#!/usr/bin/env php
<?php

/**
 * Grav Snapshot Restore Utility
 *
 * Lightweight CLI that can list and apply safe-upgrade snapshots without
 * bootstrapping the full Grav application (or any plugins).
 */

$root = dirname(__DIR__);

define('GRAV_CLI', true);
define('GRAV_REQUEST_TIME', microtime(true));

if (!file_exists($root . '/vendor/autoload.php')) {
    fwrite(STDERR, "Unable to locate vendor/autoload.php. Run composer install first.\n");
    exit(1);
}

$autoload = require $root . '/vendor/autoload.php';

if (!file_exists($root . '/index.php')) {
    fwrite(STDERR, "FATAL: Must be run from Grav root directory.\n");
    exit(1);
}

use Grav\Common\Filesystem\Folder;
use Grav\Common\Recovery\RecoveryManager;
use Grav\Common\Upgrade\SafeUpgradeService;
use Symfony\Component\Yaml\Yaml;

const RESTORE_USAGE = <<<USAGE
Grav Restore Utility

Usage:
  bin/restore list [--staging-root=/absolute/path]
      Lists all available snapshots (most recent first).

  bin/restore apply <snapshot-id> [--staging-root=/absolute/path]
      Restores the specified snapshot created by safe-upgrade.

  bin/restore remove [<snapshot-id> ...] [--staging-root=/absolute/path]
      Deletes one or more snapshots (interactive selection when no id provided).

  bin/restore snapshot [--label=\"optional description\"] [--staging-root=/absolute/path]
      Creates a manual snapshot of the current Grav core files.

  bin/restore recovery [status|clear]
      Shows the recovery flag context or clears it.

Options:
  --staging-root     Overrides the staging directory (defaults to configured value).
  --label            Optional label to store with the manual snapshot.

Examples:
  bin/restore list
  bin/restore apply stage-68eff31cc4104
  bin/restore apply stage-68eff31cc4104 --staging-root=/var/grav-backups
  bin/restore snapshot --label=\"Before plugin install\"
  bin/restore recovery status
  bin/restore recovery clear
USAGE;

/**
 * @param array $args
 * @return array{command:string,arguments:array,options:array}
 */
function parseArguments(array $args): array
{
    array_shift($args); // remove script name

    $command = null;
    $arguments = [];
    $options = [];

    while ($args) {
        $arg = array_shift($args);
        if (strncmp($arg, '--', 2) === 0) {
            $parts = explode('=', substr($arg, 2), 2);
            $name = $parts[0] ?? '';
            if ($name === '') {
                continue;
            }
            $value = $parts[1] ?? null;
            if ($value === null && $args && substr($args[0], 0, 2) !== '--') {
                $value = array_shift($args);
            }
            $options[$name] = $value ?? true;
            continue;
        }

        if (null === $command) {
            $command = $arg;
        } else {
            $arguments[] = $arg;
        }
    }

    if (null === $command) {
        $command = 'interactive';
    }

    return [
        'command' => $command,
        'arguments' => $arguments,
        'options' => $options,
    ];
}

/**
 * @param array $options
 * @return SafeUpgradeService
 */
function createUpgradeService(array $options): SafeUpgradeService
{
    $serviceOptions = ['root' => GRAV_ROOT];

    if (isset($options['staging-root']) && is_string($options['staging-root']) && $options['staging-root'] !== '') {
        $serviceOptions['staging_root'] = $options['staging-root'];
    }

    return new SafeUpgradeService($serviceOptions);
}

/**
 * @return list<array{id:string,label:?string,source_version:?string,target_version:?string,created_at:int}>
 */
function loadSnapshots(): array
{
    $manifestDir = GRAV_ROOT . '/user/data/upgrades';
    if (!is_dir($manifestDir)) {
        return [];
    }

    $files = glob($manifestDir . '/*.json') ?: [];
    rsort($files);

    $snapshots = [];
    foreach ($files as $file) {
        $decoded = json_decode(file_get_contents($file) ?: '', true);
        if (!is_array($decoded) || empty($decoded['id'])) {
            continue;
        }

