<?php

declare(strict_types=1);

require_once __DIR__ . "/lib.php";

if (session_status() === PHP_SESSION_NONE) {
    ini_set("session.use_strict_mode", "1");
    ini_set("session.cookie_httponly", "1");
    ini_set("session.cookie_samesite", "Lax");
    session_start();
}

$messages = [];
$errors = [];

function backupManageEscape($value): string
{
    return htmlspecialchars((string) $value, ENT_QUOTES, "UTF-8");
}

function backupManagePasswordConfigured(): bool
{
    return defined("BACKUP_SERVER_PASSWORD_HASH") || defined("BACKUP_SERVER_PASSWORD");
}

function backupManagePasswordMatches(string $password): bool
{
    if (defined("BACKUP_SERVER_PASSWORD_HASH")) {
        return password_verify($password, (string) BACKUP_SERVER_PASSWORD_HASH);
    }

    if (defined("BACKUP_SERVER_PASSWORD")) {
        return hash_equals((string) BACKUP_SERVER_PASSWORD, $password);
    }

    return false;
}

function backupManageIsLoggedIn(): bool
{
    return !empty($_SESSION["backup_server_logged_in"]);
}

function backupManageCsrfToken(): string
{
    if (empty($_SESSION["backup_server_csrf_token"])) {
        $_SESSION["backup_server_csrf_token"] = bin2hex(random_bytes(32));
    }

    return $_SESSION["backup_server_csrf_token"];
}

function backupManageCsrfIsValid(string $token): bool
{
    return !empty($_SESSION["backup_server_csrf_token"]) &&
        hash_equals($_SESSION["backup_server_csrf_token"], $token);
}

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

    return $filename;
}

function backupManageFormatBytes(int $bytes): string
{
    if ($bytes >= 1073741824) {
        return number_format($bytes / 1073741824, 2, ",", ".") . " GB";
    }
    if ($bytes >= 1048576) {
        return number_format($bytes / 1048576, 2, ",", ".") . " MB";
    }
    if ($bytes >= 1024) {
        return number_format($bytes / 1024, 1, ",", ".") . " KB";
    }
    return $bytes . " B";
}

function backupManageFindBackup(string $instance, string $filename): ?array
{
    foreach (backupServerReadIndex()["backups"] as $backup) {
        if (!is_array($backup)) {
            continue;
        }
        if (($backup["instance"] ?? "") === $instance && ($backup["filename"] ?? "") === $filename) {
            return $backup;
        }
    }

    return null;
}

function backupManageSendDownload(string $instance, string $filename): void
{
    $backup = backupManageFindBackup($instance, $filename);
    if ($backup === null) {
        throw new RuntimeException("Backup not found.");
    }

    $path = backupServerBackupPath($instance, $filename);
    if (is_file($path)) {
        $size = filesize($path);
        $handle = fopen($path, "rb");
        if ($size === false || $handle === false) {
            throw new RuntimeException("Backup cannot be opened.");
        }

        header("Content-Type: application/zip");
        header("Content-Disposition: attachment; filename=\"" . addcslashes($instance . "-" . $filename, "\"\\") . "\"");
        header("Content-Length: " . (string) $size);
        header("Cache-Control: private, no-store");
        header("X-Content-Type-Options: nosniff");

        fpassthru($handle);
        fclose($handle);
        exit;
    }

    if (!empty($backup["s3_uploaded_at"])) {
        if (!backupS3Enabled()) {
            throw new RuntimeException("Backup is stored in S3, but S3 is not configured. See config.php.");
        }

        $key = (string) ($backup["s3_key"] ?? "");
        if ($key === "") {
            $key = backupS3ObjectKey($instance, $filename);
        }

        backupS3SendObjectToOutput($key, $instance . "-" . $filename, (int) ($backup["size"] ?? 0));
    }

    throw new RuntimeException("Backup not found in any store.");
}

function backupManageDeleteBackup(string $instance, string $filename): void
{
    $index = backupServerReadIndex();
    $kept = [];
    $found = null;

    foreach ($index["backups"] as $backup) {
        if (
            is_array($backup) &&
            ($backup["instance"] ?? "") === $instance &&
            ($backup["filename"] ?? "") === $filename
        ) {
            $found = $backup;
            continue;
        }
        $kept[] = $backup;
    }

    if ($found === null) {
        throw new RuntimeException("Backup not found.");
    }

