name: Update OpenBSD tmux and portable

on:
  workflow_dispatch:
  schedule:
    - cron: "*/15 * * * *"

permissions:
  contents: write

concurrency:
  group: update-openbsd-and-portable
  cancel-in-progress: false

env:
  OPENBSD_SRC_URL: https://github.com/openbsd/src.git
  OPENBSD_SRC_DIR: openbsd-src
  CUTOVER_DIR: tmux-openbsd-cutover
  PORTABLE_DIR: tmux-portable
  PORTABLE_REPO: ${{ vars.TMUX_PORTABLE_REPO }}

jobs:
  update:
    runs-on: ubuntu-latest
    steps:
      - name: Configure Git identity
        run: |
          git config --global user.name "tmux update bot"
          git config --global user.email "actions@github.com"

      - name: Install git-filter-repo
        run: python3 -m pip install --user git-filter-repo

      - name: Checkout cutover repository
        uses: actions/checkout@v4
        with:
          path: ${{ env.CUTOVER_DIR }}
          fetch-depth: 0
          token: ${{ secrets.UPDATE_TOKEN || github.token }}

      - name: Check portable repo setting
        run: |
          if [ -z "$PORTABLE_REPO" ]; then
            echo "Set repository variable TMUX_PORTABLE_REPO, for example owner/tmux-portable." >&2
            exit 1
          fi

      - name: Checkout portable repository
        uses: actions/checkout@v4
        with:
          repository: ${{ env.PORTABLE_REPO }}
          path: ${{ env.PORTABLE_DIR }}
          fetch-depth: 0
          token: ${{ secrets.UPDATE_TOKEN }}

      - name: Restore OpenBSD source clone cache
        id: openbsd-cache
        uses: actions/cache/restore@v4
        with:
          path: ${{ env.OPENBSD_SRC_DIR }}
          key: openbsd-src-blobless-${{ runner.os }}-${{ github.run_id }}
          restore-keys: |
            openbsd-src-blobless-${{ runner.os }}-

      - name: Refresh OpenBSD source clone
        run: |
          set -eu

          if [ ! -d "$OPENBSD_SRC_DIR/.git" ]; then
            git clone --filter=blob:none --no-tags --single-branch --branch master \
              "$OPENBSD_SRC_URL" "$OPENBSD_SRC_DIR"
          fi

          cd "$OPENBSD_SRC_DIR"
          git remote set-url origin "$OPENBSD_SRC_URL"
          git fetch --filter=blob:none --no-tags origin master
          git switch -C master origin/master

      - name: Capture published OpenBSD tmux base
        id: openbsd-base
        run: |
          set -eu

          cd "$CUTOVER_DIR"
          if ! git rev-parse --verify -q origin/openbsd-git >/dev/null; then
            echo "origin/openbsd-git is missing; publish the openbsd-git branch before running updates." >&2
            exit 1
          fi
          echo "sha=$(git rev-parse origin/openbsd-git)" >> "$GITHUB_OUTPUT"

      - name: Filter OpenBSD tmux history
        run: |
          set -eu

          cd "$OPENBSD_SRC_DIR"
          git switch -C tmux-openbsd origin/master
          git filter-repo \
            --force \
            --refs tmux-openbsd \
            --path usr.bin/tmux/ \
            --path-rename usr.bin/tmux/: \
            --replace-refs delete-no-add

          git push "../$CUTOVER_DIR" tmux-openbsd:refs/heads/openbsd-git

      - name: Update cutover master
        id: cutover
        run: |
          set -eu

          cd "$CUTOVER_DIR"
          git switch master

          old_base="${{ steps.openbsd-base.outputs.sha }}"
          new_base=$(git rev-parse openbsd-git)

          if [ "$old_base" = "$new_base" ]; then
            echo "changed=false" >> "$GITHUB_OUTPUT"
            echo "No new OpenBSD tmux commits to import; continuing to portable merge."
          else
            if ! git merge-base --is-ancestor "$old_base" "$new_base"; then
              echo "new openbsd-git is not a descendant of origin/openbsd-git; aborting." >&2
              exit 1
            fi

            git cherry-pick "$old_base..$new_base"
            echo "changed=true" >> "$GITHUB_OUTPUT"
          fi

      - name: Push cutover repository
        if: steps.cutover.outputs.changed == 'true'
        run: |
          set -eu

          cd "$CUTOVER_DIR"
          git push origin master openbsd-git

      - name: Merge cutover into portable
        id: portable
        run: |
          set -eu

          cd "$PORTABLE_DIR"
          git config remote.tmux-openbsd.tagOpt --no-tags

          if git remote get-url tmux-openbsd >/dev/null 2>&1; then
            git remote set-url tmux-openbsd "../$CUTOVER_DIR"
          else
            git remote add tmux-openbsd "../$CUTOVER_DIR"
          fi

          git fetch --no-tags tmux-openbsd master:refs/remotes/tmux-openbsd/master
          git switch master
          git merge --no-ff --log refs/remotes/tmux-openbsd/master
          if git diff --quiet origin/master..master; then
            echo "changed=false" >> "$GITHUB_OUTPUT"
          else
            echo "changed=true" >> "$GITHUB_OUTPUT"
          fi

      - name: Push portable repository
        if: steps.portable.outputs.changed == 'true'
        run: |
          set -eu

          cd "$PORTABLE_DIR"
          git push origin master

      - name: Save OpenBSD source clone cache
        if: always()
        uses: actions/cache/save@v4
        with:
          path: ${{ env.OPENBSD_SRC_DIR }}
          key: openbsd-src-blobless-${{ runner.os }}-${{ github.run_id }}