        $snapshots[] = [
            'id' => $decoded['id'],
            'label' => $decoded['label'] ?? null,
            'source_version' => $decoded['source_version'] ?? null,
            'target_version' => $decoded['target_version'] ?? null,
            'created_at' => (int)($decoded['created_at'] ?? 0),
        ];
    }

    return $snapshots;
}

/**
 * @param list<array{id:string,label:?string,source_version:?string,target_version:?string,created_at:int}> $snapshots
 * @return string
 */
function formatSnapshotListLine(array $snapshot): string
{
    $restoreVersion = $snapshot['source_version'] ?? $snapshot['target_version'] ?? 'unknown';
    $timeLabel = formatSnapshotTimestamp($snapshot['created_at']);
    $label = $snapshot['label'] ?? null;
    $display = $label ? sprintf('%s [%s]', $label, $snapshot['id']) : $snapshot['id'];

    return sprintf('%s (restore to Grav %s, %s)', $display, $restoreVersion, $timeLabel);
}

function formatSnapshotTimestamp(int $timestamp): string
{
    if ($timestamp <= 0) {
        return 'time unknown';
    }

    try {
        $timezone = resolveTimezone();
        $dt = new DateTime('@' . $timestamp);
        $dt->setTimezone($timezone);
        $formatted = $dt->format('Y-m-d H:i:s T');
    } catch (\Throwable $e) {
        $formatted = date('Y-m-d H:i:s T', $timestamp);
    }

    return $formatted . ' (' . formatRelative(time() - $timestamp) . ')';
}

function resolveTimezone(): DateTimeZone
{
    static $resolved = null;
    if ($resolved instanceof DateTimeZone) {
        return $resolved;
    }

    $timezone = null;
    $configFile = GRAV_ROOT . '/user/config/system.yaml';
    if (is_file($configFile)) {
        try {
            $data = Yaml::parse(file_get_contents($configFile) ?: '') ?: [];
            if (!empty($data['system']['timezone']) && is_string($data['system']['timezone'])) {
                $timezone = $data['system']['timezone'];
            }
        } catch (\Throwable $e) {
            // ignore parse errors, fallback below
        }
    }

    if (!$timezone) {
        $timezone = ini_get('date.timezone') ?: 'UTC';
    }

    try {
        $resolved = new DateTimeZone($timezone);
    } catch (\Throwable $e) {
        $resolved = new DateTimeZone('UTC');
    }

    return $resolved;
}

function formatRelative(int $seconds): string
{
    if ($seconds < 5) {
        return 'just now';
    }
    $negative = $seconds < 0;
    $seconds = abs($seconds);
    $units = [
        31536000 => 'y',
        2592000 => 'mo',
        604800 => 'w',
        86400 => 'd',
        3600 => 'h',
        60 => 'm',
        1 => 's',
    ];
    foreach ($units as $size => $label) {
        if ($seconds >= $size) {
            $value = (int)floor($seconds / $size);
            $suffix = $label === 'mo' ? 'month' : ($label === 'y' ? 'year' : ($label === 'w' ? 'week' : ($label === 'd' ? 'day' : ($label === 'h' ? 'hour' : ($label === 'm' ? 'minute' : 'second')))));
            if ($value !== 1) {
                $suffix .= 's';
            }
            $phrase = $value . ' ' . $suffix;
            return $negative ? 'in ' . $phrase : $phrase . ' ago';
        }
    }

    return $negative ? 'in 0 seconds' : '0 seconds ago';
}

/**
 * @param string $snapshotId
 * @param array $options
 * @return void
 */
function applySnapshot(string $snapshotId, array $options): void
{
    try {
        $service = createUpgradeService($options);
        $manifest = $service->rollback($snapshotId);
    } catch (\Throwable $e) {
        fwrite(STDERR, "Restore failed: " . $e->getMessage() . "\n");
        exit(1);
    }

    if (!$manifest) {
        fwrite(STDERR, "Snapshot {$snapshotId} not found.\n");
        exit(1);
    }

    $version = $manifest['source_version'] ?? $manifest['target_version'] ?? 'unknown';
    echo "Restored snapshot {$snapshotId} (Grav {$version}).\n";
    if (!empty($manifest['id'])) {
        echo "Snapshot manifest: {$manifest['id']}\n";
    }
    if (!empty($manifest['backup_path'])) {
        echo "Snapshot path: {$manifest['backup_path']}\n";
    }
    exit(0);
}

/**
 * @param array $options
 * @return void
 */
function createManualSnapshot(array $options): void
{
    $label = null;
    if (isset($options['label']) && is_string($options['label'])) {
        $label = trim($options['label']);
        if ($label === '') {
            $label = null;
        }
    }

    try {
        $service = createUpgradeService($options);
        $manifest = $service->createSnapshot($label);
    } catch (\Throwable $e) {
        fwrite(STDERR, "Snapshot creation failed: " . $e->getMessage() . "\n");
        exit(1);
    }