    // Delete the S3 object first: if that fails, nothing is changed, so no
    // object is ever stranded in the bucket without an index record.
    if (!empty($found["s3_uploaded_at"])) {
        if (!backupS3Enabled()) {
            throw new RuntimeException("Backup has an S3 copy, but S3 is not configured. See config.php.");
        }

        $key = (string) ($found["s3_key"] ?? "");
        if ($key === "") {
            $key = backupS3ObjectKey($instance, $filename);
        }
        backupS3DeleteObject($key);
    }

    $path = backupServerBackupPath($instance, $filename);
    if (is_file($path)) {
        unlink($path);
    }

    backupServerWriteIndex($kept);
}

function backupManageAddInstance(string $instance): void
{
    $instance = backupServerValidateInstance($instance);
    $settings = backupServerGetSettings();
    $settings["instances"][] = $instance;
    backupServerWriteSettings($settings);
}

function backupManageRemoveInstance(string $instance): void
{
    $instance = backupServerValidateInstance($instance);
    $settings = backupServerGetSettings();
    $settings["instances"] = array_values(
        array_filter($settings["instances"], function ($existing) use ($instance) {
            return $existing !== $instance;
        }),
    );
    backupServerWriteSettings($settings);
}

function backupManageGroupBackupsByInstance(array $backups): array
{
    $grouped = [];
    foreach ($backups as $backup) {
        if (!is_array($backup)) {
            continue;
        }
        $instance = (string) ($backup["instance"] ?? "");
        $filename = basename((string) ($backup["filename"] ?? ""));
        if ($instance === "" || $filename === "") {
            continue;
        }
        $backup["filename"] = $filename;
        $path = backupServerBackupPath($instance, $filename);
        $backup["local_exists"] = is_file($path);
        $backup["size"] = $backup["local_exists"]
            ? (int) (filesize($path) ?: ($backup["size"] ?? 0))
            : (int) ($backup["size"] ?? 0);
        $grouped[$instance][] = $backup;
    }

    ksort($grouped);
    foreach ($grouped as &$records) {
        usort($records, function ($left, $right) {
            return strcmp((string) ($right["uploaded_at"] ?? ""), (string) ($left["uploaded_at"] ?? ""));
        });
    }
    unset($records);

    return $grouped;
}

function backupManageStorageLabel(array $backup): string
{
    $local = !empty($backup["local_exists"]);
    $inS3 = !empty($backup["s3_uploaded_at"]);

    if ($local && $inS3) {
        return "Local + S3";
    }
    if ($local && backupS3Enabled() && empty($backup["s3_expired"])) {
        return "Local (S3 pending)";
    }
    if ($local) {
        return "Local";
    }
    if ($inS3) {
        return "S3 only";
    }

    return "Missing";
}

function backupManageLogTail(int $lines): array
{
    $file = (string) BACKUP_SERVER_LOG_FILE;
    if (!is_file($file)) {
        return [];
    }

    $content = @file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    if (!is_array($content)) {
        return [];
    }

    return array_slice($content, -$lines);
}

if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $action = (string) ($_POST["action"] ?? "");

