name: Open / Update PR

# Triggered by any push to a non-main branch where src/ files changed.
# Opens a PR to main if one does not exist, or updates its body if it does.
# When creating a new PR it assigns the default "bump:patch" label.
# When updating an existing PR the label is NOT changed, preserving any
# manual label change (e.g. bump:minor, bump:major) made by a reviewer.
#
# Pre-requisite: create the label once in the repo:
#   gh label create "bump:patch" --color "0075ca" --description "Default patch-version bump"

on:
  push:
    branches-ignore:
      - main
    paths:
      - 'src/**'

permissions:
  contents: read
  pull-requests: write

jobs:
  pr:
    runs-on: ubuntu-latest
    if: github.actor != 'github-actions[bot]'

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

      - name: Collect src/ commits on this branch
        id: commits
        run: |
          LOG=$(git log "origin/main..HEAD" --oneline -- src/ | head -50)
          EOF=$(dd if=/dev/urandom bs=15 count=1 2>/dev/null | base64)
          echo "log<<$EOF" >> "$GITHUB_OUTPUT"
          echo "$LOG"      >> "$GITHUB_OUTPUT"
          echo "$EOF"      >> "$GITHUB_OUTPUT"

      - name: Create or update PR
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          BRANCH:  ${{ github.ref_name }}
          COMMITS: ${{ steps.commits.outputs.log }}
        run: |
          TITLE="feat: $BRANCH"

          {
            echo "## Changes in \`$BRANCH\`"
            echo ""
            echo "${COMMITS:-No src/ changes detected.}"
          } > /tmp/pr-body.md

          EXISTING=$(gh pr list \
            --head "$BRANCH" \
            --json number --jq '.[0].number' 2>/dev/null || true)

          if [[ -n "$EXISTING" ]]; then
            gh pr edit "$EXISTING" --body-file /tmp/pr-body.md
            echo "Updated PR #$EXISTING body (label unchanged)"
          else
            gh pr create \
              --title "$TITLE" \
              --body-file /tmp/pr-body.md \
              --base main \
              --head "$BRANCH" \
              --label "bump:patch"
            echo "Opened new PR with label bump:patch"
          fi