#!/bin/bash
# I, Ian Kelling, follow the GNU license recommendations at
# https://www.gnu.org/licenses/license-recommendations.en.html. They
# recommend that small programs, < 300 lines, be licensed under the
# Apache License 2.0. This file contains or is part of one or more small
# programs. If a small program grows beyond 300 lines, I plan to switch
# its license to GPL.

# Copyright 2024 Ian Kelling

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

set -e; . /usr/local/lib/bash-bear; set +e

xf=$(mktemp)
xrandr >$xf

# eg eDP-1 connected primary
laptop_out=$(awk '$3 == "primary" {print $1}' $xf)
output=$(grep -E "^(HDMI|DP)[^ ]* connected [0-9]" $xf| awk '{print $1}' ||:)

edid() {
  card=$1
  sha256sum </sys/class/drm/$card/edid | grep -oE '^.{10}'
  }

restart=false
left_right_arg=--right-of
if [[ $output ]]; then

  mode=$(grep -A1 -E "^$output" | tail -n1 | awk '{print $1}' $xf)

  primary_res=$(awk '$2 == "connected" && $3 == "primary" { print $4 }' $xf | sed 's/+.*//')
  primary_x=${primary_res%x*}

  x=${mode%x*}
  y=${mode#*x}

  half_x=$(( x / 2 ))

  x_offset=0

  # identify monitors that are always on the left.
  if [[ $output == HDMI2 && $(edid card0-HDMI-A-2) == 192efbdcef ]] || \
       [[ $output == HDMI-1 && $(edid card1-HDMI-A-1 ) == 7c58f9ac1e ]]; then
    left_right_arg=--left-of
    x_offset=$primary_x
  fi

  # some monitors need off then on to become active
  if $restart; then
    xrandr --output $output --off
    sleep 2
  fi


  # eg: 3840x2160
  echo mode=$mode
  xrandr --output $output $left_right_arg $laptop_out --mode $mode


  # This splits a monitor into 2 virtual screens, which makes it split
  # into 2 workspaces in i3, which is a much more convenient setup for
  # managing windows.
  # todo: add an option to turn this off
  # todo: do this on systems with just 1 monitor.
  #
  # /298 & 336 are millimeters. I took them from a monitor I was using. I
  # don't know if they are important, I assume not important enough to
  # change for different monitors.
  xrandr --setmonitor BIG-LEFT $half_x/298x$y/336+0+$x_offset $output
  xrandr --setmonitor BIG-RIGHT $half_x/298x$y/336+$(( x_offset + half_x ))+0 none


  for i in 2 3 4 5 6 7 8 9 10; do
    # if the workspace is already there, this will fail.
    # if the workspace doesn't exist yet, it fails with:
    # ERROR: No output matched
    i3-msg '[workspace="'$i'"]' move workspace to output $output ||:
  done
else
  xrandr --auto

fi