<?php namespace SocialNorm;

use SocialNorm\Exceptions\InvalidAuthorizationCodeException;

class SocialNorm
{
    /** @var ProviderRegistry */
	protected $providers;
	/** @var Session */
	protected $session;
	/** @var Request */
	protected $request;
	/** @var StateGenerator */
	protected $stateGenerator;

	public function __construct(
		ProviderRegistry $providers,
		Session $session,
		Request $request,
		StateGenerator $stateGenerator
	)
	{
		$this->providers = $providers;
		$this->session = $session;
		$this->request = $request;
		$this->stateGenerator = $stateGenerator;
	}

	public function registerProvider(string $alias, Provider $provider)
	{
		$this->providers->registerProvider($alias, $provider);
	}

	public function authorize(string $providerAlias)
	{
		$state = $this->stateGenerator->generate();

		$this->session->put('oauth.state', $state);

		return $this->getProvider($providerAlias)->authorizeUrl($state);
	}

	public function getUser(string $providerAlias)
	{
		$this->verifyState();
		return $this->getProvider($providerAlias)->getUser();
	}

	protected function getProvider(string $providerAlias)
	{
		return $this->providers->getProvider($providerAlias);
	}

	protected function verifyState()
	{
        if ($this->session->get('oauth.state') !== $this->request->state()) {
            throw new InvalidAuthorizationCodeException("State failed to verify");
        }
	}
}