#!/bin/sh
# Managed by ansible (pi_kiosk role).
#
# Openbox is here for one concrete reason: a browser asks to be full-screen over EWMH,
# and only a window manager answers that request. With no WM running, --kiosk was
# silently ignored and the browser fell back to its default window size in the
# top-left corner of a 1920x1080 screen - black bands down the right edge and along
# the bottom, looking exactly like an overscan problem and not being one.

xset s off
xset -dpms
xset s noblank

{% if pi_kiosk_browser == 'chromium' %}
BROWSER=chromium

# The first four flags are the difference between compositing on the GPU and
# rasterizing every frame on the CPU:
#   --use-gl=egl                 reach V3D through EGL rather than desktop GLX
#   --enable-gpu-rasterization   rasterize layer content on the GPU
#   --ignore-gpu-blocklist       Chromium's blocklist does not know this driver, and
#                                without this it quietly falls back to software
#   --enable-zero-copy           hand tiles to the compositor without a CPU copy
# The rest are about a machine nobody sits in front of: no update checks, no crash
# bubbles, no keyring prompt, no first-run wizard, no "restore pages?" after a power
# cut. Anything policy-shaped rather than flag-shaped is in
# /etc/chromium/policies/managed/.
BROWSER_ARGS="--use-gl=egl --enable-gpu-rasterization --ignore-gpu-blocklist --enable-zero-copy"
BROWSER_ARGS="$BROWSER_ARGS --noerrdialogs --disable-infobars --no-first-run"
BROWSER_ARGS="$BROWSER_ARGS --no-default-browser-check --disable-session-crashed-bubble"
BROWSER_ARGS="$BROWSER_ARGS --password-store=basic --check-for-update-interval=31536000"
BROWSER_ARGS="$BROWSER_ARGS --hide-crash-restore-bubble"

# Chromium records in its profile how it last exited. A reboot kills it rather than
# closing it, so that record says "Crashed", and the next start comes up with a restore
# prompt and a tab stuck on a blank "Loading..." page - which, on a device with no
# keyboard in front of it, it never leaves. The flags above hide the prompt but do not
# clear the state behind it; rewriting the two keys before launch does, and is the
# standard remedy for a kiosk that is powered off rather than shut down.
PREFS="$HOME/.config/chromium/Default/Preferences"
if [ -f "$PREFS" ]; then
  sed -i 's/"exit_type":"[^"]*"/"exit_type":"Normal"/; s/"exited_cleanly":false/"exited_cleanly":true/' "$PREFS"
fi
{% if pi_kiosk_mode == 'debug' %}
# Debug mode only. Binds to 127.0.0.1, so it is reachable over an ssh tunnel and from
# nowhere else. Lets the page be driven and measured from a shell - `curl
# localhost:9222/json` lists the tabs - instead of by poking XTEST key events at a
# window and hoping they land.
BROWSER_ARGS="$BROWSER_ARGS --remote-debugging-port=9222"
{% endif %}
{% else %}
BROWSER=firefox
BROWSER_ARGS=""
{% endif %}

{% if pi_kiosk_mode == 'debug' %}
# Debug session. The browser is an ordinary window with its chrome (so devtools and the
# URL bar are reachable) and is *not* relaunched when it exits - quitting it should
# leave a usable desktop, not fight you for the screen. Openbox is the session leader
# instead: when it exits (root menu -> Exit) the X session ends and .bash_profile
# starts a fresh one. Right-click the desktop for a terminal.
# shellcheck disable=SC2086  # BROWSER_ARGS is a word list on purpose
$BROWSER $BROWSER_ARGS "{{ pi_kiosk_url }}" &

exec openbox
{% else %}
openbox &

unclutter -idle 0.5 -root &

# The loop is what takes the place of a WM's "keep something on screen" job: Openbox
# manages the window, but nothing else would bring the browser back if it died.
while true; do
  # shellcheck disable=SC2086
  $BROWSER --kiosk $BROWSER_ARGS "{{ pi_kiosk_url }}"
  sleep 2
done
{% endif %}