From 0a41d91c746fa4e9c48588c29545879125b6b96e Mon Sep 17 00:00:00 2001
From: KemoNine <kemonine@kemonine.info>
Date: Fri, 14 Aug 2020 18:49:25 -0400
Subject: [PATCH] Ensure screen is on/off at boot time based on a config file
 that matches the on/off timers

---
 docs/scheduled_display.md | 83 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 82 insertions(+), 1 deletion(-)

diff --git a/docs/scheduled_display.md b/docs/scheduled_display.md
index d4f6b07..acd3937 100644
--- a/docs/scheduled_display.md
+++ b/docs/scheduled_display.md
@@ -6,12 +6,93 @@ The below is setup to turn the display on at ```0600``` and off at ```0000```. P
 
 ``` sh
 
+pip3 install -U python-dotenv
+
+cat > /etc/default/screen-on-off <<EOF
+# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+# YOU MUST TWEAK THE screen-on.timer AND screen-off.timer IF CHANGING THESE VALUES
+# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+# MUST BE A VALID TIME AND HAVE "*-*-* " AT THE START OF THE STRING
+#    Hours, Minutes and Seconds MUST be 0 padded (aka : we are using datetime.time.fromisoformat in the python3 stdlib)
+#    WE DO NOT SUPPORT DATES!!!!!
+TIME_SCREEN_ON="*-*-* 06:00:00"
+TIME_SCREEN_OFF="*-*-* 00:00:00"
+# Indicate the ON time is the following day (aka turn off at night, on following next morning)
+#    REMEMBER: MIDNIGHT IS TODAY!
+#    To set true use 'true'
+#    To set false use ''
+TIME_ON_IS_NEXT_DAY=''
+EOF
+
+cat > /usr/local/bin/screen-on-off <<EOF
+#!/usr/bin/python3
+# Load up the config file
+from pathlib import Path
+from dotenv import load_dotenv
+env_path = Path('/etc/default/screen-on-off')
+load_dotenv(dotenv_path=env_path)
+
+# Get values from env vars
+import os
+TIME_SCREEN_ON = os.getenv("TIME_SCREEN_ON")
+TIME_SCREEN_OFF = os.getenv("TIME_SCREEN_OFF")
+TIME_ON_IS_NEXT_DAY = bool(os.getenv("TIME_ON_IS_NEXT_DAY"))
+
+# Strip variables of data we don't support
+TIME_SCREEN_ON = TIME_SCREEN_ON.strip('*-*-* ')
+TIME_SCREEN_OFF = TIME_SCREEN_OFF.strip('*-*-* ')
+
+# Convert strings to timestamps
+from datetime import datetime, time, timedelta
+current = datetime.now()
+on = datetime.combine(current, time.fromisoformat(TIME_SCREEN_ON))
+off = datetime.combine(current, time.fromisoformat(TIME_SCREEN_OFF))
+
+# Adjust day of off time in case it's an overnight off
+if TIME_ON_IS_NEXT_DAY:
+    on = on + timedelta(days=1)
+
+# Let's do the quick checks to see if we are within the screen off window
+turn_on = True
+if on < off:
+    if on <= current <= off:
+        turn_on = False
+else:
+    if off <= current <= on:
+        turn_on = False
+
+# Turn screen on or off based on the schedule
+import subprocess
+if turn_on:
+    subprocess.check_call(['/opt/vc/bin/vcgencmd', 'display_power', '1'])
+else:
+    subprocess.check_call(['/opt/vc/bin/vcgencmd', 'display_power', '0'])
+EOF
+
+chmod a+x /usr/local/bin/screen-on-off
+
+cat > /etc/systemd/system/screen-on-off.service <<EOF
+[Unit]
+Description=auto-set screen on/off if rebooting (this will keep the screen off all but briefly during overnight reboots if the off window is set for overnight)
+After=getty.target
+
+[Service]
+ExecStart=/usr/local/bin/screen-on-off
+Type=oneshot
+
+[Install]
+WantedBy=multi-user.target
+EOF
+
+systemctl daemon-reload
+systemctl enable --now screen-on-off.service
+
 cat > /etc/systemd/system/screen-on.timer <<EOF
 [Unit]
 Description=Turn on display
 
 [Timer]
-OnCalendar=*-*-* 6:00:00
+OnCalendar=*-*-* 06:00:00
 Persistent=true
 
 [Install]