/*
 * Copyright (c) 2015 Andrew Kelley
 *
 * This file is part of libsoundio, which is MIT licensed.
 * See http://opensource.org/licenses/MIT
 */

#include <soundio/soundio.h>

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

__attribute__ ((cold))
__attribute__ ((noreturn))
__attribute__ ((format (printf, 1, 2)))
static void panic(const char *format, ...) {
    va_list ap;
    va_start(ap, format);
    vfprintf(stderr, format, ap);
    fprintf(stderr, "\n");
    va_end(ap);
    abort();
}

static int min_int(int a, int b) {
    return (a < b) ? a : b;
}

static void error_callback(struct SoundIoStream *stream, int err) {
    panic("stream aborted: %s", soundio_strerror(err));
}

static void audio_callback(struct SoundIoStream *stream, int frame_count_min, int frame_count_max) {
    struct SoundIoChannelArea *in_areas;
    struct SoundIoChannelArea *out_areas;
    int err;

    int frames_left = frame_count_max;

    int read_frame_count = -1;

    while (frames_left > 0) {
        int write_frame_count = frames_left;

        if ((err = soundio_stream_begin_write(stream, &out_areas, &write_frame_count)))
            panic("begin read error: %s", soundio_strerror(err));

        if (!write_frame_count)
            break;

        for (int frame = 0; frame < write_frame_count; frame += 1, read_frame_count -= 1) {
            if (read_frame_count == 0) {
                if ((err = soundio_stream_end_read(stream)))
                    panic("begin read error: %s", soundio_strerror(err));
            }
            if (read_frame_count <= 0) {
                if ((err = soundio_stream_begin_read(stream, &in_areas, &read_frame_count)))
                    panic("begin read error: %s", soundio_strerror(err));
            }
            for (int ch = 0; ch < stream->output_layout.channel_count; ch += 1) {

                memcpy(write_ptr, areas[ch].ptr, stream->bytes_per_sample);
                out_areas[ch].ptr += out_areas[ch].step;
                write_ptr += instream->bytes_per_sample;
            }
        }


        if (!areas) {
            // Due to an overflow there is a hole. Fill the ring buffer with
            // silence for the size of the hole.
            memset(write_ptr, 0, frame_count * instream->bytes_per_frame);
            fprintf(stderr, "Dropped %d frames due to internal overflow\n", frame_count);
        } else {
            for (int frame = 0; frame < frame_count; frame += 1) {
                for (int ch = 0; ch < instream->layout.channel_count; ch += 1) {
                    memcpy(write_ptr, areas[ch].ptr, instream->bytes_per_sample);
                    areas[ch].ptr += areas[ch].step;
                    write_ptr += instream->bytes_per_sample;
                }
            }
        }

        if ((err = soundio_instream_end_read(instream)))
            panic("end read error: %s", soundio_strerror(err));

        frames_left -= frame_count;
        if (frames_left <= 0)
            break;
    }
}

static void write_callback(struct SoundIoOutStream *outstream, int frame_count_min, int frame_count_max) {
    struct SoundIoChannelArea *areas;
    int frame_count;
    int err;

    char *read_ptr = soundio_ring_buffer_read_ptr(ring_buffer);
    int fill_bytes = soundio_ring_buffer_fill_count(ring_buffer);
    int fill_count = fill_bytes / outstream->bytes_per_frame;

    if (frame_count_min > fill_count) {
        // Ring buffer does not have enough data, fill with zeroes.
        for (;;) {
            if ((err = soundio_outstream_begin_write(outstream, &areas, &frame_count)))
                panic("begin write error: %s", soundio_strerror(err));
            if (frame_count <= 0)
                return;
            for (int frame = 0; frame < frame_count; frame += 1) {
                for (int ch = 0; ch < outstream->layout.channel_count; ch += 1) {
                    memset(areas[ch].ptr, 0, outstream->bytes_per_sample);
                    areas[ch].ptr += areas[ch].step;
                }
            }
            if ((err = soundio_outstream_end_write(outstream)))
                panic("end write error: %s", soundio_strerror(err));
        }
    }

    int read_count = min_int(frame_count_max, fill_count);
    int frames_left = read_count;

    while (frames_left > 0) {
        int frame_count = frames_left;

        if ((err = soundio_outstream_begin_write(outstream, &areas, &frame_count)))
            panic("begin write error: %s", soundio_strerror(err));

        if (frame_count <= 0)
            break;

        for (int frame = 0; frame < frame_count; frame += 1) {
            for (int ch = 0; ch < outstream->layout.channel_count; ch += 1) {
                memcpy(areas[ch].ptr, read_ptr, outstream->bytes_per_sample);
                areas[ch].ptr += areas[ch].step;
                read_ptr += outstream->bytes_per_sample;
            }
        }

        if ((err = soundio_outstream_end_write(outstream)))
            panic("end write error: %s", soundio_strerror(err));

        frames_left -= frame_count;
    }

    soundio_ring_buffer_advance_read_ptr(ring_buffer, read_count * outstream->bytes_per_frame);
}

static void underflow_callback(struct SoundIoStream *stream) {
    static int count = 0;
    fprintf(stderr, "underflow %d\n", ++count);
}

static void overflow_callback(struct SoundIoStream *stream) {
    static int count = 0;
    fprintf(stderr, "overflow %d\n", ++count);
}

static int usage(char *exe) {
    fprintf(stderr, "Usage: %s [options]\n"
            "Options:\n"
            "  [--backend dummy|alsa|pulseaudio|jack|coreaudio|wasapi]\n"
            "  [--device id]\n"
            "  [--raw]\n"
            "  [--latency seconds]\n"
            , exe);
    return 1;
}

