/*
 *  IXHttpClient.cpp
 *  Author: Benjamin Sergeant
 *  Copyright (c) 2019 Machine Zone, Inc. All rights reserved.
 */

#include "IXHttpClient.h"
#include "IXUrlParser.h"
#include "IXWebSocketHttpHeaders.h"
#include "IXSocketFactory.h"

#include <sstream>
#include <iomanip>
#include <vector>
#include <cstring>

#include <zlib.h>

namespace ix
{
    const std::string HttpClient::kPost = "POST";
    const std::string HttpClient::kGet = "GET";
    const std::string HttpClient::kHead = "HEAD";

    HttpClient::HttpClient()
    {

    }

    HttpClient::~HttpClient()
    {

    }

    HttpResponse HttpClient::request(
        const std::string& url,
        const std::string& verb,
        const std::string& body,
        const HttpRequestArgs& args,
        int redirects)
    {
        uint64_t uploadSize = 0;
        uint64_t downloadSize = 0;
        int code = 0;
        WebSocketHttpHeaders headers;
        std::string payload;

        std::string protocol, host, path, query;
        int port;

        if (!UrlParser::parse(url, protocol, host, path, query, port))
        {
            std::stringstream ss;
            ss << "Cannot parse url: " << url;
            return std::make_tuple(code, HttpErrorCode::UrlMalformed,
                                   headers, payload, ss.str(),
                                   uploadSize, downloadSize);
        }

        bool tls = protocol == "https";
        std::string errorMsg;
        _socket = createSocket(tls, errorMsg);

        if (!_socket)
        {
            return std::make_tuple(code, HttpErrorCode::CannotCreateSocket,
                                   headers, payload, errorMsg,
                                   uploadSize, downloadSize);
        }

        // Build request string
        std::stringstream ss;
        ss << verb << " " << path << " HTTP/1.1\r\n";
        ss << "Host: " << host << "\r\n";
        ss << "User-Agent: ixwebsocket/1.0.0" << "\r\n";
        ss << "Accept: */*" << "\r\n";

        if (args.compress)
        {
            ss << "Accept-Encoding: gzip" << "\r\n";
        }

        // Append extra headers
        for (auto&& it : args.extraHeaders)
        {
            ss << it.first << ": " << it.second << "\r\n";
        }

        if (verb == kPost)
        {
            ss << "Content-Length: " << body.size() << "\r\n";

            // Set default Content-Type if unspecified
            if (args.extraHeaders.find("Content-Type") == args.extraHeaders.end())
            {
                ss << "Content-Type: application/x-www-form-urlencoded" << "\r\n";
            }
            ss << "\r\n";
            ss << body;
        }
        else
        {
            ss << "\r\n";
        }

        std::string req(ss.str());
        std::string errMsg;
        std::atomic<bool> requestInitCancellation(false);

        // Make a cancellation object dealing with connection timeout
        auto isCancellationRequested =
            makeCancellationRequestWithTimeout(args.connectTimeout, requestInitCancellation);

        bool success = _socket->connect(host, port, errMsg, isCancellationRequested);
        if (!success)
        {
            std::stringstream ss;
            ss << "Cannot connect to url: " << url;
            return std::make_tuple(code, HttpErrorCode::CannotConnect,
                                   headers, payload, ss.str(),
                                   uploadSize, downloadSize);
        }

        // Make a new cancellation object dealing with transfer timeout
        isCancellationRequested =
            makeCancellationRequestWithTimeout(args.transferTimeout, requestInitCancellation);

        if (args.verbose)
        {
            std::stringstream ss;
            ss << "Sending " << verb << " request "
               << "to " << host << ":" << port << std::endl
               << "request size: " << req.size() << " bytes" << std::endl
               << "=============" << std::endl
               << req
               << "=============" << std::endl
               << std::endl;

            log(ss.str(), args);
        }

        if (!_socket->writeBytes(req, isCancellationRequested))
        {
            std::string errorMsg("Cannot send request");
            return std::make_tuple(code, HttpErrorCode::SendError,
                                   headers, payload, errorMsg,
                                   uploadSize, downloadSize);
        }

        uploadSize = req.size();

        auto lineResult = _socket->readLine(isCancellationRequested);
        auto lineValid = lineResult.first;
        auto line = lineResult.second;

