# Reusable multi-arch image build: one workflow, called by build-main,
# build-gateway and release. Builds natively per platform (no QEMU), pushes by
# digest, then merges the manifest list with SBOM and provenance attestations.
name: Reusable multi-arch image build

on:
  workflow_call:
    inputs:
      image:
        description: Fully qualified image name without a tag
        required: true
        type: string
      version:
        description: Version recorded in the OCI labels
        required: true
        type: string
      context:
        description: Docker build context
        required: true
        type: string
      dockerfile:
        description: Dockerfile path, relative to the context
        required: false
        default: Dockerfile
        type: string
      build-args:
        description: Newline-separated build args
        required: false
        default: ""
        type: string
      tags:
        description: Newline-separated fully qualified tags to publish
        required: true
        type: string

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

jobs:
  build:
    name: Build ${{ matrix.platform }}
    runs-on: ${{ matrix.platform == 'linux/amd64' && 'ubuntu-latest' || 'ubuntu-24.04-arm' }}
    timeout-minutes: 120
    strategy:
      fail-fast: false
      matrix:
        platform:
          - linux/amd64
          - linux/arm64
    steps:
      - name: Checkout
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1

      - name: Prepare environment
        env:
          IMAGE: ${{ inputs.image }}
        run: |
          set -euo pipefail
          pair=$(printf '%s' "${{ matrix.platform }}" | tr '/' '-')
          echo "PLATFORM_PAIR=$pair" >> "$GITHUB_ENV"
          echo "CACHE_SCOPE=$(printf '%s' "$IMAGE" | tr '/' '-')" >> "$GITHUB_ENV"

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@f87e5991a6d7451dcb8d9637bfbc97413f497069 # v4.4.1

      - name: Login to GitHub Container Registry
        uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build and push by digest
        id: build
        uses: docker/build-push-action@c3c9e263c25d99ce0380d002d59b67737d91b0dc # v7.4.0
        with:
          context: ${{ inputs.context }}
          file: ${{ inputs.context }}/${{ inputs.dockerfile }}
          platforms: ${{ matrix.platform }}
          build-args: ${{ inputs.build-args }}
          labels: |
            org.opencontainers.image.source=https://github.com/${{ github.repository }}
            org.opencontainers.image.version=${{ inputs.version }}
            org.opencontainers.image.revision=${{ github.sha }}
          outputs: type=image,name=${{ inputs.image }},push-by-digest=true,name-canonical=true,push=true,oci-mediatypes=true
          sbom: true
          provenance: mode=max
          cache-from: type=gha,scope=${{ env.CACHE_SCOPE }}-${{ matrix.platform }}
          cache-to: type=gha,mode=max,scope=${{ env.CACHE_SCOPE }}-${{ matrix.platform }}

      - name: Export digest
        run: |
          set -euo pipefail
          mkdir -p /tmp/digests
          digest="${{ steps.build.outputs.digest }}"
          touch "/tmp/digests/${digest#sha256:}"

      - name: Upload digest
        uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
        with:
          name: digests-${{ env.PLATFORM_PAIR }}
          path: /tmp/digests/*
          if-no-files-found: error
          retention-days: 1

  merge:
    name: Merge manifest list
    needs: build
    runs-on: ubuntu-latest
    timeout-minutes: 30
    steps:
      - name: Download digests
        uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
        with:
          path: /tmp/digests
          pattern: digests-*
          merge-multiple: true

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@f87e5991a6d7451dcb8d9637bfbc97413f497069 # v4.4.1

      - name: Login to GitHub Container Registry
        uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Create and push manifest list
        working-directory: /tmp/digests
        env:
          IMAGE: ${{ inputs.image }}
          TAGS: ${{ inputs.tags }}
        run: |
          set -euo pipefail
          args=()
          while IFS= read -r tag; do
            if [ -n "$tag" ]; then
              args+=("-t" "$tag")
            fi
          done <<< "$TAGS"
          refs=()
          for digest in *; do
            refs+=("$IMAGE@sha256:$digest")
          done
          docker buildx imagetools create "${args[@]}" "${refs[@]}"

      - name: Inspect image
        env:
          IMAGE: ${{ inputs.image }}
          TAGS: ${{ inputs.tags }}
        run: |
          set -euo pipefail
          first=$(printf '%s\n' "$TAGS" | head -n1)
          docker buildx imagetools inspect "$first"
          echo "### Published ${{ inputs.image }}" >> "$GITHUB_STEP_SUMMARY"
          printf '%s\n' "$TAGS" | sed 's/^/- /' >> "$GITHUB_STEP_SUMMARY"