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

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

// Write a simple WAV header (16-bit mono)
void writeWavHeader(ofstream &out, int sampleRate, int numSamples) {
    int byteRate = sampleRate * 2;
    int subchunk2Size = numSamples * 2;
    int chunkSize = 36 + subchunk2Size;

    out.write("RIFF", 4);
    out.write((char*)&chunkSize, 4);
    out.write("WAVEfmt ", 8);

    int subchunk1Size = 16;
    short audioFormat = 1, numChannels = 1, bitsPerSample = 16;
    out.write((char*)&subchunk1Size, 4);
    out.write((char*)&audioFormat, 2);
    out.write((char*)&numChannels, 2);
    out.write((char*)&sampleRate, 4);
    int byteRateVal = byteRate;
    short blockAlign = 2;
    out.write((char*)&byteRateVal, 4);
    out.write((char*)&blockAlign, 2);
    out.write((char*)&bitsPerSample, 2);

    out.write("data", 4);
    out.write((char*)&subchunk2Size, 4);
}

int main() {
    const int SAMPLE_RATE = 44100;
    vector<Note> bass = {
        {41.20, 0.5}, {41.20, 0.5}, // E
        {61.74, 0.5}, {61.74, 0.5}, // B
        {55.00, 0.5}, {55.00, 0.5}, // A
        {41.20, 0.5}, {41.20, 0.5}  // E
    };

    // Repeat bassline
    vector<Note> bassline;
    for (int i = 0; i < 8; ++i)
        bassline.insert(bassline.end(), bass.begin(), bass.end());

    // Simple melody (approximation)
    vector<Note> melody = {
        {440.0, 0.5}, {440.0, 0.5}, {392.0, 0.5}, {440.0, 0.75},
        {392.0, 0.25}, {349.0, 1.0}, {440.0, 0.5}, {392.0, 0.5},
        {349.0, 0.5}, {330.0, 0.75}, {349.0, 0.25}, {330.0, 1.0}
    };

    // Prepare samples
    vector<short> samples;
    size_t melodyIndex = 0, melodySamples = 0;
    double melodyStep = 0, melodyFreq = melody[0].freq;

    for (const auto &note : bassline) {
        int nSamples = note.duration * SAMPLE_RATE;
        double bassStep = 2 * M_PI * note.freq / SAMPLE_RATE;

        for (int i = 0; i < nSamples; ++i) {
            // Handle melody progression
            if (melodyIndex < melody.size() && melodySamples <= 0) {
                melodyFreq = melody[melodyIndex].freq;
                melodyStep = 2 * M_PI * melodyFreq / SAMPLE_RATE;
                melodySamples = melody[melodyIndex].duration * SAMPLE_RATE;
                melodyIndex++;
            }

            double bassVal = 15000 * sin(i * bassStep);
            double melVal = 12000 * sin(i * melodyStep);
            short sample = (short)((bassVal + melVal) / 2);

            samples.push_back(sample);
            melodySamples--;
        }
    }

    // Write to WAV
    ofstream out("stand_by_me_song.wav", ios::binary);
    writeWavHeader(out, SAMPLE_RATE, samples.size());
    out.write((char*)samples.data(), samples.size() * 2);
    out.close();

    cout << "Created stand_by_me_song.wav successfully!\n";
    return EXIT_SUCCESS;
}