prepare_release.yml

name: Prepare Release

# Run manually from the Actions tab.
# Creates a branch + PR that bumps the version, builds the changelog,
# and updates the docs switcher — ready to review before tagging.
on:
  workflow_dispatch:
    inputs:
      bump:
        description: "Version component to bump"
        required: true
        type: choice
        options:
          - finalize      # drop the bN suffix: release the current beta's base as stable (0.3.0b2 -> 0.3.0)
          - minor
          - bugfix
          - major
          - pre-release   # increments the bN counter on the current base version
      beta:
        description: "Mark as beta pre-release (adds bN suffix). Ignored for 'pre-release' (always beta) and 'finalize' (always stable)."
        required: false
        type: boolean
        default: false

permissions:
  contents: write        # push branch
  pull-requests: write   # open PR

jobs:
  prepare:
    name: Prepare release PR
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Set up uv
        uses: astral-sh/setup-uv@v5
        with:
          python-version: "3.13"
          enable-cache: true

      - name: Install dev dependencies
        run: uv sync

      # ── Compute the new version ──────────────────────────────────────────
      - name: Compute new version
        id: version
        env:
          BUMP: ${{ inputs.bump }}
          IS_BETA: ${{ inputs.beta }}
        run: |
          CURRENT=$(grep '^version = ' pyproject.toml | sed 's/version = "\(.*\)"/\1/')
          export CURRENT_VERSION="$CURRENT"

          NEW_VERSION=$(python3 - <<'PYEOF'
          import re, os

          current = os.environ["CURRENT_VERSION"]
          bump    = os.environ["BUMP"]
          is_beta = os.environ["IS_BETA"].lower() == "true"

          m = re.match(r"^(\d+)\.(\d+)\.(\d+)(?:b(\d+))?", current)
          major  = int(m.group(1))
          minor  = int(m.group(2))
          patch  = int(m.group(3))
          beta_n = int(m.group(4)) if m.group(4) else None
          on_beta = beta_n is not None

          if bump == "finalize":
              # Release the current beta's base as stable: just drop the bN
              # suffix, keep major.minor.patch. e.g. 0.3.0b2 -> 0.3.0.
              if not on_beta:
                  raise SystemExit(
                      f"'finalize' requires a beta base version, but current "
                      f"version {current!r} has no bN suffix. Use minor / bugfix "
                      f"/ major to start a new release instead."
                  )
              is_beta = False
          elif bump == "pre-release":
              # Keep the same base; just walk the beta counter forward.
              is_beta = True
              beta_n  = (beta_n or 0) + 1
          elif on_beta:
              # We are on a beta of the NEXT release (e.g. 0.3.0b2). The base
              # major.minor.patch is that upcoming version, so minor/bugfix/major
              # must bump relative to the LAST STABLE (base - the in-progress
              # component), not skip a whole version. The common intent from a
              # beta is 'finalize', so steer the user there rather than guess.
              raise SystemExit(
                  f"Current version {current!r} is a beta of the upcoming "
                  f"{major}.{minor}.{patch} release. To ship it, use bump="
                  f"'finalize' (-> {major}.{minor}.{patch}). A '{bump}' bump from "
                  f"a beta would skip {major}.{minor}.{patch} entirely "
                  f"(e.g. -> {'%d.%d.0' % (major, minor + 1) if bump == 'minor' else '...'}); "
                  f"that is almost never intended."
              )
          elif bump == "major":
              major, minor, patch = major + 1, 0, 0
          elif bump == "minor":
              minor, patch = minor + 1, 0
          elif bump == "bugfix":
              patch += 1

          if is_beta:
              if bump != "pre-release":
                  beta_n = 1          # fresh beta series for the new base
              print(f"{major}.{minor}.{patch}b{beta_n}", end="")
          else:
              print(f"{major}.{minor}.{patch}", end="")
          PYEOF
          )

          # Derive is_beta from the COMPUTED version (ends in bN?), not the raw
          # input — so 'finalize' is always treated as stable and a mismatched
          # beta checkbox can't mislabel the switcher / skip the root redirect.
          if [[ "$NEW_VERSION" =~ b[0-9]+$ ]]; then IS_BETA_OUT=true; else IS_BETA_OUT=false; fi

          echo "new_version=$NEW_VERSION"                  >> "$GITHUB_OUTPUT"
          echo "tag=v$NEW_VERSION"                         >> "$GITHUB_OUTPUT"
          echo "branch=release/v$NEW_VERSION"              >> "$GITHUB_OUTPUT"
          echo "is_beta=$IS_BETA_OUT"                      >> "$GITHUB_OUTPUT"
          echo "Bumping (${{ inputs.bump }}): $CURRENT → $NEW_VERSION"

      # ── Bump version strings ─────────────────────────────────────────────
      - name: Bump version in pyproject.toml
        run: |
          sed -i 's/^version = ".*"/version = "${{ steps.version.outputs.new_version }}"/' pyproject.toml

