/*
 * LLM Proxy Client - C++ Version (Linux/WSL using libcurl)
 * Dependencies: sudo apt install g++ libcurl4-openssl-dev
 * Compile: g++ -std=c++11 -O2 -Wall -Wextra -pedantic client.cpp -lcurl -o llm_client_cpp
 * Usage: ./llm_client_cpp
 */

#include <curl/curl.h>

#include <iostream>
#include <limits>
#include <sstream>
#include <stdexcept>
#include <string>

struct LLMModel {
    const char* name;
    const char* id;
};

const LLMModel MODELS[] = {
    {"Laguna S 2.1 (Free)", "poolside/laguna-s-2.1:free"},
    {"Gemini 3.6 Flash (Paid)", "google/gemini-3.6-flash"},
    {"Claude Opus 5 (Paid)", "anthropic/claude-opus-5"},
    {"Claude Fable 5 (Paid)", "anthropic/claude-fable-5"},
    {"GPT-5.6 Sol (Paid)", "openai/gpt-5.6-sol"},
    {"GPT-5.6 Luna (Paid)", "openai/gpt-5.6-luna"},
    {"Nemotron 3 Ultra (Free)", "nvidia/nemotron-3-ultra-550b-a55b:free"}
};

const std::size_t MODEL_COUNT = sizeof(MODELS) / sizeof(MODELS[0]);

class CurlGlobal {
public:
    CurlGlobal() {
        const CURLcode result = curl_global_init(CURL_GLOBAL_DEFAULT);
        if (result != CURLE_OK) {
            throw std::runtime_error(std::string("Failed to initialize libcurl: ") +
                                     curl_easy_strerror(result));
        }
    }

    ~CurlGlobal() { curl_global_cleanup(); }

    CurlGlobal(const CurlGlobal&) = delete;
    CurlGlobal& operator=(const CurlGlobal&) = delete;
};

class CurlHandle {
public:
    CurlHandle() : handle_(curl_easy_init()) {
        if (!handle_) {
            throw std::runtime_error("Failed to create libcurl handle");
        }
    }

    ~CurlHandle() { curl_easy_cleanup(handle_); }

    CurlHandle(const CurlHandle&) = delete;
    CurlHandle& operator=(const CurlHandle&) = delete;

    CURL* get() const { return handle_; }

private:
    CURL* handle_;
};

class CurlHeaders {
public:
    ~CurlHeaders() { curl_slist_free_all(headers_); }

    void append(const std::string& header) {
        curl_slist* updated = curl_slist_append(headers_, header.c_str());
        if (!updated) {
            throw std::runtime_error("Failed to allocate HTTP headers");
        }
        headers_ = updated;
    }

    curl_slist* get() const { return headers_; }

    CurlHeaders(const CurlHeaders&) = delete;
    CurlHeaders& operator=(const CurlHeaders&) = delete;
    CurlHeaders() = default;

private:
    curl_slist* headers_ = nullptr;
};

std::size_t writeResponse(char* data, std::size_t size, std::size_t count, void* output) {
    const std::size_t bytes = size * count;
    static_cast<std::string*>(output)->append(data, bytes);
    return bytes;
}

void requireCurlOption(CURLcode result, const char* option) {
    if (result != CURLE_OK) {
        throw std::runtime_error(std::string("Failed to set ") + option + ": " +
                                 curl_easy_strerror(result));
    }
}

std::string askLLM(const std::string& prompt, const LLMModel& model) {
    CurlHandle curl;
    CurlHeaders headers;
    std::string response;

    headers.append("Content-Type: text/plain; charset=utf-8");
    headers.append(std::string("X-Model: ") + model.id);

