name: Build and Push Docker Images

on:
  push:
    branches: [main]
    paths:
      - 'backend/**'
      - 'frontend/**'
      - '.github/workflows/docker-build.yml'
  pull_request:
    branches: [main]
    paths:
      - 'backend/**'
      - 'frontend/**'
  workflow_dispatch:

env:
  REGISTRY: ghcr.io
  BACKEND_IMAGE: ghcr.io/${{ github.repository_owner }}/priceghost-backend
  FRONTEND_IMAGE: ghcr.io/${{ github.repository_owner }}/priceghost-frontend

jobs:
  # Build each platform on its native runner to avoid QEMU emulation issues
  build-backend:
    strategy:
      fail-fast: false
      matrix:
        include:
          - platform: linux/amd64
            runner: ubuntu-latest
          - platform: linux/arm64
            runner: ubuntu-24.04-arm
    runs-on: ${{ matrix.runner }}
    permissions:
      contents: read
      packages: write

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

      - name: Prepare platform slug
        run: echo "PLATFORM_PAIR=$(echo '${{ matrix.platform }}' | tr '/' '-')" >> $GITHUB_ENV

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

      - name: Log in to GitHub Container Registry
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata for Backend
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.BACKEND_IMAGE }}

      - name: Build and push Backend image by digest
        id: build
        uses: docker/build-push-action@v6
        with:
          context: ./backend
          platforms: ${{ matrix.platform }}
          labels: ${{ steps.meta.outputs.labels }}
          outputs: ${{ github.event_name != 'pull_request' && format('type=image,name={0},push-by-digest=true,name-canonical=true,push=true', env.BACKEND_IMAGE) || 'type=cacheonly' }}
          cache-from: type=gha,scope=${{ env.PLATFORM_PAIR }}-backend
          cache-to: type=gha,mode=max,scope=${{ env.PLATFORM_PAIR }}-backend

      - name: Export digest
        if: github.event_name != 'pull_request'
        run: |
          mkdir -p /tmp/digests
          digest="${{ steps.build.outputs.digest }}"
          touch "/tmp/digests/${digest#sha256:}"

      - name: Upload digest
        if: github.event_name != 'pull_request'
        uses: actions/upload-artifact@v4
        with:
          name: digests-backend-${{ env.PLATFORM_PAIR }}
          path: /tmp/digests/*
          if-no-files-found: error
          retention-days: 1

  merge-backend:
    needs: build-backend
    if: github.event_name != 'pull_request'
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    steps:
      - name: Download digests
        uses: actions/download-artifact@v4
        with:
          path: /tmp/digests
          pattern: digests-backend-*
          merge-multiple: true

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

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

      - name: Extract metadata for Backend
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.BACKEND_IMAGE }}
          tags: |
            type=ref,event=branch
            type=sha,prefix=
            type=raw,value=latest,enable={{is_default_branch}}

      - name: Create manifest list and push
        working-directory: /tmp/digests
        run: |
          docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
            $(printf '${{ env.BACKEND_IMAGE }}@sha256:%s ' *)

      - name: Inspect image
        run: docker buildx imagetools inspect ${{ env.BACKEND_IMAGE }}:${{ steps.meta.outputs.version }}

  # Build each platform on its native runner to avoid QEMU emulation issues
  build-frontend:
    strategy:
      fail-fast: false
      matrix:
        include:
          - platform: linux/amd64
            runner: ubuntu-latest
          - platform: linux/arm64
            runner: ubuntu-24.04-arm
    runs-on: ${{ matrix.runner }}
    permissions:
      contents: read
      packages: write

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

      - name: Prepare platform slug
        run: echo "PLATFORM_PAIR=$(echo '${{ matrix.platform }}' | tr '/' '-')" >> $GITHUB_ENV

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

      - name: Log in to GitHub Container Registry
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata for Frontend
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.FRONTEND_IMAGE }}

      - name: Build and push Frontend image by digest
        id: build
        uses: docker/build-push-action@v6
        with:
          context: ./frontend
          platforms: ${{ matrix.platform }}
          labels: ${{ steps.meta.outputs.labels }}
          outputs: ${{ github.event_name != 'pull_request' && format('type=image,name={0},push-by-digest=true,name-canonical=true,push=true', env.FRONTEND_IMAGE) || 'type=cacheonly' }}
          cache-from: type=gha,scope=${{ env.PLATFORM_PAIR }}-frontend
          cache-to: type=gha,mode=max,scope=${{ env.PLATFORM_PAIR }}-frontend

      - name: Export digest
        if: github.event_name != 'pull_request'
        run: |
          mkdir -p /tmp/digests
          digest="${{ steps.build.outputs.digest }}"
          touch "/tmp/digests/${digest#sha256:}"

      - name: Upload digest
        if: github.event_name != 'pull_request'
        uses: actions/upload-artifact@v4
        with:
          name: digests-frontend-${{ env.PLATFORM_PAIR }}
          path: /tmp/digests/*
          if-no-files-found: error
          retention-days: 1

  merge-frontend:
    needs: build-frontend
    if: github.event_name != 'pull_request'
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    steps:
      - name: Download digests
        uses: actions/download-artifact@v4
        with:
          path: /tmp/digests
          pattern: digests-frontend-*
          merge-multiple: true

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

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

      - name: Extract metadata for Frontend
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.FRONTEND_IMAGE }}
          tags: |
            type=ref,event=branch
            type=sha,prefix=
            type=raw,value=latest,enable={{is_default_branch}}

      - name: Create manifest list and push
        working-directory: /tmp/digests
        run: |
          docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
            $(printf '${{ env.FRONTEND_IMAGE }}@sha256:%s ' *)

      - name: Inspect image
        run: docker buildx imagetools inspect ${{ env.FRONTEND_IMAGE }}:${{ steps.meta.outputs.version }}