// Copyright Epic Games, Inc. All Rights Reserved.

#include "zenhttp/auth/oidc.h"

ZEN_THIRD_PARTY_INCLUDES_START
#include <cpr/cpr.h>
#include <fmt/format.h>
#include <json11.hpp>
ZEN_THIRD_PARTY_INCLUDES_END

namespace zen {

namespace details {

	using StringArray = std::vector<std::string>;

	StringArray ToStringArray(const json11::Json JsonArray)
	{
		StringArray Result;

		const auto& Items = JsonArray.array_items();

		for (const auto& Item : Items)
		{
			Result.push_back(Item.string_value());
		}

		return Result;
	}

}  // namespace details

using namespace std::literals;

OidcClient::OidcClient(const OidcClient::Options& Options)
{
	m_BaseUrl  = std::string(Options.BaseUrl);
	m_ClientId = std::string(Options.ClientId);
}

OidcClient::InitResult
OidcClient::Initialize()
{
	ExtendableStringBuilder<256> Uri;
	Uri << m_BaseUrl << "/.well-known/openid-configuration"sv;

	cpr::Session Session;

	Session.SetOption(cpr::Url{Uri.c_str()});

	cpr::Response Response = Session.Get();

	if (Response.error)
	{
		return {.Reason = std::move(Response.error.message)};
	}

	if (Response.status_code != 200)
	{
		return {.Reason = std::move(Response.reason)};
	}

	std::string	 JsonError;
	json11::Json Json = json11::Json::parse(Response.text, JsonError);

	if (JsonError.empty() == false)
	{
		return {.Reason = std::move(JsonError)};
	}

	m_Config = {.Issuer							   = Json["issuer"].string_value(),
				.AuthorizationEndpoint			   = Json["authorization_endpoint"].string_value(),
				.TokenEndpoint					   = Json["token_endpoint"].string_value(),
				.UserInfoEndpoint				   = Json["userinfo_endpoint"].string_value(),
				.RegistrationEndpoint			   = Json["registration_endpoint"].string_value(),
				.JwksUri						   = Json["jwks_uri"].string_value(),
				.SupportedResponseTypes			   = details::ToStringArray(Json["response_types_supported"]),
				.SupportedResponseModes			   = details::ToStringArray(Json["response_modes_supported"]),
				.SupportedGrantTypes			   = details::ToStringArray(Json["grant_types_supported"]),
				.SupportedScopes				   = details::ToStringArray(Json["scopes_supported"]),
				.SupportedTokenEndpointAuthMethods = details::ToStringArray(Json["token_endpoint_auth_methods_supported"]),
				.SupportedClaims				   = details::ToStringArray(Json["claims_supported"])};

	return {.Ok = true};
}

OidcClient::RefreshTokenResult
OidcClient::RefreshToken(std::string_view RefreshToken)
{
	const std::string Body = fmt::format("grant_type=refresh_token&refresh_token={}&client_id={}", RefreshToken, m_ClientId);

	cpr::Session Session;

	Session.SetOption(cpr::Url{m_Config.TokenEndpoint.c_str()});
	Session.SetOption(cpr::Header{{"Content-Type", "application/x-www-form-urlencoded"}});
	Session.SetBody(cpr::Body{Body.data(), Body.size()});

	cpr::Response Response = Session.Post();

	if (Response.error)
	{
		return {.Reason = std::move(Response.error.message)};
	}

	if (Response.status_code != 200)
	{
		return {.Reason = fmt::format("{} ({})", Response.reason, Response.text)};
	}

	std::string	 JsonError;
	json11::Json Json = json11::Json::parse(Response.text, JsonError);

	if (JsonError.empty() == false)
	{
		return {.Reason = std::move(JsonError)};
	}

	return {.TokenType		  = Json["token_type"].string_value(),
			.AccessToken	  = Json["access_token"].string_value(),
			.RefreshToken	  = Json["refresh_token"].string_value(),
			.IdentityToken	  = Json["id_token"].string_value(),
			.Scope			  = Json["scope"].string_value(),
			.ExpiresInSeconds = static_cast<int64_t>(Json["expires_in"].int_value()),
			.Ok				  = true};
}

}  // namespace zen