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

repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
cd "$repo_root"

ictool="/Applications/Xcode/Xcode.app/Contents/Applications/Icon Composer.app/Contents/Executables/ictool"
icon_doc="$repo_root/design/brand/Burrow.icon"
output_dir_arg="${1:-design/brand/low-res}"
if [[ "$output_dir_arg" = /* ]]; then
  output_dir="$output_dir_arg"
else
  output_dir="$repo_root/$output_dir_arg"
fi
master="$output_dir/burrow-icon-1024.png"
checked_in_master="$repo_root/design/brand/burrow-owl-icon-master.png"
source_master="$checked_in_master"
sizes=(16 20 24 29 32 40 48 64 80 128 256)

require_tool() {
  if ! command -v "$1" >/dev/null 2>&1; then
    echo "error: required tool not found: $1" >&2
    exit 127
  fi
}

require_tool magick
require_tool awk

if [[ ! -x "$ictool" ]]; then
  echo "error: Icon Composer ictool not found at $ictool" >&2
  exit 127
fi

mkdir -p "$output_dir"

if [[ "${BURROW_ICON_REFRESH:-0}" == "1" ]]; then
  if ! "$ictool" "$icon_doc" \
    --export-image \
    --output-file "$master" \
    --platform iOS \
    --rendition Default \
    --width 1024 \
    --height 1024 \
    --scale 1 >/dev/null; then
    echo "warning: ictool could not export $icon_doc; falling back to $checked_in_master" >&2
    magick "$checked_in_master" -colorspace sRGB -strip "PNG24:$master"
    source_master="$checked_in_master"
  else
    source_master="$master"
  fi
else
  magick "$checked_in_master" -colorspace sRGB -strip "PNG24:$master"
fi

printf "size,colors,gray_stddev,status\n" >"$output_dir/report.csv"

for size in "${sizes[@]}"; do
  image="$output_dir/burrow-icon-${size}.png"
  magick "$source_master" -colorspace sRGB -resize "${size}x${size}!" -strip "PNG24:$image"

  actual="$(magick "$image" -format "%wx%h" info:)"
  if [[ "$actual" != "${size}x${size}" ]]; then
    echo "error: $image rendered as $actual, expected ${size}x${size}" >&2
    exit 1
  fi

  colors="$(magick "$image" -format "%k" info:)"
  stddev="$(magick "$image" -colorspace Gray -format "%[fx:standard_deviation]" info:)"
  min_colors=$((size * 4))
  if (( min_colors < 48 )); then
    min_colors=48
  fi
  if (( min_colors > 900 )); then
    min_colors=900
  fi

  awk -v size="$size" -v colors="$colors" -v min_colors="$min_colors" -v stddev="$stddev" '
    BEGIN {
      if (colors < min_colors) {
        printf "error: %dpx icon has only %d colors; expected at least %d\n", size, colors, min_colors > "/dev/stderr";
        exit 1;
      }
      if (stddev < 0.08) {
        printf "error: %dpx icon grayscale stddev is %.6f; expected at least 0.08\n", size, stddev > "/dev/stderr";
        exit 1;
      }
    }
  '

  printf "%s,%s,%s,ok\n" "$size" "$colors" "$stddev" >>"$output_dir/report.csv"
done

preview_inputs=()
pixel_preview_inputs=()
for size in 256 128 80 64 48 40 32 29 24 20 16; do
  preview="$output_dir/preview-${size}.png"
  if (( size <= 32 )); then
    filter=Point
  else
    filter=Lanczos
  fi
  magick "$output_dir/burrow-icon-${size}.png" -filter "$filter" -resize 128x128 "$preview"
  preview_inputs+=("$preview")

  if (( size <= 32 )); then
    pixel_preview="$output_dir/pixel-preview-${size}.png"
    magick "$output_dir/burrow-icon-${size}.png" -filter Point -resize 128x128 "$pixel_preview"
    pixel_preview_inputs+=("$pixel_preview")
  fi
done

magick -background "#202020" -gravity center "${preview_inputs[@]}" +append "$output_dir/preview-strip.png"
magick -background "#202020" -gravity center "${pixel_preview_inputs[@]}" +append "$output_dir/pixel-preview-strip.png"

echo "low-res icon exports written to $output_dir"