int main(int argc, char **argv) {
    char *exe = argv[0];
    enum SoundIoBackend backend = SoundIoBackendNone;
    char *device_id = NULL;
    bool raw = false;

    double microphone_latency = 0.2; // seconds

    for (int i = 1; i < argc; i += 1) {
        char *arg = argv[i];
        if (arg[0] == '-' && arg[1] == '-') {
            if (strcmp(arg, "--raw") == 0) {
                raw = true;
            } else if (++i >= argc) {
                return usage(exe);
            } else if (strcmp(arg, "--backend") == 0) {
                if (strcmp("dummy", argv[i]) == 0) {
                    backend = SoundIoBackendDummy;
                } else if (strcmp("alsa", argv[i]) == 0) {
                    backend = SoundIoBackendAlsa;
                } else if (strcmp("pulseaudio", argv[i]) == 0) {
                    backend = SoundIoBackendPulseAudio;
                } else if (strcmp("jack", argv[i]) == 0) {
                    backend = SoundIoBackendJack;
                } else if (strcmp("coreaudio", argv[i]) == 0) {
                    backend = SoundIoBackendCoreAudio;
                } else if (strcmp("wasapi", argv[i]) == 0) {
                    backend = SoundIoBackendWasapi;
                } else {
                    fprintf(stderr, "Invalid backend: %s\n", argv[i]);
                    return 1;
                }
            } else if (strcmp(arg, "--device") == 0) {
                device_id = argv[i];
            } else if (strcmp(arg, "--latency") == 0) {
                microphone_latency = atof(argv[i]);
            } else {
                return usage(exe);
            }
        } else {
            return usage(exe);
        }
    }
    struct SoundIo *soundio = soundio_create();
    if (!soundio)
        panic("out of memory");

    int err = (backend == SoundIoBackendNone) ?
        soundio_connect(soundio) : soundio_connect_backend(soundio, backend);
    if (err)
        panic("error connecting: %s", soundio_strerror(err));

    soundio_flush_events(soundio);

    int default_out_device_index = soundio_default_output_device_index(soundio);
    if (default_out_device_index < 0)
        panic("no output device found");

    int default_in_device_index = soundio_default_input_device_index(soundio);
    if (default_in_device_index < 0)
        panic("no output device found");

    struct SoundIoDevice *in_device;
    
    if (device_id) {
        bool found = false;
        for (int i = 0; i < soundio_input_device_count(soundio); i += 1) {
            struct SoundIoDevice *device = soundio_get_input_device(soundio, i);
            if (device->is_raw == raw && strcmp(device->id, device_id) == 0) {
                in_device = device;
                found = true;
                break;
            }
            soundio_device_unref(device);
        }
        if (!found)
            panic("invalid input device id: %s", device_id);
    } else {
        in_device = soundio_get_input_device(soundio, default_in_device_index);
    }

    struct SoundIoDevice *out_device;

    bool found = false;
    for (int i = 0; i < soundio_output_device_count(soundio); i += 1) {
        struct SoundIoDevice *device = soundio_get_output_device(soundio, i);
        if (device->is_raw == in_device->is_raw && strcmp(device->id, in_device->id) == 0) {
            out_device = device;
            found = true;
            break;
        }
        soundio_device_unref(device);
    }
    if (!found)
        panic("invalid output device id: %s", in_device->id);


    fprintf(stderr, "Input device: %s\n", in_device->name);
    fprintf(stderr, "Output device: %s\n", out_device->name);

    struct SoundIoStream *stream = soundio_stream_create(in_device, out_device);
    if (!stream)
        panic("out of memory");
    stream->software_latency = microphone_latency;
    stream->audio_callback = audio_callback;
    stream->underflow_callback = underflow_callback;
    stream->overflow_callback = overflow_callback;
    stream->error_callback = error_callback;

    if ((err = soundio_instream_open(instream))) {
        fprintf(stderr, "unable to open input stream: %s", soundio_strerror(err));
        return 1;
    }

    struct SoundIoOutStream *outstream = soundio_outstream_create(out_device);
    if (!outstream)
        panic("out of memory");
    outstream->software_latency = microphone_latency;

    if ((err = soundio_outstream_open(outstream))) {
        fprintf(stderr, "unable to open output stream: %s", soundio_strerror(err));
        return 1;
    }

    int capacity = microphone_latency * 2 * instream->sample_rate * instream->bytes_per_frame;
    ring_buffer = soundio_ring_buffer_create(soundio, capacity);
    if (!ring_buffer)
        panic("unable to create ring buffer: out of memory");
    char *buf = soundio_ring_buffer_write_ptr(ring_buffer);
    int fill_count = microphone_latency * outstream->sample_rate * outstream->bytes_per_frame;
    memset(buf, 0, fill_count);
    soundio_ring_buffer_advance_write_ptr(ring_buffer, fill_count);

    if ((err = soundio_instream_start(instream)))
        panic("unable to start input device: %s", soundio_strerror(err));

    if ((err = soundio_outstream_start(outstream)))
        panic("unable to start output device: %s", soundio_strerror(err));

    for (;;)
        soundio_wait_events(soundio);

    soundio_outstream_destroy(outstream);
    soundio_instream_destroy(instream);
    soundio_device_unref(in_device);
    soundio_device_unref(out_device);
    soundio_destroy(soundio);
    return 0;
}