    if ($action === "login") {
        if (!backupManagePasswordConfigured()) {
            $errors[] = "No password is configured.";
        } elseif (backupManagePasswordMatches((string) ($_POST["password"] ?? ""))) {
            session_regenerate_id(true);
            $_SESSION["backup_server_logged_in"] = true;
            $messages[] = "Logged in.";
        } else {
            $errors[] = "Wrong password.";
        }
    } elseif ($action === "logout") {
        unset($_SESSION["backup_server_logged_in"], $_SESSION["backup_server_csrf_token"]);
        $messages[] = "Logged out.";
    } elseif (!backupManageIsLoggedIn()) {
        $errors[] = "Login required.";
    } elseif (!backupManageCsrfIsValid((string) ($_POST["csrf_token"] ?? ""))) {
        $errors[] = "Invalid token. Please reload the page and try again.";
    } else {
        try {
            if ($action === "update_retention") {
                $settings = backupServerGetSettings();
                $settings["retention"] = max(1, (int) ($_POST["retention"] ?? BACKUP_SERVER_RETENTION));
                if (isset($_POST["s3_retention"])) {
                    $settings["s3_retention"] = max(1, (int) $_POST["s3_retention"]);
                }
                backupServerWriteSettings($settings);
                // May issue S3 deletes for backups that now age out of the archive.
                backupServerApplyRetentionAll();
                $messages[] = "Retention updated.";
            } elseif ($action === "add_instance") {
                backupManageAddInstance((string) ($_POST["instance"] ?? ""));
                $messages[] = "Instance added.";
            } elseif ($action === "remove_instance") {
                backupManageRemoveInstance((string) ($_POST["instance"] ?? ""));
                $messages[] = "Instance removed.";
            } elseif ($action === "download") {
                backupManageSendDownload(
                    backupServerValidateInstance((string) ($_POST["instance"] ?? "")),
                    backupManageValidateFilename((string) ($_POST["filename"] ?? "")),
                );
            } elseif ($action === "delete") {
                backupManageDeleteBackup(
                    backupServerValidateInstance((string) ($_POST["instance"] ?? "")),
                    backupManageValidateFilename((string) ($_POST["filename"] ?? "")),
                );
                $messages[] = "Backup deleted.";
            } elseif ($action === "s3_sync") {
                if (!backupS3Enabled()) {
                    throw new RuntimeException("S3 is not configured. See config.php.");
                }
                $uploaded = 0;
                $pending = 0;
                foreach (backupServerIndexInstances() as $syncInstance) {
                    $result = backupServerSyncInstanceS3($syncInstance);
                    $uploaded += $result["uploaded"];
                    $pending += $result["pending"];
                    if ($result["error"] !== null) {
                        $errors[] = "S3 upload for " . $syncInstance . " failed: " . $result["error"];
                    }
                    backupServerApplyRetention($syncInstance);
                }
                $messages[] = "S3 sync finished: " . $uploaded . " uploaded, " . $pending . " still pending.";
            }
        } catch (Throwable $exception) {
            $errors[] = $exception->getMessage();
        }
    }
}

try {
    $settings = backupServerGetSettings();
    $groupedBackups = backupManageGroupBackupsByInstance(backupServerReadIndex()["backups"]);
} catch (Throwable $exception) {
    $settings = [
        "retention" => max(1, (int) BACKUP_SERVER_RETENTION),
        "s3_retention" => max(1, (int) BACKUP_SERVER_S3_RETENTION),
        "instances" => [],
    ];
    $groupedBackups = [];
    $errors[] = $exception->getMessage();
}

$s3Enabled = backupS3Enabled();
$s3PendingCount = 0;
$s3LastErrors = [];
if ($s3Enabled) {
    foreach ($groupedBackups as $instanceBackups) {
        foreach ($instanceBackups as $backup) {
            if (!empty($backup["local_exists"]) && empty($backup["s3_uploaded_at"])) {
                $s3PendingCount++;
            }
            if (!empty($backup["s3_last_error"]) && count($s3LastErrors) < 5) {
                $s3LastErrors[] = ($backup["instance"] ?? "") . "/" . ($backup["filename"] ?? "") .
                    ": " . $backup["s3_last_error"];
            }
        }
    }
}
$s3LogTail = backupManageLogTail(20);

?>
<!DOCTYPE html>
<html lang="de">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Backup Management</title>
</head>
<body>
    <h1>Backup Management</h1>

