 1) {
        throw new RuntimeException("Prüfsumme im Manifest ist ungültig.");
    }

    return [
        "version" => $version,
        "package_url" => $packageUrl,
        "sha256" => $sha256,
        "size" => $size,
        "published_at" => $publishedAt,
    ];
}

/**
 * Checks whether a newer release is available.
 *
 * @return array{current: string, latest: string, available: bool, manifest: array}
 */
function manageUpdateCheck(): array
{
    $manifest = manageUpdateFetchManifest();
    $current = manageClientVersion();

    $available = $current === ""
        ? true
        : version_compare(
            manageVersionCompareValue($manifest["version"]),
            manageVersionCompareValue($current),
            ">",
        );

    return [
        "current" => $current,
        "latest" => $manifest["version"],
        "available" => $available,
        "manifest" => $manifest,
    ];
}

// ---------------------------------------------------------------------------
// Download and extraction
// ---------------------------------------------------------------------------

function manageUpdateDownloadPackage(array $manifest, string $targetFile): void
{
    manageEnsureDir(dirname($targetFile));

    $version = (string) $manifest["version"];
    $response = manageClientRequest(
        "GET",
        "package.php?version=" . rawurlencode($version),
        null,
        "application/json",
        (int) MANAGE_HTTP_TIMEOUT_LONG,
    );

    if ($response["status"] < 200 || $response["status"] >= 300) {
        throw new RuntimeException(manageClientErrorMessage($response["status"], $response["body"]));
    }
    if ($response["body"] === "") {
        throw new RuntimeException("Das heruntergeladene Paket ist leer.");
    }

    if (file_put_contents($targetFile, $response["body"], LOCK_EX) === false) {
        throw new RuntimeException("Das heruntergeladene Paket konnte nicht gespeichert werden.");
    }

    if ($manifest["size"] > 0 && filesize($targetFile) !== $manifest["size"]) {
        unlink($targetFile);
        throw new RuntimeException("Größe des heruntergeladenen Pakets stimmt nicht überein.");
    }

    $actualHash = strtolower(hash_file("sha256", $targetFile) ?: "");
    if ($actualHash !== $manifest["sha256"]) {
        unlink($targetFile);
        throw new RuntimeException("Prüfsumme des Pakets stimmt nicht überein.");
    }
}

// Rejects zip-slip and anything else that would escape the stage directory.
function manageUpdateValidateZipEntry(string $entry): bool
{
    $entry = str_replace("\\", "/", $entry);
    $normalized = trim($entry, "/");

    if (
        $normalized === "" ||
        str_contains($entry, "\0") ||
        str_starts_with($entry, "/") ||
        preg_match('/^[A-Za-z]:\//', $entry) === 1
    ) {
        return false;
    }

    foreach (explode("/", $normalized) as $segment) {
        if ($segment === "" || $segment === "." || $segment === "..") {
            return false;
        }
    }

    return true;
}

function manageUpdateExtractPackage(string $zipFile, string $stageDir): void
{
    if (!class_exists("ZipArchive")) {
        throw new RuntimeException("Die PHP-Erweiterung ZipArchive ist nicht verfügbar.");
    }

    manageRemoveDir($stageDir);
    manageEnsureDir($stageDir);

    $zip = new ZipArchive();
    if ($zip->open($zipFile) !== true) {
        throw new RuntimeException("Das heruntergeladene Paket ist keine lesbare ZIP-Datei.");
    }

    $sanityPaths = is_array(MANAGE_UPDATE_SANITY_PATHS) ? MANAGE_UPDATE_SANITY_PATHS : [];
    $hasAppFile = $sanityPaths === [];

    for ($i = 0; $i < $zip->numFiles; $i++) {
        $name = (string) $zip->getNameIndex($i);
        if (!manageUpdateValidateZipEntry($name)) {
            $zip->close();
            throw new RuntimeException("Das Paket enthält einen unsicheren Pfad: " . $name);
        }

        foreach ($sanityPaths as $sanityPath) {
            $sanityPath = trim(str_replace("\\", "/", (string) $sanityPath), "/");
            if ($sanityPath === "") {
                continue;
            }
            if ($name === $sanityPath || str_starts_with($name, $sanityPath . "/")) {
                $hasAppFile = true;
            }
        }
    }

    if (!$hasAppFile) {
        $zip->close();
        throw new RuntimeException(
            "Das Paket sieht nicht wie ein Release dieser Anwendung aus (erwartet: " .
            implode(", ", array_map("strval", $sanityPaths)) . ").",
        );
    }

    if (!$zip->extractTo($stageDir)) {
        $zip->close();
        throw new RuntimeException("Das Paket konnte nicht entpackt werden.");
    }

    $zip->close();
}

// ---------------------------------------------------------------------------
// Deployment
// ---------------------------------------------------------------------------

function manageUpdateRelativePath(string $path, string $baseDir): string
{
    return ltrim(str_replace("\\", "/", substr($path, strlen($baseDir))), "/");
}

/**
 * Whether a path from the package must be left alone.
 *
 * A configured entry ending in "/" protects the directory and everything below
 * it; anything else matches the exact path.
 */
function manageUpdateShouldSkipPath(string $relativePath): bool
{
    $relativePath = trim(str_replace("\\", "/", $relativePath), "/");
    if ($relativePath === "") {
        return true;
    }