    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_URL,
                                       "https://ttl0110-llm-proxy.hf.space/ask"),
                      "request URL");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_HTTPHEADER, headers.get()),
                      "request headers");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_POST, 1L), "POST method");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_POSTFIELDS, prompt.c_str()),
                      "request body");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_POSTFIELDSIZE_LARGE,
                                       static_cast<curl_off_t>(prompt.size())),
                      "request body size");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_WRITEFUNCTION, writeResponse),
                      "response callback");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_WRITEDATA, &response),
                      "response destination");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_CONNECTTIMEOUT, 30L),
                      "connection timeout");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_TIMEOUT, 120L),
                      "request timeout");
    requireCurlOption(curl_easy_setopt(curl.get(), CURLOPT_USERAGENT,
                                       "LLM-Proxy-Cpp-Client/1.0"),
                      "user agent");

    const CURLcode result = curl_easy_perform(curl.get());
    if (result != CURLE_OK) {
        throw std::runtime_error(std::string("Request failed: ") + curl_easy_strerror(result));
    }

    long statusCode = 0;
    const CURLcode statusResult = curl_easy_getinfo(curl.get(), CURLINFO_RESPONSE_CODE, &statusCode);
    if (statusResult != CURLE_OK) {
        throw std::runtime_error(std::string("Failed to read HTTP status: ") +
                                 curl_easy_strerror(statusResult));
    }
    if (statusCode < 200 || statusCode >= 300) {
        throw std::runtime_error("Server returned HTTP " + std::to_string(statusCode) +
                                 (response.empty() ? "" : ": " + response));
    }

    return response;
}

std::size_t selectModel() {
    std::cout << "Chon Model LLM:\n";
    for (std::size_t i = 0; i < MODEL_COUNT; ++i) {
        std::cout << i + 1 << ". " << MODELS[i].name << '\n';
    }

    int choice = 0;
    while (choice < 1 || choice > static_cast<int>(MODEL_COUNT)) {
        std::cout << "Nhap lua chon (1-" << MODEL_COUNT << "): ";
        if (!(std::cin >> choice)) {
            std::cin.clear();
        }
        std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
    }
    return static_cast<std::size_t>(choice - 1);
}

int main() {
    try {
        CurlGlobal curlGlobal;

        std::cout << "=== C++ LLM Assistant (HuggingFace Proxy) ===\n\n";
        const LLMModel& selectedModel = MODELS[selectModel()];
        std::cout << "Ban da chon: " << selectedModel.name << "\n\n";

        std::cout << "Nhap prompt prefix (bo trong neu khong dung): ";
        std::string promptPrefix;
        std::getline(std::cin, promptPrefix);

        std::cout << "Huong dan: Nhap prompt cua ban. Nhap 'SUBMIT' o dong cuoi de gui.\n";
        std::cout << "Nhap 'EXIT' o mot dong rieng de thoat.\n";

        while (true) {
            std::cout << "\nBan [" << selectedModel.name << "]:\n";

            std::ostringstream prompt;
            std::string line;
            bool exitRequested = false;
            while (std::getline(std::cin, line)) {
                if (line == "EXIT") {
                    exitRequested = true;
                    break;
                }
                if (line == "SUBMIT") {
                    break;
                }
                if (prompt.tellp() > 0) {
                    prompt << '\n';
                }
                prompt << line;
            }

            if (exitRequested || !std::cin) {
                break;
            }

            const std::string promptText = prompt.str();
            if (promptText.empty()) {
                std::cout << "Prompt trong, vui long nhap lai.\n";
                continue;
            }

            const std::string fullPrompt = promptPrefix.empty()
                ? promptText
                : promptPrefix + "\n\n" + promptText;

            std::cout << "Thinking...\n";
            try {
                std::cout << "\n[LLM]: " << askLLM(fullPrompt, selectedModel) << '\n';
            } catch (const std::exception& error) {
                std::cout << "\nError: " << error.what() << '\n';
            }
            std::cout << "-------------------------------------------\n";
        }

        std::cout << "Tam biet!\n";
        return 0;
    } catch (const std::exception& error) {
        std::cerr << "Fatal error: " << error.what() << '\n';
        return 1;
    }
}