<?php
// ─── Restore helpers (shared) ────────────────────────────────────────────────
//
// Counterpart to functions_backup.php. Restores an artefact produced by
// backups/db_backup.php or backups/backup_maker.php.
//
// Path assumptions (when this file lives at <host>/shared/platform-tools/):
//   backup_dir()        → <host>/backups/          (source of artefacts)
//   BACKUP_FILES_DIR    → subtree the files backup archives, relative to <host>
//
// Public API:
//   restore_inspect(string $filename): array
//   restore_db(PDO, string $filename, array $opt = []): array
//   restore_files(string $filename, array $opt = []): array
//
// EVERY restore is destructive. Both restore_db() and restore_files() take a
// safety backup of the CURRENT state first and return its filename in the
// report, so a restore of the wrong artefact is itself recoverable. Pass
// ['safety' => false] only from a caller that has already taken one.

require_once __DIR__ . '/functions_backup.php';
require_once __DIR__ . '/functions_migrations.php';   // migrations_split_sql()

/**
 * Abre um artefacto, com a chave de encriptação quando existe.
 *
 * Os backups passaram a sair encriptados com AES-256 (ver db_backup.php), mas
 * os anteriores estão em claro. setPassword() num ZIP não encriptado é
 * inofensivo -- é ignorado -- por isso a mesma chamada serve os dois e não é
 * preciso adivinhar qual é qual pelo nome do ficheiro.
 */
function restore_open_zip(string $path): ?ZipArchive
{
    $zip = new ZipArchive();
    if ($zip->open($path) !== true) {
        return null;
    }
    $key = function_exists('platform_backup_key') ? platform_backup_key() : null;
    if ($key !== null) {
        $zip->setPassword($key);
    }
    return $zip;
}

function restore_site_root(): string {
    return dirname(__DIR__, 2);
}

/**
 * Takes a backup of the CURRENT state, synchronously, and returns its filename.
 *
 * Deliberately does NOT use backup_trigger(): that fires an HTTP self-call at
 * base_url(), which (a) is defined in the host app rather than the toolkit, so
 * it is absent when the runner is invoked standalone, and (b) requires the host
 * to resolve its own public name -- which containerised hosts frequently cannot.
 * Including the worker in-process is synchronous, needs no network, and removes
 * the race where we polled for the artefact to appear.
 */
function restore_safety_backup(string $type): ?string {
    $before = array_column(backup_list(), 'filename');
    $script = __DIR__ . '/backups/' . ($type === 'db' ? 'db_backup.php' : 'backup_maker.php');
    if (!is_file($script)) return null;

    // The workers gate non-CLI invocation on BACKUP_TOKEN. Satisfy that guard
    // explicitly for the in-process call, then restore the superglobal.
    $prevGet = $_GET;
    $_GET['token'] = defined('BACKUP_TOKEN') ? BACKUP_TOKEN : '';
    ob_start();
    try {
        include $script;                    // echoes progress; we discard it
    } catch (Throwable $e) {
        ob_end_clean();
        $_GET = $prevGet;
        return null;
    }
    ob_end_clean();
    $_GET = $prevGet;

    clearstatcache();
    $new = array_diff(array_column(backup_list(), 'filename'), $before);
    return $new ? (string) reset($new) : null;
}

/**
 * Validates an artefact and reports what restoring it would do. Never mutates
 * anything — safe to call from a confirmation screen.
 */
function restore_inspect(string $filename): array {
    $out = ['ok' => false, 'filename' => $filename, 'type' => null, 'entries' => 0, 'error' => null];

    // Reuse the backup naming contract rather than inventing a second one: this
    // is what stops ../../ and absolute paths reaching ZipArchive::open().
    if (!backup_filename_is_safe($filename)) {
        $out['error'] = 'Nome de ficheiro inválido.';
        return $out;
    }

    $path = backup_dir() . '/' . $filename;
    if (!is_file($path)) {
        $out['error'] = 'Ficheiro não encontrado.';
        return $out;
    }
    $out['path'] = $path;
    $out['size_bytes'] = filesize($path) ?: 0;
    $out['size_human'] = backup_human_size($out['size_bytes']);

    // Type comes from the name, matching how backup_list() labels them.
    $out['type'] = str_starts_with($filename, 'db_backup_') ? 'db' : 'files';

    if (!class_exists('ZipArchive')) {
        $out['error'] = 'Extensão zip indisponível.';
        return $out;
    }
    $zip = restore_open_zip($path);
    if ($zip === null) {
        $out['error'] = 'ZIP ilegível ou corrompido.';
        return $out;
    }

