#!/usr/bin/env bash
set -euo pipefail

WP_DIR="$HOME/Pictures/Wallpapers"
aspect_name() {
  local w="$1"
  local h="$2"
  local a="$w"
  local b="$h"
  local t
  local aspect

  while (( b != 0 )); do
    t=$b
    b=$(( a % b ))
    a=$t
  done

  aspect="$(( w / a ))x$(( h / a ))"

  case "$aspect" in
    64x27|43x18)
      echo "21x9"
      ;;
    8x5)
      echo "16x10"
      ;;
    *)
      echo "$aspect"
      ;;
  esac
}

process_wallpapers() {
  wallpapers=()
  while read -r line; do
    if [[ "$line" == *"+*"* ]]; then
      role="primary"
    else
      role="secondary"
    fi
  
    geom="$(awk '{print $3}' <<< "$line")"
  
    width="${geom%%/*}"
    rest="${geom#*x}"
    height="${rest%%/*}"
  
    aspect="$(aspect_name "$width" "$height")"
    wallpapers+=("$WP_DIR/$aspect-$role.png")
  done < <(xrandr --listmonitors | tail -n +2)
  
  count="${#wallpapers[@]}"
  
  modes=()
  for (( i=0; i<${#wallpapers[@]}; i++ )); do
    modes+=("zoom")
  done

  echo "${wallpapers[@]}"

  hydrapaper --cli "${wallpapers[@]}" --mode "${modes[@]}"
}

last_applied=""
pending=""

while true; do
    current="$(xrandr --query 2>/dev/null | grep ' connected' || true)"

    if [[ "$current" != "$pending" ]]; then
        pending="$current"
    elif [[ "$current" != "$last_applied" ]]; then
        last_applied="$current"
        process_wallpapers
    fi

    sleep 1
done