From e4bbb1d11c1daca72be740ea6b2b8d6fb5392350 Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gunnar@beutner.de>
Date: Tue, 5 Dec 2023 12:02:03 +0100
Subject: [PATCH] Add build timestamp to the version number (#1145)

I've found this rather useful when repeatedly deploying updated firmware
images to a large number of nodes.

The patch carefully avoids full rebuilds of any "real" source files by
putting the timestamp into a separate .cpp file. It also works around
PlatformIO's build cache that would happily permanently cache the timestamp
file if we were using __DATE__.

The Python script isn't entirely necessary because we could just simply
touch the timestamp file via extra_scripts to force a rebuild. But we'd
need _some_ kind of script anyway and this way we can format the timestamp
more easily than is possible with C++.
---
 .gitignore              | 1 +
 platformio.ini          | 1 +
 src/build_timestamp.cpp | 6 ++++++
 src/build_timestamp.h   | 1 +
 src/main.cpp            | 2 +-
 src/main.h              | 1 +
 update_ts.py            | 6 ++++++
 7 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 src/build_timestamp.cpp
 create mode 100644 src/build_timestamp.h
 create mode 100644 update_ts.py

diff --git a/.gitignore b/.gitignore
index b7a08be..febe05b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,4 @@ CMakeLists.txt
 CMakeListsPrivate.txt
 platformio_override.ini
 node_modules
+src/build_timestamp_value.h
diff --git a/platformio.ini b/platformio.ini
index 2fd2a2e..b2990e2 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -61,6 +61,7 @@ board_build.partitions = partitions_singleapp.csv
 monitor_speed = 115200
 monitor_filters = esp32_exception_decoder, time
 upload_speed = 1500000
+extra_scripts = update_ts.py
 
 [esp32]
 extends = common
diff --git a/src/build_timestamp.cpp b/src/build_timestamp.cpp
new file mode 100644
index 0000000..0ce9be8
--- /dev/null
+++ b/src/build_timestamp.cpp
@@ -0,0 +1,6 @@
+#include "build_timestamp.h"
+#include "build_timestamp_value.h"
+
+const char *getBuildTimestamp() {
+    return BUILD_TIMESTAMP;
+}
diff --git a/src/build_timestamp.h b/src/build_timestamp.h
new file mode 100644
index 0000000..16ebb3f
--- /dev/null
+++ b/src/build_timestamp.h
@@ -0,0 +1 @@
+const char *getBuildTimestamp();
diff --git a/src/main.cpp b/src/main.cpp
index 3436700..e3c9c4c 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -91,7 +91,7 @@ bool sendTelemetry(unsigned int totalSeen, unsigned int totalFpSeen, unsigned in
 #ifdef VERSION
     doc["ver"] = String(VERSION);
 #else
-    doc["ver"] = ESP.getSketchMD5();
+    doc["ver"] = ESP.getSketchMD5() + "-" + getBuildTimestamp();
 #endif
 
     if (!BleFingerprintCollection::countIds.isEmpty())
diff --git a/src/main.h b/src/main.h
index 90a4f9d..fa00c10 100644
--- a/src/main.h
+++ b/src/main.h
@@ -27,6 +27,7 @@
 #include "globals.h"
 #include "mqtt.h"
 #include "string_utils.h"
+#include "build_timestamp.h"
 #ifdef M5STICK
 #include <AXP192.h>
 #endif
diff --git a/update_ts.py b/update_ts.py
new file mode 100644
index 0000000..caf45e3
--- /dev/null
+++ b/update_ts.py
@@ -0,0 +1,6 @@
+#!/usr/bin/env python3
+from datetime import datetime
+
+with open("src/build_timestamp_value.h", "w") as fp:
+    timestamp = datetime.now().strftime("%Y-%m-%dT%H:%M:%S")
+    fp.write(f'#define BUILD_TIMESTAMP "{timestamp}"')