scd4x: rewrite in python

2 files changed, 88 insertions, 51 deletions

diff --git a/scd4x b/scd4x
index aae5919..e0a496f 100755
--- a/scd4x
+++ b/scd4x
@@ -1,51 +1,37 @@
-#!/usr/bin/perl
-use warnings;
-use strict;
-use English;
-use POSIX;
-use JSON;
-use Net::MQTT::Simple;
-
-my $file = shift;
-my $host = shift;
-
-my $json = JSON->new->allow_nonref;
-my $mqtt;
-
-my $values;
-my $pvalues;
-my $serial;
-
-sub read_json_file {
-	my $filename = shift;
-	my $content;
-
-	open FILE, '<', $filename or die "read $filename: $!";
-	{ local $/; undef $/; $content = <FILE> }
-	close FILE;
-
-	return $json->decode($content);
-}
-
-if (defined($host)) {
-	$mqtt = Net::MQTT::Simple->new($host) or die "mqtt init (server $host)"
-}
-
-for (;;) {
-	$values = read_json_file($file);
-	$serial = $values->{'serial'};
-	for my $key ('co2', 'temperature', 'humidity') {
-		next if defined($pvalues->{$key}) and $pvalues->{$key} eq $values->{$key};
-		my $topic = "sensors/" . $key . "/scd4x/" . $serial;
-		if (defined($mqtt)) {
-			$mqtt->retain( $topic => $values->{$key} );
-		} else {
-			my $ts = POSIX::ctime(time());
-			chomp($ts);
-			printf("[%s] %-40s: %s\n",
-			       $ts, $topic, $values->{$key});
-		}
-	}
-	$pvalues = $values;
-	sleep 60;
-}
+#!/usr/bin/python3
+import sys
+import json
+
+import paho.mqtt.client as mqtt
+
+def main():
+    if len(sys.argv) < 3:
+        print(len(sys.argv))
+        print(f'usage: {sys.argv[0]} json-file mqtt-host')
+        return 1
+
+    filename = sys.argv[1]
+    mqtthost = sys.argv[2]
+
+    client = mqtt.Client()
+    client.connect(mqtthost, 1883)
+
+    pvalues = {}
+    while True:
+        with open(filename, 'r', encoding = 'utf-8') as f:
+            values = json.loads(f.read())
+
+        for key in ('co2', 'temperature', 'humidity'):
+            curr = values.get(key)
+            prev = pvalues.get(key)
+            if prev and prev == curr:
+                continue
+
+            topic = f'sensors/{key}/scd4x/{values.get("serial")}'
+            #print(f'{topic} = {curr}')
+            client.publish(topic, curr)
+
+        pvalues = values
+
+if __name__ == '__main__':
+    sys.exit(main())
diff --git a/scd4x.pl b/scd4x.pl
new file mode 100755
index 0000000..aae5919
--- /dev/null
+++ b/scd4x.pl
@@ -0,0 +1,51 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+use English;
+use POSIX;
+use JSON;
+use Net::MQTT::Simple;
+
+my $file = shift;
+my $host = shift;
+
+my $json = JSON->new->allow_nonref;
+my $mqtt;
+
+my $values;
+my $pvalues;
+my $serial;
+
+sub read_json_file {
+	my $filename = shift;
+	my $content;
+
+	open FILE, '<', $filename or die "read $filename: $!";
+	{ local $/; undef $/; $content = <FILE> }
+	close FILE;
+
+	return $json->decode($content);
+}
+
+if (defined($host)) {
+	$mqtt = Net::MQTT::Simple->new($host) or die "mqtt init (server $host)"
+}
+
+for (;;) {
+	$values = read_json_file($file);
+	$serial = $values->{'serial'};
+	for my $key ('co2', 'temperature', 'humidity') {
+		next if defined($pvalues->{$key}) and $pvalues->{$key} eq $values->{$key};
+		my $topic = "sensors/" . $key . "/scd4x/" . $serial;
+		if (defined($mqtt)) {
+			$mqtt->retain( $topic => $values->{$key} );
+		} else {
+			my $ts = POSIX::ctime(time());
+			chomp($ts);
+			printf("[%s] %-40s: %s\n",
+			       $ts, $topic, $values->{$key});
+		}
+	}
+	$pvalues = $values;
+	sleep 60;
+}