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

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

VERSION_FILE="VERSION"
BRANCH="main"

usage() {
  echo "Usage: $0 patch|minor|major" >&2
  exit 1
}

BUMP="${1:-}"
case "$BUMP" in
  patch | minor | major) ;;
  *) usage ;;
esac

if [[ "$(git rev-parse --abbrev-ref HEAD)" != "$BRANCH" ]]; then
  echo "Error: releases must be cut from $BRANCH" >&2
  exit 1
fi

if [[ -n "$(git status --porcelain)" ]]; then
  echo "Error: working tree is not clean; commit or stash first" >&2
  exit 1
fi

git fetch origin "$BRANCH"
if ! git merge-base --is-ancestor "origin/$BRANCH" HEAD; then
  echo "Error: $BRANCH is behind origin/$BRANCH; pull first" >&2
  exit 1
fi

CURRENT="$(<"$VERSION_FILE")"
if [[ ! "$CURRENT" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
  echo "Error: $VERSION_FILE contains '$CURRENT', expected X.Y.Z" >&2
  exit 1
fi

IFS=. read -r MAJOR MINOR PATCH <<<"$CURRENT"
case "$BUMP" in
  major) NEW="$((MAJOR + 1)).0.0" ;;
  minor) NEW="$MAJOR.$((MINOR + 1)).0" ;;
  patch) NEW="$MAJOR.$MINOR.$((PATCH + 1))" ;;
esac

# docker-publish.yml only runs tag builds for v* refs, so the tag needs the prefix.
TAG="v$NEW"
if git rev-parse -q --verify "refs/tags/$TAG" >/dev/null; then
  echo "Error: tag $TAG already exists" >&2
  exit 1
fi

printf '%s\n' "$NEW" >"$VERSION_FILE"
git add "$VERSION_FILE"
git commit -m "Release $NEW"
git tag -a "$TAG" -m "Release $NEW"
git push origin "$BRANCH" "$TAG"

echo "Released $CURRENT -> $NEW (tag $TAG)"