#include <iostream>
#include <vector>
#include <thread>
#include <mutex>
#include <fstream>
#include <string>
#include <curl/curl.h>
#include <random>

using namespace std;

const int NUM_THREADS = 12;
mutex log_mutex;

// Koleksi User-Agent Modern (Desktop & Mobile)
const vector<string> USER_AGENTS = {
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36",
    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36",
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:125.0) Gecko/20100101 Firefox/125.0",
    "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36",
    "Mozilla/5.0 (iPhone; CPU iPhone OS 17_4_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4.1 Mobile/15E148 Safari/604.1",
    "Mozilla/5.0 (Linux; Android 14; SM-S928B) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Mobile Safari/537.36",
    "Mozilla/5.0 (iPad; CPU OS 17_4_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/124.0.6367.111 Mobile/15E148 Safari/604.1",
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36 Edg/124.0.0.0"
};

size_t write_data(void *ptr, size_t size, size_t nmemb, FILE *stream) {
    return fwrite(ptr, size, nmemb, stream);
}

bool download_chunk(const string& url, const string& out_filename, long start_byte, long end_byte, int thread_id) {
    CURL *curl;
    FILE *fp;
    CURLcode res;
    
    curl = curl_easy_init();
    if (curl) {
        fp = fopen(out_filename.c_str(), "wb");
        string range = to_string(start_byte) + "-" + to_string(end_byte);
        
        // 1. Pilih User-Agent acak/berbeda untuk thread ini
        string selected_ua = USER_AGENTS[thread_id % USER_AGENTS.size()];
        
        // 2. Rakit Header HTTP Siluman (Mirip Request Video Asli)
        struct curl_slist *headers = NULL;
        headers = curl_slist_append(headers, ("User-Agent: " + selected_ua).c_str());
        headers = curl_slist_append(headers, "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8");
        headers = curl_slist_append(headers, "Accept-Language: en-US,en;q=0.9,id;q=0.8");
        headers = curl_slist_append(headers, "Connection: keep-alive");
        headers = curl_slist_append(headers, "Sec-Fetch-Dest: video"); // Manipulasi bahwa ini adalah request elemen <video>
        headers = curl_slist_append(headers, "Sec-Fetch-Mode: no-cors");
        headers = curl_slist_append(headers, "Sec-Fetch-Site: cross-site");
        headers = curl_slist_append(headers, "Cache-Control: no-cache");
        headers = curl_slist_append(headers, "Pragma: no-cache");

        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_RANGE, range.c_str());
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers); // Pasang header siluman
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
        curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);  // Ikuti jika server melempar redirect (CDN behavior)
        curl_easy_setopt(curl, CURLOPT_MAXREDIRS, 5L);
        
        int retries = 3;
        while (retries > 0) {
            res = curl_easy_perform(curl);
            if (res == CURLE_OK) break;
            retries--;
            this_thread::sleep_for(chrono::milliseconds(500)); // Delay super singkat jika gagal, lalu hantam lagi
        }
        
        fclose(fp);
        curl_slist_free_all(headers); // Bersihkan memory header
        curl_easy_cleanup(curl);
        
        lock_guard<mutex> guard(log_mutex);
        if (res == CURLE_OK) {
            cout << "Thread " << thread_id << " (UA: " << selected_ua.substr(13, 15) << "...) Selesai!\n";
            return true;
        } else {
            cout << "Thread " << thread_id << " Gagal: " << curl_easy_strerror(res) << "\n";
            return false;
        }
    }
    return false;
}

int main(int argc, char* argv[]) {
    if (argc < 4) {
        cout << "Usage: ./speedster <URL> <OUTPUT_FILE> <TOTAL_SIZE>\n";
        return 1;
    }

    string url = argv[1];
    string output_file = argv[2];
    long total_size = stol(argv[3]);

    long chunk_size = total_size / NUM_THREADS;
    vector<thread> threads;
    vector<string> temp_files;

    cout << "[Speedster Engine] Memulai 12 Threads Siluman Paralel...\n";

    for (int i = 0; i < NUM_THREADS; ++i) {
        long start_byte = i * chunk_size;
        long end_byte = (i == NUM_THREADS - 1) ? total_size - 1 : (start_byte + chunk_size - 1);
        string temp_file = output_file + ".part" + to_string(i);
        temp_files.push_back(temp_file);
        
        threads.emplace_back(download_chunk, url, temp_file, start_byte, end_byte, i);
    }

    for (auto& t : threads) {
        t.join();
    }

    cout << "[Speedster Engine] Merging chunks...\n";
    ofstream final_file(output_file, ios_base::binary);
    for (const string& temp_file : temp_files) {
        ifstream file_chunk(temp_file, ios_base::binary);
        final_file << file_chunk.rdbuf();
        file_chunk.close();
        remove(temp_file.c_str());
    }
    final_file.close();

    cout << "[Speedster Engine] Selesai: " << output_file << "\n";
    return 0;
}