        if (!lineValid)
        {
            std::string errorMsg("Cannot retrieve status line");
            return std::make_tuple(code, HttpErrorCode::CannotReadStatusLine,
                                   headers, payload, errorMsg,
                                   uploadSize, downloadSize);
        }

        if (args.verbose)
        {
            std::stringstream ss;
            ss << "Status line " << line;
            log(ss.str(), args);
        }

        if (sscanf(line.c_str(), "HTTP/1.1 %d", &code) != 1)
        {
            std::string errorMsg("Cannot parse response code from status line");
            return std::make_tuple(code, HttpErrorCode::MissingStatus,
                                   headers, payload, errorMsg,
                                   uploadSize, downloadSize);
        }

        auto result = parseHttpHeaders(_socket, isCancellationRequested);
        auto headersValid = result.first;
        headers = result.second;

        if (!headersValid)
        {
            std::string errorMsg("Cannot parse http headers");
            return std::make_tuple(code, HttpErrorCode::HeaderParsingError,
                                   headers, payload, errorMsg,
                                   uploadSize, downloadSize);
        }

        // Redirect ?
        if ((code >= 301 && code <= 308) && args.followRedirects)
        {
            if (headers.find("Location") == headers.end())
            {
                std::string errorMsg("Missing location header for redirect");
                return std::make_tuple(code, HttpErrorCode::MissingLocation,
                                       headers, payload, errorMsg,
                                       uploadSize, downloadSize);
            }

            if (redirects >= args.maxRedirects)
            {
                std::stringstream ss;
                ss << "Too many redirects: " << redirects;
                return std::make_tuple(code, HttpErrorCode::TooManyRedirects,
                                       headers, payload, ss.str(),
                                       uploadSize, downloadSize);
            }

            // Recurse
            std::string location = headers["Location"];
            return request(location, verb, body, args, redirects+1);
        }

        if (verb == "HEAD")
        {
            return std::make_tuple(code, HttpErrorCode::Ok,
                                   headers, payload, std::string(),
                                   uploadSize, downloadSize);
        }

        // Parse response:
        if (headers.find("Content-Length") != headers.end())
        {
            ssize_t contentLength = -1;
            ss.str("");
            ss << headers["Content-Length"];
            ss >> contentLength;

            payload.reserve(contentLength);

            auto chunkResult = _socket->readBytes(contentLength,
                                                  args.onProgressCallback,
                                                  isCancellationRequested);
            if (!chunkResult.first)
            {
                errorMsg = "Cannot read chunk";
                return std::make_tuple(code, HttpErrorCode::ChunkReadError,
                                       headers, payload, errorMsg,
                                       uploadSize, downloadSize);
            }
            payload += chunkResult.second;
        }
        else if (headers.find("Transfer-Encoding") != headers.end() &&
                 headers["Transfer-Encoding"] == "chunked")
        {
            std::stringstream ss;

            while (true)
            {
                lineResult = _socket->readLine(isCancellationRequested);
                line = lineResult.second;

                if (!lineResult.first)
                {
                    return std::make_tuple(code, HttpErrorCode::ChunkReadError,
                                           headers, payload, errorMsg,
                                           uploadSize, downloadSize);
                }

                uint64_t chunkSize;
                ss.str("");
                ss << std::hex << line;
                ss >> chunkSize;

                if (args.verbose)
                {
                    std::stringstream oss;
                    oss << "Reading " << chunkSize << " bytes"
                        << std::endl;
                    log(oss.str(), args);
                }

                payload.reserve(payload.size() + chunkSize);

                // Read a chunk
                auto chunkResult = _socket->readBytes(chunkSize,
                                                      args.onProgressCallback,
                                                      isCancellationRequested);
                if (!chunkResult.first)
                {
                    errorMsg = "Cannot read chunk";
                    return std::make_tuple(code, HttpErrorCode::ChunkReadError,
                                           headers, payload, errorMsg,
                                           uploadSize, downloadSize);
                }
                payload += chunkResult.second;

                // Read the line that terminates the chunk (\r\n)
                lineResult = _socket->readLine(isCancellationRequested);

                if (!lineResult.first)
                {
                    return std::make_tuple(code, HttpErrorCode::ChunkReadError,
                                           headers, payload, errorMsg,
                                           uploadSize, downloadSize);
                }

                if (chunkSize == 0) break;
            }
        }
        else if (code == 204)
        {
            ; // 204 is NoContent response code
        }
        else
        {
            std::string errorMsg("Cannot read http body");
            return std::make_tuple(code, HttpErrorCode::CannotReadBody,
                                   headers, payload, errorMsg,
                                   uploadSize, downloadSize);
        }

        downloadSize = payload.size();