      - name: Bump version in docs/conf.py
        run: |
          sed -i 's/^release = ".*"/release = "${{ steps.version.outputs.new_version }}"/' docs/conf.py

      # ── Build changelog ──────────────────────────────────────────────────
      - name: Build changelog with towncrier
        run: |
          FRAGMENT_COUNT=$(find upcoming_changes -maxdepth 1 -name "*.rst" \
                            ! -name "README.rst" | wc -l)
          if [ "$FRAGMENT_COUNT" -eq 0 ]; then
            echo "⚠ No news fragments found — skipping towncrier (CHANGELOG.rst unchanged)."
          else
            uvx towncrier build --yes --version "${{ steps.version.outputs.new_version }}"
          fi

      # ── Update docs switcher.json ────────────────────────────────────────
      - name: Update docs/switcher.json
        env:
          VERSION_TAG: ${{ steps.version.outputs.tag }}
          IS_BETA: ${{ steps.version.outputs.is_beta }}
        shell: python
        run: |
          import json, re, pathlib, os

          version = os.environ["VERSION_TAG"]
          is_beta = os.environ["IS_BETA"].lower() == "true"

          path = pathlib.Path("docs/_root/switcher.json")
          text = path.read_text()
          # The file may contain a trailing comma; strip it before parsing.
          text_clean = re.sub(r",(\s*[\]\}])", r"\1", text)
          entries = json.loads(text_clean)

          # Remove any existing entry for this version (makes the step idempotent).
          entries = [e for e in entries if e.get("version") != version]

          label = f"{version} (beta)" if is_beta else f"{version} (stable)"
          url   = f"https://cssfrancis.github.io/anyplotlib/{version}/"
          # Insert right after the "dev" entry so newest stable floats to top.
          entries.insert(1, {"name": label, "version": version, "url": url})

          path.write_text(json.dumps(entries, indent=2) + "\n")

      # ── Update root redirect for stable releases ─────────────────────────
      - name: Update root redirect (stable releases only)
        if: ${{ steps.version.outputs.is_beta == 'false' && inputs.bump != 'pre-release' }}
        env:
          VERSION_TAG: ${{ steps.version.outputs.tag }}
        shell: python
        run: |
          import re, pathlib, os

          version = os.environ["VERSION_TAG"]
          path = pathlib.Path("docs/_root/index.html")
          text = path.read_text()

          text = re.sub(r'(content="0; url=)[^"]+(")',       rf"\g<1>{version}/\2",   text)
          text = re.sub(r'(rel="canonical" href=")[^"]+(")', rf"\g<1>{version}/\2",   text)
          text = re.sub(r'(<a href=")[^"]+(">[^<]*</a>)',    rf"\g<1>{version}/\2",   text)
          text = re.sub(r'(Redirecting to <a href="[^"]+">)[^<]*(</a>)',
                        rf"\g<1>{version} documentation\2", text)

          path.write_text(text)

      # ── Commit and push ──────────────────────────────────────────────────
      - name: Configure git
        run: |
          git config user.name  "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

      - name: Commit release changes
        run: |
          git checkout -b "${{ steps.version.outputs.branch }}"

          # Stage version bumps, updated changelog, and consumed fragments.
          git add pyproject.toml docs/conf.py CHANGELOG.rst
          git add docs/_root/switcher.json docs/_root/index.html
          git add -A upcoming_changes/    # stages deleted fragment files

          git commit -m "chore: prepare release ${{ steps.version.outputs.tag }}"
          git push origin "${{ steps.version.outputs.branch }}"

      # ── Open pull request ────────────────────────────────────────────────
      - name: Open pull request
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          TAG: ${{ steps.version.outputs.tag }}
          BRANCH: ${{ steps.version.outputs.branch }}
        run: |
          gh pr create \
            --title "Release ${TAG}" \
            --base  main \
            --head  "${BRANCH}" \
            --body  "## Release ${TAG}

          > Auto-generated by the **Prepare Release** workflow.

          ### What changed
          - Version bumped to \`${TAG}\` in \`pyproject.toml\` and \`docs/conf.py\`
          - \`CHANGELOG.rst\` updated from towncrier fragments
          - \`docs/_root/switcher.json\` updated with the new version entry
          $([ '${{ steps.version.outputs.is_beta }}' = 'false' ] && echo '- Root redirect updated to point to this release' || echo '')

          ### Review checklist
          - [ ] \`CHANGELOG.rst\` reads well — edit the fragment text directly if needed
          - [ ] Version strings are correct in \`pyproject.toml\` and \`docs/conf.py\`
          - [ ] \`switcher.json\` has the right label and URL
          - [ ] CI passes

          ### After merging
          Create and push the tag to trigger the Release and Docs workflows:
          \`\`\`bash
          git fetch origin
          git tag ${TAG} origin/main
          git push origin ${TAG}
          \`\`\`"