#!/usr/bin/env bash
# rice-wallpaper - the desktop background.
#
#   rice-wallpaper set <image>      set it and remember it
#   rice-wallpaper restore          set the remembered one (session start)
#   rice-wallpaper theme-default    set the active theme's own wallpaper
#   rice-wallpaper next             the next image in the list
#   rice-wallpaper list             images from the rice, ~/.config/rice/wallpapers and ~/Pictures/Wallpapers
#   rice-wallpaper thumb <image>    a cached 400x250 thumbnail for the pickers
set -uo pipefail

RICE_DIR="${RICE_DIR:-$(cd "$(dirname "$(readlink -f "$0")")/.." && pwd)}"
state="${XDG_STATE_HOME:-$HOME/.local/state}/rice"
remembered="$state/wallpaper"
thumbs="${XDG_CACHE_HOME:-$HOME/.cache}/rice/thumbs"
mkdir -p "$state" "$thumbs"

list() {
  find -L "$RICE_DIR/wallpapers" "${XDG_CONFIG_HOME:-$HOME/.config}/rice/wallpapers" "$HOME/Pictures/Wallpapers" \
    -maxdepth 1 -type f \( -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.png' -o -iname '*.webp' \) 2>/dev/null | sort
}

apply() {
  [[ -f $1 ]] || { echo "rice-wallpaper: no such image: $1" >&2; return 1; }
  feh --no-fehbg --bg-fill "$1" && realpath -- "$1" > "$remembered"
}

case "${1:-}" in
  set) apply "${2:?usage: rice-wallpaper set <image>}" ;;
  restore)
    if [[ -f $remembered && -f $(cat "$remembered") ]]; then apply "$(cat "$remembered")"; else "$0" theme-default; fi
    ;;
  theme-default)
    name=$(rice-theme get wallpaper 2>/dev/null || true)
    [[ -z $name ]] && exit 0
    if [[ -f $name ]]; then apply "$name";
    elif [[ -f $RICE_DIR/wallpapers/$name ]]; then apply "$RICE_DIR/wallpapers/$name";
    elif [[ -f ${XDG_CONFIG_HOME:-$HOME/.config}/rice/wallpapers/$name ]]; then apply "${XDG_CONFIG_HOME:-$HOME/.config}/rice/wallpapers/$name";
    elif [[ -f $HOME/Pictures/Wallpapers/$name ]]; then apply "$HOME/Pictures/Wallpapers/$name";
    fi
    ;;
  next)
    mapfile -t all < <(list)
    (( ${#all[@]} > 0 )) || exit 1
    current=$(cat "$remembered" 2>/dev/null)
    for i in "${!all[@]}"; do
      if [[ ${all[$i]} == "$current" ]]; then apply "${all[$(( (i + 1) % ${#all[@]} ))]}"; exit; fi
    done
    apply "${all[0]}"
    ;;
  list) list ;;
  thumb)
    img="${2:?usage: rice-wallpaper thumb <image>}"
    out="$thumbs/$(printf '%s:%s' "$img" "$(stat -c %Y -- "$img" 2>/dev/null)" | sha1sum | cut -c1-16).jpg"
    if [[ ! -s $out ]] && command -v magick >/dev/null; then
      magick "${img}[0]" -thumbnail '400x250^' -gravity center -extent 400x250 -quality 85 "$out" 2>/dev/null
    fi
    if [[ -s $out ]]; then echo "$out"; else echo "$img"; fi
    ;;
  *) sed -n '2,10p' "$0" | sed 's/^# \{0,1\}//'; exit 2 ;;
esac