From 315ef9def0e9c6ba4259140182f656931a164079 Mon Sep 17 00:00:00 2001
From: lashman <lashman@robotbrush.com>
Date: Wed, 31 Dec 2025 20:08:59 +0200
Subject: [PATCH] offline puzzle cache

---
 frontend/src/offline.ts | 73 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 frontend/src/offline.ts

diff --git a/frontend/src/offline.ts b/frontend/src/offline.ts
new file mode 100644
index 0000000..b4da499
--- /dev/null
+++ b/frontend/src/offline.ts
@@ -0,0 +1,73 @@
+import type { GenerateResponse } from './types'
+
+const DB_NAME = 'cruciverb-offline'
+const DB_VERSION = 1
+
+function openDB(): Promise<IDBDatabase> {
+  return new Promise((resolve, reject) => {
+    const req = indexedDB.open(DB_NAME, DB_VERSION)
+    req.onupgradeneeded = () => {
+      const db = req.result
+      if (!db.objectStoreNames.contains('puzzles')) {
+        db.createObjectStore('puzzles', { keyPath: 'id' })
+      }
+      if (!db.objectStoreNames.contains('progress')) {
+        db.createObjectStore('progress', { keyPath: 'puzzleId' })
+      }
+      if (!db.objectStoreNames.contains('pending')) {
+        db.createObjectStore('pending', { keyPath: 'id', autoIncrement: true })
+      }
+    }
+    req.onsuccess = () => resolve(req.result)
+    req.onerror = () => reject(req.error)
+  })
+}
+
+export async function cachePuzzle(id: string, data: GenerateResponse): Promise<void> {
+  const db = await openDB()
+  const tx = db.transaction('puzzles', 'readwrite')
+  tx.objectStore('puzzles').put({ id, data, cached_at: Date.now() })
+  return new Promise((resolve, reject) => { tx.oncomplete = () => resolve(); tx.onerror = () => reject(tx.error) })
+}
+
+export async function getCachedPuzzle(id: string): Promise<GenerateResponse | null> {
+  const db = await openDB()
+  return new Promise((resolve, reject) => {
+    const tx = db.transaction('puzzles', 'readonly')
+    const req = tx.objectStore('puzzles').get(id)
+    req.onsuccess = () => resolve(req.result?.data || null)
+    req.onerror = () => reject(req.error)
+  })
+}
+
+export async function saveProgress(puzzleId: string, entries: string[][]): Promise<void> {
+  const db = await openDB()
+  const tx = db.transaction('progress', 'readwrite')
+  tx.objectStore('progress').put({ puzzleId, entries, saved_at: Date.now() })
+  return new Promise((resolve, reject) => { tx.oncomplete = () => resolve(); tx.onerror = () => reject(tx.error) })
+}
+
+export async function getProgress(puzzleId: string): Promise<string[][] | null> {
+  const db = await openDB()
+  return new Promise((resolve, reject) => {
+    const tx = db.transaction('progress', 'readonly')
+    const req = tx.objectStore('progress').get(puzzleId)
+    req.onsuccess = () => resolve(req.result?.entries || null)
+    req.onerror = () => reject(req.error)
+  })
+}
+
+export function isOnline(): boolean {
+  return navigator.onLine
+}
+
+export function onOnlineChange(callback: (online: boolean) => void): () => void {
+  const onOnline = () => callback(true)
+  const onOffline = () => callback(false)
+  window.addEventListener('online', onOnline)
+  window.addEventListener('offline', onOffline)
+  return () => {
+    window.removeEventListener('online', onOnline)
+    window.removeEventListener('offline', onOffline)
+  }
+}