    <?php foreach ($messages as $message): ?>
        <p><strong><?php echo backupManageEscape($message); ?></strong></p>
    <?php endforeach; ?>

    <?php foreach ($errors as $error): ?>
        <p><strong>Error:</strong> <?php echo backupManageEscape($error); ?></p>
    <?php endforeach; ?>

    <?php if (!backupManageIsLoggedIn()): ?>
        <form method="POST">
            <input type="hidden" name="action" value="login">
            <p>
                <label for="password">Password</label><br>
                <input type="password" id="password" name="password" required>
            </p>
            <button type="submit">Login</button>
        </form>
    <?php else: ?>
        <form method="POST">
            <input type="hidden" name="action" value="logout">
            <button type="submit">Logout</button>
        </form>

        <h2>Settings</h2>
        <form method="POST">
            <input type="hidden" name="action" value="update_retention">
            <input type="hidden" name="csrf_token" value="<?php echo backupManageEscape(backupManageCsrfToken()); ?>">
            <p>
                <label for="retention">Local backups retained per instance</label><br>
                <input type="number" id="retention" name="retention" min="1" required value="<?php echo (int) $settings["retention"]; ?>">
            </p>
            <?php if ($s3Enabled): ?>
                <p>
                    <label for="s3_retention">S3 backups retained per instance</label><br>
                    <input type="number" id="s3_retention" name="s3_retention" min="1" required value="<?php echo (int) $settings["s3_retention"]; ?>">
                </p>
            <?php endif; ?>
            <button type="submit">Save retention</button>
        </form>

        <h2>S3 archive</h2>
        <?php if (!$s3Enabled): ?>
            <p>S3 storage is not configured. Set the <code>BACKUP_SERVER_S3_*</code> constants in <code>config.php</code> to enable it.</p>
        <?php else: ?>
            <p>
                Endpoint: <code><?php echo backupManageEscape(BACKUP_SERVER_S3_ENDPOINT); ?></code>,
                Bucket: <code><?php echo backupManageEscape(BACKUP_SERVER_S3_BUCKET); ?></code>
                <?php if (trim((string) BACKUP_SERVER_S3_PREFIX, "/") !== ""): ?>
                    , Prefix: <code><?php echo backupManageEscape(trim((string) BACKUP_SERVER_S3_PREFIX, "/")); ?></code>
                <?php endif; ?>
            </p>
            <p>Pending uploads: <?php echo (int) $s3PendingCount; ?></p>
            <form method="POST">
                <input type="hidden" name="action" value="s3_sync">
                <input type="hidden" name="csrf_token" value="<?php echo backupManageEscape(backupManageCsrfToken()); ?>">
                <button type="submit">Retry S3 uploads now</button>
            </form>
            <?php if (!empty($s3LastErrors)): ?>
                <p><strong>Recent upload errors:</strong></p>
                <ul>
                    <?php foreach ($s3LastErrors as $s3LastError): ?>
                        <li><?php echo backupManageEscape($s3LastError); ?></li>
                    <?php endforeach; ?>
                </ul>
            <?php endif; ?>
            <?php if (!empty($s3LogTail)): ?>
                <details>
                    <summary>S3 log (last <?php echo count($s3LogTail); ?> lines)</summary>
                    <pre><?php echo backupManageEscape(implode("\n", $s3LogTail)); ?></pre>
                </details>
            <?php endif; ?>
        <?php endif; ?>

        <h2>Upload endpoint</h2>
        <p>Distributed instances should upload to <code>upload.php</code>.</p>

        <h2>Allowed instances</h2>
        <form method="POST">
            <input type="hidden" name="action" value="add_instance">
            <input type="hidden" name="csrf_token" value="<?php echo backupManageEscape(backupManageCsrfToken()); ?>">
            <p>
                <label for="instance">Instance identifier</label><br>
                <input type="text" id="instance" name="instance" required pattern="[A-Za-z0-9][A-Za-z0-9._-]*" maxlength="120">
            </p>
            <button type="submit">Add instance</button>
        </form>

