#!/usr/bin/env sh

# Sets the correct DPI for your monitor instead of the generic '100'
# ❗ Make sure there is no DPI entry in your Xresources already!

file=~/.config/Xresources

grep 'Xft.dpi' "$file" && xrdb -merge "$file" && exit

info=$(xrandr | grep ' connected')

width=$(echo "$info" | rev | cut -d ' ' -f 3 | rev)
width_in=$(echo "${width%mm}" | awk '{print $1 * 0.039370}')

height=$(echo "$info" | rev | cut -d ' ' -f 1 | rev)
height_in=$(echo "${height%mm}" | awk '{print $1 * 0.039370}')

px=$(echo "$info" | cut -d ' ' -f 4)

width_px=${px%x*}

height_px=${px#*x}
height_px=${height_px%%+*}

diagonal_px=$(awk -v w="$width_px" -v h="$height_px" \
   'BEGIN{print sqrt(w*w+h*h)}')

diagonal_in=$(awk -v w="$width_in" -v h="$height_in" \
   'BEGIN{print sqrt(w*w + h*h)}')

dpi=$(awk -v dp="$diagonal_px" -v di="$diagonal_in" \
   'BEGIN{print dp / di}')

echo "Xft.dpi: $dpi" >> "$file"
xrdb -merge "$file"