#!/usr/bin/env sh

######################################################################
# @author      : swytch (adapted from Luke Smith - lukesmith.xyz)
# @file        : displayselect
# @license     : GPLv3
# @created     : Wednesday May 20, 2020 18:04:01 CEST
#
# @description : detect displays and select an organisation
######################################################################


twoscreen() { # If multi-monitor is selected and there are two screens.
    mirror=$(printf "no\\nyes" | dmenu -i -p "Mirror displays?")
    # Mirror displays using native resolution of external display and a scaled
    # version for the internal display
    if [ "$mirror" = "yes" ]; then
		external=$(echo "$screens" | dmenu -i -p "Optimize resolution for:")
		internal=$(echo "$screens" | grep -v -w "$external")

		res_external=$(xrandr --query | sed -n "/^$external/,/\+/p" | \
			tail -n 1 | awk '{print $1}')
		res_internal=$(xrandr --query | sed -n "/^$internal/,/\+/p" | \
			tail -n 1 | awk '{print $1}')

		res_ext_x=$(echo $res_external | sed 's/x.*//')
		res_ext_y=$(echo $res_external | sed 's/.*x//')
		res_int_x=$(echo $res_internal | sed 's/x.*//')
		res_int_y=$(echo $res_internal | sed 's/.*x//')

		scale_x=$(echo "$res_ext_x / $res_int_x" | bc -l)
		scale_y=$(echo "$res_ext_y / $res_int_y" | bc -l)

		xrandr --output "$external" --auto --scale 1.0x1.0 \
			--output "$internal" --auto --same-as "$external" \
			--scale "$scale_x"x"$scale_y"
    else
                primary=$(echo "$screens" | dmenu -i -p "Select primary display:")
                secondary=$(echo "$screens" | grep -v -w "$primary")
                direction=$(printf "left\\nright" | dmenu -i -p "What side of $primary should $secondary be on?")
                rotation=$(printf "normal\\nleft\\nright" | dmenu -i -p "Rotate $secondary?")
                setup
	fi
	}

default() {
                [ -z "$primary" ] && primary=$(echo "$allposs" | grep -w "connected primary" | awk '{ print $1 }')
                secondary=$(echo "$screens" | grep -v -w "$primary")
                direction="left"
                rotation="normal"
                mode="mode 2560x1440"

                setup
}

external() {
                internal=$(echo "$screens" | dmenu -i -p "Select internal display:")
                screens=$(echo "$screens" | grep -v -w "$internal")
                primary=$(echo "$screens" | dmenu -i -p "Select primary display:")
                xrandr --output $primary --primary && default
}

setup() {
                [ -z "$mode" ] && mode="auto"
                xrandr --output "$primary" --primary --auto --scale 1.0x1.0 \
                        --output "$secondary" --"$direction"-of "$primary" --$mode

                [ -n "$internal" ] && xrandr --output "$internal" --off
}

morescreen() { # If multi-monitor is selected and there are more than two screens.
	primary=$(echo "$screens" | dmenu -i -p "Select primary display:")
	secondary=$(echo "$screens" | grep -v -w "$primary" | dmenu -i -p "Select secondary display:")
	direction=$(printf "left\\nright" | dmenu -i -p "What side of $primary should $secondary be on?")
	tertiary=$(echo "$screens" | grep -v -w "$primary" | grep -v "$secondary" | dmenu -i -p "Select third display:")
	xrandr --output "$primary" --auto --output "$secondary" --"$direction"-of "$primary" --auto --output "$tertiary" --"$(printf "left\\nright" | grep -v "$direction")"-of "$primary" --auto
	}

multimon() { # Multi-monitor handler.
	case "$(echo "$screens" | wc -l)" in
		1) xrandr $(echo "$allposs" | grep -v -w "$screens" | awk '{print "--output", $1, "--off"}' | tr '\n' ' ') ;;
		2) twoscreen ;;
		*) morescreen ;;
	esac ;}

# Get all possible displays
allposs=$(xrandr -q | grep -w "connected")

# Get all connected screens.
screens=$(echo "$allposs" | awk '{print $1}')

# Get user choice including multi-monitor and manual selection:
chosen=$(printf "default\\nexternal\\nmulti-monitor\\n%s\\nmanual selection" "$screens" | dmenu -i -p "Select display arangement:") &&
case "$chosen" in
        "default") default ;;
        "external") external ;;
	"manual selection") arandr ; exit ;;
	"multi-monitor") multimon ;;
	*) xrandr --output "$chosen" --auto --scale 1.0x1.0 $(echo "$allposs" | grep -v "$chosen" | awk '{print "--output", $1, "--off"}' | tr '\n' ' ') ;;
esac

setbg		# Fix background if screen size/arangement has changed.
pgrep -x dunst >/dev/null && kill -9 $(pidof dunst) && setsid dunst & # Restart dunst to ensure proper location on screen