// tb_sample_ntt.cpp - Verilator C++ testbench for sample_ntt_sync
//
// Reads test vectors from +VECTOR_FILE= plusarg.
// Each line: "RHO_HEX K_HEX I_HEX J_HEX"
//   RHO_HEX: 64 hex chars (32 bytes, MSB-first per byte pair)
//   K_HEX, I_HEX, J_HEX: single hex digits
//
// Drives DUT, waits for 256 coefficients via valid_o handshake,
// prints "RESULT: CCC" for each (12-bit hex).
//
// Clock: 10ns period. Reset: 2 cycles. Timeout: 2,000,000 cycles.

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <cstdlib>
#include <cstdint>
#include <cstring>
#include "Vsample_ntt_sync.h"
#include "verilated.h"

#define CLK_PERIOD_NS     10.0
#define TIMEOUT_CYCLES    2000000
#define Q                 3329
#define N_COEFFS          256

static vluint64_t main_time = 0;

double sc_time_stamp() {
    return main_time;
}

static void posedge(Vsample_ntt_sync* dut) {
    dut->clk = !dut->clk;
    main_time += (vluint64_t)(CLK_PERIOD_NS / 2.0);
    dut->eval();
    dut->clk = !dut->clk;
    main_time += (vluint64_t)(CLK_PERIOD_NS / 2.0);
    dut->eval();
}

static int hex_char_to_nibble(char c) {
    if (c >= '0' && c <= '9') return c - '0';
    if (c >= 'A' && c <= 'F') return c - 'A' + 10;
    if (c >= 'a' && c <= 'f') return c - 'a' + 10;
    return 0;
}

static void parse_rho(const std::string& hex, Vsample_ntt_sync* dut) {
    for (int w = 0; w < 8; w++) dut->rho_i[w] = 0;

    int byte_count = 0;
    for (size_t i = 0; i < hex.length() && byte_count < 32; i += 2) {
        while (i < hex.length() && (hex[i] == ' ' || hex[i] == '\t')) i++;
        if (i + 1 >= hex.length()) break;

        char high_c = hex[i];
        char low_c  = hex[i + 1];
        uint8_t byte_val = (hex_char_to_nibble(high_c) << 4) |
                            hex_char_to_nibble(low_c);

        int word_idx = byte_count / 4;
        int byte_off = byte_count % 4;
        if (word_idx < 8) {
            dut->rho_i[word_idx] |= ((uint32_t)byte_val << (byte_off * 8));
        }
        byte_count++;
    }
}

int main(int argc, char** argv) {
    Verilated::commandArgs(argc, argv);

    const char* vector_file = NULL;
    for (int i = 1; i < argc; i++) {
        std::string arg(argv[i]);
        if (arg.rfind("+VECTOR_FILE=", 0) == 0) {
            vector_file = argv[i] + 13;
        }
    }

    if (!vector_file) {
        std::cerr << "ERROR: +VECTOR_FILE= not specified" << std::endl;
        return 1;
    }

    std::ifstream infile(vector_file);
    if (!infile.is_open()) {
        std::cerr << "ERROR: Cannot open vector file: " << vector_file << std::endl;
        return 1;
    }

    Vsample_ntt_sync* dut = new Vsample_ntt_sync;

    // Initialize
    dut->clk    = 0;
    dut->rst_n  = 0;
    for (int i = 0; i < 8; i++) dut->rho_i[i] = 0;
    dut->k_i    = 0;
    dut->i_idx  = 0;
    dut->j_idx  = 0;
    dut->valid_i = 0;
    dut->ready_i = 0;

    // Reset: 2 full cycles
    for (int i = 0; i < 2; i++) posedge(dut);
    dut->rst_n = 1;

    dut->ready_i = 1;

    std::string line;
    vluint64_t cycle = 0;
    int vec_count = 0;

    while (std::getline(infile, line)) {
        if (line.empty() || line[0] == '#') continue;

        std::string rho_hex, k_str, i_str, j_str;
        std::istringstream iss(line);
        if (!(iss >> rho_hex >> k_str >> i_str >> j_str)) {
            std::cerr << "ERROR: Malformed input line: " << line << std::endl;
            continue;
        }

        if (rho_hex.length() < 64) {
            std::cerr << "ERROR: RHO_HEX too short" << std::endl;
            continue;
        }

        int k_val = 0, i_val = 0, j_val = 0;
        if (!k_str.empty()) k_val = hex_char_to_nibble(k_str[0]);
        if (!i_str.empty()) i_val = hex_char_to_nibble(i_str[0]);
        if (!j_str.empty()) j_val = hex_char_to_nibble(j_str[0]);

        // Set inputs
        parse_rho(rho_hex, dut);
        dut->k_i   = k_val & 0x7;
        dut->i_idx = i_val & 0x3;
        dut->j_idx = j_val & 0x3;
        dut->valid_i = 1;

        // Wait for ready_o (DUT must be IDLE)
        while (!dut->ready_o && cycle < TIMEOUT_CYCLES) {
            posedge(dut);
            cycle++;
        }
        if (cycle >= TIMEOUT_CYCLES) {
            std::cerr << "ERROR: Timeout waiting for ready_o (vec "
                      << vec_count << ")" << std::endl;
            goto done;
        }

        // Capture edge
        posedge(dut);
        cycle++;
        dut->valid_i = 0;

        // Wait for and print 256 coefficients
        int coeff_count = 0;
        while (coeff_count < N_COEFFS && cycle < TIMEOUT_CYCLES) {
            while (!dut->valid_o && cycle < TIMEOUT_CYCLES) {
                posedge(dut);
                cycle++;
            }
            if (cycle >= TIMEOUT_CYCLES) {
                std::cerr << "ERROR: Timeout waiting for coeff "
                          << coeff_count << " (vec " << vec_count << ")"
                          << std::endl;
                goto done;
            }

            uint32_t coeff_val = (uint32_t)(dut->coeff_o) & 0xFFF;
            printf("RESULT: %03X\n", coeff_val);

            posedge(dut);
            cycle++;
            coeff_count++;
        }

        vec_count++;
    }

done:
    infile.close();
    delete dut;

    if (vec_count == 0) {
        std::cerr << "ERROR: No vectors processed" << std::endl;
        return 1;
    }

    return 0;
}