#!/bin/sh
set -eu
cd -- "$(dirname "$0")/../.."
. ./ci/sub/lib.sh

help() {
  cat <<EOF
usage: $0 [--rebuild] <version>

$0 implements the D2 release process.

Flags:

--rebuild: Normally the release script will avoid rebuilding release assets if they
           already exist but if you changed something and need to force rebuild, use
           this flag.
--prerelease: Pass to mark the release on GitHub as a pre-release. For pre-releases the
               version format should include a suffix like v0.0.99-alpha.1
               As well, for pre-releases the script will not overwrite changelogs/next.md
               with changelogs/template.md and instead keep it the same as
               changelogs/v0.0.99-alpha.1.md. This is because you want to maintain the
               changelog entries for the eventual final release.
--dry-run: Print the commands that would be ran without executing them.

Process:

Let's say you passed in v0.0.99 as the version:

1. It creates branch v0.0.99 based on master if one does not already exist.
   - It then checks it out.
2. It moves changelogs/next.md to changelogs/v0.0.99.md if there isn't already a
   changelogs/v0.0.99.md.
   - If the move occured, changelogs/next.md is replaced with changelogs/template.md.
3. If the current commit does not have a title of v0.0.99 then a new commit with said
   title will be created with all uncommitted changes.
   - If the current commit does, then the uncommitted changes will be amended to the commit.
4. It pushes branch v0.0.99 to origin.
5. It creates a v0.0.99 git tag if one does not already exist.
   If one does, it ensures the v0.0.99 tag points to the current commit.
   Then it pushes the tag to origin.
6. It creates a draft GitHub release for the tag if one does not already exist.
   - It will also set the release notes to match changelogs/v0.0.99.md even
     if the release already exists.
7. It creates a draft PR for branch v0.0.99 into master if one does not already exist.
8. It builds the release assets if they do not exist.
   Pass --rebuild to force rebuilding all release assets.
9. It uploads the release assets overwriting any existing assets on the release.

Only a draft release will be created so do not fret if something goes wrong.
You can just rerun the script again as it is fully idempotent.

To complete the release, merge the release PR and then publish the draft release.

Testing:

For testing, change the origin remote to a private throwaway repository and push master to
it. Then the PR, tag and draft release will be generated against said throwaway
repository.

Example:
  $0 v0.0.99
EOF
}

main() {
  while :; do
    flag_parse "$@"
    case "$FLAG" in
      h|help)
        help
        return 0
        ;;
      rebuild)
        flag_noarg && shift "$FLAGSHIFT"
        REBUILD=1
        ;;
      prerelease)
        flag_noarg && shift "$FLAGSHIFT"
        PRERELEASE=1
        ;;
      dry-run)
        flag_noarg && shift "$FLAGSHIFT"
        DRY_RUN=1
        ;;
      '')
        shift "$FLAGSHIFT"
        break
        ;;
      *)
        flag_errusage "unrecognized flag $FLAGRAW"
        ;;
    esac
  done

  if [ $# -ne 1 ]; then
    flag_errusage "first argument must be release version like v0.0.99"
  fi
  VERSION="$1"
  shift

  header '1_ensure_branch' && _1_ensure_branch
  header '2_ensure_changelog' && _2_ensure_changelog
  header '3_ensure_commit' && _3_ensure_commit
  header '4_push_branch' && _4_push_branch
  header '5_ensure_tag' && _5_ensure_tag
  header '6_ensure_release' && _6_ensure_release
  header '7_ensure_pr' && _7_ensure_pr
  header '8_ensure_assets' && _8_ensure_assets
  header '9_upload_assets' && _9_upload_assets

  COLOR=2 header 'final steps'
  cat >&2 <<EOF
1. Review and test the release: $release_url
2. Merge the PR: $pr_url
3. Publish the release!
EOF
}

_1_ensure_branch() {
  if [ -z "$(git branch --list "$VERSION")" ]; then
    sh_c git branch "$VERSION" master
  fi
  sh_c git checkout -q "$VERSION"
}

_2_ensure_changelog() {
  if [ -f "./ci/release/changelogs/$VERSION.md" ]; then
    log "./ci/release/changelogs/$VERSION.md"
    return 0
  fi

  sh_c cp "./ci/release/changelogs/next.md" "./ci/release/changelogs/$VERSION.md"
  if [ -z "${PRERELEASE-}" ]; then
    sh_c cp "./ci/release/changelogs/template.md" "./ci/release/changelogs/next.md"
  fi
}

_3_ensure_commit() {
  sh_c git add --all
  if [ "$(git show --no-patch --format=%s)" = "$VERSION" ]; then
    sh_c git commit --allow-empty --amend --no-edit
  else
    sh_c git commit --allow-empty -m "$VERSION"
  fi
}

_4_push_branch() {
  if git rev-parse @{u} >/dev/null 2>&1; then
    sh_c git push -f origin "refs/heads/$VERSION"
  else
    sh_c git push -fu origin "refs/heads/$VERSION"
  fi
}

_5_ensure_tag() {
  sh_c git tag --force -a "$VERSION" -m "$VERSION"
  sh_c git push -f origin "refs/tags/$VERSION"
}

_6_ensure_release() {
  release_url="$(gh release view "$VERSION" --json=url '--template={{ .url }}' 2>/dev/null || true)"
  if [ -n "$release_url" ]; then
    release_url="$(sh_c gh release edit \
      --draft \
      --notes-file "./ci/release/changelogs/$VERSION.md" \
      ${PRERELEASE:+--prerelease} \
      "--title=$VERSION" \
      "$VERSION" | tee /dev/stderr)"
    return 0
  fi
  release_url="$(sh_c gh release create \
    --draft \
    --notes-file "./ci/release/changelogs/$VERSION.md" \
    ${PRERELEASE:+--prerelease} \
    "--title=$VERSION" \
    "$VERSION" | tee /dev/stderr)"
}

_7_ensure_pr() {
  # We do not use gh pr view as that includes closed PRs.
  pr_url="$(gh pr list --head "$VERSION" --json=url '--template={{ range . }}{{ .url }}{{end}}')"
  body="Will be available at $(gh repo view --json=url '--template={{ .url }}')/releases/tag/$VERSION"
  if [ -n "$pr_url" ]; then
    sh_c gh pr edit --body "$body" "$VERSION"
    return 0
  fi

  pr_url="$(sh_c gh pr create --fill --body "$body" | tee /dev/stderr)"
}

_8_ensure_assets() {
  sh_c ./ci/release/build.sh ${REBUILD:+--rebuild}
}

_9_upload_assets() {
  sh_c gh release upload --clobber "$VERSION" "./ci/release/build/$VERSION"/*.tar.gz
}

main "$@"