require "rails_helper"

RSpec.describe ApiController do
  controller do
    def index
      respond_to do |format|
        format.text { render plain: "Plain text" }
        format.json { render json: "JSON" }
      end
    end
    
    def show
      respond_to do |format|
        format.text { render plain: "Plain text" }
        format.any { render plain: "Fallback" }
      end
    end
  end

  it "returns the first format when given no Accept header" do
    get :index

    expect(response.media_type).to eq("text/plain")
  end

  it "returns the first format when given a wildcard Accept header" do
    request.headers["Accept"] = "*/*"

    get :index

    expect(response.media_type).to eq("text/plain")
  end

  it "returns the first format when given Safari and Chrome's default Accept header" do
    request.headers["Accept"] = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8"

    get :index

    expect(response.media_type).to eq("text/plain")
  end

  it "returns a text/plain response when explicitly requested" do
    request.headers["Accept"] = "text/plain"

    get :index

    expect(response.media_type).to eq("text/plain")
  end

  it "returns an application/json response when explicitly requested" do
    request.headers["Accept"] = "application/json"

    get :index

    expect(response.media_type).to eq("application/json")
  end

  it "raises an error if given an unsupported MIME type" do
    request.headers["Accept"] = "image/webp"

    expect { get :index }.to raise_error(ActionController::UnknownFormat)
  end
  
  it "does not raise an error when given an unsupported MIME type if an 'any' format is present" do
    request.headers["Accept"] = "image/webp"

    get :show, params: { id: 1 }

    expect(response.body).to eq("Fallback")
  end

  it "raises an error when given an invalid MIME type" do
    request.headers["Accept"] = "not a valid MIME type"

    expect { get :index }.to raise_error(Mime::Type::InvalidMimeType)
  end

  it "raises an error when given an invalid MIME type even if an 'any' format is present" do
    request.headers["Accept"] = "not a valid MIME type"

    expect { get :show, params: { id: 1 } }.to raise_error(Mime::Type::InvalidMimeType)
  end
end