2 files changed, 53 insertions, 0 deletions

diff --git a/src/smart-relay.rtk b/src/smart-relay.rtk
new file mode 100644
index 0000000..270780a
--- /dev/null
+++ b/src/smart-relay.rtk
@@ -0,0 +1,48 @@
+(module smart-relay racket/base
+  (require mqtt-client)
+  (provide main)
+
+  (define (make-send-to-dev data)
+    (lambda (dev)
+      (with-output-to-file dev
+        #:exists 'truncate
+        #:mode 'binary
+        (lambda ()
+          (write-bytes data)))))
+
+  (define send-message-on
+    (make-send-to-dev (bytes  #xA0 #x01 #x01 #xA2)))
+  (define send-message-off
+    (make-send-to-dev (bytes  #xA0 #x01 #x00 #xA1)))
+
+  (define (make-toggle-relay dev)
+    (let ((turn-on? #t))
+      (lambda ()
+        (displayln (format "Relay on ~a toggled" dev))
+        (if turn-on?
+            (send-message-on dev)
+            (send-message-off dev))
+        (set! turn-on? (not turn-on?)))))
+
+  (define (main #:host        [host        "localhost"]
+                #:username    [username    #f]
+                #:password    [password    #f]
+                #:client-name [client-name "smart-relay"]
+                #:topic-name  [topic-name  "hsp/bobma/smart-relay"]
+                #:relay-dev   [relay-dev   "/dev/ttyUSB0"])
+    (define toggle-relay (make-toggle-relay relay-dev))
+    (mqtt/with-client (host client-name)
+      (mqtt/with-connection (#:keep-alive-interval 20
+                             #:clean-session       #t
+                             #:username            username
+                             #:password            password)
+
+        (mqtt/subscribe topic-name)
+        (let loop ()
+          (mqtt/with-message-recv (topic payload)
+            (displayln (format "Message \"~a\" recieved on topic \"~a\"" payload topic))
+            (cond
+              ((string=? (bytes->string/utf-8 payload)
+                         "toggle")
+               (toggle-relay))))
+          (loop))))))
diff --git a/src/smart-relay.sh b/src/smart-relay.sh
new file mode 100755
index 0000000..af5fa26
--- /dev/null
+++ b/src/smart-relay.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+raco pkg install mqtt-client
+racket -e "(begin (require (file \"smart-relay.rtk\")) (main $@))"
+