name: Update Nix Flake

on:
  schedule:
    - cron: "30 0 * * *" # daily run
  workflow_dispatch: {}

jobs:
  update-flake:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          token: "${{ gitea.token }}"
          fetch-depth: 0
          ref: flake-updates

      - name: Git config
        shell: bash
        run: |
          git config user.name "Gitea Actions"
          git config user.email "actions@gitea.local"

      - name: Merge main branch
        shell: bash
        run: |
            commits_ahead=$(git rev-list --count HEAD..origin/main)
            echo "Commits ahead: $commits_ahead"
            git log --oneline -5
            echo "----------"
            git log --oneline -5 origin/main

            if [ $commits_ahead -ne 0 ]
            then
              git fetch origin
              git merge --squash origin/main || true # do not exit script on merge conflict
              git push --force-with-lease

              # solve potential merge conflict by taking flake.lock from main
              git checkout origin/main -- flake.lock
              git commit -m "Merge main branch squashed $(date -I)"
            else
              echo "Merge not necessary"
            fi

      - name: Set up Nix
        uses: cachix/install-nix-action@v31

      - name: Update Flake
        run: nix flake update

      - name: Commit and push changes
        shell: bash
        run: |
          git add flake.lock
          if git diff --quiet; then
            echo "No changes to commit."
          else
            git commit -m "Update flake.lock $(date -I)"
            git push origin flake-updates
          fi