name: Generate Release Notes

on:
  workflow_run:
    workflows: ["Release"]
    types:
      - completed

permissions:
  contents: write
  copilot-requests: write

jobs:
  generate-release-notes:
    runs-on: ubuntu-latest
    timeout-minutes: 15
    if: github.repository == 'donutbrowser/donutbrowser' && github.event.workflow_run.conclusion == 'success' && startsWith(github.event.workflow_run.head_branch, 'v')

    steps:
      - name: Checkout repository
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 #v7.0.1
        with:
          fetch-depth: 0
          persist-credentials: false

      - name: Get release info
        id: get-release
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          TAG_NAME: ${{ github.event.workflow_run.head_branch }}
        run: |
          # head_branch is a tag name chosen by whoever pushed it; never let
          # anything but a plain version reach the API path or the prompt.
          if [[ ! "$TAG_NAME" =~ ^v[0-9]+\.[0-9]+\.[0-9]+([.-][0-9A-Za-z.-]+)?$ ]]; then
            echo "::error::Refusing tag with unexpected characters"
            exit 1
          fi
          echo "tag-name=$TAG_NAME" >> "$GITHUB_OUTPUT"

          # Get release info by tag
          RELEASE_INFO=$(gh api "/repos/$GITHUB_REPOSITORY/releases/tags/$TAG_NAME")
          RELEASE_ID=$(echo "$RELEASE_INFO" | jq -r '.id')
          IS_PRERELEASE=$(echo "$RELEASE_INFO" | jq -r '.prerelease')

          echo "release-id=$RELEASE_ID" >> "$GITHUB_OUTPUT"
          echo "is-prerelease=$IS_PRERELEASE" >> "$GITHUB_OUTPUT"

          if [ "$IS_PRERELEASE" = "true" ]; then
            echo "Skipping release notes generation for prerelease"
          fi

      - name: Get previous release tag
        id: get-previous-tag
        if: steps.get-release.outputs.is-prerelease == 'false'
        env:
          CURRENT_TAG: ${{ steps.get-release.outputs.tag-name }}
        run: |
          PREVIOUS_TAG=$(git tag --sort=-version:refname | grep -E '^v[0-9]+\.[0-9]+\.[0-9]+$' | grep -vxF "$CURRENT_TAG" | head -n 1)

          if [ -z "$PREVIOUS_TAG" ]; then
            echo "No previous release found, using initial commit"
            PREVIOUS_TAG=$(git rev-list --max-parents=0 HEAD)
          fi

          {
            echo "current-tag=$CURRENT_TAG"
            echo "previous-tag=$PREVIOUS_TAG"
          } >> "$GITHUB_OUTPUT"
          echo "Previous release: $PREVIOUS_TAG"
          echo "Current release: $CURRENT_TAG"

      - name: Get commit messages between releases
        id: get-commits
        if: steps.get-release.outputs.is-prerelease == 'false'
        env:
          PREVIOUS_TAG: ${{ steps.get-previous-tag.outputs.previous-tag }}
          CURRENT_TAG: ${{ steps.get-previous-tag.outputs.current-tag }}
        run: |
          git log --pretty=format:"- %s (%h by %an)" "$PREVIOUS_TAG".."$CURRENT_TAG" --no-merges > commits.txt
          echo "Collected $(wc -l < commits.txt) commits"

      - name: Set up Copilot CLI
        id: copilot
        if: steps.get-release.outputs.is-prerelease == 'false'
        uses: ./.github/actions/setup-copilot-cli

      - name: Generate release notes with AI
        id: generate-notes
        if: steps.get-release.outputs.is-prerelease == 'false'
        uses: actions/ai-inference@2c43c91ae16266ca159d311430343c67a5ffa222 # v3
        with:
          prompt-file: .github/prompts/release-notes.prompt.yml
          input: |
            version: ${{ steps.get-previous-tag.outputs.current-tag }}
          file_input: |
            commits: ./commits.txt
          # Runs the CLI without AGENTS.md as instructions, without the GitHub
          # MCP server and without auto-update; see setup-copilot-cli.
          copilot-cli-path: ${{ steps.copilot.outputs.launcher }}
        env:
          # The Copilot CLI reads its credential from the environment; the
          # workflow token carries it under the `copilot-requests` permission
          # granted above, so no PAT is needed.
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Update release with generated notes
        if: steps.get-release.outputs.is-prerelease == 'false'
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          RESPONSE_FILE: ${{ steps.generate-notes.outputs.response-file }}
          RESPONSE_OUTPUT: ${{ steps.generate-notes.outputs.response }}
          RELEASE_ID: ${{ steps.get-release.outputs.release-id }}
        run: |
          # Prefer reading from the response file to avoid output truncation
          if [ -n "$RESPONSE_FILE" ] && [ -f "$RESPONSE_FILE" ]; then
            RELEASE_NOTES=$(cat "$RESPONSE_FILE")
          else
            RELEASE_NOTES="$RESPONSE_OUTPUT"
          fi

          # An empty answer would PATCH the release body to nothing and wipe
          # the notes the release already has.
          if [ -z "${RELEASE_NOTES//[[:space:]]/}" ]; then
            echo "::error::The generated release notes are empty; leaving the release unchanged"
            exit 1
          fi

          gh api --method PATCH "/repos/$GITHUB_REPOSITORY/releases/$RELEASE_ID" \
            --field body="$RELEASE_NOTES" --silent

          echo "Release notes updated"

      - name: Cleanup
        if: always()
        run: |
          rm -f commits.txt