    $snapshotId = $manifest['id'] ?? null;
    if (!$snapshotId) {
        $snapshotId = 'unknown';
    }
    $version = $manifest['source_version'] ?? $manifest['target_version'] ?? 'unknown';

    echo "Created snapshot {$snapshotId} (Grav {$version}).\n";
    if ($label) {
        echo "Label: {$label}\n";
    }
    if (!empty($manifest['backup_path'])) {
        echo "Snapshot path: {$manifest['backup_path']}\n";
    }

    exit(0);
}

/**
 * @param list<array{id:string,source_version:?string,target_version:?string,created_at:int}> $snapshots
 * @return string|null
 */
function promptSnapshotSelection(array $snapshots): ?string
{
    echo "Available snapshots:\n";
    foreach ($snapshots as $index => $snapshot) {
        $line = formatSnapshotListLine($snapshot);
        $number = $index + 1;
        echo sprintf("  [%d] %s\n", $number, $line);
    }

    $default = $snapshots[0]['id'];
    echo "\nSelect a snapshot to restore [1]: ";
    $input = trim((string)fgets(STDIN));

    if ($input === '') {
        return $default;
    }

    if (ctype_digit($input)) {
        $idx = (int)$input - 1;
        if (isset($snapshots[$idx])) {
            return $snapshots[$idx]['id'];
        }
    }

    foreach ($snapshots as $snapshot) {
        if (strcasecmp($snapshot['id'], $input) === 0) {
            return $snapshot['id'];
        }
    }

    echo "Invalid selection. Aborting.\n";
    return null;
}

/**
 * @param list<array{id:string,source_version:?string,target_version:?string,created_at:int}> $snapshots
 * @return array<string>
 */
function promptSnapshotsRemoval(array $snapshots): array
{
    echo "Available snapshots:\n";
    foreach ($snapshots as $index => $snapshot) {
        $line = formatSnapshotListLine($snapshot);
        $number = $index + 1;
        echo sprintf("  [%d] %s\n", $number, $line);
    }

    echo "\nSelect snapshots to remove (comma or space separated numbers / ids, 'all' for everything, empty to cancel): ";
    $input = trim((string)fgets(STDIN));

    if ($input === '') {
        return [];
    }

    $inputLower = strtolower($input);
    if ($inputLower === 'all' || $inputLower === '*') {
        return array_values(array_unique(array_column($snapshots, 'id')));
    }

    $tokens = preg_split('/[\\s,]+/', $input, -1, PREG_SPLIT_NO_EMPTY) ?: [];
    $selected = [];
    foreach ($tokens as $token) {
        if (ctype_digit($token)) {
            $idx = (int)$token - 1;
            if (isset($snapshots[$idx])) {
                $selected[] = $snapshots[$idx]['id'];
                continue;
            }
        }

        foreach ($snapshots as $snapshot) {
            if (strcasecmp($snapshot['id'], $token) === 0) {
                $selected[] = $snapshot['id'];
                break;
            }
        }
    }

    return array_values(array_unique(array_filter($selected)));
}

/**
 * @param string $snapshotId
 * @return array{success:bool,message:string}
 */
function removeSnapshot(string $snapshotId): array
{
    $manifestDir = GRAV_ROOT . '/user/data/upgrades';
    $manifestPath = $manifestDir . '/' . $snapshotId . '.json';
    if (!is_file($manifestPath)) {
        return [
            'success' => false,
            'message' => "Snapshot {$snapshotId} not found."
        ];
    }

    $manifest = json_decode(file_get_contents($manifestPath) ?: '', true);
    if (!is_array($manifest)) {
        return [
            'success' => false,
            'message' => "Snapshot {$snapshotId} manifest is invalid."
        ];
    }

    $pathsToDelete = [];
    foreach (['package_path', 'backup_path'] as $key) {
        if (!empty($manifest[$key]) && is_string($manifest[$key])) {
            $pathsToDelete[] = $manifest[$key];
        }
    }

    $errors = [];

    foreach ($pathsToDelete as $path) {
        if (!$path) {
            continue;
        }
        if (!file_exists($path)) {
            continue;
        }
        try {
            if (is_dir($path)) {
                Folder::delete($path);
            } else {
                @unlink($path);
            }
        } catch (\Throwable $e) {
            $errors[] = "Unable to remove {$path}: " . $e->getMessage();
        }
    }

    if (!@unlink($manifestPath)) {
        $errors[] = "Unable to delete manifest file {$manifestPath}.";
    }

    if ($errors) {
        return [
            'success' => false,
            'message' => implode(' ', $errors)
        ];
    }

    return [
        'success' => true,
        'message' => "Removed snapshot {$snapshotId}."
    ];
}

