package com.greenpepper.extensions.guice;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Module;
import com.greenpepper.reflect.DefaultFixture;
import com.greenpepper.reflect.Fixture;
import com.greenpepper.systemunderdevelopment.DefaultSystemUnderDevelopment;

public class GuiceSystemUnderDevelopment extends DefaultSystemUnderDevelopment
{

	private Injector injector;
	private List<String> moduleNames = new ArrayList<String>();

	public GuiceSystemUnderDevelopment()
	{
	}

	public GuiceSystemUnderDevelopment(String... moduleNames)
	{
		Collections.addAll(this.moduleNames, moduleNames);
	}

	@Override
	public Fixture getFixture(String name, String... params)
			throws Throwable
	{
		lazilyInstantiateModulesAndInjector();

		Fixture fixture;

		if (params.length != 0)
		{
			// When params are used, we use the PlainOldSystemUnderDevelopment to instantiate the fixture
			// these params are passed to the constructor
			// Then we use Guice to inject members
			fixture = super.getFixture(name, params);
			injector.injectMembers(fixture.getTarget());
		}
		else
		{
			// Use Guice to instantiate
			Class<?> klass = loadType(name).getUnderlyingClass();
			Object target = injector.getInstance(klass);
			fixture = new DefaultFixture(target);
		}

		return fixture;
	}

	private void lazilyInstantiateModulesAndInjector()
			throws Exception
	{
		if (injector == null)
		{
			List<Module> modules = convertModuleNamesToModules();
			injector = Guice.createInjector(modules);
		}
	}

	private List<Module> convertModuleNamesToModules()
			throws Exception
	{
		List<Module> modules = new ArrayList<Module>(moduleNames.size());
		for (String moduleName : moduleNames)
		{
			Class<?> klass = loadType(moduleName).getUnderlyingClass();
			modules.add((Module)klass.newInstance());
		}
		return modules;
	}

	public void addModules(String... moduleNames)
	{
		if (injector == null)
		{
			Collections.addAll(this.moduleNames, moduleNames);
		}
		else
		{
			throw new IllegalStateException("Cannot add module after a fixture has been instantiated");
		}
	}
}