    $protected = is_array(MANAGE_UPDATE_PROTECTED_PATHS) ? MANAGE_UPDATE_PROTECTED_PATHS : [];

    foreach ($protected as $entry) {
        $entry = str_replace("\\", "/", (string) $entry);
        $isDirectory = str_ends_with($entry, "/");
        $entry = trim($entry, "/");
        if ($entry === "") {
            continue;
        }

        if ($relativePath === $entry) {
            return true;
        }
        if ($isDirectory && str_starts_with($relativePath, $entry . "/")) {
            return true;
        }
        // A protected directory named without a trailing slash still protects
        // its contents; the trailing slash only documents the intent.
        if (!$isDirectory && str_starts_with($relativePath, $entry . "/")) {
            return true;
        }
    }

    return false;
}

function manageUpdateCopyWithBackup(string $stageDir, string $appRoot, string $backupDir): array
{
    manageEnsureDir($backupDir);

    $copied = 0;
    $backedUp = 0;
    $skipped = 0;

    $items = new RecursiveIteratorIterator(
        new RecursiveDirectoryIterator($stageDir, FilesystemIterator::SKIP_DOTS),
        RecursiveIteratorIterator::SELF_FIRST,
    );

    foreach ($items as $item) {
        $relativePath = manageUpdateRelativePath($item->getPathname(), $stageDir);
        if (manageUpdateShouldSkipPath($relativePath)) {
            $skipped++;
            continue;
        }

        $targetPath = $appRoot . DIRECTORY_SEPARATOR . $relativePath;

        if ($item->isDir()) {
            manageEnsureDir($targetPath);
            continue;
        }

        manageEnsureDir(dirname($targetPath));

        if (file_exists($targetPath)) {
            $backupPath = $backupDir . DIRECTORY_SEPARATOR . $relativePath;
            manageEnsureDir(dirname($backupPath));
            if (!copy($targetPath, $backupPath)) {
                throw new RuntimeException("Datei konnte nicht gesichert werden: " . $relativePath);
            }
            $backedUp++;
        }

        if (!copy($item->getPathname(), $targetPath)) {
            throw new RuntimeException("Datei konnte nicht ausgerollt werden: " . $relativePath);
        }

        @chmod($targetPath, fileperms($item->getPathname()) & 0777);
        $copied++;
    }

    return ["copied" => $copied, "backed_up" => $backedUp, "skipped" => $skipped];
}

// Keeps only the backup directory of the run that just finished.
function manageUpdateCleanupOldBackups(string $keepBackupDir): int
{
    $backupRoot = rtrim(manageUpdateBackupRoot(), "/\\");
    if (!is_dir($backupRoot)) {
        return 0;
    }

    $keepRealPath = realpath($keepBackupDir);
    $backupRootRealPath = realpath($backupRoot);
    if ($keepRealPath === false || $backupRootRealPath === false) {
        return 0;
    }

    $removed = 0;
    foreach (new DirectoryIterator($backupRootRealPath) as $item) {
        if ($item->isDot() || !$item->isDir()) {
            continue;
        }

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

        manageRemoveDir($path);
        if (is_dir($path)) {
            throw new RuntimeException("Altes Backup-Verzeichnis konnte nicht entfernt werden: " . $path);
        }
        $removed++;
    }

    return $removed;
}

/**
 * Downloads, verifies and deploys one release, then runs the post-update step.
 *
 * $options:
 *   force     bool  redeploy even when no newer version is available
 *   skip_hook bool  deploy files only, run neither migrations nor the callback
 *
 * The returned array always reports deployment and post-update separately:
 * a failed hook does not undo a successful deployment.
 */
function manageUpdateApply(array $options = []): array
{
    $force = !empty($options["force"]);
    $skipHook = !empty($options["skip_hook"]);

    $appRoot = manageClientAppRoot();
    $check = manageUpdateCheck();
    $manifest = $check["manifest"];

    if (!$check["available"] && !$force) {
        throw new RuntimeException(
            "Es ist kein neueres Update verfügbar. Mit der Option \"force\" kann dasselbe Paket erneut ausgerollt werden.",
        );
    }

    $runId = date("Ymd-His");
    $workDir = manageUpdateWorkDir() . $runId;
    $stageDir = $workDir . DIRECTORY_SEPARATOR . "stage";
    $zipFile = $workDir . DIRECTORY_SEPARATOR . "package.zip";
    $backupDir = manageUpdateBackupRoot() . $runId . "-" . $manifest["version"];

    manageEnsureDir($workDir);

    try {
        manageUpdateDownloadPackage($manifest, $zipFile);
        manageUpdateExtractPackage($zipFile, $stageDir);
        $result = manageUpdateCopyWithBackup($stageDir, $appRoot, $backupDir);
    } finally {
        manageRemoveDir($workDir);
    }

    $removedBackups = manageUpdateCleanupOldBackups($backupDir);

    manageClientLog("INFO", "Update deployed", [
        "from_version" => $check["current"],
        "to_version" => $manifest["version"],
        "copied" => $result["copied"],
        "backed_up" => $result["backed_up"],
        "backup_dir" => $backupDir,
    ]);

    $report = [
        "deployed" => true,
        "from_version" => $check["current"],
        "to_version" => $manifest["version"],
        "version" => manageClientVersion(),
        "copied" => $result["copied"],
        "backed_up" => $result["backed_up"],
        "skipped" => $result["skipped"],
        "removed_backups" => $removedBackups,
        "backup_dir" => $backupDir,
        "hook" => null,
    ];

    if ($skipHook) {
        $report["hook"] = [
            "success" => true,
            "skipped" => true,
            "migrations" => ["applied" => [], "pending" => count(manageUpdatePendingMigrations())],
        ];

        return $report;
    }

    // The version constant may already be loaded in this process from the old
    // code, so to_version is taken from the manifest rather than re-read.
    $report["hook"] = manageUpdateRunPostHook([
        "from_version" => $check["current"],
        "to_version" => $manifest["version"],
        "backup_dir" => $backupDir,
        "run_id" => $runId,
    ]);

    return $report;
}