name: Prepare release

env:
  GIT_AUTHOR_EMAIL: "packages@datadoghq.com"
  GIT_AUTHOR_NAME: "ci.datadog-api-spec"

on:
  workflow_dispatch:
    inputs:
      version:
        description: New version number (e.g. '1.2.3' without the 'v' prefix)

jobs:
  prepare_release:
    name: Create release PR
    runs-on: ubuntu-latest
    steps:
      - name: Get GitHub App token
        id: get_token
        uses: tibdex/github-app-token@v1
        with:
          app_id: ${{ secrets.PIPELINE_GITHUB_APP_ID }}
          private_key: ${{ secrets.PIPELINE_GITHUB_APP_PRIVATE_KEY }}
      - uses: actions/checkout@v2
        with:
          fetch-depth: 0
          token: ${{ steps.get_token.outputs.token }}

      - name: Setup Git
        run: |
          git config user.name "${GIT_AUTHOR_NAME}"
          git config user.email "${GIT_AUTHOR_EMAIL}"

      - name: Set up Ruby 2.6
        uses: ruby/setup-ruby@v1
        with:
          ruby-version: 2.6

      - name: Calculate version
        id: get_version
        run: |
          if [ "${VERSION}" = "" ] ; then
            LATEST_TAG=$(git describe --tags --abbrev=0)
            NEXT_TAG=$(echo ${LATEST_TAG#v} | awk '{split($0, a, "."); print a[1] "." a[2] + 1 "." a[3]}')
            echo ::set-output name=version::$NEXT_TAG
          else
            echo ::set-output name=version::$VERSION
          fi
        env:
          VERSION: ${{ github.event.inputs.version }}

      - name: Bump version
        run: |
          git switch -c "release/${RELEASE_VERSION}"
          bundle install
          bundle exec gem bump -v "${RELEASE_VERSION}"
          git push -f --set-upstream origin "release/${RELEASE_VERSION}"
        env:
          RELEASE_VERSION: ${{ steps.get_version.outputs.version }}

      - name: Create PR
        uses: actions/github-script@v5
        env:
          RELEASE_VERSION: ${{ steps.get_version.outputs.version }}
          BASE: ${{ github.event.ref }}
        with:
          github-token: ${{ steps.get_token.outputs.token }}
          script: |
            const { data: notes } = await github.rest.repos.generateReleaseNotes({
              owner: context.repo.owner,
              repo: context.repo.repo,
              tag_name: `v${process.env.RELEASE_VERSION}`,
            });
            const today = new Date().toJSON().slice(0, 10);
            const header = [`# CHANGELOG\n\n## ${process.env.RELEASE_VERSION} / ${today}\n`];
            const changes = header.concat(notes.body.split("\n").slice(3));
            const { data: content } = await github.rest.repos.getContent({
              owner: context.repo.owner,
              repo: context.repo.repo,
              path: "CHANGELOG.md",
            });
            const rawContent = Buffer.from(content.content, "base64")
              .toString("utf-8")
              .split("\n");
            const newContent = changes.concat(rawContent.slice(1)).join("\n");
            await github.rest.repos.createOrUpdateFileContents({
              owner: context.repo.owner,
              repo: context.repo.repo,
              message: "Update CHANGELOG",
              content: Buffer.from(newContent).toString("base64"),
              path: "CHANGELOG.md",
              branch: `release/${process.env.RELEASE_VERSION}`,
              sha: content.sha,
            });
            const { data: pr } = await github.rest.pulls.create({
              owner: context.repo.owner,
              repo: context.repo.repo,
              head: `release/${process.env.RELEASE_VERSION}`,
              base: process.env.BASE,
              title: `Release ${process.env.RELEASE_VERSION}`,
              body: "Update CHANGELOG",
            });
            await github.rest.issues.addLabels({
              issue_number: pr.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              labels: ["changelog/no-changelog"],
            });