#!/usr/bin/env bash
# ---------------------------------------------------------------------------
#  Apply a wallpaper with feh and remember the choice.
#
#    set-wallpaper                 # restore the remembered wallpaper
#    set-wallpaper /path/img.png   # set a specific image
#    set-wallpaper --random        # pick a random one from the wallpaper dir
#    set-wallpaper --cache         # (re)build the betterlockscreen cache
#
#  The current selection is stored in $XDG_STATE_HOME/current-wallpaper.
# ---------------------------------------------------------------------------
set -uo pipefail

WALLPAPER_DIR="${WALLPAPER_DIR:-${XDG_DATA_HOME:-$HOME/.local/share}/wallpapers}"
STATE_DIR="${XDG_STATE_HOME:-$HOME/.local/state}"
STATE_FILE="$STATE_DIR/current-wallpaper"
MODE="${FEH_MODE:---bg-fill}"

mkdir -p "$STATE_DIR" "$WALLPAPER_DIR"

pick_random() {
  find -L "$WALLPAPER_DIR" -type f \
    \( -iname '*.png' -o -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.webp' \) \
    | shuf -n1
}

first_available() {
  find -L "$WALLPAPER_DIR" -type f \
    \( -iname '*.png' -o -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.webp' \) \
    | sort | head -n1
}

cache_lockscreen=0
target=""

case "${1:-}" in
  --random)  target="$(pick_random)" ;;
  --cache)   cache_lockscreen=1 ;;
  "")        target="$(cat "$STATE_FILE" 2>/dev/null || true)" ;;
  -*)        echo "unknown option: $1" >&2; exit 2 ;;
  *)         target="$1"; cache_lockscreen=1 ;;
esac

# Fall back through: remembered -> anything in the dir -> a flat Macchiato base
if [[ -z "$target" || ! -f "$target" ]]; then
  target="$(first_available)"
fi

if [[ -z "$target" || ! -f "$target" ]]; then
  echo "set-wallpaper: no image found in $WALLPAPER_DIR — using a flat colour" >&2
  command -v xsetroot >/dev/null && xsetroot -solid "#24273a"
  exit 0
fi

command -v feh >/dev/null || { echo "set-wallpaper: feh is not installed" >&2; exit 1; }

feh --no-fehbg "$MODE" "$target"
printf '%s\n' "$target" > "$STATE_FILE"

# Keep the lock screen in sync with the desktop. Caching is slow (imagemagick
# blurs the image at every resolution), so only do it when the image changed.
if [[ "$cache_lockscreen" == "1" ]] && command -v betterlockscreen >/dev/null; then
  ( betterlockscreen --update "$target" --blur 0.5 >/dev/null 2>&1 &
    disown ) 2>/dev/null || true
fi