name: update
on:
  workflow_dispatch: # allows manual triggering
    inputs:
      branch:
        description: "Branch to update"
        type: choice
        options:
          - "stable & unstable"
          - "main"
          - "nixos-24.05"
  schedule:
    - cron: "0 12 * * SAT" # runs weekly on Saturday at noon

jobs:
  lockfile:
    strategy:
      matrix:
        # This allows to update both stable & unstable branches, but not both when triggered
        # manually
        branch: ["main", "nixos-24.05"]
        selectedBranch: ["${{ inputs.branch }}"]
        exclude:
          - selectedBranch: main
            branch: "nixos-24.05"
          - selectedBranch: "nixos-24.05"
            branch: main

    name: Update the flake inputs and generate options
    runs-on: ubuntu-latest
    timeout-minutes: 40

    permissions:
      contents: write
      pull-requests: write

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          ssh-key: ${{ secrets.CI_UPDATE_SSH_KEY }}
          ref: ${{ matrix.branch }}

      - name: Install Nix
        uses: cachix/install-nix-action@v26
        with:
          nix_path: nixpkgs=channel:nixos-unstable
          github_access_token: ${{ secrets.GITHUB_TOKEN }}

      - name: Configure git
        run: |
          git config user.name 'github-actions[bot]'
          git config user.email '41898282+github-actions[bot]@users.noreply.github.com'

      - name: Update flake.lock
        id: flake_lock
        run: |
          old=$(git show --no-patch --format=%h)
          nix flake update --commit-lock-file
          new=$(git show --no-patch --format=%h)
          if [ "$old" != "$new" ]; then
            echo "body<<EOF" >> "$GITHUB_OUTPUT"
            git show --no-patch --format=%b >> "$GITHUB_OUTPUT"
            echo "EOF" >> "$GITHUB_OUTPUT"
          fi

      - name: Update autogenerated files
        id: generate
        run: |
          old=$(git show --no-patch --format=%h)
          nix run .#generate-files -- --commit
          new=$(git show --no-patch --format=%h)
          if [ "$old" != "$new" ]; then
            summary=$(git show --no-patch --format=%s)
            echo "summary=$summary" >> "$GITHUB_OUTPUT"
            echo "body<<EOF" >> "$GITHUB_OUTPUT"
            git show --no-patch --format=%b >> "$GITHUB_OUTPUT"
            echo "EOF" >> "$GITHUB_OUTPUT"
          fi

      - name: Create Pull Request
        id: pr
        uses: peter-evans/create-pull-request@v6
        with:
          branch: update/${{ matrix.branch }}
          base: ${{ matrix.branch }}
          delete-branch: true
          team-reviewers: |
            nix-community/nixvim
          title: |
            [${{ matrix.branch }}] Update flake.lock & generated files
          body: |
            ## Flake lockfile
            ```
            ${{ steps.flake_lock.outputs.body || 'No changes' }}
            ```

            ## Generate
            ${{ steps.generate.outputs.body || steps.generate.outputs.summary || 'No changes' }}

      - name: Print summary
        if: ${{ steps.pr.outputs.pull-request-number }}
        run: |
          num="${{ steps.pr.outputs.pull-request-number }}"
          pr_url="${{ steps.pr.outputs.pull-request-url }}"
          pr_branch="${{ steps.pr.outputs.pull-request-branch }}"
          head="${{ steps.pr.outputs.pull-request-head-sha }}"
          operation="${{ steps.pr.outputs.pull-request-operation }}"

          # stdout
          echo "${head:0:6} pushed to ${pr_branch}"
          echo "${pr} was ${operation}."

          # markdown summary
          echo "## ${{ matrix.branch }}" >> $GITHUB_STEP_SUMMARY
          echo >> $GITHUB_STEP_SUMMARY
          echo "\`${head:0:6}\` pushed to \`${pr_branch}\`" >> $GITHUB_STEP_SUMMARY
          echo >> $GITHUB_STEP_SUMMARY
          echo "[#${num}](${pr_url}) was ${operation}." >> $GITHUB_STEP_SUMMARY
          echo >> $GITHUB_STEP_SUMMARY