name: Docker Build + Push
description: Build and push Docker images with buildx and layer caching for Gitea Actions
author: eric

inputs:
  dockerfile:
    description: Path to Dockerfile (relative to build_context)
    default: Dockerfile
  context:
    description: Build context path (relative to repo root)
    default: .
  image-name:
    description: Full image name (e.g. registry/image or image)
    required: true
  tags:
    description: Additional tags as CSV appended to defaults
    default: ""
  cache-from:
    description: Cache source (e.g. type=gha, or image:tag)
    default: ""
  cache-to:
    description: Cache destination for buildx (type=gha or type=local)
    default: type=local,dest=/tmp/buildx-cache,mode=max
  platforms:
    description: Target platforms as CSV (e.g. linux/amd64,linux/arm64)
    default: linux/amd64
  push:
    description: Push images to registry after build
    default: "false"
  build-args:
    description: Build args as CSV KEY=VALUE
    default: ""

outputs:
  image:
    description: Full image name with tag
    value: ${{ steps.meta.outputs.image }}
  tag:
    description: The primary tag used (date-SHA)
    value: ${{ steps.meta.outputs.tag }}
  digest:
    description: Image digest (only available after push)
    value: ${{ steps.push-digest.outputs.digest }}

runs:
  using: composite
  env:
    DOCKER_HOST: tcp://docker.local:2375
    DOCKER_BUILDKIT: "1"
    BUILDKIT_HOST: tcp://docker.local:2375

  steps:
    - name: Set up QEMU for multi-platform builds
      shell: bash
      if: inputs.platforms != 'linux/amd64'
      run: |
        docker run --rm --privileged multiarch/qemu-user-static --reset -p yes 2>/dev/null || true

    - name: Set up Docker Buildx
      id: buildx
      shell: bash
      run: |
        mkdir -p $HOME/.docker/cli-plugins
        curl -fsSL https://github.com/docker/buildx/releases/download/v0.12.1/buildx-v0.12.1.linux-amd64 \
          -o $HOME/.docker/cli-plugins/docker-buildx
        chmod +x $HOME/.docker/cli-plugins/docker-buildx
        docker buildx version

        # Create a builder instance (reuse if exists)
        docker buildx create \
          --name gitea-builder \
          --driver docker-container \
          --driver-opt image=moby/buildkit:buildx-stable-1 \
          --driver-opt network=host \
          --use \
          2>/dev/null || docker buildx use gitea-builder

        docker buildx inspect --bootstrap

    - name: Compute metadata
      id: meta
      shell: bash
      run: |
        # Generate tags
        TAGS="latest"
        if [ -n "${{ inputs.tags }}" ]; then
          TAGS="$TAGS,${{ inputs.tags }}"
        fi

        SHORT_SHA="$(git rev-parse --short HEAD 2>/dev/null || echo 'local')"
        DATE_TAG="$(date +%Y-%m-%d)"
        TAG="$DATE_TAG-$SHORT_SHA"
        TAGS="$TAGS,$TAG"

        # Add git tag if this is a tag push
        if [ "${{ github.ref_type }}" = "tag" ] || [[ "${{ github.ref }}" == refs/tags/* ]]; then
          TAG_NAME="${1#refs/tags/}"
          TAGS="$TAGS,$TAG_NAME"
        fi

        echo "image=${{ inputs.image-name }}" >> $GITHUB_OUTPUT
        echo "tag=$TAG" >> $GITHUB_OUTPUT
        echo "tags=$TAGS" >> $GITHUB_OUTPUT

    - name: Build image
      id: build
      shell: bash
      env:
        DOCKER_BUILDKIT: "1"
      run: |
        set -x
        CACHE_FROM_FLAG=""
        if [ -n "${{ inputs.cache-from }}" ]; then
          CACHE_FROM_FLAG="--cache-from=${{ inputs.cache-from }}"
        fi

        BUILD_ARGS_FLAG=""
        if [ -n "${{ inputs.build-args }}" ]; then
          for arg in $(echo "${{ inputs.build-args }}" | tr ',' ' '); do
            BUILD_ARGS_FLAG="$BUILD_ARGS_FLAG --build-arg=$arg"
          done
        fi

        PLATFORM_FLAG=""
        if [ "${{ inputs.platforms }}" != "linux/amd64" ]; then
          PLATFORM_FLAG="--platform=${{ inputs.platforms }}"
        fi

        PUSH_FLAG=""
        if [ "${{ inputs.push }}" = "true" ]; then
          PUSH_FLAG="--push"
        fi

        docker buildx build \
          $PLATFORM_FLAG \
          --tag "${{ inputs.image-name }}:${{ steps.meta.outputs.tag }}" \
          --tag "${{ inputs.image-name }}:latest" \
          $(for t in $(echo ${{ steps.meta.outputs.tags }} | tr ',' ' '); do echo -n "--tag ${{ inputs.image-name }}:$t "; done) \
          --file ${{ inputs.context }}/${{ inputs.dockerfile }} \
          --cache-to=${{ inputs.cache-to }} \
          $CACHE_FROM_FLAG \
          $BUILD_ARGS_FLAG \
          --progress=plain \
          $PUSH_FLAG \
          ${{ inputs.context }}

    - name: Get image digest
      id: push-digest
      shell: bash
      if: inputs.push == 'true'
      run: |
        DIGEST="$(docker inspect "${{ inputs.image-name }}:${{ steps.meta.outputs.tag }}" --format '{{.Digest}}' 2>/dev/null)"
        echo "digest=$DIGEST" >> $GITHUB_OUTPUT
        echo "digest_full=${{ inputs.image-name }}@$DIGEST" >> $GITHUB_OUTPUT