name: Upstream release

# Watches Modrinth for a new Modrinth App release, rebuilds Modrinth Enhanced
# on top of it, and publishes a release of our own if everything still works.
# When the patches changed since our last release of that upstream version,
# it publishes them again as a revision: v1.2.3-2, v1.2.3-3, ...
#
# Nothing is published unless the patches applied, the checks passed and all
# three platforms built, so an upstream change that breaks a patch stops here
# and reports a failure instead of shipping a broken build.

on:
  schedule:
    - cron: '17 6 * * *'
  workflow_dispatch:
    inputs:
      upstream-ref:
        description: Build this upstream tag instead of the newest one
        type: string
        required: false

permissions:
  contents: write

concurrency:
  group: upstream-release
  cancel-in-progress: false

jobs:
  detect:
    name: Detect
    runs-on: ubuntu-latest
    outputs:
      upstream: ${{ steps.check.outputs.upstream }}
      tag: ${{ steps.check.outputs.tag }}
      proceed: ${{ steps.check.outputs.proceed }}
    steps:
      - uses: actions/checkout@v4

      - name: Decide what to release
        id: check
        env:
          REQUESTED: ${{ inputs.upstream-ref }}
        run: |
          set -euo pipefail
          current="$(tr -d '[:space:]' < upstream.txt)"
          upstream="${REQUESTED:-$(scripts/latest-upstream.sh)}"
          echo "upstream=$upstream" >> "$GITHUB_OUTPUT"
          echo "Upstream release: $upstream (we are on $current)"

          # Our newest release of it, as "<revision> <tag>". The plain tag is
          # revision 1.
          last="$(
            git ls-remote --tags --refs origin "$upstream" "$upstream-*" |
              sed 's#.*refs/tags/##' |
              awk -v up="$upstream" '
                $0 == up { print 1, $0; next }
                index($0, up "-") == 1 {
                  n = substr($0, length(up) + 2)
                  if (n ~ /^[0-9]+$/) print n, $0
                }' |
              sort -n |
              tail -1
          )"

          if [ -z "$last" ]; then
            tag="$upstream"
          else
            revision="${last%% *}"
            last_tag="${last#* }"
            git fetch --no-tags --depth=1 origin "refs/tags/$last_tag:refs/tags/$last_tag"
            # Only what goes into the build counts, not docs or CI.
            if git diff --quiet "$last_tag" HEAD -- patches scripts; then
              echo "$last_tag already ships the current patches; nothing to do."
              echo "proceed=false" >> "$GITHUB_OUTPUT"
              exit 0
            fi
            tag="$upstream-$((revision + 1))"
          fi

          echo "tag=$tag" >> "$GITHUB_OUTPUT"
          echo "proceed=true" >> "$GITHUB_OUTPUT"
          echo "Releasing $tag"

  build:
    name: Build
    needs: detect
    if: needs.detect.outputs.proceed == 'true'
    uses: ./.github/workflows/build.yml
    with:
      upstream-ref: ${{ needs.detect.outputs.upstream }}

  release:
    name: Release
    needs: [detect, build]
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Record the upstream release we build against
        env:
          UPSTREAM: ${{ needs.detect.outputs.upstream }}
        run: |
          set -euo pipefail
          printf '%s\n' "$UPSTREAM" > upstream.txt
          if git diff --quiet -- upstream.txt; then
            echo "upstream.txt already points at $UPSTREAM"
            exit 0
          fi
          git config user.name 'github-actions[bot]'
          git config user.email '41898282+github-actions[bot]@users.noreply.github.com'
          git commit -m "Track upstream $UPSTREAM" -- upstream.txt
          git push origin HEAD:${{ github.event.repository.default_branch }}

      - name: Download installers
        uses: actions/download-artifact@v4
        with:
          path: artifacts
          merge-multiple: true

      - name: Publish the release
        env:
          GH_TOKEN: ${{ github.token }}
          TAG: ${{ needs.detect.outputs.tag }}
          UPSTREAM: ${{ needs.detect.outputs.upstream }}
        run: |
          set -euo pipefail
          ls -la artifacts
          # Every patch by its subject, so the list never falls behind.
          patches="$(
            for patch in patches/0*.patch; do
              awk '/^Subject: /{
                s = $0
                sub(/^Subject: (\[PATCH[^]]*\] )?/, "", s)
                while ((getline line) > 0 && line ~ /^ /) s = s line
                print "- " s
                exit
              }' "$patch"
            done
          )"
          notes="$(cat <<EOF
          Modrinth Enhanced $TAG, built from [Modrinth App $UPSTREAM](https://github.com/modrinth/code/releases/tag/$UPSTREAM).

          Same app as upstream, with the patches in \`patches/\` applied:

          $patches

          It keeps using the same data directory as the official Modrinth App,
          so instances, settings and accounts carry over. Do not run both at
          the same time.

          See the upstream release notes for everything else that changed.
          EOF
          )"
          # The tag goes on the commit that was built, not on whatever main is
          # by now, so the next run compares against the patches it shipped.
          gh release create "$TAG" \
            --target "$(git rev-parse HEAD)" \
            --title "Modrinth Enhanced $TAG" \
            --notes "$notes" \
            artifacts/*