        <?php if (empty($settings["instances"])): ?>
            <p>No instances allowed. Uploads will be rejected until an instance is added.</p>
        <?php else: ?>
            <table border="1" cellpadding="6" cellspacing="0">
                <thead>
                    <tr>
                        <th>Instance</th>
                        <th>Actions</th>
                    </tr>
                </thead>
                <tbody>
                    <?php foreach ($settings["instances"] as $instance): ?>
                        <tr>
                            <td><?php echo backupManageEscape($instance); ?></td>
                            <td>
                                <form method="POST" style="display:inline" onsubmit="return confirm('Remove this allowed instance? Existing backups remain visible; S3 objects remain until retention or manual delete.');">
                                    <input type="hidden" name="action" value="remove_instance">
                                    <input type="hidden" name="csrf_token" value="<?php echo backupManageEscape(backupManageCsrfToken()); ?>">
                                    <input type="hidden" name="instance" value="<?php echo backupManageEscape($instance); ?>">
                                    <button type="submit">Remove</button>
                                </form>
                            </td>
                        </tr>
                    <?php endforeach; ?>
                </tbody>
            </table>
        <?php endif; ?>

        <h2>Backups</h2>
        <?php if (empty($groupedBackups)): ?>
            <p>No backups uploaded.</p>
        <?php else: ?>
            <?php foreach ($groupedBackups as $instance => $backups): ?>
                <h3><?php echo backupManageEscape($instance); ?></h3>
                <table border="1" cellpadding="6" cellspacing="0">
                    <thead>
                        <tr>
                            <th>Uploaded</th>
                            <th>Filename</th>
                            <th>Size</th>
                            <th>Storage</th>
                            <th>SHA-256</th>
                            <th>Source IP</th>
                            <th>Actions</th>
                        </tr>
                    </thead>
                    <tbody>
                        <?php foreach ($backups as $backup): ?>
                            <tr>
                                <td><?php echo backupManageEscape($backup["uploaded_at"] ?? ""); ?></td>
                                <td><?php echo backupManageEscape($backup["filename"] ?? ""); ?></td>
                                <td><?php echo backupManageEscape(backupManageFormatBytes((int) ($backup["size"] ?? 0))); ?></td>
                                <td title="<?php echo backupManageEscape($backup["s3_last_error"] ?? ""); ?>"><?php echo backupManageEscape(backupManageStorageLabel($backup)); ?></td>
                                <td><?php echo backupManageEscape($backup["sha256"] ?? ""); ?></td>
                                <td><?php echo backupManageEscape($backup["source_ip"] ?? ""); ?></td>
                                <td>
                                    <form method="POST" style="display:inline">
                                        <input type="hidden" name="action" value="download">
                                        <input type="hidden" name="csrf_token" value="<?php echo backupManageEscape(backupManageCsrfToken()); ?>">
                                        <input type="hidden" name="instance" value="<?php echo backupManageEscape($instance); ?>">
                                        <input type="hidden" name="filename" value="<?php echo backupManageEscape($backup["filename"] ?? ""); ?>">
                                        <button type="submit">Download</button>
                                    </form>
                                    <form method="POST" style="display:inline" onsubmit="return confirm('Delete this backup from all stores?');">
                                        <input type="hidden" name="action" value="delete">
                                        <input type="hidden" name="csrf_token" value="<?php echo backupManageEscape(backupManageCsrfToken()); ?>">
                                        <input type="hidden" name="instance" value="<?php echo backupManageEscape($instance); ?>">
                                        <input type="hidden" name="filename" value="<?php echo backupManageEscape($backup["filename"] ?? ""); ?>">
                                        <button type="submit">Delete</button>
                                    </form>
                                </td>
                            </tr>
                        <?php endforeach; ?>
                    </tbody>
                </table>
            <?php endforeach; ?>
        <?php endif; ?>
    <?php endif; ?>
</body>
</html>