    $entries = [];
    $unsafe  = [];
    // BACKUP_FILES_DIR pode listar várias pastas (ver backup_maker.php), por
    // isso o artefacto traz entradas com prefixos diferentes. Validar contra um
    // único prefixo marcaria TODAS as outras como inseguras e o restore
    // recusava um backup perfeitamente válido.
    $prefixes = array_values(array_filter(array_map(
        fn($d) => trim($d, " \t/"),
        explode(',', defined('BACKUP_FILES_DIR') ? BACKUP_FILES_DIR : 'uploads')
    ), fn($d) => $d !== ''));
    if (!$prefixes) { $prefixes = ['uploads']; }

    for ($i = 0; $i < $zip->numFiles; $i++) {
        $name = (string) $zip->getNameIndex($i);
        $entries[] = $name;

        // Zip-slip: an entry may not escape the extraction root. Absolute paths,
        // parent traversal, and Windows drive/UNC prefixes are all rejected.
        if (str_starts_with($name, '/')
            || str_contains($name, '..')
            || preg_match('#^[A-Za-z]:#', $name)
            || str_starts_with($name, '\\\\')) {
            $unsafe[] = $name;
            continue;
        }
        // A files artefact may only contain the archived subtree. This keeps an
        // extraction from writing anywhere else in the repo -- which matters
        // doubly when the source tree is mounted read-only.
        if ($out['type'] === 'files' && $name !== '') {
            $inScope = false;
            foreach ($prefixes as $pfx) {
                if ($name === $pfx || str_starts_with($name, $pfx . '/')) { $inScope = true; break; }
            }
            if (!$inScope) $unsafe[] = $name;
        }
    }

    if ($out['type'] === 'db') {
        $sqlEntries = array_values(array_filter($entries, fn($e) => str_ends_with(strtolower($e), '.sql')));
        if (count($sqlEntries) !== 1) {
            $zip->close();
            $out['error'] = 'Esperava exactamente um .sql no ZIP, encontrei ' . count($sqlEntries) . '.';
            return $out;
        }
        $out['sql_entry'] = $sqlEntries[0];
        $st = $zip->statName($sqlEntries[0]);
        $out['sql_bytes'] = $st['size'] ?? 0;
    }

    $zip->close();

    $out['entries'] = count($entries);
    if ($unsafe) {
        $out['error'] = 'ZIP contém caminhos inseguros: ' . implode(', ', array_slice($unsafe, 0, 5));
        $out['unsafe'] = $unsafe;
        return $out;
    }

    $out['ok'] = true;
    return $out;
}

/**
 * Restores a database artefact. Replaces the current schema and data.
 *
 * $opt:
 *   safety            bool  take a safety dump first (default true)
 *   drop_extra_tables bool  drop tables absent from the dump (default true)
 */
function restore_db(PDO $pdo, string $filename, array $opt = []): array {
    $safety     = $opt['safety']            ?? true;
    $dropExtra  = $opt['drop_extra_tables'] ?? true;

    $report = ['ok' => false, 'filename' => $filename, 'safety_backup' => null,
               'statements' => 0, 'applied' => 0, 'dropped_extra' => [], 'error' => null];

    $info = restore_inspect($filename);
    if (!$info['ok'])            { $report['error'] = $info['error']; return $report; }
    if ($info['type'] !== 'db')  { $report['error'] = 'Não é um backup de base de dados.'; return $report; }

    // Safety first: capture the state we are about to destroy.
    if ($safety) {
        $report['safety_backup'] = restore_safety_backup('db');
        if ($report['safety_backup'] === null) {
            $report['error'] = 'Backup de segurança falhou — restauro abortado.';
            return $report;
        }
    }

    $zip = restore_open_zip($info['path']);
    if ($zip === null) { $report['error'] = 'ZIP ilegível.'; return $report; }
    $sql = $zip->getFromName($info['sql_entry']);
    $zip->close();
    if ($sql === false || $sql === '') { $report['error'] = 'Dump vazio.'; return $report; }

    $tablesBefore = restore_current_tables($pdo);

    // Reuse the migration splitter: it is string-, backtick- and comment-aware,
    // so it will not sever a statement inside a quoted value.
    $statements = migrations_split_sql($sql);
    $report['statements'] = count($statements);

    $pdo->exec('SET FOREIGN_KEY_CHECKS = 0');
    try {
        foreach ($statements as $st) {
            if (trim($st) === '') continue;
            $pdo->exec($st);
            $report['applied']++;
        }

