#include "pch.h"
#include "HttpServer.h"
#include <sstream>
#include <functional>

#pragma comment(lib, "ws2_32.lib")


HttpServer::HttpServer() : server_socket_(INVALID_SOCKET), running_(false), thread_handle_(nullptr) {
}

HttpServer::~HttpServer() {
    Stop();
}

bool HttpServer::Start() {
    if (running_) return true;
    
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
        return false;
    }
    
    server_socket_ = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket_ == INVALID_SOCKET) {
        WSACleanup();
        return false;
    }
    
    sockaddr_in server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(Config::HTTP_PORT);
    
    if (bind(server_socket_, (struct sockaddr*)&server_addr, sizeof(server_addr)) == SOCKET_ERROR) {
        closesocket(server_socket_);
        WSACleanup();
        return false;
    }
    
    if (listen(server_socket_, SOMAXCONN) == SOCKET_ERROR) {
        closesocket(server_socket_);
        WSACleanup();
        return false;
    }
    
    // 设置socket超时参数，防止recv/send阻塞
    DWORD recv_timeout = Config::SOCKET_RECV_TIMEOUT_MS;
    DWORD send_timeout = Config::SOCKET_SEND_TIMEOUT_MS;
    
    if (setsockopt(server_socket_, SOL_SOCKET, SO_RCVTIMEO, (char*)&recv_timeout, sizeof(recv_timeout)) == SOCKET_ERROR ||
        setsockopt(server_socket_, SOL_SOCKET, SO_SNDTIMEO, (char*)&send_timeout, sizeof(send_timeout)) == SOCKET_ERROR) {
        closesocket(server_socket_);
        WSACleanup();
        return false;
    }
    
    running_ = true;
    thread_handle_ = CreateThread(NULL, 0, ServerThread, this, 0, NULL);
    
    return thread_handle_ != nullptr;
}

void HttpServer::Stop() {
    running_ = false;
    if (server_socket_ != INVALID_SOCKET) {
        closesocket(server_socket_);
        server_socket_ = INVALID_SOCKET;
    }
    if (thread_handle_) {
        WaitForSingleObject(thread_handle_, 5000);
        CloseHandle(thread_handle_);
        thread_handle_ = nullptr;
    }
    WSACleanup();
}

void HttpServer::SetRouteHandler(const std::string& path, 
                                std::function<HttpResponse(const HttpRequest&)> handler) {
    route_handlers_[path] = handler;
}

DWORD WINAPI HttpServer::ServerThread(LPVOID lpParam) {
    HttpServer* server = static_cast<HttpServer*>(lpParam);
    
    while (server->running_) {
        SOCKET client_socket = accept(server->server_socket_, NULL, NULL);
        if (client_socket == INVALID_SOCKET) {
            if (server->running_) {
                continue;
            }
            break;
        }
        
        // 添加异常保护，确保任何异常都不会导致服务线程崩溃
        try {
            server->HandleClient(client_socket);
        }
        catch (...) {
            // 捕获所有异常，确保socket正确关闭
            // 异常不影响服务器继续运行
        }
        
        closesocket(client_socket);
    }
    
    return 0;
}

void HttpServer::HandleClient(SOCKET client_socket) {
    // 读取完整的HTTP请求
    std::string raw_request = ReadCompleteRequest(client_socket);
    if (raw_request.empty()) {
        // 读取失败或超时，直接返回
        return;
    }
    
    HttpRequest request = ParseRequest(raw_request);
    HttpResponse response;
    
    // OPTIONS预检请求处理（CORS支持）
    if (request.method == "OPTIONS") {
        response.status_code = 200;
        response.body = "";
        SendResponse(client_socket, response);
        return;
    }
    
    // 查找路由处理器
    auto handler_it = route_handlers_.find(request.path);
    if (handler_it != route_handlers_.end()) {
        response = handler_it->second(request);
    } else {
        response.status_code = 404;
        response.body = "{\"error\":\"Not Found\"}";
    }
    
    SendResponse(client_socket, response);
}

HttpRequest HttpServer::ParseRequest(const std::string& raw_request) {
    HttpRequest request;
    std::istringstream stream(raw_request);
    std::string line;
    
    // 解析请求行
    if (std::getline(stream, line)) {
        std::istringstream request_line(line);
        std::string path_with_query;
        request_line >> request.method >> path_with_query;
        
        // 处理查询参数
        size_t query_pos = path_with_query.find('?');
        if (query_pos != std::string::npos) {
            request.path = path_with_query.substr(0, query_pos);
            request.query = path_with_query.substr(query_pos + 1);
        } else {
            request.path = path_with_query;
        }
    }
    
