name: Deploy

# Define when the workflow should run
on:
  # Allow manual triggering of the workflow from the Actions tab
  workflow_dispatch:

  # Allow inputs to be passed when manually triggering the workflow from the Actions tab
    inputs:
      DOCKERFILE_PATH:
        type: string
        description: 'Path to the Dockerfile'
        required: true
        default: 'dockerfiles/debian_mini'

      IMAGE_SIZE:
        type: string
        description: 'Image size, 950M max'
        required: true
        default: '600M'

      DEPLOY_TO_GITHUB_PAGES:
        type: boolean
        description: 'Deploy to Github pages'
        required: true
        default: true

      GITHUB_RELEASE:
        type: boolean
        description: 'Upload GitHub release'
        required: true
        default: false

jobs:

  guard_clause:
      runs-on: ubuntu-latest
  
      env:
        GH_TOKEN: ${{ github.token }} # As required by the GitHub-CLI  

      permissions:
        actions: 'write' # Required in order to terminate the workflow run.
  
      steps:
        - uses: actions/checkout@v3
        # Guard clause that cancels the workflow in case of an invalid DOCKERFILE_PATH and/or incorrectly configured Github Pages. 
        # The main reason for choosing this workaround for aborting the workflow is the fact that it does not display the workflow as successful, which can set false expectations.
        - name: DOCKERFILE_PATH.
          shell: bash
          run: |
            # We check whether the Dockerfile_path is valid. 
            if [ ! -f ${{ github.event.inputs.DOCKERFILE_PATH }} ]; then
                echo "::error title=Invalid Dockerfile path::No file found at ${{ github.event.inputs.DOCKERFILE_PATH }}"
                echo "terminate=true" >> $GITHUB_ENV
            fi

        - name: Github Pages config guard clause
          if: ${{ github.event.inputs.DEPLOY_TO_GITHUB_PAGES == 'true' }}
          run: |
            # We use the Github Rest api to get information regarding pages for the Github Repository and store it into a temporary file named "pages_response".
            set +e
            gh api \
              -H "Accept: application/vnd.github+json" \
              -H "X-GitHub-Api-Version: 2022-11-28" \
              /repos/${{ github.repository_owner }}/$(basename ${{ github.repository }})/pages > pages_response

            # We make sure Github Pages has been enabled for this repository.
            if [ "$?" -ne 0 ]; then
              echo "::error title=Potential pages configuration error.::Please make sure you have enabled Github pages for the ${{ github.repository }} repository. If already enabled then Github pages might be down"
              echo "terminate=true" >> $GITHUB_ENV
            fi
            set -e

            # We make sure the Github pages build & deployment source is set to "workflow" (Github Actions). Instead of a "legacy" (branch).
            if [[ "$(jq --compact-output --raw-output .build_type pages_response)" != "workflow" ]]; then
                echo "Undefined behaviour, Make sure the Github Pages source is correctly configured in the Github Pages settings."
                echo "::error title=Pages configuration error.::Please make sure you have correctly picked \"Github Actions\" as the build and deployment source for the Github Pages."
                echo "terminate=true" >> $GITHUB_ENV
            fi
            rm pages_response

        - name: Terminate run if error occurred.
          run: |
            if [[ $terminate == "true" ]]; then
              gh run cancel ${{ github.run_id }}
              gh run watch ${{ github.run_id }}
            fi

  build:
    needs: guard_clause # Dependency
    runs-on: ubuntu-latest # Image to run the worker on.

    env:
      TAG: "ext2-webvm-base-image" # Tag of docker image.
      IMAGE_SIZE: '${{ github.event.inputs.IMAGE_SIZE }}'
      DEPLOY_DIR: /webvm_deploy/ # Path to directory where we host the final image from.

    permissions: # Permissions to grant the GITHUB_TOKEN.
      contents: write  # Required permission to make a github release.

    steps:
      # Checks-out our repository under $GITHUB_WORKSPACE, so our job can access it
      - uses: actions/checkout@v3

