#include "Scratchpad.h"
#include <fstream>
#include <array>
#include <memory>
#include <filesystem>
#include <iostream>

// Helper: Execute shell command and capture output
std::string exec(const char* cmd) {
    std::array<char, 128> buffer;
    std::string result;
    std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd, "r"), pclose);
    if (!pipe) {
        throw std::runtime_error("popen() failed!");
    }
    while (fgets(buffer.data(), buffer.size(), pipe.get()) != nullptr) {
        result += buffer.data();
    }
    return result;
}

void Scratchpad::runCode(const HttpRequestPtr& req, std::function<void (const HttpResponsePtr &)> &&callback)
{
    // 1. Auth Check
    auto authHeader = req->getHeader("X-API-Key");
    if (authHeader != API_KEY)
    {
        Json::Value error;
        error["error"] = "Unauthorized. Invalid API Key.";
        auto resp = HttpResponse::newHttpJsonResponse(error);
        resp->setStatusCode(k401Unauthorized);
        callback(resp);
        return;
    }

    // 2. Get Code from Body
    auto json = req->getJsonObject();
    if (!json || !(*json)["code"].isString())
    {
        Json::Value error;
        error["error"] = "Invalid JSON. 'code' field required.";
        auto resp = HttpResponse::newHttpJsonResponse(error);
        resp->setStatusCode(k400BadRequest);
        callback(resp);
        return;
    }
    
    std::string userCode = (*json)["code"].asString();
    
    // 3. Compile and Run
    Json::Value ret;
    try {
        std::string output = compileAndRun(userCode);
        ret["status"] = "success";
        ret["output"] = output;
    } catch (const std::exception& e) {
        ret["status"] = "error";
        ret["error"] = e.what();
    }

    auto resp = HttpResponse::newHttpJsonResponse(ret);
    callback(resp);
}

std::string Scratchpad::compileAndRun(const std::string& code)
{
    // A. Write to temp file
    std::string filename = "temp_scratchpad.cpp";
    std::string binary = "./temp_scratchpad";
    
    std::ofstream out(filename);
    out << code;
    out.close();

    // B. Compile (Clang++)
    // Using -std=c++20 and linking nothing extra for now
    std::string compileCmd = "clang++ -std=c++20 " + filename + " -o " + binary + " 2>&1";
    std::string compileOut = exec(compileCmd.c_str());

    // Check if compilation failed (binary doesn't exist)
    if (!std::filesystem::exists(binary)) {
        return "Compilation Error:\n" + compileOut;
    }

    // C. Execute
    // Timeout logic should be added here later (e.g., using 'timeout' cmd)
    std::string runCmd = binary + " 2>&1"; 
    std::string runOut = exec(runCmd.c_str());

    // Cleanup
    std::filesystem::remove(filename);
    std::filesystem::remove(binary);

    return runOut;
}

void Scratchpad::status(const HttpRequestPtr& req, std::function<void (const HttpResponsePtr &)> &&callback)
{
    Json::Value ret;
    ret["status"] = "online";
    ret["version"] = "2.1 (Execution Engine)";
    ret["compiler"] = "Clang 19.1.7";
    ret["note"] = "Send POST to /scratchpad/run with header 'X-API-Key'";
    auto resp = HttpResponse::newHttpJsonResponse(ret);
    callback(resp);
}