#include "sound/wav.h"
#include <stdint.h>
#include <stdio.h>


static void write_u16(FILE *f, uint16_t v) {
    uint8_t b[2];
    b[0] = (uint8_t)(v & 0xff);
    b[1] = (uint8_t)((v >> 8) & 0xff);
    fwrite(b, 1, 2, f);
}

static void write_u32(FILE *f, uint32_t v) {
    uint8_t b[4];
    b[0] = (uint8_t)(v & 0xff);
    b[1] = (uint8_t)((v >> 8) & 0xff);
    b[2] = (uint8_t)((v >> 16) & 0xff);
    b[3] = (uint8_t)((v >> 24) & 0xff);
    fwrite(b, 1, 4, f);
}

int wave_open(wav_t *wav, const char *filename, uint32_t sample_rate) {

    wav->file = fopen(filename, "wb");
    if (!wav->file)
        return 0;

    wav->sample_rate = sample_rate;
    wav->samples_written = 0;

    /* RIFF header */
    fwrite((uint8_t[]){'R','I','F','F'}, 1, 4, wav->file);
    write_u32(wav->file, 0);               // Placeholder for file size
    fwrite((uint8_t[]){'W','A','V','E'}, 1, 4, wav->file);

    /* fmt chunk */
    fwrite((uint8_t[]){'f','m','t',' '}, 1, 4, wav->file);
    write_u32(wav->file, 16);               // PCM chunk size
    write_u16(wav->file, 1);                // Audio format (1 = PCM)
    write_u16(wav->file, 1);                // Channels (1 = mono)
    write_u32(wav->file, sample_rate);      // Sample rate
    write_u32(wav->file, sample_rate * 2);  // Byte rate (sr * block_align)
    write_u16(wav->file, 2);                // Block align (mono 16-bit = 2)
    write_u16(wav->file, 16);               // Bits per sample

    /* data chunk */
    fwrite((uint8_t[]){'d','a','t','a'}, 1, 4, wav->file);
    write_u32(wav->file, 0);  // Placeholder for data size

    return 1;
}
void wave_write_sample(wav_t *wav, int16_t sample) {
    write_u16(wav->file, (uint16_t)sample);
    wav->samples_written++;
}

void wave_close(wav_t *wav) {

    uint32_t data_size = wav->samples_written * 2;
    uint32_t file_size = 36 + data_size;

    /* Patch RIFF size */
    fseek(wav->file, 4, SEEK_SET);
    write_u32(wav->file, file_size);

    /* Patch data chunk size */
    fseek(wav->file, 40, SEEK_SET);
    write_u32(wav->file, data_size);

    fclose(wav->file);
}