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

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

threshold="${THRESHOLD_PERCENT:-30}"
output_file="${1:-}"

if [[ -n "$output_file" ]]; then
  exec >"$output_file"
fi

if [[ ! -d docs/en || ! -d docs/cs ]]; then
  echo "ERROR: expected docs/en and docs/cs directories."
  exit 1
fi

tmp_dir="$(mktemp -d)"
trap 'rm -rf "$tmp_dir"' EXIT

(cd docs/en && rg --files -g '*.md' | sort) >"$tmp_dir/en_files.txt"
(cd docs/cs && rg --files -g '*.md' | sort) >"$tmp_dir/cs_files.txt"

comm -23 "$tmp_dir/en_files.txt" "$tmp_dir/cs_files.txt" >"$tmp_dir/missing_in_cs.txt"
comm -13 "$tmp_dir/en_files.txt" "$tmp_dir/cs_files.txt" >"$tmp_dir/extra_in_cs.txt"
comm -12 "$tmp_dir/en_files.txt" "$tmp_dir/cs_files.txt" >"$tmp_dir/common_files.txt"

missing_count="$(wc -l <"$tmp_dir/missing_in_cs.txt" | tr -d ' ')"
extra_count="$(wc -l <"$tmp_dir/extra_in_cs.txt" | tr -d ' ')"

# Report any TODO markers in Czech files.
todo_count="$(
  (rg -n '\bTODO\b' docs/cs --glob '*.md' --glob '!README.md' || true) | wc -l | tr -d ' '
)"

echo "# Translation Parity Report (docs/en -> docs/cs)"
echo
echo "## Summary"
echo
echo "- English files: $(wc -l <"$tmp_dir/en_files.txt" | tr -d ' ')"
echo "- Czech files: $(wc -l <"$tmp_dir/cs_files.txt" | tr -d ' ')"
echo "- Missing in Czech: $missing_count"
echo "- Extra in Czech: $extra_count"
echo "- Czech TODO markers (excluding docs/cs/README.md): $todo_count"
echo

if [[ "$missing_count" -gt 0 ]]; then
  echo "## Missing Czech Files"
  echo
  while IFS= read -r rel; do
    echo "- docs/cs/$rel"
  done <"$tmp_dir/missing_in_cs.txt"
  echo
fi

if [[ "$extra_count" -gt 0 ]]; then
  echo "## Extra Czech Files"
  echo
  while IFS= read -r rel; do
    echo "- docs/cs/$rel"
  done <"$tmp_dir/extra_in_cs.txt"
  echo
fi

echo "## Line Count Delta (warnings at >= ${threshold}%)"
echo
echo "| File | EN lines | CS lines | Delta |"
echo "| --- | ---: | ---: | ---: |"

warn_count=0
while IFS= read -r rel; do
  en_lines="$(wc -l <"docs/en/$rel" | tr -d ' ')"
  cs_lines="$(wc -l <"docs/cs/$rel" | tr -d ' ')"

  if [[ "$en_lines" -eq 0 ]]; then
    delta_percent="n/a"
    abs_percent=0
  else
    abs_percent="$(
      awk -v en="$en_lines" -v cs="$cs_lines" 'BEGIN{
        d = cs - en; if (d < 0) d = -d;
        printf "%.1f", (d / en) * 100
      }'
    )"
    delta_percent="${abs_percent}%"
  fi

  echo "| \`$rel\` | $en_lines | $cs_lines | $delta_percent |"

  if [[ "$en_lines" -gt 0 ]]; then
    over="$(
      awk -v p="$abs_percent" -v t="$threshold" 'BEGIN{if (p >= t) print 1; else print 0}'
    )"
    if [[ "$over" -eq 1 ]]; then
      warn_count=$((warn_count + 1))
    fi
  fi
done <"$tmp_dir/common_files.txt"

echo
echo "Large-delta warnings: $warn_count"

status=0
if [[ "$missing_count" -gt 0 || "$todo_count" -gt 0 ]]; then
  status=1
fi

echo
if [[ "$status" -eq 0 ]]; then
  echo "Result: PASS"
else
  echo "Result: FAIL (missing files and/or TODO markers found)"
fi

exit "$status"