name: Bump version.txt

on:
  push:
    branches: [ "main" ]
    # Avoid infinite loop when this workflow commits version.txt.
    paths-ignore:
      - "version.txt"

concurrency:
  group: bump-version-${{ github.ref }}
  cancel-in-progress: true

permissions:
  contents: write

jobs:
  bump:
    if: github.actor != 'github-actions[bot]'
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Bump patch version in version.txt
        shell: bash
        run: |
          set -euo pipefail

          file="version.txt"
          if [[ ! -f "$file" ]]; then
            echo "0.0.1" > "$file"
          else
            v="$(tr -d '[:space:]' < "$file")"
            if [[ "$v" =~ ^([0-9]+)\.([0-9]+)\.([0-9]+)$ ]]; then
              major="${BASH_REMATCH[1]}"
              minor="${BASH_REMATCH[2]}"
              patch="${BASH_REMATCH[3]}"
              patch="$((patch + 1))"
              echo "${major}.${minor}.${patch}" > "$file"
            else
              echo "version.txt has invalid format: '$v' (expected x.y.z)" >&2
              exit 1
            fi
          fi

          echo "New version: $(cat "$file")"

      - name: Commit and push
        shell: bash
        run: |
          set -euo pipefail
          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

          # If version didn't change for any reason, do nothing.
          git add version.txt
          if git diff --cached --quiet; then
            echo "No changes to commit."
            exit 0
          fi

          git commit -m "chore: bump version [skip ci]"
          git push