name: "Setup Buildx (tiny)"
description: "Create & optionally use a docker buildx builder with an optional random name."
inputs:
  name:
    description: "Builder name. If empty, a random name is generated."
    required: false
    default: ""
  use:
    description: "Whether to set the builder as current (default: true)."
    required: false
    default: "true"
  driver:
    description: "Buildx driver (default: docker-container)."
    required: false
    default: "docker-container"
  image:
    description: "Optional BuildKit image (e.g. moby/buildkit:v0.15.2). If empty, not passed."
    required: false
    default: ""
outputs:
  name:
    description: "The effective builder name."
    value: ${{ steps.main.outputs.name }}
runs:
  using: "composite"
  steps:
    - id: main
      shell: bash
      run: |
        set -euo pipefail

        # Inputs
        IN_NAME="${{ inputs.name }}"
        IN_USE="${{ inputs.use }}"
        IN_DRIVER="${{ inputs.driver }}"
        IN_IMAGE="${{ inputs.image }}"

        # Generate random name if empty (lowercase, 8 chars)
        if [[ -z "${IN_NAME}" ]]; then
          if command -v uuidgen >/dev/null 2>&1; then
            RAND="$(uuidgen | tr 'A-Z' 'a-z' | tr -cd 'a-z0-9' | cut -c1-8)"
          else
            RAND="$(head -c 12 /dev/urandom | tr -cd 'a-z0-9' | cut -c1-8)"
          fi
          BUILDER_NAME="builder-${RAND}"
        else
          BUILDER_NAME="${IN_NAME}"
        fi

        # Compose driver-opts if image provided
        DRIVER_OPTS=()
        if [[ -n "${IN_IMAGE}" ]]; then
          DRIVER_OPTS+=(--driver-opt "image=${IN_IMAGE}")
        fi

        # If builder exists: optionally use it; else create it
        if docker buildx inspect "${BUILDER_NAME}" >/dev/null 2>&1; then
          echo "ℹ️  Builder '${BUILDER_NAME}' already exists."
          if [[ "${IN_USE}" == "true" ]]; then
            docker buildx use "${BUILDER_NAME}"
            echo "✅ Using existing builder: ${BUILDER_NAME}"
          fi
        else
          CMD=(docker buildx create --name "${BUILDER_NAME}" --driver "${IN_DRIVER}" "${DRIVER_OPTS[@]}")
          if [[ "${IN_USE}" == "true" ]]; then
            CMD+=("--use")
          fi
          echo "+ ${CMD[*]}"
          "${CMD[@]}"
          echo "✅ Created${IN_USE:+ and using} builder: ${BUILDER_NAME}"
        fi

        # Output for downstream steps
        echo "name=${BUILDER_NAME}" >> "$GITHUB_OUTPUT"