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

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

missing_count=0

while IFS=$'\t' read -r src link; do
  case "$link" in
    ''|'#'*|mailto:*|http://*|https://*)
      continue
      ;;
  esac

  # Remove optional anchors and query strings for filesystem checks.
  target="${link%%#*}"
  target="${target%%\?*}"

  [[ -z "$target" ]] && continue

  if [[ "$target" == /* ]]; then
    # Treat /path as repository-root relative for markdown in GitHub.
    path="${repo_root}${target}"
  else
    path="$(dirname "$src")/$target"
  fi

  if [[ ! -e "$path" ]]; then
    printf 'BROKEN: %s -> %s (missing: %s)\n' "$src" "$link" "$path"
    missing_count=$((missing_count + 1))
  fi
done < <(
  while IFS= read -r file; do
    perl -ne 'while(/\[[^\]]*\]\(([^)]+)\)/g){print "$ARGV\t$1\n"}' "$file"
  done < <(rg --files -g '*.md')
)

if [[ "$missing_count" -gt 0 ]]; then
  printf '\nFound %d broken markdown link(s).\n' "$missing_count"
  exit 1
fi

echo "Markdown local links: OK"