From e49173cfdda723db283da0ad3cdab6c508d43821 Mon Sep 17 00:00:00 2001
From: Daniel <dan@telent.net>
Date: Sun, 18 May 2025 18:23:27 +0000
Subject: [PATCH] hook nmea messages up to widgets

---
 pkgs/maps/main.fnl | 113 +++++++++++++++++++++++++++++++++++++--------
 1 file changed, 95 insertions(+), 18 deletions(-)

diff --git a/pkgs/maps/main.fnl b/pkgs/maps/main.fnl
index 34a5970..4486f49 100644
--- a/pkgs/maps/main.fnl
+++ b/pkgs/maps/main.fnl
@@ -2,6 +2,8 @@
 (local { : fdopen } (require :posix.stdio))
 (local nmea (require :nmea))
 
+(import-macros { : define-tests : expect : expect= } :assert)
+
 (local {
         : Gtk
         : OsmGpsMap
@@ -20,6 +22,16 @@ label.readout {
 }
 ")
 
+(local utc-offset
+       (let [now (os.time)
+             localt (os.date "*t" now)
+             utct (os.date "!*t" now)]
+         (tset localt :isdst false)
+         (os.difftime (os.time localt) (os.time utct))))
+
+
+
+
 (fn styles []
   (let [style_provider (Gtk.CssProvider)]
     (Gtk.StyleContext.add_provider_for_screen
@@ -38,20 +50,73 @@ label.readout {
                            :on_destroy Gtk.main_quit
                            }))
 
-(fn osm-widget []
-  (doto (OsmGpsMap.Map {})
-    (tset :map-source  OsmGpsMap.MapSource_t.OPENSTREETMAP)
-    (: :set_center_and_zoom 52.595 -0.1 14)
-    (: :layer_add (OsmGpsMap.MapOsd {
-                                     :show_copyright true
-                                     ; :show_coordinates true
-                                     :show_scale true
-                                     }))
-    ))
+(local state-widgets { })
+
+(fn osm-widget []
+  (let [w
+        (doto (OsmGpsMap.Map {})
+          (tset :map-source  OsmGpsMap.MapSource_t.OPENSTREETMAP)
+          (: :set_center_and_zoom 52.595 -0.1 17)
+          (: :layer_add (OsmGpsMap.MapOsd {
+                                           :show_copyright true
+                                        ; :show_coordinates true
+                                           :show_scale true
+                                           }))
+          )]
+    (tset state-widgets :osm w)
+    w))
+
+
+(fn readout [name text]
+  (let [w
+        (doto (Gtk.Label {:label text : name})
+          (-> (: :get_style_context)
+              (: :add_class :readout)))]
+    (tset state-widgets name w)
+    w))
+
+(local knot-in-m-s
+       (/ 1852 ; metres in nautical mile
+          3600 ; seconds in an hour
+          ))
+
+(fn hhmmss [seconds-since-midnight]
+  (let [s (% seconds-since-midnight 60)
+        m (% (// (- seconds-since-midnight s) 60) 60)
+        h (// (- seconds-since-midnight (* m 60) s) 3600)]
+    (string.format "%d:%02d:%02d" h m s)))
+
+(expect= (hhmmss (+ 45 (* 60 12) (* 60 60 3))) "3:12:45")
+
+
+(local
+ app-state {
+            :time-of-day 0
+            :elapsed-time 0
+            :speed 14
+            :lat 49
+            :lon 0
+            :course 22
+            }
+ )
+
+
+(fn merge [table1 table2]
+  (collect [k v (pairs table2) &into table1]
+    k v))
+
+
+(fn update-app-state [new-vals]
+  (merge app-state new-vals)
+  (each [name widget (pairs state-widgets)]
+    (case name
+      :speed (widget:set_label
+              (string.format "%.1f km/h" (* app-state.speed 3.6)))
+      :osm (widget:set_center app-state.lat app-state.lon)
+      :time (widget:set_label
+             (hhmmss (+ utc-offset app-state.time-of-day)))
+      )))
 
-(fn readout [text]
-  (doto (Gtk.Label {:label text})
-    (-> (: :get_style_context) (: :add_class :readout))))
 
 (fn readouts []
   (doto (Gtk.Box
@@ -60,9 +125,10 @@ label.readout {
           :halign Gtk.Align.END
           })
     (-> (: :get_style_context) (: :add_class :readouts))
-    (: :add (readout "21:05:00"))
-    (: :add (readout "00:00"))
-    (: :add (readout "25 km/h"))))
+    (: :add (readout :time ""))
+    (: :add (readout :elapsed-time ""))
+    (: :add (readout :speed "0"))))
+
 (local socket-path (or (. arg 1) "/var/run/gnss-share.sock"))
 
 (local gnss-socket
@@ -75,8 +141,19 @@ label.readout {
   (each [l #(socket:read "l")]
     ; (print "gnss" l)
     (if (not (= l ""))
-        (print (view (nmea.parse l)))))
-
+        (let [message (nmea.parse l)]
+          (case message
+            { : lat : lon : utc}
+            (update-app-state
+             {
+              : lat : lon
+              :time-of-day
+              (let [(h m s) (string.match utc "(..)(..)(..)")]
+                (+ s (* m 60) (* h 60 60)))
+              }
+             )
+            { : speed-knots }
+            (update-app-state { :speed (* speed-knots knot-in-m-s) })))))
   true)
 
 (let [sock (gnss-socket:get_socket)