# .github/workflows/docker-publish.yml

name: Docker Image CI for Electricity Calculator

# Controls when the workflow will run
on:
  push:
    branches: [ "main" ] # Triggers on pushes to the main branch
  # Allows you to run this workflow manually from the Actions tab
  workflow_dispatch:

jobs:
  build_and_push_to_ghcr:
    name: Build and Push to GitHub Container Registry
    runs-on: ubuntu-latest # Use the latest Ubuntu runner

    permissions:
      contents: read      # Needed to checkout the repository
      packages: write     # Needed to push to GitHub Packages (GHCR)
      # id-token: write    # Uncomment if using OIDC for authentication with a cloud provider

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        # This step checks out your repository under $GITHUB_WORKSPACE, so your workflow can access it.

      - name: Log in to GitHub Container Registry
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }} # Your GitHub username or organization name
          password: ${{ secrets.GITHUB_TOKEN }}
        # This step logs in to GHCR using a GITHUB_TOKEN, which is automatically generated for each job run.
        # The GITHUB_TOKEN has permissions to push to GHCR if 'packages: write' is set for the job.

      - name: Extract metadata (tags, labels) for Docker
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ghcr.io/${{ github.repository_owner }}/electricity-calculator-app
          # Generates tags:
          # - 'latest' for the default branch
          # - Git tag if a tag is pushed
          # - Git SHA as a tag
          tags: |
            type=schedule
            type=ref,event=branch
            type=ref,event=pr
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=semver,pattern={{major}}
            type=sha
            latest

      - name: Build and push Docker image
        uses: docker/build-push-action@v5
        with:
          context: . # Build context is the root of the repository (where Dockerfile is)
          file: ./Dockerfile # Explicitly specify the Dockerfile name if it's not 'Dockerfile' or is in a subdirectory
          push: true # Actually push the image after building
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
        # This step builds the Docker image using the Dockerfile in your repository
        # and pushes it to GHCR with the tags generated in the previous step.

      - name: Image digest
        run: echo ${{ steps.build_and_push.outputs.digest }}
        # Optional: Outputs the digest of the pushed image.