# Nix container build workflow
# Triggers on pushes to main that modify containers/*, or via manual dispatch.
# Detects which containers changed, builds from default.nix, and pushes via
# skopeo with commit-SHA-based tags: vX.Y.Z-<sha>-nix
name: Build Container (Nix)

on:
  push:
    branches: [main]
    paths: ['containers/**']
  workflow_dispatch:
    inputs:
      container:
        description: 'Container name (directory under containers/)'
        required: true
        type: string
      ref:
        description: 'Commit SHA to build (defaults to current HEAD)'
        required: false
        type: string

jobs:
  detect:
    runs-on: nix-container-builder
    outputs:
      containers: ${{ steps.list.outputs.containers }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 2

      - name: Detect changed containers
        id: list
        run: |
          if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
            CONTAINERS='["${{ inputs.container }}"]'
          else
            CONTAINERS=$(git diff --name-only HEAD~1 HEAD -- containers/ \
              | cut -d/ -f2 | sort -u \
              | jq -R -s -c 'split("\n") | map(select(length > 0))')
          fi
          echo "containers=$CONTAINERS" >> "$GITHUB_OUTPUT"
          echo "Containers to build: $CONTAINERS"

  build:
    needs: detect
    if: needs.detect.outputs.containers != '[]'
    runs-on: nix-container-builder
    strategy:
      matrix:
        container: ${{ fromJson(needs.detect.outputs.containers) }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Check for default.nix
        id: check
        run: |
          if [ -f "containers/${{ matrix.container }}/default.nix" ]; then
            echo "exists=true" >> "$GITHUB_OUTPUT"
          else
            echo "No default.nix for ${{ matrix.container }} — skipping"
            echo "exists=false" >> "$GITHUB_OUTPUT"
          fi

      - name: Extract version and SHA
        if: steps.check.outputs.exists == 'true'
        id: meta
        run: |
          CONTAINER="${{ matrix.container }}"
          NIX_FILE="containers/$CONTAINER/default.nix"

          # Try extracting version = "..." from the nix file (e.g. ntfy)
          VERSION=$(grep -m1 '^\s*version\s*=\s*"' "$NIX_FILE" \
            | sed 's/.*"\(.*\)".*/\1/' || true)

          # Fall back to CONTAINER_APP_VERSION from Dockerfile (e.g. nettest)
          if [ -z "$VERSION" ] && [ -f "containers/$CONTAINER/Dockerfile" ]; then
            VERSION=$(grep -m1 '^ARG CONTAINER_APP_VERSION=' \
              "containers/$CONTAINER/Dockerfile" \
              | sed 's/^ARG CONTAINER_APP_VERSION=//')
          fi

          # Last resort: dagger call nix-version for nixpkgs packages (e.g. authentik)
          if [ -z "$VERSION" ]; then
            VERSION=$(dagger call nix-version --package="$CONTAINER")
          fi

          if [ -z "$VERSION" ]; then
            echo "Error: Could not determine version for $CONTAINER"
            exit 1
          fi

          REF="${{ inputs.ref }}"
          if [ -z "$REF" ]; then
            REF="${GITHUB_SHA}"
          fi
          SHORT_SHA=$(echo "$REF" | head -c 7)

          # Ensure version starts with 'v'
          case "$VERSION" in
            v*) ;;
            *) VERSION="v${VERSION}" ;;
          esac

          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
          echo "sha=$SHORT_SHA" >> "$GITHUB_OUTPUT"
          echo "Version: $VERSION, SHA: $SHORT_SHA"

      - name: Resolve nixpkgs
        if: steps.check.outputs.exists == 'true'
        id: nixpkgs
        run: |
          NIXPKGS_PATH=$(nix flake metadata nixpkgs --json | jq -r '.path')
          echo "Resolved nixpkgs: $NIXPKGS_PATH"
          echo "path=$NIXPKGS_PATH" >> "$GITHUB_OUTPUT"

      - name: Build with nix
        if: steps.check.outputs.exists == 'true'
        env:
          NIX_PATH: "nixpkgs=${{ steps.nixpkgs.outputs.path }}"
        run: |
          echo "Building containers/${{ matrix.container }}/default.nix"
          echo "NIX_PATH=$NIX_PATH"
          nix-build "containers/${{ matrix.container }}/default.nix" -o result
          echo "Build complete: $(readlink result)"

      - name: Push to registry
        if: steps.check.outputs.exists == 'true'
        run: |
          CONTAINER="${{ matrix.container }}"
          VERSION="${{ steps.meta.outputs.version }}"
          SHORT_SHA="${{ steps.meta.outputs.sha }}"
          IMAGE="registry.ops.eblu.me/blumeops/$CONTAINER:${VERSION}-${SHORT_SHA}-nix"

          echo "Pushing to $IMAGE"
          skopeo copy \
            "docker-archive:result" \
            "docker://$IMAGE"
          echo "Push complete: $IMAGE"