#include "TcpServer.h"
#include "FileTransferProtocol.h"
#include <iostream>
#include <fstream>
#include <filesystem>
#include <ws2tcpip.h>

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

namespace fs = std::filesystem;

TcpServer::TcpServer() = default;

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

bool TcpServer::Start(int port) {
    if (running_) return true;

    // Initialize Winsock
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
        std::cerr << "WSAStartup failed" << std::endl;
        return false;
    }

    listenSocket_ = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (listenSocket_ == INVALID_SOCKET) {
        std::cerr << "Socket creation failed" << std::endl;
        WSACleanup();
        return false;
    }

    sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_addr.s_addr = INADDR_ANY;
    serverAddr.sin_port = htons(port);

    if (bind(listenSocket_, (sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR) {
        std::cerr << "Bind failed" << std::endl;
        closesocket(listenSocket_);
        WSACleanup();
        return false;
    }

    if (listen(listenSocket_, 1) == SOCKET_ERROR) {
        std::cerr << "Listen failed" << std::endl;
        closesocket(listenSocket_);
        WSACleanup();
        return false;
    }

    running_ = true;
    acceptThread_ = std::thread(&TcpServer::AcceptLoop, this);

    std::cout << "TCP Server started on port " << port << std::endl;
    return true;
}

void TcpServer::Stop() {
    running_ = false;
    if (listenSocket_ != INVALID_SOCKET) {
        closesocket(listenSocket_);
        listenSocket_ = INVALID_SOCKET;
    }
    if (clientSocket_ != INVALID_SOCKET) {
        closesocket(clientSocket_);
        clientSocket_ = INVALID_SOCKET;
    }
    if (acceptThread_.joinable()) acceptThread_.join();
    if (clientThread_.joinable()) clientThread_.join();
    
    // Close any open file stream
    if (currentFileStream_) {
        currentFileStream_->close();
        delete currentFileStream_;
        currentFileStream_ = nullptr;
    }
}

void TcpServer::AcceptLoop() {
    while (running_) {
        sockaddr_in clientAddr;
        int clientAddrLen = sizeof(clientAddr);
        SOCKET client = accept(listenSocket_, (sockaddr*)&clientAddr, &clientAddrLen);
        
        if (client == INVALID_SOCKET) {
            if (running_) std::cerr << "Accept failed" << std::endl;
            break;
        }

        std::cout << "Client connected for File Transfer" << std::endl;

        // Close previous client if any
        if (clientSocket_ != INVALID_SOCKET) {
            closesocket(clientSocket_);
            if (clientThread_.joinable()) clientThread_.join();
        }

        clientSocket_ = client;
        clientThread_ = std::thread(&TcpServer::ClientHandler, this, clientSocket_);
    }
}

void TcpServer::ClientHandler(SOCKET clientSocket) {
    while (running_) {
        CommonHeader header;
        if (!ReceiveBytes(clientSocket, &header, sizeof(header))) {
            std::cout << "Client disconnected" << std::endl;
            break;
        }

        std::vector<uint8_t> payload(header.payloadSize);
        if (header.payloadSize > 0) {
            if (!ReceiveBytes(clientSocket, payload.data(), header.payloadSize)) {
                break;
            }
        }

        PacketType type = static_cast<PacketType>(header.type);
        switch (type) {
            case PacketType::FileHeader:
                HandleFileHeader(clientSocket, payload);
                break;
            case PacketType::FileData:
                HandleFileData(payload);
                break;
            case PacketType::FileEnd:
                HandleFileEnd();
                break;
            case PacketType::FolderHeader:
                HandleFolderHeader(payload);
                break;
            case PacketType::DirEntry:
                HandleDirEntry(payload);
                break;
            case PacketType::FileHeaderV2:
                HandleFileHeaderV2(payload);
                break;
            case PacketType::FolderEnd:
                break;
            default:
                break;
        }
    }
    closesocket(clientSocket);
    clientSocket_ = INVALID_SOCKET;
}

bool TcpServer::ReceiveBytes(SOCKET sock, void* buffer, int size) {
    char* ptr = (char*)buffer;
    int remaining = size;
    while (remaining > 0) {
        int received = recv(sock, ptr, remaining, 0);
        if (received <= 0) return false;
        ptr += received;
        remaining -= received;
    }
    return true;
}

bool TcpServer::SendBytes(SOCKET sock, const void* buffer, int size) {
    const char* ptr = (const char*)buffer;
    int remaining = size;
    while (remaining > 0) {
        int sent = send(sock, ptr, remaining, 0);
        if (sent <= 0) return false;
        ptr += sent;
        remaining -= sent;
    }
    return true;
}

void TcpServer::HandleFileHeader(SOCKET sock, const std::vector<uint8_t>& payload) {
    if (payload.size() < sizeof(FileMetadata)) return;
    const FileMetadata* meta = reinterpret_cast<const FileMetadata*>(payload.data());
    
    std::lock_guard<std::mutex> lock(fileMutex_);
    
