/*
 * This file is a part of Winix
 * and is distributed under the 2-Clause BSD licence.
 * Author: Tomasz Sowa <t.sowa@ttmath.org>
 */

/* 
 * Copyright (c) 2010-2022, Tomasz Sowa
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 */
 
#include "functionbase.h"
#include "functions.h"
#include "templates/templates.h"


namespace Winix
{


FunctionBase::FunctionBase()
{
	follow_symlinks = true;
	template_index  = size_t(-1);
	need_ssl		= false;
	need_session	= true;
	register_default_models = true;
	post_max_object_items = 0;
	post_max_table_items = 0;
	post_max_all_items = 0;
	post_max_nested_objects = 0;

	fun.item_content.user_id    = -1;
	fun.item_content.group_id   = -1;
	fun.item_content.privileges = 07555;
	fun.parent_id  = -1;
	fun.id         = -1;
	fun.type       = Item::file;

	db = nullptr;
	functions = nullptr;
	templates = nullptr;
}


FunctionBase::~FunctionBase()
{
}



//void FunctionBase::SetConfig(Config * pconfig)
//{
//	config = pconfig;
//}


//void FunctionBase::SetCur(Cur * pcur)
//{
//	cur = pcur;
//}



void FunctionBase::SetDb(Db * pdb)
{
	db = pdb;
}


//void FunctionBase::SetSystem(System * psystem)
//{
//	system = psystem;
//}


void FunctionBase::SetFunctions(Functions * pfunctions)
{
	functions = pfunctions;
}


void FunctionBase::SetTemplates(Templates * ptemplates)
{
	templates = ptemplates;
}


//void FunctionBase::SetSynchro(Synchro * psynchro)
//{
//	synchro = psynchro;
//}


//void FunctionBase::SetSessionManager(SessionManager * pmanager)
//{
//	session_manager = pmanager;
//}


void FunctionBase::Init()
{
	// this method is called only once at the beginning
	// when winix starts
}


void FunctionBase::Finish()
{
	// this method is called only once at the end
	// when winix finishes
}


bool FunctionBase::HasAccess()
{
	// true by default
	return true;
}


/*
 * this is in a response to the normal OPTIONS method (not cors request)
 */
void FunctionBase::AddAllowMethodsHeader()
{
	cur->request->out_headers.add(Header::allow, L"GET, HEAD, POST, PUT, DELETE, OPTIONS, PATCH");
}


bool FunctionBase::IsCorsMethodAvailable(Request::Method method)
{
	return method == Request::get || method == Request::head || method == Request::post || method == Request::put ||
		   method == Request::delete_ ||method == Request::patch;
}


bool FunctionBase::IsOriginAvailable(const std::wstring & origin_url)
{
	if( config )
	{
		if( !config->allowed_origins.empty() )
		{
			// origin_url can be a "null" string
			// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Origin
			// but in such a case the "null" should be put to the config as well
			return is_in_list(origin_url, config->allowed_origins);
		}
		else
		{
			if( config->allow_all_origins )
			{
				return true;
			}
		}
	}

	return false;
}


bool FunctionBase::AreCorsCredentialsAvailable()
{
	return config && config->access_control_allow_credentials;
}


bool FunctionBase::AreCorsHeadersAvailable(const std::wstring & headers)
{
	// true by default for all headers
	// headers are comma separated
	return true;
}


/*
 * method is the value of Access-Control-Request-Method header sent by the client
 */
void FunctionBase::AddAccessControlAllowMethodsHeader(Request::Method method)
{
	cur->request->AddHeader(Header::access_control_allow_methods, L"GET, HEAD, POST, PUT, DELETE, OPTIONS, PATCH");
}


/*
 * origin_url is the value of Origin header sent by the client
 * origin_url can be: "null"
 * https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Origin
 *
 */
void FunctionBase::AddAccessControlAllowOriginHeader(const std::wstring & origin_url)
{
	if( config )
	{
		if( !config->allowed_origins.empty() )
		{
			// method IsOriginAvailable(..) was called beforehand so now we assume
			// that the origin_url is permitted (and is valid as a header)
			cur->request->AddHeader(Header::access_control_allow_origin, origin_url);
		}
		else
		{
			if( config->allow_all_origins )
			{
				cur->request->AddHeader(Header::access_control_allow_origin, L"*");
			}
		}
	}
}


/*
 * headers is the value of Access-Control-Request-Headers header sent by the client
 */
void FunctionBase::AddAccessControlAllowHeadersHeader(const std::wstring & headers)
{
	if( Header::is_header_value_correct(headers) )
	{
		cur->request->AddHeader(Header::access_control_allow_headers, headers);
	}
}


void FunctionBase::AddAccessControlMaxAgeHeader()
{
	// default 24 hours
	cur->request->AddHeader(Header::access_control_max_age, 86400);
}


void FunctionBase::AddAccessControlAllowCredentialsHeader()
{
	cur->request->AddHeader(Header::access_control_allow_credentials, L"true");
}


void FunctionBase::AddAccessControlExposeHeadersHeader()
{
	if( config )
	{
		if( !config->access_control_expose_headers.empty() )
		{
			pt::WTextStream headers;
			bool is_first = true;

			for(std::wstring & str : config->access_control_expose_headers)
			{
				if( !is_first )
					headers << ", ";

				headers << str;
				is_first = false;
			}

			cur->request->AddHeader(Header::access_control_expose_headers, headers);
		}
	}
}