      # Setting the IMAGE_NAME variable in GITHUB_ENV to <Dockerfile name>_<date>_<run_id>.ext2.
      - name: Generate the image_name.
        id: image_name_gen
        run: |
          echo "IMAGE_NAME=$(basename ${{ github.event.inputs.DOCKERFILE_PATH }})_$(date +%Y%m%d)_${{ github.run_id }}.ext2" >> $GITHUB_ENV

      # Create directory to host the image from.
      - run: sudo mkdir -p $DEPLOY_DIR

      # Build the i386 Dockerfile image.
      - run: docker build . --tag $TAG --file ${{ github.event.inputs.DOCKERFILE_PATH }} --platform=i386
      
      # Run the docker image so that we can export the container.
      # Run the Docker container with the Google Public DNS nameservers: 8.8.8.8, 8.8.4.4
      - run: |
          docker run --dns 8.8.8.8 --dns 8.8.4.4 -d $TAG
          echo "CONTAINER_ID=$(sudo docker ps -aq)" >> $GITHUB_ENV

      # We extract the CMD, we first need to figure whether the Dockerfile uses CMD or an Entrypoint.
      - name: Extracting CMD / Entrypoint and args
        shell: bash
        run: |
          cmd=$(sudo docker inspect --format='{{json .Config.Cmd}}' $CONTAINER_ID)
          entrypoint=$(sudo docker inspect --format='{{json .Config.Entrypoint}}' $CONTAINER_ID)
          if [[ $entrypoint != "null" && $cmd != "null" ]]; then
            echo "CMD=$( sudo docker inspect $CONTAINER_ID | jq --compact-output '.[0].Config.Entrypoint' )" >> $GITHUB_ENV
            echo "ARGS=$( sudo docker inspect $CONTAINER_ID | jq --compact-output '.[0].Config.Cmd' )" >> $GITHUB_ENV
          elif [[ $cmd != "null" ]]; then
            echo "CMD=$( sudo docker inspect $CONTAINER_ID | jq --compact-output '.[0].Config.Cmd[:1]' )" >> $GITHUB_ENV
            echo "ARGS=$( sudo docker inspect $CONTAINER_ID | jq --compact-output '.[0].Config.Cmd[1:]' )" >> $GITHUB_ENV
          else
            echo "CMD=$( sudo docker inspect $CONTAINER_ID | jq --compact-output '.[0].Config.Entrypoint[:1]' )" >> $GITHUB_ENV
            echo "ARGS=$( sudo docker inspect $CONTAINER_ID | jq --compact-output '.[0].Config.Entrypoint[1:]' )" >> $GITHUB_ENV
          fi

      # We extract the ENV, CMD/Entrypoint and cwd from the Docker container with docker inspect.
      - name: Extracting env, args and cwd.
        shell: bash
        run: |
          echo "ENV=$( sudo docker inspect $CONTAINER_ID | jq --compact-output  '.[0].Config.Env' )" >> $GITHUB_ENV
          echo "CWD=$( sudo docker inspect $CONTAINER_ID | jq --compact-output '.[0].Config.WorkingDir' )" >> $GITHUB_ENV

      # We create and mount the base ext2 image to extract the Docker container's filesystem its contents into.
      - name: Create ext2 image.
        run: |
         # Preallocate space for the ext2 image
         sudo fallocate -l $IMAGE_SIZE ${IMAGE_NAME}
         # Format to ext2 linux kernel revision 0
         sudo mkfs.ext2 -r 0 ${IMAGE_NAME}
         # Mount the ext2 image to modify it
         sudo mount -o loop -t ext2 ${IMAGE_NAME} /mnt/

      # We opt for 'docker cp --archive' over 'docker save' since our focus is solely on the end product rather than individual layers and metadata.
      # However, it's important to note that despite being specified in the documentation, the '--archive' flag does not currently preserve uid/gid information when copying files from the container to the host machine.
      # Another compelling reason to use 'docker cp' is that it preserves resolv.conf.
      - name: Export and unpack container filesystem contents into mounted ext2 image.
        run: | 
          sudo docker cp -a ${CONTAINER_ID}:/ /mnt/
          sudo umount /mnt/
      # Result is an ext2 image for webvm.