        // The dump DROPs and CREATEs everything it knows about, but a table that
        // exists here and not in the dump would survive and leave the schema in
        // a state the artefact never described.
        if ($dropExtra) {
            $after = restore_current_tables($pdo);
            $inDump = [];
            if (preg_match_all('/DROP TABLE IF EXISTS `([^`]+)`/i', $sql, $m)) $inDump = $m[1];
            if (preg_match_all('/CREATE TABLE `([^`]+)`/i', $sql, $m2)) $inDump = array_merge($inDump, $m2[1]);
            $inDump = array_unique($inDump);
            foreach ($after as $t) {
                if (!in_array($t, $inDump, true)) {
                    $pdo->exec('DROP TABLE `' . str_replace('`', '``', $t) . '`');
                    $report['dropped_extra'][] = $t;
                }
            }
        }
    } catch (Throwable $e) {
        $report['error'] = 'Erro no statement #' . ($report['applied'] + 1) . ': ' . $e->getMessage();
        $pdo->exec('SET FOREIGN_KEY_CHECKS = 1');
        return $report;
    }
    // Always restore FK enforcement -- the dump switches it off and never back on.
    $pdo->exec('SET FOREIGN_KEY_CHECKS = 1');

    $report['tables_before'] = count($tablesBefore);
    $report['tables_after']  = count(restore_current_tables($pdo));
    $report['ok'] = true;
    return $report;
}

/** Table names in the current schema. Buffered so no cursor is left open. */
function restore_current_tables(PDO $pdo): array {
    $st = $pdo->query("SHOW FULL TABLES WHERE Table_type = 'BASE TABLE'");
    $rows = $st->fetchAll(PDO::FETCH_COLUMN);   // fetchAll, not fetch: leaving an
    $st->closeCursor();                          // unbuffered cursor open makes the
    return $rows ?: [];                          // next exec() fail with error 2014.
}

/**
 * Restores a files artefact into BACKUP_FILES_DIR.
 *
 * $opt:
 *   safety bool  archive the current subtree first (default true)
 *   purge  bool  delete files absent from the artefact (default false)
 */
function restore_files(string $filename, array $opt = []): array {
    $safety = $opt['safety'] ?? true;
    $purge  = $opt['purge']  ?? false;

    $report = ['ok' => false, 'filename' => $filename, 'safety_backup' => null,
               'extracted' => 0, 'purged' => 0, 'error' => null];

    $info = restore_inspect($filename);
    if (!$info['ok'])              { $report['error'] = $info['error']; return $report; }
    if ($info['type'] !== 'files') { $report['error'] = 'Não é um backup de ficheiros.'; return $report; }

    $root   = restore_site_root();
    $prefix = trim(defined('BACKUP_FILES_DIR') ? BACKUP_FILES_DIR : 'uploads', '/');

    // Empty BACKUP_FILES_DIR means the host keeps no local files (see
    // backup_maker.php). Without this guard $target would collapse to the
    // repository root and a files artefact would be extracted over the source.
    if ($prefix === '') {
        $report['error'] = 'Restauro de ficheiros desactivado (BACKUP_FILES_DIR vazio) — este host não guarda ficheiros localmente.';
        return $report;
    }

    $target = $root . '/' . $prefix;

    if (!is_dir($target))     { $report['error'] = "Pasta de destino não existe: $target"; return $report; }
    if (!is_writable($target)){ $report['error'] = "Pasta de destino não é escrevível: $target"; return $report; }

    if ($safety) {
        $report['safety_backup'] = restore_safety_backup('files');
        if ($report['safety_backup'] === null) {
            $report['error'] = 'Backup de segurança falhou — restauro abortado.';
            return $report;
        }
    }

    $zip = restore_open_zip($info['path']);
    if ($zip === null) { $report['error'] = 'ZIP ilegível.'; return $report; }

    $seen = [];
    for ($i = 0; $i < $zip->numFiles; $i++) {
        $name = (string) $zip->getNameIndex($i);
        if ($name === '' || str_ends_with($name, '/')) continue;

        // restore_inspect() already rejected unsafe names, but re-check here:
        // the guard must sit immediately before the write, not only in a
        // separate function a future caller might skip.
        if (str_contains($name, '..') || str_starts_with($name, '/')
            || !str_starts_with($name, $prefix . '/')) {
            continue;
        }
        $dest = $root . '/' . $name;
        $dir  = dirname($dest);
        if (!is_dir($dir) && !@mkdir($dir, 0775, true) && !is_dir($dir)) continue;

        $data = $zip->getFromIndex($i);
        if ($data === false) continue;
        if (@file_put_contents($dest, $data) !== false) {
            $report['extracted']++;
            $seen[] = $dest;
        }
    }
    $zip->close();

    // Optional exact-mirror: remove anything the artefact does not contain.
    // Off by default -- a partial artefact would otherwise delete live uploads.
    if ($purge) {
        $it = new RecursiveIteratorIterator(
            new RecursiveDirectoryIterator($target, RecursiveDirectoryIterator::SKIP_DOTS),
            RecursiveIteratorIterator::CHILD_FIRST
        );
        foreach ($it as $f) {
            if ($f->isFile() && !in_array($f->getPathname(), $seen, true)
                && basename($f->getPathname()) !== '.htaccess') {
                if (@unlink($f->getPathname())) $report['purged']++;
            }
        }
    }

    $report['ok'] = true;
    return $report;
}