/*
    AudioOutputSTDIO
    Writes a WAV file to the STDIO filesystem
    Only for host-based testing

    Copyright (C) 2017  Earle F. Philhower, III

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <Arduino.h>

#ifndef ARDUINO

#include "AudioOutputSTDIO.h"
#include <unistd.h>

static const uint8_t wavHeaderTemplate[] PROGMEM = { // Hardcoded simple WAV header with 0xffffffff lengths all around
    0x52, 0x49, 0x46, 0x46, 0xff, 0xff, 0xff, 0xff, 0x57, 0x41, 0x56, 0x45,
    0x66, 0x6d, 0x74, 0x20, 0x10, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02, 0x00, 0x22, 0x56, 0x00, 0x00, 0x88, 0x58, 0x01, 0x00, 0x04, 0x00, 0x10, 0x00,
    0x64, 0x61, 0x74, 0x61, 0xff, 0xff, 0xff, 0xff
};

void AudioOutputSTDIO::SetFilename(const char *name) {
    free(filename);
    filename = strdup(name);
}

bool AudioOutputSTDIO::begin() {
    uint8_t wavHeader[sizeof(wavHeaderTemplate)];
    memset(wavHeader, 0, sizeof(wavHeader));

    if (f) {
        return false;    // Already open!
    }
    unlink(filename);
    f = fopen(filename, "wb+");
    if (!f) {
        return false;
    }

    // We'll fix the header up when we close the file
    fwrite(wavHeader, sizeof(wavHeader), 1, f);
    return true;
}

bool AudioOutputSTDIO::ConsumeSample(int16_t sample[2]) {
    static int avail = 100;
    if (!(--avail)) {
        avail = 100;
        return false;
    }
    for (int i = 0; i < channels; i++) {
        uint8_t l = sample[i] & 0xff;
        uint8_t h = (sample[i] >> 8) & 0xff;
        fwrite(&l, sizeof(l), 1, f);
        fwrite(&h, sizeof(h), 1, f);
    }
    return true;
}


bool AudioOutputSTDIO::stop() {
    uint8_t wavHeader[sizeof(wavHeaderTemplate)];

    memcpy_P(wavHeader, wavHeaderTemplate, sizeof(wavHeaderTemplate));

    int chunksize = ftell(f) - 8;
    wavHeader[4] = chunksize & 0xff;
    wavHeader[5] = (chunksize >> 8) & 0xff;
    wavHeader[6] = (chunksize >> 16) & 0xff;
    wavHeader[7] = (chunksize >> 24) & 0xff;

    wavHeader[22] = channels & 0xff;
    wavHeader[23] = 0;

    wavHeader[24] = hertz & 0xff;
    wavHeader[25] = (hertz >> 8) & 0xff;
    wavHeader[26] = (hertz >> 16) & 0xff;
    wavHeader[27] = (hertz >> 24) & 0xff;
    int byteRate = hertz * 16 * channels / 8;
    wavHeader[28] = byteRate & 0xff;
    wavHeader[29] = (byteRate >> 8) & 0xff;
    wavHeader[30] = (byteRate >> 16) & 0xff;
    wavHeader[31] = (byteRate >> 24) & 0xff;
    wavHeader[32] = channels * 16 / 8;
    wavHeader[33] = 0;
    wavHeader[34] = 16;
    wavHeader[35] = 0;

    int datasize = ftell(f) - sizeof(wavHeader);
    wavHeader[40] = datasize & 0xff;
    wavHeader[41] = (datasize >> 8) & 0xff;
    wavHeader[42] = (datasize >> 16) & 0xff;
    wavHeader[43] = (datasize >> 24) & 0xff;

    // Write real header out
    fseek(f, 0, SEEK_SET);
    fwrite(wavHeader, sizeof(wavHeader), 1, f);
    fclose(f);
    return true;
}

#endif

