#!/usr/bin/env bash

set -euo pipefail

repo_root="$(cd "$(dirname "$0")/.." && pwd)"
cd "$repo_root"

version_file="internal/homesick/version/version.go"
primary_changelog="CHANGELOG.md"
compat_changelog="changelog.md"

current_version="$(sed -n 's/^const String = "\([^"]*\)"$/\1/p' "$version_file")"
if [[ -z "$current_version" ]]; then
  echo "Failed to read current version from ${version_file}" >&2
  exit 1
fi

bump="$(awk '
  BEGIN { in_unreleased = 0; section = ""; has_entries = 0; bump = "" }
  /^## \[Unreleased\]/ { in_unreleased = 1; next }
  /^## \[/ && in_unreleased { exit }
  /^### / && in_unreleased { section = substr($0, 5); next }
  in_unreleased && /^- / {
    has_entries = 1
    if (section == "Breaking" || section == "Removed") {
      bump = "major"
    } else if (section == "Added") {
      if (bump != "major") {
        bump = "minor"
      }
    } else if (bump == "") {
      bump = "patch"
    }
  }
  END {
    if (!has_entries) {
      print "none"
      exit
    }
    if (bump == "") {
      bump = "patch"
    }
    print bump
  }
' "$primary_changelog")"

if [[ "$bump" == "none" ]]; then
  echo "No unreleased changelog entries found; skipping release preparation."
  exit 0
fi

IFS=. read -r major minor patch <<< "$current_version"
case "$bump" in
  major)
    major=$((major + 1))
    minor=0
    patch=0
    ;;
  minor)
    minor=$((minor + 1))
    patch=0
    ;;
  patch)
    patch=$((patch + 1))
    ;;
  *)
    echo "Unsupported bump type: ${bump}" >&2
    exit 1
    ;;
esac

next_version="${major}.${minor}.${patch}"
tag="v${next_version}"
today="$(date -u +%F)"

if git rev-parse -q --verify "refs/tags/${tag}" >/dev/null; then
  echo "Tag ${tag} already exists; skipping release preparation."
  exit 0
fi

unreleased_line="$(grep -n '^## \[Unreleased\]' "$primary_changelog" | cut -d: -f1)"
if [[ -z "$unreleased_line" ]]; then
  echo "Missing [Unreleased] section in ${primary_changelog}" >&2
  exit 1
fi

next_heading_line="$(awk -v start="$unreleased_line" 'NR > start && /^## \[/ { print NR; exit }' "$primary_changelog")"
total_lines="$(wc -l < "$primary_changelog" | tr -d ' ')"
if [[ -z "$next_heading_line" ]]; then
  next_heading_line=$((total_lines + 1))
fi

tmp_changelog="$(mktemp)"
{
  sed -n "1,$((unreleased_line - 1))p" "$primary_changelog"
  echo "## [Unreleased]"
  echo
  echo "### Breaking"
  echo
  echo "### Added"
  echo
  echo "### Changed"
  echo
  echo "### Fixed"
  echo
  echo "### Removed"
  echo
  echo "## [${next_version}] - ${today}"
  echo
  sed -n "$((unreleased_line + 2)),$((next_heading_line - 1))p" "$primary_changelog"
  if (( next_heading_line <= total_lines )); then
    sed -n "${next_heading_line},${total_lines}p" "$primary_changelog"
  fi
} > "$tmp_changelog"

tmp_version="$(mktemp)"
sed "s/^const String = \".*\"$/const String = \"${next_version}\"/" "$version_file" > "$tmp_version"

mv "$tmp_version" "$version_file"
mv "$tmp_changelog" "$primary_changelog"
cp "$primary_changelog" "$compat_changelog"

git config user.name "gitea-actions[bot]"
git config user.email "gitea-actions[bot]@users.noreply.local"

git add "$version_file" "$primary_changelog" "$compat_changelog"
git commit -m "chore(release): prepare ${tag}"
git tag "$tag"
git push origin HEAD:main
git push origin "$tag"

echo "Prepared ${tag} from ${current_version} with a ${bump} bump."