From 2a6be5d50a719eaa8f66142cea85b9b0b2bd2c09 Mon Sep 17 00:00:00 2001
From: Hector van der Aa <hector@h3cx.dev>
Date: Wed, 29 Jul 2026 17:43:57 +0100
Subject: [PATCH] Initial disk pairing impl

---
 main.py | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 54 insertions(+), 2 deletions(-)

diff --git a/main.py b/main.py
index 2c9705a..5ca126f 100644
--- a/main.py
+++ b/main.py
@@ -1,11 +1,13 @@
 from functools import partial
+import json
+from pathlib import Path
 from queue import Empty, Queue
 from time import sleep
 from typing import Literal
 import pyudev
 from gpiozero import LED, Button
 from threading import Thread, Event
-from dataclasses import dataclass
+from dataclasses import asdict, dataclass
 
 red = LED(17)
 yellow = LED(27)
@@ -23,11 +25,36 @@ class DiskEvent:
 DiskState = Literal["disconnected", "pairing", "connecting", "connected"]
 
 
+@dataclass
+class Config:
+    diskSerial: str = ""
+
+
 @dataclass
 class AppState:
     stopEvent = Event()
     diskEventQueue: Queue[DiskEvent] = Queue()
     diskState: DiskState = "disconnected"
+    config = Config()
+
+
+def saveConfig(config: Config, path: Path) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+
+    with path.open("w", encoding="utf-8") as file:
+        json.dump(asdict(config), file, indent=4)
+
+
+def loadOrCreateConfig(path: Path) -> Config:
+    if not path.exists():
+        config = Config()
+        saveConfig(config, path)
+        return config
+
+    with path.open("r", encoding="utf-8") as file:
+        rawConfig = json.load(file)
+
+    return Config(**rawConfig)
 
 
 def onButtonPressed(state: AppState) -> None:
@@ -98,9 +125,25 @@ def ledWorker(state: AppState) -> None:
         state.stopEvent.wait(0.25)
 
 
+def findDiskNode(serial: str) -> str | None:
+    context = pyudev.Context()
+
+    for device in context.list_devices(
+        subsystem="block",
+        DEVTYPE="disk",
+    ):
+        deviceSerial = device.get("ID_SERIAL_SHORT") or device.get("ID_SERIAL")
+
+        if deviceSerial == serial:
+            return device.device_node
+
+    return None
+
+
 def main() -> None:
     try:
         state = AppState()
+        state.config = loadOrCreateConfig("config.json")
         button.when_activated = partial(onButtonPressed, state)
 
         diskPollThread = Thread(
@@ -124,7 +167,16 @@ def main() -> None:
         while True:
             try:
                 event = state.diskEventQueue.get_nowait()
-                print(event)
+                if (
+                    state.diskState == "pairing"
+                    and event.event == "connected"
+                    and event.serial != "Unknown"
+                ):
+                    state.config.diskSerial = event.serial
+                    saveConfig(state.config, "config.json")
+                    print(findDiskNode(state.config.diskSerial))
+                    state.diskState = "connected"
+
             except Empty:
                 sleep(1)