#include <iostream>
#include <fstream>
#include <cmath>
#include <vector>
#include <cstdlib>
using namespace std;

struct Note {
    double freq;      // Hz
    double duration;  // seconds
};

// Write 44-byte WAV header
void write_wav_header(ofstream &out, int sample_rate, int num_samples) {
    int byte_rate = sample_rate * 2; // 16-bit mono
    int block_align = 2;             // 16-bit mono

    int subchunk2_size = num_samples * 2;

    out.write("RIFF", 4);
    int chunk_size = 36 + subchunk2_size;
    out.write((char*)&chunk_size, 4);
    out.write("WAVE", 4);

    out.write("fmt ", 4);
    int subchunk1_size = 16;
    short audio_format = 1;
    short num_channels = 1;
    short bits_per_sample = 16;

    out.write((char*)&subchunk1_size, 4);
    out.write((char*)&audio_format, 2);
    out.write((char*)&num_channels, 2);
    out.write((char*)&sample_rate, 4);
    out.write((char*)&byte_rate, 4);
    out.write((char*)&block_align, 2);
    out.write((char*)&bits_per_sample, 2);

    out.write("data", 4);
    out.write((char*)&subchunk2_size, 4);
}

int main() {
    const int sample_rate = 44100;

    // FULL “Stand By Me” bassline pattern (looped)
    vector<Note> bass = {
        {41.20, 0.50}, {41.20, 0.50}, // E
        {61.74, 0.50}, {61.74, 0.50}, // B
        {55.00, 0.50}, {55.00, 0.50}, // A
        {41.20, 0.50}, {41.20, 0.50}  // E
    };

    // Repeat pattern 4 times (typical intro)
    vector<Note> song;
    for (int i = 0; i < 4; i++)
        for (auto &n : bass) song.push_back(n);

    // Count samples
    int total_samples = 0;
    for (auto &n : song)
        total_samples += (int)(n.duration * sample_rate);

    ofstream out("standbyme.wav", ios::binary);
    write_wav_header(out, sample_rate, total_samples);

    // Generate audio
    for (auto &n : song) {
        int ns = (int)(n.duration * sample_rate);
        double step = 2 * M_PI * n.freq / sample_rate;

        for (int i = 0; i < ns; i++) {
            short sample = (short)(30000 * sin(i * step));
            out.write((char*)&sample, 2);
        }
    }

    out.close();
    cout << "Created standbyme.wav successfully.\n";

    return EXIT_SUCCESS;
}