void FunctionBase::AddCorsPreflightRequestHeaders(const std::wstring & origin, Request::Method method, const std::wstring * request_headers)
{
	AddAccessControlAllowMethodsHeader(method);
	AddAccessControlAllowOriginHeader(origin);
	AddAccessControlMaxAgeHeader();
	AddAccessControlExposeHeadersHeader();

	if( AreCorsCredentialsAvailable() )
	{
		AddAccessControlAllowCredentialsHeader();
	}

	if( request_headers )
	{
		AddAccessControlAllowHeadersHeader(*request_headers);
	}

	log << log3 << "FunctionBase: this cors request is permitted" << logend;
}


void FunctionBase::AddCorsNormalRequestHeaders(const std::wstring & origin)
{
	AddAccessControlAllowOriginHeader(origin);

	if( AreCorsCredentialsAvailable() )
	{
		AddAccessControlAllowCredentialsHeader();
	}
}


void FunctionBase::CheckCorsPreflightRequest(const std::wstring & origin, const std::wstring & method_string)
{
	pt::Space * cors_headers = cur->request->headers_in.get_space_nc(L"Access_Control_Request_Headers");
	Request::Method method = Request::CheckRequestMethod(method_string.c_str());

	if( IsCorsMethodAvailable(method) )
	{
		bool cors_headers_available = true;
		std::wstring * headers = nullptr;

		if( cors_headers && cors_headers->is_wstr() )
		{
			headers = cors_headers->get_wstr();
			cors_headers_available = AreCorsHeadersAvailable(*headers);
		}

		if( cors_headers_available )
		{
			AddCorsPreflightRequestHeaders(origin, method, headers);
		}
		else
		{
			if( headers )
			{
				log << log2 << "FunctionBase: these cors headers: " << *headers << " are not permitted in cors requests" << logend;
			}
		}
	}
	else
	{
		log << log2 << "FunctionBase: this method: " << method_string << " is not permitted in cors requests" << logend;
	}
}


void FunctionBase::AddResponseHeadersForOrigin(const std::wstring & origin)
{
	if( cur->request->method == Request::Method::options )
	{
		pt::Space * cors_method = cur->request->headers_in.get_space_nc(L"Access_Control_Request_Method"); // FastCGI changes '-' to '_'
		cur->request->http_status = Header::status_204_no_content;

		if( cors_method && cors_method->is_wstr() )
		{
			/*
			 * this is a preflight request
			 * https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request
			 * (we allow Access-Control-Request-Headers not to be present)
			 */

			if( config->are_cors_preflight_requests_available )
			{
				CheckCorsPreflightRequest(origin, *cors_method->get_wstr());
			}
			else
			{
				log << log2 << "FunctionBase: cors requests are disabled" << logend;
			}
		}
		else
		{
			/*
			 * this is not a preflight cors request
			 */
			AddAllowMethodsHeader();
			AddCorsNormalRequestHeaders(origin);
		}
	}
	else
	{
		AddCorsNormalRequestHeaders(origin);
	}
}


void FunctionBase::CheckOriginHeader()
{
	pt::Space * origin = cur->request->headers_in.get_space_nc(L"Origin");

	if( origin && origin->is_wstr() )
	{
		if( IsOriginAvailable(*origin->get_wstr()) )
		{
			AddResponseHeadersForOrigin(*origin->get_wstr());
		}
		else
		{
			cur->request->http_status = Header::status_204_no_content;
			log << log2 << "FunctionBase: this origin: " << *origin->get_wstr() << " is not permitted for cors requests" << logend;
		}

		/*
		 * https://portswigger.net/research/exploiting-cors-misconfigurations-for-bitcoins-and-bounties
		 * https://security.stackexchange.com/questions/151590/vary-origin-response-header-and-cors-exploitation
		 * It's important to include the Vary: Origin header to prevent caching. The header indicates that the response
		 * is in some way dependent on the origin and should therefore not be served from cache for any other origin.
		 * If the header is missing, cache poisoning attacks might be possible
		 */
		cur->request->AddHeader(Header::very, Header::origin);
	}
	else
	{
		if( cur->request->method == Request::Method::options )
		{
			AddAllowMethodsHeader();
		}
	}
}



void FunctionBase::MakeGet()
{
	// do nothing by default
}

void FunctionBase::MakeHead()
{
	// by default call MakeGet() but we do not return any content at the end of the request
	MakeGet();
}

void FunctionBase::MakePost()
{
	// do nothing by default
}

void FunctionBase::MakePut()
{
	// do nothing by default
}

void FunctionBase::MakeDelete()
{
	// do nothing by default
}

void FunctionBase::MakeConnect()
{
	// do nothing by default
}

void FunctionBase::MakeOptions()
{
	// do nothing by default
}

void FunctionBase::MakeTrace()
{
	// do nothing by default
}

void FunctionBase::MakePatch()
{
	// do nothing by default
}


void FunctionBase::Clear()
{
	// do nothing by default
}



void FunctionBase::ContinueMakeGet()
{
	// do nothing by default
}

void FunctionBase::ContinueMakeHead()
{
	// do nothing by default
}

void FunctionBase::ContinueMakePost()
{
	// do nothing by default
}

void FunctionBase::ContinueMakePut()
{
	// do nothing by default
}

void FunctionBase::ContinueMakeDelete()
{
	// do nothing by default
}

void FunctionBase::ContinueMakeConnect()
{
	// do nothing by default
}

void FunctionBase::ContinueMakeOptions()
{
	// do nothing by default
}

void FunctionBase::ContinueMakeTrace()
{
	// do nothing by default
}

void FunctionBase::ContinueMakePatch()
{
	// do nothing by default
}


} // namespace Winix