        // If the content was compressed with gzip, decode it
        if (headers["Content-Encoding"] == "gzip")
        {
            std::string decompressedPayload;
            if (!gzipInflate(payload, decompressedPayload))
            {
                std::string errorMsg("Error decompressing payload");
                return std::make_tuple(code, HttpErrorCode::Gzip,
                                       headers, payload, errorMsg,
                                       uploadSize, downloadSize);
            }
            payload = decompressedPayload;
        }

        return std::make_tuple(code, HttpErrorCode::Ok,
                               headers, payload, std::string(),
                               uploadSize, downloadSize);
    }

    HttpResponse HttpClient::get(const std::string& url,
                                 const HttpRequestArgs& args)
    {
        return request(url, kGet, std::string(), args);
    }

    HttpResponse HttpClient::head(const std::string& url,
                                  const HttpRequestArgs& args)
    {
        return request(url, kHead, std::string(), args);
    }

    HttpResponse HttpClient::post(const std::string& url,
                                  const HttpParameters& httpParameters,
                                  const HttpRequestArgs& args)
    {
        return request(url, kPost, serializeHttpParameters(httpParameters), args);
    }

    HttpResponse HttpClient::post(const std::string& url,
                                  const std::string& body,
                                  const HttpRequestArgs& args)
    {
        return request(url, kPost, body, args);
    }

    std::string HttpClient::urlEncode(const std::string& value)
    {
        std::ostringstream escaped;
        escaped.fill('0');
        escaped << std::hex;

        for (std::string::const_iterator i = value.begin(), n = value.end();
             i != n; ++i)
        {
            std::string::value_type c = (*i);

            // Keep alphanumeric and other accepted characters intact
            if (isalnum(c) || c == '-' || c == '_' || c == '.' || c == '~')
            {
                escaped << c;
                continue;
            }

            // Any other characters are percent-encoded
            escaped << std::uppercase;
            escaped << '%' << std::setw(2) << int((unsigned char) c);
            escaped << std::nouppercase;
        }

        return escaped.str();
    }

    std::string HttpClient::serializeHttpParameters(const HttpParameters& httpParameters)
    {
        std::stringstream ss;
        size_t count = httpParameters.size();
        size_t i = 0;

        for (auto&& it : httpParameters)
        {
            ss << urlEncode(it.first)
               << "="
               << urlEncode(it.second);

            if (i++ < (count-1))
            {
               ss << "&";
            }
        }
        return ss.str();
    }

    bool HttpClient::gzipInflate(
        const std::string& in,
        std::string& out)
    {
        z_stream inflateState;
        std::memset(&inflateState, 0, sizeof(inflateState));

        inflateState.zalloc = Z_NULL;
        inflateState.zfree = Z_NULL;
        inflateState.opaque = Z_NULL;
        inflateState.avail_in = 0;
        inflateState.next_in = Z_NULL;

        if (inflateInit2(&inflateState, 16+MAX_WBITS) != Z_OK)
        {
            return false;
        }

        inflateState.avail_in = (uInt) in.size();
        inflateState.next_in = (unsigned char *)(const_cast<char *>(in.data()));

        const int kBufferSize = 1 << 14;

        std::unique_ptr<unsigned char[]> compressBuffer =
            std::make_unique<unsigned char[]>(kBufferSize);

        do
        {
            inflateState.avail_out = (uInt) kBufferSize;
            inflateState.next_out = compressBuffer.get();

            int ret = inflate(&inflateState, Z_SYNC_FLUSH);

            if (ret == Z_NEED_DICT || ret == Z_DATA_ERROR || ret == Z_MEM_ERROR)
            {
                inflateEnd(&inflateState);
                return false;
            }

            out.append(
                reinterpret_cast<char *>(compressBuffer.get()),
                kBufferSize - inflateState.avail_out
            );
        } while (inflateState.avail_out == 0);

        inflateEnd(&inflateState);
        return true;
    }

    void HttpClient::log(const std::string& msg,
                         const HttpRequestArgs& args)
    {
        if (args.logger)
        {
            args.logger(msg);
        }
    }
}