name: CI

on:
  push:
    branches:
      - main
  pull_request:

jobs:
  check:
    runs-on: x86_64
    steps:
      - uses: actions/checkout@v4
      - name: Check flake
        run: |
          source /etc/bashrc
          nix flake check

  list-packages:
    runs-on: x86_64
    outputs:
      packages: ${{ steps.set-matrix.outputs.packages }}
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - id: set-matrix
        run: |
          source /etc/bashrc
          ALL_PACKAGES=$(nix flake show --json | nix run nixpkgs#jq -- -r '.packages."x86_64-linux" | keys[]')
          
          if [ "${{ github.event_name }}" == "pull_request" ]; then
            echo "Detecting changed packages for PR..."
            BASE_REF="${{ github.base_ref }}"
            # Ensure the base branch is available for diffing
            git fetch origin "$BASE_REF" --depth=1
            CHANGED_FILES=$(git diff --name-only "origin/$BASE_REF"...HEAD)
            
            if echo "$CHANGED_FILES" | grep -qE 'flake.nix|flake.lock'; then
              echo "Flake files changed, building all packages."
              SELECTED_PACKAGES=$(echo "$ALL_PACKAGES" | nix run nixpkgs#jq -- -R . | nix run nixpkgs#jq -- -s -c .)
            else
              # Extract package names from pkgs/<name>/
              CHANGED_PKGS=$(echo "$CHANGED_FILES" | grep '^pkgs/' | cut -d'/' -f2 | sort -u || true)
              
              FINAL_PKGS=()
              for pkg in $CHANGED_PKGS; do
                if echo "$ALL_PACKAGES" | grep -q "^$pkg$"; then
                  FINAL_PKGS+=("$pkg")
                fi
              done
              
              if [ ${#FINAL_PKGS[@]} -eq 0 ]; then
                SELECTED_PACKAGES="[]"
              else
                SELECTED_PACKAGES=$(printf '%s\n' "${FINAL_PKGS[@]}" | nix run nixpkgs#jq -- -R . | nix run nixpkgs#jq -- -s -c .)
              fi
            fi
          else
            echo "Push event, listing all packages."
            SELECTED_PACKAGES=$(echo "$ALL_PACKAGES" | nix run nixpkgs#jq -- -R . | nix run nixpkgs#jq -- -s -c .)
          fi
          
          echo "packages=$SELECTED_PACKAGES" >> $GITHUB_OUTPUT

  build:
    needs: [check, list-packages]
    runs-on: x86_64
    if: ${{ fromJson(needs.list-packages.outputs.packages)[0] != null }}
    strategy:
      fail-fast: false
      matrix:
        package: ${{ fromJson(needs.list-packages.outputs.packages) }}

    steps:
      - name: Checkout code
        uses: actions/checkout@v4

      - name: Build package
        run: |
          source /etc/bashrc
          nix build .#${{ matrix.package }}

      - name: Cache & Push to Attic
        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
        env:
          ATTIC_SERVER: ${{ secrets.ATTIC_SERVER }}
          ATTIC_TOKEN: ${{ secrets.ATTIC_TOKEN }}
        run: |
          source /etc/bashrc
          nix shell nixpkgs#attic-client -c bash -c "
            attic login mizuki \"$ATTIC_SERVER\" \"$ATTIC_TOKEN\"
            attic cache info public
            attic push public ./result
          "