$cli = parseArguments($argv);
$command = $cli['command'];
$arguments = $cli['arguments'];
$options = $cli['options'];

switch ($command) {
    case 'interactive':
        $snapshots = loadSnapshots();
        if (!$snapshots) {
            echo "No snapshots found. Run bin/gpm self-upgrade (with safe upgrade enabled) to create one.\n";
            exit(0);
        }

        $selection = promptSnapshotSelection($snapshots);
        if (!$selection) {
            exit(1);
        }

        applySnapshot($selection, $options);
        break;

    case 'list':
        $snapshots = loadSnapshots();
        if (!$snapshots) {
            echo "No snapshots found. Run bin/gpm self-upgrade (with safe upgrade enabled) to create one.\n";
            exit(0);
        }

        echo "Available snapshots:\n";
        foreach ($snapshots as $snapshot) {
            echo '  - ' . formatSnapshotListLine($snapshot) . "\n";
        }
        exit(0);

    case 'remove':
        $snapshots = loadSnapshots();
        if (!$snapshots) {
            echo "No snapshots found. Nothing to remove.\n";
            exit(0);
        }

        $selectedIds = [];
        if ($arguments) {
            foreach ($arguments as $arg) {
                if (!$arg) {
                    continue;
                }
                $selectedIds[] = $arg;
            }
        } else {
            $selectedIds = promptSnapshotsRemoval($snapshots);
            if (!$selectedIds) {
                echo "No snapshots selected. Aborting.\n";
                exit(1);
            }
        }

        $selectedIds = array_values(array_unique($selectedIds));
        echo "Snapshots selected for removal:\n";
        foreach ($selectedIds as $id) {
            echo "  - {$id}\n";
        }

        $autoConfirm = isset($options['yes']) || isset($options['y']);
        if (!$autoConfirm) {
            echo "\nThis action cannot be undone. Proceed? [y/N] ";
            $confirmation = strtolower(trim((string)fgets(STDIN)));
            if (!in_array($confirmation, ['y', 'yes'], true)) {
                echo "Aborted.\n";
                exit(1);
            }
        }

        $success = 0;
        foreach ($selectedIds as $id) {
            $result = removeSnapshot($id);
            echo $result['message'] . "\n";
            if ($result['success']) {
                $success++;
            }
        }

        exit($success > 0 ? 0 : 1);

    case 'apply':
        $snapshotId = $arguments[0] ?? null;
        if (!$snapshotId) {
            echo "Missing snapshot id.\n\n" . RESTORE_USAGE . "\n";
            exit(1);
        }

        applySnapshot($snapshotId, $options);
        break;

    case 'snapshot':
        createManualSnapshot($options);
        break;

    case 'recovery':
        $action = strtolower($arguments[0] ?? 'status');
        $manager = new RecoveryManager(GRAV_ROOT);

        switch ($action) {
            case 'clear':
                if ($manager->isActive()) {
                    $manager->clear();
                    echo "Recovery flag cleared.\n";
                } else {
                    echo "Recovery mode is not active.\n";
                }
                exit(0);

            case 'status':
                if (!$manager->isActive()) {
                    echo "Recovery mode is not active.\n";
                    exit(0);
                }

                $context = $manager->getContext();
                if (!$context) {
                    echo "Recovery flag present but context could not be parsed.\n";
                    exit(1);
                }

                $created = isset($context['created_at']) ? date('c', (int)$context['created_at']) : 'unknown';
                $token = $context['token'] ?? '(missing)';
                $message = $context['message'] ?? '(no message)';
                $plugin = $context['plugin'] ?? '(none detected)';
                $file = $context['file'] ?? '(unknown file)';
                $line = $context['line'] ?? '(unknown line)';

                echo "Recovery flag context:\n";
                echo "  Token:   {$token}\n";
                echo "  Message: {$message}\n";
                echo "  Plugin:  {$plugin}\n";
                echo "  File:    {$file}\n";
                echo "  Line:    {$line}\n";
                echo "  Created: {$created}\n";

                $window = $manager->getUpgradeWindow();
                if ($window) {
                    $expires = isset($window['expires_at']) ? date('c', (int)$window['expires_at']) : 'unknown';
                    $reason = $window['reason'] ?? '(unknown)';
                    echo "  Window:  active ({$reason}, expires {$expires})\n";
                } else {
                    echo "  Window:  inactive\n";
                }
                exit(0);

            default:
                echo "Unknown recovery action: {$action}\n\n" . RESTORE_USAGE . "\n";
                exit(1);
        }

    case 'help':
    default:
        echo RESTORE_USAGE . "\n";
        exit($command === 'help' ? 0 : 1);
}