From 6ff038b4d29ec761336c807f4a79831c99f29d67 Mon Sep 17 00:00:00 2001
From: stuebinm
Date: Thu, 7 Apr 2022 00:30:14 +0200
Subject: flora is a trainspotter now

(well, a trainschedulespotter to be precise)
---
 flora/configuration.nix       |  1 +
 flora/services/urlwatcher.nix | 24 +++++++++++++++++++
 flora/services/urlwatcher.scm | 56 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 81 insertions(+)
 create mode 100644 flora/services/urlwatcher.nix
 create mode 100644 flora/services/urlwatcher.scm

diff --git a/flora/configuration.nix b/flora/configuration.nix
index fde327b..aa0602b 100644
--- a/flora/configuration.nix
+++ b/flora/configuration.nix
@@ -14,6 +14,7 @@
     ./services/blog.nix
     ./services/znc.nix
     ./services/mail.nix
+    ./services/urlwatcher.nix
   ];
   
   # Use the GRUB 2 boot loader.
diff --git a/flora/services/urlwatcher.nix b/flora/services/urlwatcher.nix
new file mode 100644
index 0000000..56e043a
--- /dev/null
+++ b/flora/services/urlwatcher.nix
@@ -0,0 +1,24 @@
+{ config, lib, pkgs, ... }:
+
+{
+  systemd.services.urlwatcher-ilztal = {
+    enable = true;
+    description = "script watching the ilztalbahn gtfs for changes";
+    wantedBy = [ "multi-user.target" ];
+    after = [ "network.target" ];
+    serviceConfig.Type = "simple";
+    path = [ pkgs.git ];
+    script = ''
+      ${pkgs.gauche}/bin/gosh ${pkgs.copyPathToStore ./urlwatcher.scm}
+    '';
+  };
+
+  systemd.timers.wikibot = {
+    wantedBy = [ "timers.target" ];
+    timerConfig = {
+      Unit = "urlwatcher-ilztal.service";
+      OnBootSec = "5h";
+      OnActiveSec = "1d";
+    };
+  };
+}
diff --git a/flora/services/urlwatcher.scm b/flora/services/urlwatcher.scm
new file mode 100644
index 0000000..2884c05
--- /dev/null
+++ b/flora/services/urlwatcher.scm
@@ -0,0 +1,56 @@
+#!/usr/bin/env gosh
+
+(use gauche.process)
+(use srfi-13)
+(use srfi-19)
+(use file.util)
+
+(define url "https://ilztalbahn.eu/wp-content/uploads/2020/07/gtfs.zip")
+(define cachefile "/tmp/urlwatch-cache")
+(define storagedir "/var/lib/urlwatch-ilztal")
+
+(do-process `(mkdir "-p" ,storagedir))
+
+(define (get-hash url)
+  (string-trim-both
+   (process-output->string `((curl ,url)
+                             (sha256sum)))))
+
+(define hash
+  (get-hash url))
+
+(define pretty-date
+  (date->string (time-utc->date (current-time)) "~5"))
+
+(define (hash-did-change oldhash newhash)
+  (print (format "the url's hash has changed to ~s!" newhash))
+  (let ([newfile (string-append storagedir "/" newhash)])
+    (do-process `(curl ,url "-o" ,newfile))
+    (let ([diff (if oldhash
+                    (let ([oldfile (string-append storagedir "/" oldhash)])
+                      (process-output->string `(zipcmp ,oldfile ,newfile)))
+                    "")])
+      (do-pipeline `((echo ,(format "
+From: urlwatcher@flora.stuebinm.eu
+Subject: Ilztalbahn GTFS Update
+
+Neuer hash: ~a
+Link: ~a
+
+~a
+
+(~a)
+
+" newhash url diff pretty-date))
+                     (sendmail "stuebinm@disroot.org")))
+      (sexp-list->file
+       cachefile
+       (list (list pretty-date newhash))
+       :if-exists :append))))
+
+(if (file-is-writable? cachefile)
+    (let ([oldhash (cadr (last (file->sexp-list cachefile)))])
+      (if (equal? (cadr (last (file->sexp-list cachefile))) hash)
+          (print (format "url did not change, hash remains ~a" hash))
+          (hash-did-change oldhash hash)))
+    (hash-did-change #f hash))
-- 
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