name: Build and Publish Docker Image

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

concurrency:
  group: docker-publish
  cancel-in-progress: true

jobs:
  push_to_registry:
    name: Push Docker image to Docker Hub
    runs-on: ubuntu-latest
    timeout-minutes: 30
    # DOCKERHUB_USERNAME and DOCKERHUB_TOKEN live in the `production` environment,
    # not repo-wide secrets. Any future workflow that tries to push to Docker Hub
    # without declaring this environment will fail to resolve the credentials,
    # which is exactly the blast-radius reduction we want. Adding a required
    # reviewer to the environment in repo settings also turns every release into
    # a manual-approval gate without any workflow change.
    environment: production
    permissions:
      contents: read
      # Required for cosign keyless signing via GitHub OIDC.
      id-token: write
    steps:
      - name: Check out the repo
        uses: actions/checkout@v6

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v4
        with:
          platforms: arm64

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v4

      - name: Log in to Docker Hub
        uses: docker/login-action@v4
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Install cosign
        uses: sigstore/cosign-installer@cad07c2e89fa2edd6e2d7bab4c1aa38e53f76003 # v4.1.1

      - name: Extract metadata (tags, labels) for Docker
        id: meta
        uses: docker/metadata-action@v6
        with:
          images: saelix/sencho
          # On a v-tag push we publish:
          #   latest           always points at the newest release
          #   X.Y.Z            the immutable semver tag
          #   X.Y              moving minor tag for users who want latest patch
          # The pre-1.0 constraint hides the {{major}}-only tag until we ship 1.0,
          # since on 0.x every minor is potentially breaking.
          tags: |
            type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/v') }}
            type=semver,pattern={{version}},enable=${{ startsWith(github.ref, 'refs/tags/v') }}
            type=semver,pattern={{major}}.{{minor}},enable=${{ startsWith(github.ref, 'refs/tags/v') }}

      # Build an amd64-only variant into the local daemon first so Trivy can
      # scan the exact release artifact before it is tagged and pushed. This
      # keeps vulnerable releases out of the `latest` and semver tags that
      # users actually pull. Because the push-build step that follows runs in
      # the same job against the same buildkit daemon, it reuses this build's
      # layers from the daemon's in-memory cache (observed wall-time: the
      # push-build typically finishes faster than the scan-build despite
      # producing multi-arch output). The `cache-from` pull is just a
      # cold-start fallback for the first-ever run or when the buildkit daemon
      # is fresh; we intentionally do NOT write `cache-to` here because the
      # push-build below writes a strictly better (multi-arch, mode=max)
      # cache entry moments later. The tag lives in the `localhost/` namespace
      # so a future `push: false` -> `push: true` mistake cannot publish it.
      # Scanning only amd64 is a defensible proxy for the multi-arch release:
      # distro package CVEs are arch-agnostic at the manifest level, and
      # arch-specific container-relevant CVEs are extraordinarily rare.
      - name: Build release image for pre-publish scan (amd64, loaded)
        uses: docker/build-push-action@v7
        with:
          context: .
          push: false
          load: true
          platforms: linux/amd64
          tags: localhost/sencho:release-scan
          cache-from: type=registry,ref=saelix/sencho:buildcache

      - name: Re-scan release image for vulnerabilities (Trivy)
        # Gates the release on the same HIGH/CRITICAL policy as the PR scan.
        # Entries in .trivyignore at the repo root are honored so the acknowledged
        # CVE list is the single source of truth across PR CI and release CI.
        uses: aquasecurity/trivy-action@57a97c7e7821a5776cebc9bb87c984fa69cba8f1 # v0.35.0
        with:
          image-ref: localhost/sencho:release-scan
          exit-code: '1'
          severity: 'CRITICAL,HIGH'
          format: 'table'

      - name: Build and push Docker image
        id: build
        uses: docker/build-push-action@v7
        with:
          context: .
          push: true
          platforms: linux/amd64,linux/arm64
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=registry,ref=saelix/sencho:buildcache
          cache-to: type=registry,ref=saelix/sencho:buildcache,mode=max
          # SBOM + provenance attestations are embedded as OCI referrers on the
          # published image. Inspect with: docker buildx imagetools inspect <img>
          sbom: true
          provenance: mode=max

      - name: Sign published image with cosign (keyless)
        # Signs every tag produced by metadata-action using the ambient GitHub
        # OIDC token. No private keys, no secrets. Users verify with:
        #   cosign verify saelix/sencho:<tag> \
        #     --certificate-identity-regexp "https://github.com/AnsoCode/Sencho/.*" \
        #     --certificate-oidc-issuer https://token.actions.githubusercontent.com
        env:
          TAGS: ${{ steps.meta.outputs.tags }}
          DIGEST: ${{ steps.build.outputs.digest }}
        run: |
          # Build a single cosign invocation with every tag pinned to the digest.
          # All tags resolve to the same manifest, so one call signs them all and
          # saves N-1 Rekor/Fulcio round trips. On workflow_dispatch $TAGS is empty
          # and the refs array stays empty, so we no-op cleanly.
          refs=()
          while IFS= read -r tag; do
            [ -n "$tag" ] || continue
            refs+=("${tag}@${DIGEST}")
          done <<< "$TAGS"
          if [ ${#refs[@]} -gt 0 ]; then
            cosign sign --yes "${refs[@]}"
          else
            echo "No tags to sign (likely a workflow_dispatch run on a non-tag ref)."
          fi