    // 解析请求头
    while (std::getline(stream, line) && line != "\r") {
        size_t colon_pos = line.find(':');
        if (colon_pos != std::string::npos) {
            std::string key = line.substr(0, colon_pos);
            std::string value = line.substr(colon_pos + 2);
            if (!value.empty() && value.back() == '\r') {
                value.pop_back();
            }
            request.headers[key] = value;
        }
    }
    
    // 解析请求体
    std::string body_line;
    while (std::getline(stream, body_line)) {
        request.body += body_line + "\n";
    }
    if (!request.body.empty()) {
        request.body.pop_back(); // 移除最后的换行符
    }
    
    return request;
}

std::string HttpServer::ReadCompleteRequest(SOCKET client_socket) {
    std::string complete_request;
    char buffer[Config::BUFFER_SIZE];
    int total_received = 0;
    int content_length = -1;
    bool headers_complete = false;
    size_t header_end_pos = 0;
    
    try {
        // First, read headers to determine Content-Length
        while (!headers_complete && total_received < Config::MAX_REQUEST_SIZE) {
            int bytes_received = recv(client_socket, buffer, sizeof(buffer) - 1, 0);
            
            // Check for recv errors and timeout
            if (bytes_received == SOCKET_ERROR) {
                int error = WSAGetLastError();
                if (error == WSAETIMEDOUT) {
                    return "";  // Timeout, return empty
                }
                return "";  // Other network error, return empty
            }
            
            if (bytes_received <= 0) {
                return "";  // Connection closed or no data
            }
            
            buffer[bytes_received] = '\0';
            complete_request.append(buffer, bytes_received);
            total_received += bytes_received;
            
            // Check if headers are complete (look for \r\n\r\n)
            size_t header_separator = complete_request.find("\r\n\r\n");
            if (header_separator != std::string::npos) {
                headers_complete = true;
                header_end_pos = header_separator + 4;
                
                // Parse Content-Length from headers
                std::string headers_part = complete_request.substr(0, header_end_pos);
                size_t cl_pos = headers_part.find("Content-Length:");
                if (cl_pos != std::string::npos) {
                    size_t cl_start = cl_pos + 15; // Length of "Content-Length:"
                    size_t cl_end = headers_part.find("\r\n", cl_start);
                    if (cl_end != std::string::npos) {
                        std::string cl_str = headers_part.substr(cl_start, cl_end - cl_start);
                        // Remove leading/trailing whitespace
                        cl_str.erase(0, cl_str.find_first_not_of(" \t"));
                        cl_str.erase(cl_str.find_last_not_of(" \t") + 1);
                        try {
                            content_length = std::stoi(cl_str);
                        } catch (...) {
                            content_length = 0;
                        }
                    }
                }
                break;
            }
        }
        
        // If no Content-Length header found, assume no body or return what we have
        if (content_length < 0) {
            return complete_request;
        }
        
        // Check if request size exceeds limit
        if (content_length > Config::MAX_REQUEST_SIZE) {
            return "";  // Request too large
        }
        
        // Calculate how much body data we already have
        int current_body_length = complete_request.length() - header_end_pos;
        
        // Read remaining body data if needed
        while (current_body_length < content_length && total_received < Config::MAX_REQUEST_SIZE) {
            int bytes_needed = content_length - current_body_length;
            int bytes_to_read = min(bytes_needed, sizeof(buffer) - 1);
            
            int bytes_received = recv(client_socket, buffer, bytes_to_read, 0);
            
            if (bytes_received == SOCKET_ERROR) {
                int error = WSAGetLastError();
                if (error == WSAETIMEDOUT) {
                    break;  // Timeout, return what we have
                }
                break;  // Other error, return what we have
            }
            
            if (bytes_received <= 0) {
                break;  // Connection closed
            }
            
            buffer[bytes_received] = '\0';
            complete_request.append(buffer, bytes_received);
            current_body_length += bytes_received;
            total_received += bytes_received;
        }
        
    } catch (...) {
        // Any exception during reading, return empty
        return "";
    }
    
    return complete_request;
}

void HttpServer::SendResponse(SOCKET client_socket, const HttpResponse& response) {
    std::ostringstream response_stream;
    
    // 状态行
    response_stream << "HTTP/1.1 " << response.status_code << " ";
    switch (response.status_code) {
        case 200: response_stream << "OK"; break;
        case 404: response_stream << "Not Found"; break;
        case 500: response_stream << "Internal Server Error"; break;
        default: response_stream << "Unknown"; break;
    }
    response_stream << "\r\n";
    
    // 响应头
    for (const auto& header : response.headers) {
        response_stream << header.first << ": " << header.second << "\r\n";
    }
    response_stream << "Content-Length: " << response.body.length() << "\r\n";
    response_stream << "Connection: close\r\n\r\n";
    
    // 响应体
    response_stream << response.body;
    
    std::string response_str = response_stream.str();
    send(client_socket, response_str.c_str(), (int)response_str.length(), 0);
}