package sound

/*
#cgo pkg-config: gstreamer-1.0
#include <gst/gst.h>
#include <stdlib.h>
static GstElement *start_sound(const void *data, size_t length, double volume, double pan, const char *sink, GError **error) {
    if (!gst_init_check(NULL, NULL, error)) return NULL;
    gchar *description = g_strdup_printf("appsrc name=source ! wavparse ! audioconvert ! audioresample ! audiopanorama name=panorama ! volume name=volume ! %s", sink);
    GError *parse_error = NULL;
    GstElement *pipeline = gst_parse_launch(description, &parse_error);
    g_free(description);
    if (parse_error != NULL) {
        if (pipeline) gst_object_unref(pipeline);
        g_error_free(parse_error);
        // audiopanorama is an optional GStreamer plugin. Preserve playback
        // when it is unavailable; the typed cue remains safely centered.
        description = g_strdup_printf("appsrc name=source ! wavparse ! audioconvert ! audioresample ! volume name=volume ! %s", sink);
        pipeline = gst_parse_launch(description, error);
        g_free(description);
        if (*error != NULL) { if (pipeline) gst_object_unref(pipeline); return NULL; }
    }
    GstElement *source = gst_bin_get_by_name(GST_BIN(pipeline), "source");
    GstElement *gain = gst_bin_get_by_name(GST_BIN(pipeline), "volume");
	GstElement *panorama = gst_bin_get_by_name(GST_BIN(pipeline), "panorama");
    g_object_set(gain, "volume", volume, NULL);
	if (panorama != NULL) g_object_set(panorama, "panorama", pan, NULL);
    gst_object_unref(gain);
	if (panorama != NULL) gst_object_unref(panorama);
    GstBuffer *buffer = gst_buffer_new_allocate(NULL, length, NULL);
    gst_buffer_fill(buffer, 0, data, length);
    GstFlowReturn flow;
    g_signal_emit_by_name(source, "push-buffer", buffer, &flow);
    gst_buffer_unref(buffer);
    g_signal_emit_by_name(source, "end-of-stream", &flow);
    gst_object_unref(source);
    if (gst_element_set_state(pipeline, GST_STATE_PLAYING) == GST_STATE_CHANGE_FAILURE) {
        g_set_error_literal(error, g_quark_from_static_string("cthulhu-sound"), 1, "cannot start audio pipeline");
        gst_element_set_state(pipeline, GST_STATE_NULL); gst_object_unref(pipeline); return NULL;
    }
    return pipeline;
}
static int poll_sound(GstElement *pipeline, GError **error) {
    GstBus *bus = gst_element_get_bus(pipeline);
    GstMessage *message = gst_bus_timed_pop_filtered(bus, 20 * GST_MSECOND, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
    gst_object_unref(bus);
    if (message == NULL) return 0;
    int result = 1;
    if (GST_MESSAGE_TYPE(message) == GST_MESSAGE_ERROR) {
        gst_message_parse_error(message, error, NULL); result = -1;
    }
    gst_message_unref(message); return result;
}
static void stop_sound(GstElement *pipeline) {
    gst_element_set_state(pipeline, GST_STATE_NULL); gst_object_unref(pipeline);
}
*/
import "C"

import (
	"context"
	"errors"
	"fmt"
	"unsafe"
)

type Player interface {
	Play(context.Context, []byte, float64, float64) error
}

type NativePlayer struct{ Sink string }

func (player NativePlayer) Play(ctx context.Context, data []byte, volume, pan float64) error {
	if err := ctx.Err(); err != nil {
		return err
	}
	if len(data) == 0 {
		return errors.New("empty sound")
	}
	sink := map[string]string{"auto": "autoaudiosink", "pipewire": "pipewiresink", "pulse": "pulsesink", "alsa": "alsasink", "test": "fakesink"}[player.Sink]
	if sink == "" {
		return fmt.Errorf("unknown sound sink %q", player.Sink)
	}
	nativeSink := C.CString(sink)
	defer C.free(unsafe.Pointer(nativeSink))
	var nativeErr *C.GError
	pan = normalizedPan(pan)
	pipeline := C.start_sound(unsafe.Pointer(&data[0]), C.size_t(len(data)), C.double(volume), C.double(pan), nativeSink, &nativeErr)
	if nativeErr != nil {
		defer C.g_error_free(nativeErr)
		return errors.New(C.GoString(nativeErr.message))
	}
	if pipeline == nil {
		return errors.New("cannot create sound pipeline")
	}
	defer C.stop_sound(pipeline)
	for {
		if err := ctx.Err(); err != nil {
			return err
		}
		result := C.poll_sound(pipeline, &nativeErr)
		if nativeErr != nil {
			defer C.g_error_free(nativeErr)
			return errors.New(C.GoString(nativeErr.message))
		}
		if result > 0 {
			return nil
		}
	}
}