name: Publish Flatpak repository to Pages

on:
  release:
    types: [published]
  workflow_dispatch:
    inputs:
      release_tag:
        description: "Published GitHub release tag to publish (for example, v1.2.3)"
        required: true
        type: string

permissions:
  contents: read

concurrency:
  group: flatpak-pages-${{ github.repository }}
  cancel-in-progress: false

jobs:
  build:
    name: Build Flatpak repository
    # Pre-releases (rc builds) never reach the stable branch: a published pre-release is skipped
    # here, and the validation step below refuses a manual tag with a pre-release suffix.
    if: github.event_name != 'release' || !github.event.release.prerelease
    runs-on: ubuntu-24.04
    permissions:
      contents: read
      # configure-pages only reads the Pages configuration (base_url); deploy needs write.
      pages: read
    env:
      GH_TOKEN: ${{ github.token }}
      RELEASE_TAG: ${{ github.event.release.tag_name || inputs.release_tag }}
      APP_ID: ai.storyteller.gridcraft
    steps:
      - name: Configure Pages
        id: pages
        uses: actions/configure-pages@45bfe0192ca1faeb007ade9deae92b16b8254a0d # v6.0.0

      - name: Install Flatpak repository tools
        run: |
          sudo apt-get update
          sudo apt-get install -y --no-install-recommends flatpak ostree

      - name: Download and validate release bundles
        shell: bash
        run: |
          set -euo pipefail
          tag="$RELEASE_TAG"
          if ! printf '%s' "$tag" | grep -Eq '^v(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(-((0|[1-9][0-9]*|[0-9]*[A-Za-z-][0-9A-Za-z-]*)(\.(0|[1-9][0-9]*|[0-9]*[A-Za-z-][0-9A-Za-z-]*))*))?(\+[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$'; then
            echo "::error::Release tag '$tag' is not strict SemVer prefixed with v"
            exit 1
          fi
          # A pre-release has a "-" before any "+build" metadata (v1.2.3-rc.1).
          case "${tag%%+*}" in
            *-*)
              echo "::error::$tag is a pre-release; only stable releases are published to the Flatpak repository"
              exit 1
              ;;
          esac
          published_tag="$(gh api "repos/$GITHUB_REPOSITORY/releases/tags/$tag" --jq \
            'select(.draft == false and .prerelease == false and .published_at != null) | .tag_name')"
          if [[ "$published_tag" != "$tag" ]]; then
            echo "::error::$tag is not a published stable (non-pre-release) release in $GITHUB_REPOSITORY"
            exit 1
          fi

          version="${tag#v}"
          mkdir -p bundles
          gh release download "$tag" --repo "$GITHUB_REPOSITORY" \
            --pattern SHA256SUMS.txt --dir bundles
          for arch in x86_64 aarch64; do
            asset="gridcraft-$version-linux-$arch.flatpak"
            gh release download "$tag" --repo "$GITHUB_REPOSITORY" \
              --pattern "$asset" --dir bundles
            test -s "bundles/$asset"
            (
              cd bundles
              awk -v file="$asset" '$2 == file || $2 == "*" file { print; found=1 } END { exit !found }' \
                SHA256SUMS.txt | sha256sum --check -
            )
          done
          test "$(find bundles -maxdepth 1 -type f -name '*.flatpak' | wc -l)" -eq 2

          for arch in x86_64 aarch64; do
            asset="bundles/gridcraft-$version-linux-$arch.flatpak"
            validation_repo="$(mktemp -d)"
            ostree --repo="$validation_repo" init --mode=archive-z2
            flatpak build-import-bundle "$validation_repo" "$asset"
            expected_ref="app/$APP_ID/$arch/stable"
            ostree --repo="$validation_repo" refs | grep -Fxq "$expected_ref" || {
              echo "::error::$(basename "$asset") does not contain $expected_ref"
              exit 1
            }
            rm -rf "$validation_repo"
          done

      - name: Build repository and site
        shell: bash
        env:
          PAGES_BASE_URL: ${{ steps.pages.outputs.base_url }}
        run: |
          set -euo pipefail
          site="$RUNNER_TEMP/site"
          repo_dir="$site/flatpak/repo"
          mkdir -p "$repo_dir"
          ostree --repo="$repo_dir" init --mode=archive-z2

          previous_url="${PAGES_BASE_URL%/}/flatpak/repo"
          if curl --fail --silent --show-error --location \
            --output /dev/null "$previous_url/summary"; then
            ostree --repo="$repo_dir" remote add --no-gpg-verify previous "$previous_url"
            ostree --repo="$repo_dir" pull --mirror previous
            ostree --repo="$repo_dir" remote delete previous
          fi

          version="${RELEASE_TAG#v}"
          for arch in x86_64 aarch64; do
            flatpak build-import-bundle "$repo_dir" \
              "bundles/gridcraft-$version-linux-$arch.flatpak"
          done
          # Prune unreachable objects and keep at most 3 commits per ref, so the Pages repository
          # (re-mirrored and re-deployed on every release) does not grow without bound.
          flatpak build-update-repo \
            --prune --prune-depth=3 \
            --title="GridCraft" \
            --comment='Official GridCraft releases' \
            --description='Official Flatpak repository for GridCraft' \
            --homepage="https://github.com/$GITHUB_REPOSITORY" \
            --default-branch=stable \
            "$repo_dir"

          for arch in x86_64 aarch64; do
            ostree --repo="$repo_dir" rev-parse "app/$APP_ID/$arch/stable" >/dev/null
          done
          test -s "$repo_dir/summary"

          base_url="${PAGES_BASE_URL%/}"
          repo_url="$base_url/flatpak/repo/"
          cat >"$site/flatpak/gridcraft.flatpakrepo" <<META
          [Flatpak Repo]
          Title=GridCraft
          Comment=Official GridCraft releases
          Description=Official Flatpak repository for GridCraft
          Url=$repo_url
          Homepage=https://github.com/$GITHUB_REPOSITORY
          META
          cat >"$site/flatpak/index.html" <<HTML
          <!doctype html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1"><title>GridCraft Flatpak repository</title></head><body><main><h1>GridCraft Flatpak repository</h1><p>Latest published release: <strong>$RELEASE_TAG</strong></p><p><a href="gridcraft.flatpakrepo">Add the GridCraft repository</a></p><pre>flatpak remote-add --if-not-exists gridcraft $base_url/flatpak/gridcraft.flatpakrepo
          flatpak install gridcraft $APP_ID</pre></main></body></html>
          HTML
          cat >"$site/index.html" <<HTML
          <!doctype html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1"><title>GridCraft downloads</title></head><body><main><h1>GridCraft downloads</h1><p><a href="flatpak/">Flatpak repository</a></p><p><a href="https://github.com/$GITHUB_REPOSITORY/releases/tag/$RELEASE_TAG">Release assets</a></p></main></body></html>
          HTML
          touch "$site/.nojekyll"

      - name: Upload Pages artifact
        uses: actions/upload-pages-artifact@fc324d3547104276b827a68afc52ff2a11cc49c9 # v5.0.0
        with:
          path: ${{ runner.temp }}/site
          include-hidden-files: true

  deploy:
    name: Deploy Pages
    needs: build
    runs-on: ubuntu-24.04
    permissions:
      pages: write
      id-token: write
    environment:
      name: github-pages
      url: ${{ steps.deployment.outputs.page_url }}
    steps:
      - name: Deploy to GitHub Pages
        id: deployment
        uses: actions/deploy-pages@368f82528645a54fb793d4d04e342629a3f51346 # v5.0.1