#!/usr/bin/env bash
# Generate Android adaptive launcher icons from source PNGs.
# Usage: ./scripts/gen-icons.sh
#
# Source images should be 1024x1024. Base icon sources are read from
# composeApp/src/androidMain/res/{fg,bg,mono}.png. Partner foregrounds live
# in composeApp/src/androidMain/app-icon-assets/<slug>_{fg,mono}.png and are
# generated as alternate launcher icons using the default background.

set -euo pipefail

RES="$(dirname "$0")/../composeApp/src/androidMain/res"
FG="$RES/fg.png"
BG="$RES/bg.png"
MONO="$RES/mono.png"
PARTNER_FG="$(dirname "$0")/../composeApp/src/androidMain/app-icon-assets"

for source in "$FG" "$BG" "$MONO"; do
  if [[ ! -f "$source" ]]; then
    echo "missing icon source: $source" >&2
    exit 2
  fi
done

DENSITIES=(mdpi hdpi xhdpi xxhdpi xxxhdpi)
declare -A SIZES=(["mdpi"]=48 ["hdpi"]=72 ["xhdpi"]=96 ["xxhdpi"]=144 ["xxxhdpi"]=192)
declare -A ADAPTIVE=(["mdpi"]=108 ["hdpi"]=162 ["xhdpi"]=216 ["xxhdpi"]=324 ["xxxhdpi"]=432)

generate_icon() {
  local name="$1"
  local fg="$2"
  local bg="$3"
  local mono="$4"

  for density in "${DENSITIES[@]}"; do
    local s=${SIZES[$density]}
    local a=${ADAPTIVE[$density]}
    local d="$RES/mipmap-$density"
    mkdir -p "$d"

    magick "$fg" -resize "${a}x${a}" -quality 90 "$d/${name}_foreground.webp"
    magick "$bg" -resize "${a}x${a}" -quality 90 "$d/${name}_background.webp"
    magick "$mono" -resize "${a}x${a}" -quality 90 "$d/${name}_monochrome.webp"

    magick \( "$bg" -resize "${s}x${s}" \) \( "$fg" -resize "${s}x${s}" \) \
      -composite -quality 90 "$d/${name}.webp"

    magick \( "$bg" -resize "${s}x${s}" \) \( "$fg" -resize "${s}x${s}" \) \
      -composite \
      \( -size "${s}x${s}" xc:none -fill white -draw "circle $((s/2)),$((s/2)) $((s/2)),0" \) \
      -compose DstIn -composite -quality 90 "$d/${name}_round.webp"
  done
}

write_adaptive_icon() {
  local name="$1"
  local file="$RES/mipmap-anydpi-v26/${name}.xml"
  mkdir -p "$(dirname "$file")"
  cat >"$file" <<XML
<?xml version="1.0" encoding="utf-8"?>
<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
    <background android:drawable="@mipmap/${name}_background"/>
    <foreground android:drawable="@mipmap/${name}_foreground"/>
    <monochrome android:drawable="@mipmap/${name}_monochrome"/>
</adaptive-icon>
XML
}

write_alias_adaptive_icon() {
  local alias="$1"
  local target="$2"
  local file="$RES/mipmap-anydpi-v26/${alias}.xml"
  mkdir -p "$(dirname "$file")"
  cat >"$file" <<XML
<?xml version="1.0" encoding="utf-8"?>
<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
    <background android:drawable="@mipmap/${target}_background"/>
    <foreground android:drawable="@mipmap/${target}_foreground"/>
    <monochrome android:drawable="@mipmap/${target}_monochrome"/>
</adaptive-icon>
XML
}

generate_icon "ic_launcher" "$FG" "$BG" "$MONO"
write_adaptive_icon "ic_launcher"
write_alias_adaptive_icon "ic_launcher_round" "ic_launcher"

if [[ -d "$PARTNER_FG" ]]; then
  shopt -s nullglob
  for partner_fg in "$PARTNER_FG"/*_fg.png; do
    slug="$(basename "$partner_fg" _fg.png)"
    partner_mono="$PARTNER_FG/${slug}_mono.png"
    if [[ ! -f "$partner_mono" ]]; then
      echo "skipping $slug: missing $partner_mono" >&2
      continue
    fi
    name="ic_launcher_${slug}"
    generate_icon "$name" "$partner_fg" "$BG" "$partner_mono"
    write_adaptive_icon "$name"
    write_alias_adaptive_icon "${name}_round" "$name"
    echo "generated partner icon: $slug"
  done
  shopt -u nullglob
fi

for density in "${DENSITIES[@]}"; do
  echo "$density: ${SIZES[$density]}px launcher, ${ADAPTIVE[$density]}px adaptive"
done

echo "done"