    // Save to Desktop by default
    std::string desktopPath = getenv("USERPROFILE");
    desktopPath += "\\Desktop\\";
    
    currentFileName_ = desktopPath + std::string(meta->fileName);
    currentFileSize_ = meta->fileSize;
    receivedBytes_ = 0;

    if (currentFileStream_) {
        delete currentFileStream_;
    }
    currentFileStream_ = new std::ofstream(currentFileName_, std::ios::binary);
    
    std::cout << "Receiving file: " << currentFileName_ << " (" << currentFileSize_ << " bytes)" << std::endl;
}

void TcpServer::HandleFileData(const std::vector<uint8_t>& payload) {
    std::lock_guard<std::mutex> lock(fileMutex_);
    if (currentFileStream_ && currentFileStream_->is_open()) {
        currentFileStream_->write((const char*)payload.data(), payload.size());
        receivedBytes_ += payload.size();
        
        // Optional: Progress log
        // std::cout << "\rProgress: " << (receivedBytes_ * 100 / currentFileSize_) << "%" << std::flush;
    }
}

void TcpServer::HandleFileEnd() {
    std::lock_guard<std::mutex> lock(fileMutex_);
    if (currentFileStream_) {
        currentFileStream_->close();
        delete currentFileStream_;
        currentFileStream_ = nullptr;
        std::cout << "\nFile received successfully!" << std::endl;
        
        if (fileReceivedCallback_) {
            fileReceivedCallback_(currentFileName_);
        }
    }
}

bool TcpServer::SendFile(const std::string& filePath) {
    if (clientSocket_ == INVALID_SOCKET) {
        std::cerr << "No client connected" << std::endl;
        return false;
    }

    std::ifstream file(filePath, std::ios::binary | std::ios::ate);
    if (!file.is_open()) {
        std::cerr << "Cannot open file: " << filePath << std::endl;
        return false;
    }

    uint64_t fileSize = file.tellg();
    file.seekg(0, std::ios::beg);

    fs::path p(filePath);
    std::string filename = p.filename().string();

    // 1. Send Header
    CommonHeader header;
    header.type = (uint8_t)PacketType::FileHeader;
    header.payloadSize = sizeof(FileMetadata);

    FileMetadata meta;
    meta.fileSize = fileSize;
    strncpy_s(meta.fileName, filename.c_str(), sizeof(meta.fileName) - 1);

    if (!SendBytes(clientSocket_, &header, sizeof(header))) return false;
    if (!SendBytes(clientSocket_, &meta, sizeof(meta))) return false;

    // 2. Send Data
    const int CHUNK_SIZE = 64 * 1024; // 64KB
    std::vector<char> buffer(CHUNK_SIZE);
    
    uint64_t sent = 0;
    while (sent < fileSize) {
        file.read(buffer.data(), CHUNK_SIZE);
        int bytesRead = (int)file.gcount();
        
        CommonHeader dataHeader;
        dataHeader.type = (uint8_t)PacketType::FileData;
        dataHeader.payloadSize = bytesRead;
        
        if (!SendBytes(clientSocket_, &dataHeader, sizeof(dataHeader))) return false;
        if (!SendBytes(clientSocket_, buffer.data(), bytesRead)) return false;
        
        sent += bytesRead;
        std::cout << "\rSending: " << (sent * 100 / fileSize) << "%" << std::flush;
    }
    std::cout << std::endl;

    // 3. Send End
    CommonHeader endHeader;
    endHeader.type = (uint8_t)PacketType::FileEnd;
    endHeader.payloadSize = 0;
    SendBytes(clientSocket_, &endHeader, sizeof(endHeader));

