name: Build and publish container image to GHCR

on:
  push:
    branches:
      - main
    tags:
      - 'v*'
  workflow_dispatch:

concurrency:
  group: publish-${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

permissions:
  contents: read
  packages: write
  id-token: write
  attestations: write

env:
  IMAGE_DESCRIPTION: Fizzy is Kanban as it should be. Not as it has been.
  SOURCE_URL: https://github.com/${{ github.repository }}

jobs:
  build:
    name: Build and push image (${{ matrix.arch }})
    runs-on: ${{ matrix.runner }}
    timeout-minutes: 45
    strategy:
      fail-fast: false
      matrix:
        include:
          - runner: ubuntu-latest
            platform: linux/amd64
            arch: amd64
          - runner: ubuntu-24.04-arm
            platform: linux/arm64
            arch: arm64
    env:
      REGISTRY: ghcr.io
      IMAGE_NAME: ${{ github.repository }}
    steps:
      - name: Checkout
        uses: actions/checkout@v6

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3.12.0

      - name: Log in to GHCR
        uses: docker/login-action@v3.7.0
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Compute canonical image name (lowercase)
        id: vars
        shell: bash
        run: |
          set -eu
          IMAGE_REF="${IMAGE_NAME:-$GITHUB_REPOSITORY}"
          CANONICAL_IMAGE="${REGISTRY}/${IMAGE_REF,,}"
          echo "canonical=${CANONICAL_IMAGE}" >> "$GITHUB_OUTPUT"

      - name: Extract Docker metadata (tags, labels) with arch suffix
        id: meta
        uses: docker/metadata-action@v5.10.0
        with:
          images: ${{ steps.vars.outputs.canonical }}
          tags: |
            type=ref,event=branch
            type=ref,event=tag
            type=sha,format=short,prefix=sha-
            type=semver,pattern={{version}},enable=${{ startsWith(github.ref, 'refs/tags/v') }}
            type=semver,pattern={{major}}.{{minor}},enable=${{ startsWith(github.ref, 'refs/tags/v') }}
            type=semver,pattern={{major}},enable=${{ startsWith(github.ref, 'refs/tags/v') }}
          flavor: |
            latest=false
            suffix=-${{ matrix.arch }}
          labels: |
            org.opencontainers.image.source=${{ env.SOURCE_URL }}

      - name: Build and push (${{ matrix.platform }})
        id: build
        uses: docker/build-push-action@v6.19.2
        with:
          context: .
          file: Dockerfile
          build-args: |
            OCI_SOURCE=${{ env.SOURCE_URL }}
            OCI_DESCRIPTION=${{ env.IMAGE_DESCRIPTION }}
          platforms: ${{ matrix.platform }}
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha,scope=${{ matrix.platform }}
          cache-to: type=gha,scope=${{ matrix.platform }},mode=max
          sbom: false
          provenance: false

      - name: Attest image provenance (per-arch)
        if: github.event_name != 'pull_request'
        uses: actions/attest-build-provenance@v4.1.0
        with:
          subject-name: ${{ steps.vars.outputs.canonical }}
          subject-digest: ${{ steps.build.outputs.digest }}
          push-to-registry: false

  manifest:
    name: Create multi-arch manifest and sign
    needs: build
    if: github.event_name != 'pull_request'
    runs-on: ubuntu-latest
    timeout-minutes: 20
    env:
      REGISTRY: ghcr.io
      IMAGE_NAME: ${{ github.repository }}
    steps:
      - name: Set up Docker Buildx (for imagetools)
        uses: docker/setup-buildx-action@v3.12.0

      - name: Log in to GHCR
        uses: docker/login-action@v3.7.0
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Compute canonical image name (lowercase)
        id: vars
        shell: bash
        run: |
          set -eu
          IMAGE_REF="${IMAGE_NAME:-$GITHUB_REPOSITORY}"
          CANONICAL_IMAGE="${REGISTRY}/${IMAGE_REF,,}"
          echo "canonical=${CANONICAL_IMAGE}" >> "$GITHUB_OUTPUT"

      - name: Compute base tags (no suffix)
        id: meta
        uses: docker/metadata-action@v5.10.0
        with:
          images: ${{ steps.vars.outputs.canonical }}
          tags: |
            type=ref,event=branch
            type=ref,event=tag
            type=sha,format=short,prefix=sha-
            type=semver,pattern={{version}},enable=${{ startsWith(github.ref, 'refs/tags/v') }}
            type=semver,pattern={{major}}.{{minor}},enable=${{ startsWith(github.ref, 'refs/tags/v') }}
            type=semver,pattern={{major}},enable=${{ startsWith(github.ref, 'refs/tags/v') }}
            type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/v') }}
          flavor: |
            latest=false
          labels: |
            org.opencontainers.image.source=${{ env.SOURCE_URL }}

      - name: Create multi-arch manifests
        shell: bash
        run: |
          set -eu
          tags="${{ steps.meta.outputs.tags }}"
          echo "Creating manifests for tags:"
          printf '%s\n' "$tags"
          while IFS= read -r tag; do
            [ -z "$tag" ] && continue
            echo "Creating manifest for $tag"
            src_tag="$tag"
            if [[ "$tag" == *:latest && "${GITHUB_REF}" == refs/tags/* ]]; then
              ref="${GITHUB_REF#refs/tags/}"
              src_tag="${tag%:latest}:$ref"
            fi
            if [ -n "${IMAGE_DESCRIPTION:-}" ]; then
              docker buildx imagetools create \
                --tag "$tag" \
                --annotation "index:org.opencontainers.image.description=${IMAGE_DESCRIPTION}" \
                "${src_tag}-amd64" \
                "${src_tag}-arm64"
            else
              docker buildx imagetools create \
                --tag "$tag" \
                "${src_tag}-amd64" \
                "${src_tag}-arm64"
            fi
          done <<< "$tags"

      - name: Install Cosign
        uses: sigstore/cosign-installer@v4.0.0

      - name: Cosign sign all tags (keyless OIDC)
        shell: bash
        run: |
          set -eu
          tags="${{ steps.meta.outputs.tags }}"
          printf '%s\n' "$tags"
          while IFS= read -r tag; do
            [ -z "$tag" ] && continue
            echo "Signing $tag"
            cosign sign --yes "$tag"
          done <<< "$tags"