      # Move required files for gh-pages deployment to the deployment directory $DEPLOY_DIR.
      - run: sudo mv assets examples xterm favicon.ico index.html login.html network.js scrollbar.css serviceWorker.js tower.ico $DEPLOY_DIR
      
      # The .txt suffix enabled HTTP compression for free
      - name: Generate image split chunks and .meta file
        run: |
          sudo split ${{ env.IMAGE_NAME }} ${{ env.DEPLOY_DIR }}/${{ env.IMAGE_NAME }}.c -a 6 -b 128k -x --additional-suffix=.txt
          sudo bash -c "stat -c%s ${{ env.IMAGE_NAME }} > ${{ env.DEPLOY_DIR }}/${{ env.IMAGE_NAME }}.meta"
      # This step updates the default index.html file by performing the following actions:
      #   1. Replaces all occurrences of IMAGE_URL with the URL to the image.
      #   2. Replaces all occurrences of DEVICE_TYPE to bytes.
      #   3. Replace CMD with the Dockerfile entry command.
      #   4. Replace args with the Dockerfile CMD / Entrypoint args.
      #   5. Replace ENV with the container's environment values.
      - name: Adjust index.html
        run: |
          sudo sed -i 's#IMAGE_URL#"${{ env.IMAGE_NAME }}"#g' ${{ env.DEPLOY_DIR }}index.html
          sudo sed -i 's#DEVICE_TYPE#"github"#g' ${{ env.DEPLOY_DIR }}index.html
          sudo sed -i 's#CMD#${{ env.CMD }}#g' ${{ env.DEPLOY_DIR }}index.html
          sudo sed -i 's#ARGS#${{ env.ARGS }}#g' ${{ env.DEPLOY_DIR }}index.html
          sudo sed -i 's#ENV#${{ env.ENV }}#g' ${{ env.DEPLOY_DIR }}index.html
          sudo sed -i 's#CWD#${{ env.CWD }}#g' ${{ env.DEPLOY_DIR }}index.html

      # We generate index.list files for our httpfs to function properly.
      - name: make index.list
        shell: bash
        run: |
          find $DEPLOY_DIR -type d | while read -r dir;
          do
            index_list="$dir/index.list";
            sudo rm -f "$index_list";
            sudo ls "$dir" | sudo tee "$index_list" > /dev/null;
            sudo chmod +rw "$index_list";     
            sudo echo "created $index_list"; 
          done

      # Create a gh-pages artifact in order to deploy to gh-pages.
      - name: Upload GitHub Pages artifact
        uses: actions/upload-pages-artifact@v2
        with:
          # Path of the directory containing the static assets for our gh pages deployment.
          path: ${{ env.DEPLOY_DIR }} # optional, default is _site/

      - name: github release # To upload our final ext2 image as a github release.
        if: ${{ github.event.inputs.GITHUB_RELEASE == 'true' }}
        uses: softprops/action-gh-release@v0.1.15
        with:
          target_commitish: ${{ github.sha }} # Last commit on the GITHUB_REF branch or tag
          tag_name: ext2_image
          fail_on_unmatched_files: 'true' # Fail in case of no matches with the file(s) glob(s).
          files: | # Assets to upload as release.
            ${{ env.IMAGE_NAME }}

  deploy_to_github_pages: # Job that deploys the github-pages artifact to github-pages.
    if: ${{ github.event.inputs.DEPLOY_TO_GITHUB_PAGES == 'true' }}
    needs: build
    environment:
      name: github-pages
      url: ${{ steps.deployment.outputs.page_url }}

    # Grant GITHUB_TOKEN the permissions required to make a Pages deployment
    permissions:
      pages: write      # to deploy to Pages
      id-token: write   # to verify the deployment originates from an appropriate source

    runs-on: ubuntu-latest
    steps:
      # Deployment to github pages
      - name: Deploy GitHub Pages site
        id: deployment
        uses: actions/deploy-pages@v3
