name: Update (Post Release) README URLs

on:
  release:
    types:
      - published
      - released
  workflow_dispatch:
    inputs:
      tag:
        description: 'Release tag (e.g., v0.10.2)'
        required: true
        type: string

permissions:
  contents: read

concurrency:
  group: update-post-release-readme-urls
  cancel-in-progress: true

jobs:
  update:
    # Keep prereleases from replacing the stable README download buttons.
    if: github.event_name == 'workflow_dispatch' || !github.event.release.prerelease
    runs-on: ubuntu-latest
    env:
      README_BRANCH: automation/update-readme-release-links
      RELEASE_TAG: ${{ github.event.release.tag_name || inputs.tag }}
    steps:
      - uses: actions/checkout@v6
        with:
          ref: main
          persist-credentials: false

      - uses: pnpm/setup@v2
        with:
          runtime: node@26.7.0
          cache: true
          install: false
      - run: pnpm install --frozen-lockfile

      - name: Update README download links
        run: pnpm -F @proj-airi/stage-tamagotchi exec tsx scripts/update-readme-download-links.ts "$RELEASE_TAG"

      - name: Pull with rebase
        run: git pull origin main --rebase --autostash

      - name: Prepare README release update
        id: prepare
        env:
          GH_TOKEN: ${{ secrets.PAT_SLASH_COMMAND_DISPATCH }}
        run: |
          # The updater is only allowed to publish the generated README link changes.
          if ! git diff --quiet -- . ':(exclude)README.md' ':(exclude)docs/README*.md'; then
            echo "::error::Unexpected non-README changes were generated."
            git status --short
            exit 1
          fi

          git add README.md 'docs/README*.md'
          if git diff --cached --quiet; then
            echo "No README release links changed."
            echo "changed=false" >> "$GITHUB_OUTPUT"
            exit 0
          fi

          if [ -z "$GH_TOKEN" ]; then
            echo "::error::PAT_SLASH_COMMAND_DISPATCH is required so the README update PR triggers required checks."
            exit 1
          fi

          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git remote set-url origin "https://x-access-token:${GH_TOKEN}@github.com/${GITHUB_REPOSITORY}.git"

          REMOTE_BRANCH="$(git ls-remote --heads origin "refs/heads/${README_BRANCH}")"
          if [ -n "$REMOTE_BRANCH" ]; then
            git fetch origin "${README_BRANCH}:refs/remotes/origin/${README_BRANCH}"
          fi

          git checkout -B "$README_BRANCH"
          PR_TITLE="chore: update README release artifacts to ${RELEASE_TAG}"
          git commit -m "$PR_TITLE"
          git push --force-with-lease origin "$README_BRANCH"

          echo "changed=true" >> "$GITHUB_OUTPUT"
          echo "pr_title=$PR_TITLE" >> "$GITHUB_OUTPUT"

      - name: Create or update README release PR
        if: steps.prepare.outputs.changed == 'true'
        uses: actions/github-script@v8
        env:
          PR_TITLE: ${{ steps.prepare.outputs.pr_title }}
        with:
          github-token: ${{ secrets.PAT_SLASH_COMMAND_DISPATCH }}
          script: |
            const { owner, repo } = context.repo;
            const head = `${owner}:${process.env.README_BRANCH}`;
            const body = [
              '## Description',
              '',
              `Updates stable desktop download links after the ${process.env.RELEASE_TAG} release.`,
              '',
              '## Linked Issues',
              '',
              'None.',
              '',
              '## Additional Context',
              '',
              'Generated by the post-release README workflow.',
            ].join('\n');

            const { data: openPullRequests } = await github.rest.pulls.list({
              owner,
              repo,
              state: 'open',
              base: 'main',
              head,
              per_page: 1,
            });

            let pullRequest;
            if (openPullRequests.length > 0) {
              const { data } = await github.rest.pulls.update({
                owner,
                repo,
                pull_number: openPullRequests[0].number,
                title: process.env.PR_TITLE,
                body,
              });
              pullRequest = data;
              core.info(`Updated pull request #${pullRequest.number}.`);
            }
            else {
              const { data } = await github.rest.pulls.create({
                owner,
                repo,
                base: 'main',
                head: process.env.README_BRANCH,
                title: process.env.PR_TITLE,
                body,
              });
              pullRequest = data;
              core.info(`Created pull request #${pullRequest.number}.`);
            }

            if (!pullRequest.auto_merge) {
              await github.graphql(
                `mutation EnableAutoMerge($pullRequestId: ID!) {
                  enablePullRequestAutoMerge(input: {
                    pullRequestId: $pullRequestId
                    mergeMethod: SQUASH
                  }) {
                    pullRequest {
                      number
                    }
                  }
                }`,
                {
                  pullRequestId: pullRequest.node_id,
                },
              );
              core.info(`Enabled squash auto-merge for pull request #${pullRequest.number}.`);
            }