#!/usr/bin/env bash
#
# monitor setup script using xrandr and fzf to manage multiple monitors and/or
# set resolutions and refresh rates.

command -v xrandr &>/dev/null || exit 1
command -v fzf &>/dev/null || exit 1

xrandr_q="$(xrandr -q)"

# Get outputs currently in use as regex matching either one (e.g. `HDMI-0|DP-0`)
in_use="$( <<<"$xrandr_q" \
	tac |                          # Reverse for non-greedy matches
	sed -En '/\*/,/ connected/p' | # lines from selected config to it's name
	grep -Po '^.*(?= connected)' | # only the name
	tr '\n' '|'                    # format into regex
)"
in_use="${in_use%|}" # remove trailing `|`

# Get all outputs in a table in the form `<name> <res> [*]`
formatted="$(<<<"$xrandr_q" \
	grep -wA1 connected |                      # output line and highest res
	awk '{ print $1 }' |                       # only name and resolution
	grep -ve -- |                              # remove grep's match separator
	paste - - |                                # join name and res
	sed -E "s/($in_use).*/&\t*/" |             # append `*` to all in-use
	column -t                                  # tabularize
)"

# Select all outputs to-use
selected=( $(<<<"$formatted" \
	fzf -m --cycle --header "Select outputs" | # select
	cut -d' ' -f1                              # only output name
) )
# Abort if nothing was selected
(( ${#selected[@]} )) || exit 1

# Regex to match either one of the selected outputs
selected_regex="$(<<<"${selected[@]}" tr ' ' '|')"

# Gather non-selected outputs
non_selected=( $(<<<"$xrandr_q" \
	grep connected |             # list lines with output ({,dis}connected)
	grep -Ev "$selected_regex" | # filter out selected ones
	cut -d' ' -f1                # only output name
) )

# Choose primary
primary="$(<<<"$formatted" \
	grep -E "$selected_regex" | # use formatted for more information
	fzf --cycle --select-1 --header "Select primary" |
	cut -d' ' -f1 # name only
)"
[[ $primary ]] || exit 1

# Build the `xrandr` command
xrandr_cmd=(xrandr)

# Keep track of width to place the outputs side-by-side
width=0

for out in "${selected[@]}"; do
	xrandr_cmd+=(--output "$out" --rotate normal)
	[[ $out != $primary ]] || xrandr_cmd+=(--primary)

	all_res="$(<<<"$xrandr_q" sed -En "
		# all resolution lines for selected output (+ junk lines first and last)
		/$out/,/^[^ ]/ {
			# on lines that contain a resolution
			/^ / {
				# only print the resolution
				s/^ *([^ ]*).*/\1/p
			}
		}"
	)"
	res="$(<<<"$all_res" fzf --cycle --header "Select resolution for $out")"
	[[ $res ]] || exit 1

	xrandr_cmd+=(--mode "$res")

	rates="$(<<<"$xrandr_q" sed -En "
		# all resolution lines for selected output
		/$out/,/^[^ ]/ {
			# on line with the selected resolution
			/^ *$res/ {
				# remove resolution and whitespace
				s/^ *$res *//
				# fix formatting when preferred mode is not the current one
				s/ \+/+/
				# put each rate on a new line
				s/ +/\n/g

				p
			}
		}"
	)"
	rate="$(<<<"$rates" fzf --cycle --header "Select refresh rate for $out")"
	[[ $rate ]] || exit 1
	rate="${rate%%[*+]*}" # remove current and preferred mode indicator
	xrandr_cmd+=(--rate "$rate")

	xrandr_cmd+=(--pos "${width}x0")
	: "$((width+=${res%%x*}))"
done

for out in "${non_selected[@]}"; do
	xrandr_cmd+=(--output "$out" --off)
done

# Print for debugging purposes and finally execute it
printf "%s\n" "${xrandr_cmd[*]}"
"${xrandr_cmd[@]}"