    std::cout << "File sent successfully" << std::endl;
    return true;
}

void TcpServer::SetFileReceivedCallback(FileReceivedCallback cb) {
    fileReceivedCallback_ = cb;
}
bool TcpServer::SendFolder(const std::string& folderPath) {
    if (clientSocket_ == INVALID_SOCKET) {
        std::cerr << "No client connected" << std::endl;
        return false;
    }
    fs::path root(folderPath);
    if (!fs::exists(root) || !fs::is_directory(root)) {
        std::cerr << "Invalid folder: " << folderPath << std::endl;
        return false;
    }
    std::string rootName = root.filename().string();
    {
        CommonHeader hdr;
        hdr.type = (uint8_t)PacketType::FolderHeader;
        hdr.payloadSize = (uint32_t)rootName.size();
        if (!SendBytes(clientSocket_, &hdr, sizeof(hdr))) return false;
        if (hdr.payloadSize > 0) {
            if (!SendBytes(clientSocket_, rootName.data(), (int)rootName.size())) return false;
        }
    }
    auto norm = [](std::string s) {
        for (auto& c : s) if (c == '\\') c = '/';
        return s;
    };
    for (auto it = fs::recursive_directory_iterator(root); it != fs::recursive_directory_iterator(); ++it) {
        const fs::path p = it->path();
        fs::path rel = fs::relative(p, root);
        std::string relStr = norm(rel.string());
        if (it->is_directory()) {
            CommonHeader hdr;
            hdr.type = (uint8_t)PacketType::DirEntry;
            hdr.payloadSize = (uint32_t)relStr.size();
            if (!SendBytes(clientSocket_, &hdr, sizeof(hdr))) return false;
            if (hdr.payloadSize > 0) {
                if (!SendBytes(clientSocket_, relStr.data(), (int)relStr.size())) return false;
            }
        } else if (it->is_regular_file()) {
            uint64_t fileSize = (uint64_t)fs::file_size(p);
            std::vector<uint8_t> header;
            uint16_t pathLen = (uint16_t)std::min<size_t>(relStr.size(), 65535);
            header.resize(8 + 2 + pathLen);
            std::memcpy(header.data(), &fileSize, 8);
            std::memcpy(header.data() + 8, &pathLen, 2);
            std::memcpy(header.data() + 10, relStr.data(), pathLen);
            CommonHeader hdr;
            hdr.type = (uint8_t)PacketType::FileHeaderV2;
            hdr.payloadSize = (uint32_t)header.size();
            if (!SendBytes(clientSocket_, &hdr, sizeof(hdr))) return false;
            if (!SendBytes(clientSocket_, header.data(), (int)header.size())) return false;
            std::ifstream file(p, std::ios::binary);
            if (!file.is_open()) continue;
            const int CHUNK_SIZE = 64 * 1024;
            std::vector<char> buffer(CHUNK_SIZE);
            while (file) {
                file.read(buffer.data(), CHUNK_SIZE);
                int bytesRead = (int)file.gcount();
                if (bytesRead <= 0) break;
                CommonHeader dh;
                dh.type = (uint8_t)PacketType::FileData;
                dh.payloadSize = bytesRead;
                if (!SendBytes(clientSocket_, &dh, sizeof(dh))) { file.close(); return false; }
                if (!SendBytes(clientSocket_, buffer.data(), bytesRead)) { file.close(); return false; }
            }
            file.close();
            CommonHeader endH;
            endH.type = (uint8_t)PacketType::FileEnd;
            endH.payloadSize = 0;
            if (!SendBytes(clientSocket_, &endH, sizeof(endH))) return false;
        }
    }
    CommonHeader fin;
    fin.type = (uint8_t)PacketType::FolderEnd;
    fin.payloadSize = 0;
    if (!SendBytes(clientSocket_, &fin, sizeof(fin))) return false;
    std::cout << "Folder sent successfully" << std::endl;
    return true;
}

void TcpServer::HandleFolderHeader(const std::vector<uint8_t>& payload) {
    std::string desktopPath = getenv("USERPROFILE");
    desktopPath += "\\Desktop\\";
    std::string rootName;
    if (!payload.empty()) {
        rootName.assign(reinterpret_cast<const char*>(payload.data()), payload.size());
        size_t pos = rootName.find('\0');
        if (pos != std::string::npos) rootName = rootName.substr(0, pos);
    } else {
        rootName = "AndroidFolder";
    }
    baseFolderRoot_ = desktopPath + rootName;
    try {
        fs::create_directories(baseFolderRoot_);
    } catch (...) {}
    std::cout << "Receiving folder: " << baseFolderRoot_ << std::endl;
}

void TcpServer::HandleDirEntry(const std::vector<uint8_t>& payload) {
    if (baseFolderRoot_.empty()) return;
    std::string rel;
    rel.assign(reinterpret_cast<const char*>(payload.data()), payload.size());
    size_t pos = rel.find('\0');
    if (pos != std::string::npos) rel = rel.substr(0, pos);
    std::string path = baseFolderRoot_ + "\\" + rel;
    try {
        fs::create_directories(path);
    } catch (...) {}
    std::cout << "Create dir: " << path << std::endl;
}

void TcpServer::HandleFileHeaderV2(const std::vector<uint8_t>& payload) {
    if (payload.size() < sizeof(uint64_t) + sizeof(uint16_t)) return;
    const uint8_t* p = payload.data();
    uint64_t sz = *reinterpret_cast<const uint64_t*>(p);
    p += sizeof(uint64_t);
    uint16_t pathLen = *reinterpret_cast<const uint16_t*>(p);
    p += sizeof(uint16_t);
    if (payload.size() < sizeof(uint64_t) + sizeof(uint16_t) + pathLen) return;
    std::string rel(reinterpret_cast<const char*>(p), pathLen);
    std::string full = baseFolderRoot_.empty() ? rel : (baseFolderRoot_ + "\\" + rel);
    {
        std::lock_guard<std::mutex> lock(fileMutex_);
        if (currentFileStream_) {
            delete currentFileStream_;
            currentFileStream_ = nullptr;
        }
        currentFileName_ = full;
        currentFileSize_ = sz;
        receivedBytes_ = 0;
        fs::create_directories(fs::path(full).parent_path());
        currentFileStream_ = new std::ofstream(full, std::ios::binary);
    }
    std::cout << "Receiving file: " << full << " (" << sz << " bytes)" << std::endl;
}