From f60e3a3f89549b4ce88df20888c08a01062d086a Mon Sep 17 00:00:00 2001
From: clerie <git@clerie.de>
Date: Sun, 20 Jun 2021 12:19:35 +0200
Subject: [PATCH] Let data get expired.

---
 README.md            | 7 ++++++-
 iot_data/__init__.py | 9 ++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 1c3d78c..1c0eca6 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,8 @@ Content type is considered too:
 curl -X POST -d '{"key": "value"}' -H 'Content-Type: application/json' http://iot-data.clerie.de/ingress/asdf1234/
 ```
 
+Check for the last data input with the `Last-Modified` header.
+
 ## Deployment
 Init codebase
 ```
@@ -38,12 +40,15 @@ Create `config.json` with the following contents and edit values for your needs:
     "key": "asdf1234"
   },
   "sensor2": {
-    "key": "supersecret"
+    "key": "supersecret",
+    "delete-after": 60
   },
 }
 
 ```
 
+`delete-after`: Specifies the seconds after which the data gets discarded and no data is returned.
+
 Starten und updaten lässt sich die Flask-App folgendermaßen:
 ```
 cd iot-data/
diff --git a/iot_data/__init__.py b/iot_data/__init__.py
index a13ba3e..0213789 100644
--- a/iot_data/__init__.py
+++ b/iot_data/__init__.py
@@ -3,6 +3,7 @@
 from flask import Flask, abort, request, make_response
 import json
 import os
+import time
 
 app = Flask(__name__)
 
@@ -32,6 +33,7 @@ def ingress(key):
         values[keys[key]] = {
             "payload": request.data,
             "content-type": content_type,
+            "last-modified": time.time(),
         }
     else:
         return make_response("", 404)
@@ -42,10 +44,15 @@ def ingress(key):
 def data(name):
     if not name in config:
         return make_response("", 404)
+    if name in values:
+        if "delete-after" in config[name]:
+            if (values[name]["last-modified"] + config[name]["delete-after"]) < time.time():
+                values.pop(name)
     if not name in values:
         return make_response("", 404)
     resp = make_response(values[name]["payload"], 200)
-    resp.headers['content-type'] = values[name]["content-type"]
+    resp.headers['Content-Type'] = values[name]["content-type"]
+    resp.headers['Last-Modified'] = time.strftime("%a, %d %b %Y %H:%M:%S GMT", time.gmtime(values[name]["last-modified"]))
     return resp
 
 if __name__ == "__main__":