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

OUT="README.md"

# Header + hidden anchor + TOC
cat > "$OUT" <<EOF
# Wallpapers Collection
<a name="top"></a>

## Table of Contents
EOF

for dir in */; do
  dir_name="${dir%/}"
  anchor=$(printf '%s' "$dir_name" \
    | tr '[:upper:]' '[:lower:]' \
    | sed 's/ /-/g; s/[^a-z0-9-]//g')
  echo "- [${dir_name}](#${anchor})" >> "$OUT"
done

echo -e "\n---\n" >> "$OUT"

# Sections for each folder and images
for dir in */; do
  dir_name="${dir%/}"
  anchor=$(printf '%s' "$dir_name" \
    | tr '[:upper:]' '[:lower:]' \
    | sed 's/ /-/g; s/[^a-z0-9-]//g')

  echo "## ${dir_name}" >> "$OUT"
  echo "" >> "$OUT"

  echo "**[⇧ back to top](#top)**" >> "$OUT"
  echo "" >> "$OUT"

  for img in "${dir}"*.{png,jpg,jpeg,gif}; do
    [ -f "$img" ] || continue
    fn="$(basename "${img%.*}")"
    rel="$(echo "$img" | sed 's|^\./||')"
    size=$(du -h "$img" | cut -f1)

    echo "### ${fn} — _${size}_ " >> "$OUT"
    echo "" >> "$OUT"
    echo "<img src=\"${rel}\" alt=\"${fn}\" />" >> "$OUT"
    echo "" >> "$OUT"
  done

  echo "" >> "$OUT"
done