From 24080bb8b9b84b2bc300a727105abd602f44310f Mon Sep 17 00:00:00 2001
From: Tom Hempel <tom.hempel2001@gmail.com>
Date: Wed, 27 May 2026 20:03:47 +0200
Subject: [PATCH] implemented incremental schema migration for questionnaire,
 added categoryKey column if missing, and improved error handling in
 questionnaire retrieval

---
 db_init.php                 | 80 ++++++++++++++++++++++++++++---------
 handlers/questionnaires.php | 38 ++++++++++--------
 2 files changed, 83 insertions(+), 35 deletions(-)

diff --git a/db_init.php b/db_init.php
index 7886281..0ffab33 100644
--- a/db_init.php
+++ b/db_init.php
@@ -8,6 +8,54 @@ define('QDB_LOCK', __DIR__ . '/uploads/.qdb_lock');
 define('QDB_SCHEMA', __DIR__ . '/schema.sql');
 define('QDB_VERSION', 4);
 
+function qdb_column_exists(PDO $pdo, string $table, string $column): bool {
+    $stmt = $pdo->query('PRAGMA table_info(' . $table . ')');
+    foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $col) {
+        if (($col['name'] ?? '') === $column) {
+            return true;
+        }
+    }
+    return false;
+}
+
+/**
+ * Apply incremental schema fixes. Returns true if the temp DB was modified.
+ */
+function qdb_apply_migrations(PDO $pdo, string $schemaSql): bool {
+    $changed = false;
+
+    if (!qdb_column_exists($pdo, 'questionnaire', 'categoryKey')) {
+        $pdo->exec("ALTER TABLE questionnaire ADD COLUMN categoryKey TEXT NOT NULL DEFAULT ''");
+        $changed = true;
+    }
+
+    $currentVersion = (int)$pdo->query('PRAGMA user_version')->fetchColumn();
+    if ($currentVersion < QDB_VERSION) {
+        $pdo->exec('PRAGMA foreign_keys = OFF;');
+        $pdo->exec($schemaSql);
+        if (!qdb_column_exists($pdo, 'questionnaire', 'categoryKey')) {
+            $pdo->exec("ALTER TABLE questionnaire ADD COLUMN categoryKey TEXT NOT NULL DEFAULT ''");
+        }
+        $pdo->exec('PRAGMA user_version = ' . QDB_VERSION . ';');
+        $pdo->exec('PRAGMA foreign_keys = ON;');
+        $changed = true;
+    }
+
+    return $changed;
+}
+
+function qdb_acquire_lock() {
+    $lockFp = fopen(QDB_LOCK, 'c');
+    if ($lockFp === false) {
+        throw new Exception('Could not open lock file');
+    }
+    if (!flock($lockFp, LOCK_EX)) {
+        fclose($lockFp);
+        throw new Exception('Could not acquire lock');
+    }
+    return $lockFp;
+}
+
 /**
  * Decrypt the master DB file into a temp SQLite file, or create a fresh one
  * from schema.sql if no DB exists yet.
@@ -67,26 +115,20 @@ function qdb_open(bool $writable = false): array {
     $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
     $pdo->exec("PRAGMA foreign_keys = ON;");
 
-    // Schema upgrade: apply CREATE TABLE IF NOT EXISTS for any missing tables
-    $currentVersion = (int)$pdo->query("PRAGMA user_version")->fetchColumn();
-    if ($currentVersion < QDB_VERSION) {
-        $pdo->exec("PRAGMA foreign_keys = OFF;");
-        $pdo->exec($sql);
-        if ($currentVersion < 4) {
-            $cols = $pdo->query("PRAGMA table_info(questionnaire)")->fetchAll(PDO::FETCH_ASSOC);
-            $hasCategory = false;
-            foreach ($cols as $col) {
-                if (($col['name'] ?? '') === 'categoryKey') {
-                    $hasCategory = true;
-                    break;
-                }
-            }
-            if (!$hasCategory) {
-                $pdo->exec("ALTER TABLE questionnaire ADD COLUMN categoryKey TEXT NOT NULL DEFAULT ''");
-            }
+    $schemaChanged = qdb_apply_migrations($pdo, $sql);
+
+    // Read-only opens discard the temp file; persist one-off migrations to the master DB.
+    if ($schemaChanged && !$writable) {
+        $migrateLock = qdb_acquire_lock();
+        try {
+            qdb_save($tmpDb, $migrateLock);
+        } catch (Throwable $e) {
+            @unlink($tmpDb);
+            flock($migrateLock, LOCK_UN);
+            fclose($migrateLock);
+            throw $e;
         }
-        $pdo->exec("PRAGMA user_version = " . QDB_VERSION . ";");
-        $pdo->exec("PRAGMA foreign_keys = ON;");
+        return qdb_open(false);
     }
 
     return [$pdo, $tmpDb, $lockFp];
diff --git a/handlers/questionnaires.php b/handlers/questionnaires.php
index 5e49f9c..56d5b50 100644
--- a/handlers/questionnaires.php
+++ b/handlers/questionnaires.php
@@ -6,23 +6,29 @@ switch ($method) {
 
 case 'GET':
     [$pdo, $tmpDb, $lockFp] = qdb_open(false);
-    $rows = $pdo->query("
-        SELECT q.questionnaireID, q.name, q.version, q.state,
-               q.orderIndex, q.showPoints, q.conditionJson, q.categoryKey,
-               COUNT(qu.questionID) AS questionCount
-        FROM questionnaire q
-        LEFT JOIN question qu ON qu.questionnaireID = q.questionnaireID
-        GROUP BY q.questionnaireID
-        ORDER BY q.orderIndex, q.name
-    ")->fetchAll(PDO::FETCH_ASSOC);
-    foreach ($rows as &$r) {
-        $r['orderIndex']  = (int)$r['orderIndex'];
-        $r['showPoints']  = (int)$r['showPoints'];
-        $r['conditionJson'] = $r['conditionJson'] ?: '{}';
+    try {
+        $rows = $pdo->query("
+            SELECT q.questionnaireID, q.name, q.version, q.state,
+                   q.orderIndex, q.showPoints, q.conditionJson, q.categoryKey,
+                   COUNT(qu.questionID) AS questionCount
+            FROM questionnaire q
+            LEFT JOIN question qu ON qu.questionnaireID = q.questionnaireID
+            GROUP BY q.questionnaireID
+            ORDER BY q.orderIndex, q.name
+        ")->fetchAll(PDO::FETCH_ASSOC);
+        foreach ($rows as &$r) {
+            $r['orderIndex']  = (int)$r['orderIndex'];
+            $r['showPoints']  = (int)$r['showPoints'];
+            $r['conditionJson'] = $r['conditionJson'] ?: '{}';
+        }
+        unset($r);
+        qdb_discard($tmpDb, $lockFp);
+        json_success(['questionnaires' => $rows]);
+    } catch (Throwable $e) {
+        qdb_discard($tmpDb, $lockFp);
+        error_log('questionnaires GET: ' . $e->getMessage());
+        json_error('SERVER_ERROR', 'Server error', 500);
     }
-    unset($r);
-    qdb_discard($tmpDb, $lockFp);
-    json_success(['questionnaires' => $rows]);
     break;
 
 case 'POST':