name: Release notes from commits

on:
  release:
    types: [published]

permissions:
  contents: write

jobs:
  generate-notes:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0 # fetch all tags/commits for range and logs

      - name: Compute previous tag
        id: prev
        env:
          CURRENT_TAG: ${{ github.event.release.tag_name }}
        shell: bash
        run: |
          set -e
          git fetch --tags --force
          if [ -z "$CURRENT_TAG" ]; then
            echo "No current tag found from release payload" 1>&2
            exit 1
          fi
          # Sort by version, pick the latest tag that is not the current tag
          PREV_TAG=$(git tag --sort=-v:refname | grep -v "^${CURRENT_TAG}$" | head -n 1 || true)
          echo "Previous tag: $PREV_TAG"
          echo "prev_tag=$PREV_TAG" >> "$GITHUB_OUTPUT"

      - name: Generate release notes from commits
        id: gen
        env:
          CURRENT_TAG: ${{ github.event.release.tag_name }}
          PREV_TAG: ${{ steps.prev.outputs.prev_tag }}
          REPO: ${{ github.repository }}
        shell: bash
        run: |
          set -e
          if [ -n "$PREV_TAG" ]; then
            RANGE="$PREV_TAG..$CURRENT_TAG"
            echo "# Release $CURRENT_TAG" > RELEASE_NOTES.md
            echo >> RELEASE_NOTES.md
            echo "[Full Changelog](https://github.com/$REPO/compare/$PREV_TAG...$CURRENT_TAG)" >> RELEASE_NOTES.md
            echo >> RELEASE_NOTES.md
          else
            RANGE="$CURRENT_TAG"
            echo "# Release $CURRENT_TAG" > RELEASE_NOTES.md
            echo >> RELEASE_NOTES.md
          fi

          echo "## Changes" >> RELEASE_NOTES.md
          echo >> RELEASE_NOTES.md
          # Use commit subjects; skip merge commits for clarity
          git log --no-merges --pretty=format:'- %s (%h) by %an' $RANGE >> RELEASE_NOTES.md || true

          echo "Generated notes:" && echo "-----" && cat RELEASE_NOTES.md && echo "-----"

      - name: Update GitHub Release body
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const notes = fs.readFileSync('RELEASE_NOTES.md', 'utf8');
            const releaseId = context.payload.release.id;
            await github.rest.repos.updateRelease({
              owner: context.repo.owner,
              repo: context.repo.repo,
              release_id: releaseId,
              body: notes,
            });