From 7798666c81b390183e2e227232d936abf0cc4a65 Mon Sep 17 00:00:00 2001
From: stuebinm
Date: Sat, 11 Mar 2023 01:36:35 +0100
Subject: simple on-board tools

these are just enough to send train positions to tracktrain with the
current API, but are somewhat brittle (e.g. will fail if not restarted
between trips, etc.)
---
 tools/obu-guess-trip | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100755 tools/obu-guess-trip

(limited to 'tools/obu-guess-trip')

diff --git a/tools/obu-guess-trip b/tools/obu-guess-trip
new file mode 100755
index 0000000..478ba2b
--- /dev/null
+++ b/tools/obu-guess-trip
@@ -0,0 +1,75 @@
+#!/usr/bin/env gosh
+
+(use rfc.http)
+(use rfc.uri)
+(use rfc.json)
+(use file.util)
+(use srfi-19)
+(use gauche.collection)
+(use gauche.parseopt)
+(use gauche.process)
+
+
+(define (main args)
+  (let-args
+   (cdr args)
+   ((adir "d|dir=s")
+    (baseurl "u|url=s")
+    (statefile "s|statefile=s")
+    (help "h|help" => (cut show-help (car args)))
+    . restargs)
+   (if (equal? baseurl #f)
+       (show-help (car args))
+       (guesstimate
+        (if (equal? adir #f) "." adir)
+        baseurl
+        (if statefile statefile "./obu-state.edn")))
+   (exit 0)))
+
+
+(define (show-help progname)
+  (display (format
+"~a: tracktrain's on-board guesstimater for which trip you're on
+
+Arguments:
+ -u --url: base url of the tracktrain server [required]
+ -s --statefile: state file
+ -c --config: config file (default is /etc/tracktrain/obu.conf)
+ -h --help: display this help
+" progname))
+  (exit 0))
+
+(define (guesstimate dir url statefile)
+  (define stops (fetch-stations url))
+  (define pos
+    (with-input-from-process `(obu-ping -s ,statefile -n 1 -d) read))
+  (define trip (assoc-ref (closest-stop-to stops pos) 'trip))
+  (display trip))
+
+(define (closest-stop-to stops pos)
+  (define stops-by-station
+    (apply vector-append (vector->list
+      (vector-map (lambda (trip)
+                    (vector-map
+                     (lambda (stop) (cons `(trip . ,(assoc-ref trip 'trip)) stop))
+                     (assoc-ref trip 'stops)))
+                  stops))))
+  (find-min
+   stops-by-station
+   :key (lambda (stop)
+          (+ (square (- (assoc-ref pos 'lat) (assoc-ref stop 'lat)))
+             (square (- (assoc-ref pos 'lon) (assoc-ref stop 'lon)))))
+   :default (vector-ref stops 0)))
+
+(define (fetch-stations url)
+  (define day (date->string (current-date) "~1"))
+  (define tls
+    (equal? (uri-ref url 'scheme) 'https))
+  (parameterize
+      ; replace all json keys with symbols; everything else is confusing
+      ([json-object-handler
+        (cut map (lambda p `(,(string->symbol (car (car p))) . ,(cdr (car p)))) <>)])
+    (parse-json-string
+     (values-ref (http-get (uri-ref url 'host+port)
+                           (format "/api/timetable/stops/~a" day)
+                           :secure tls) 2))))
-- 
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