//============================================================================
// clang++ -o sslclient sslclient.cpp -lssl -lcrypto -L/usr/local/opt/openssl/lib -I/usr/local/opt/openssl/include
//============================================================================
//

#include "sslclient.h"

#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/socket.h>

#include <iostream>
#include <regex>
#include <sstream>
#include <string>


HttpClient::HttpClient(){};

std::pair<int, std::string> HttpClient::doGetRequest(const std::string &url, const std::unordered_map<std::string, std::string> &headers) {
	// ^(?:((?:https?|s?ftp):)\/\/)([^:\/\s]+)(?::(\d*))?(?:\/([^\s?#]+)?([?][^?#]*)?(#.*)?)?
	//  viz test
	//  https://api.iextrading.com:443/1.0/stock/market/batch?symbols=cah,khc,syf,jnj&types=quote#muhehe
	//  https://stackoverflow.com/questions/25896916/parse-http-headers-in-c
	
	std::regex rgx{R"(^(?:((?:https?|s?ftp):)//)([^:/\s]+)(?::(\d*))?(?:/([^\s?#]+)?([?][^?#]*)?(#.*)?)?)"};
	std::smatch matches;

	if (std::regex_search(url, matches, rgx)) {
		for (size_t i = 0; i < matches.size(); ++i) {
			switch (i) {
			case 0:
				full_url = matches[i].str();
				break;
			case 1:
				proto = matches[i].str();
				break;
			case 2:
				server = matches[i].str();
				break;
			case 3:
				port = matches[i].str();
				break;
			case 4:
				uri = matches[i].str();
				break;
			case 5:
				params = matches[i].str();
				break;
			case 6:
				href = matches[i].str();
				break;
			}
			// std::cout << i << ": '" << matches[i].str() << "'\n";
		}
	} else {
		std::cerr << "Match not found\n";	// TODO better message
	}

	std::string headers_string = "";
	for (auto it = headers.begin(); it != headers.end(); ++it) {
		headers_string.append("\r\n" + it->first + ": " + it->second);
 	}

	std::string request = "GET " + full_url + " HTTP/1.0\r\nHost: " + server + headers_string + "\r\n\r\n";

	int bytes_read = sslRequest(server, request);

	std::string::size_type position = ssl_read_packet.find("\r\n\r\n");
	if (position == std::string::npos) {
		std::cerr << "substring not found" << std::endl; // TODO invalid packet
	}

	std::string hdr = ssl_read_packet.substr(0, position);
	auto status_pos = hdr.find("\r\n");

	std::string status_str = hdr.substr(0, status_pos);
	hdr = hdr.substr(status_pos + 2, hdr.length() - 2 - status_pos);

	// TODO parse status code
	std::regex status_rgx{"^HTTP/\\d\\.\\d (\\d{3}) .+$"};
	std::smatch status_matches;
	if (std::regex_search(status_str, status_matches, status_rgx)) {
		if (status_matches.size() > 1) {
				auto sta = status_matches[1].str();		// string "200"
				// std::cout << "status: " << sta << std::endl;
		}
	}

	std::string body = ssl_read_packet.substr(position + 4, ssl_read_packet.length() - 4 - position);


	std::istringstream resp(hdr);
	std::string header;
	std::string::size_type index;
	while (std::getline(resp, header) && header != "\r") {
		index = header.find(": ", 0);
		if (index != std::string::npos) {
			headers_map.insert(std::make_pair(header.substr(0, index), header.substr(index + 1)));
		}
	}

	// for(auto& kv: headers_map) {
	//     std::cout << "KEY: `" << kv.first << "`, VALUE: `" << kv.second << '`' << std::endl;
	// }

	// TODO if error return error desc in string
	return std::make_pair(200, body);
};

std::string HttpClient::inetAddress(std::string hostname) {
	hostent *record = gethostbyname(hostname.c_str());
	if (record == NULL) {
		std::cerr << hostname << " is unavailable" << std::endl;
		exit(1);
	}
	in_addr *address = (in_addr *)record->h_addr;
	std::string ip_address = inet_ntoa(*address);

	return ip_address;
}

int HttpClient::sslRecvPacket() {
	ssl_read_packet.resize(4096);
	ssl_read_packet.clear();

	int len = 16384;
	char buf[len + 1];
	do {
		len = SSL_read(ssl, buf, len);
		buf[len] = 0;
		ssl_read_packet.append((const char *)buf);
	} while (len > 0);

	if (len < 0) {
		int err = SSL_get_error(ssl, len);
		if (err == SSL_ERROR_WANT_READ)
			return 0;
		if (err == SSL_ERROR_WANT_WRITE)
			return 0;
		if (err == SSL_ERROR_ZERO_RETURN || err == SSL_ERROR_SYSCALL || err == SSL_ERROR_SSL)
			return -1;
	}

	return ssl_read_packet.length();
}

int HttpClient::sslSendPacket(std::string buf) {
	int len = SSL_write(ssl, buf.c_str(), strlen(buf.c_str()));
	if (len < 0) {
		int err = SSL_get_error(ssl, len);
		switch (err) {
		case SSL_ERROR_WANT_WRITE:
			return 0;
		case SSL_ERROR_WANT_READ:
			return 0;
		case SSL_ERROR_ZERO_RETURN:
		case SSL_ERROR_SYSCALL:
		case SSL_ERROR_SSL:
		default:
			return -1;
		}
	}

	return buf.length();
}

int HttpClient::sslRequest(const std::string &server_name, const std::string &request) {
	// create socket
	int s;
	s = socket(AF_INET, SOCK_STREAM, 0);
	if (!s) {
		printf("Error creating socket.\n");
		return -1;
	}

	// socket address
	std::string server_ip = inetAddress(server_name);
	struct sockaddr_in sa;
	memset(&sa, 0, sizeof(sa));
	sa.sin_family = AF_INET;
	sa.sin_addr.s_addr = inet_addr(server_ip.c_str());
	sa.sin_port = htons(443);
	socklen_t socklen = sizeof(sa);

	// connect to server
	if (connect(s, (struct sockaddr *)&sa, socklen)) {
		printf("Error connecting to server.\n");
		return -1;
	}

	SSL_library_init();
	SSLeay_add_ssl_algorithms();
	SSL_load_error_strings();
	const SSL_METHOD *meth = TLSv1_2_client_method();
	SSL_CTX *ctx = SSL_CTX_new(meth);
	ssl = SSL_new(ctx);
	if (!ssl) {
		printf("Error creating SSL.\n");
		log_ssl();
		return -1;
	}
	sock = SSL_get_fd(ssl);
	SSL_set_fd(ssl, s);
	
	SSL_ctrl(ssl, SSL_CTRL_SET_TLSEXT_HOSTNAME, TLSEXT_NAMETYPE_host_name, (void*)server.c_str());

	int err = SSL_connect(ssl);
	if (err <= 0) {
		printf("Error creating SSL connection.  err=%x\n", err);
		log_ssl();
		fflush(stdout);
		return -1;
	}

	// log cipher
	// printf ("SSL connection using %s\n", SSL_get_cipher (ssl));

	// send request
	sslSendPacket(request);

	// read response and return its length
	return sslRecvPacket();
}

void HttpClient::log_ssl() {
	int err;
	while ((err = ERR_get_error())) {
		char *str = ERR_error_string(err, 0);
		if (!str)
			return;
		std::cerr << str << std::endl;
	}
}