// Copyright 2015-2019 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at

//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License
#ifndef _ESP_VAD_H_
#define _ESP_VAD_H_

#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

#define SAMPLE_RATE_HZ 16000      //Supports 32000, 16000, 8000
#define VAD_FRAME_LENGTH_MS 30    //Supports 10ms, 20ms, 30ms

/**
 * @brief Sets the VAD operating mode. A more aggressive (higher mode) VAD is more
 * restrictive in reporting speech.
 */
typedef enum {
    VAD_MODE_0 = 0,
    VAD_MODE_1,
    VAD_MODE_2,
    VAD_MODE_3,
    VAD_MODE_4
} vad_mode_t;

typedef enum {
    VAD_SILENCE = 0,
    VAD_SPEECH
} vad_state_t;

typedef void* vad_handle_t;

/**
 * @brief Creates an instance to the VAD structure.
 *
 * @param vad_mode          Sets the VAD operating mode.
 *
 * @param sample_rate_hz    The Sampling frequency (Hz) can be 32000, 16000, 8000, default: 16000.
 *
 * @param one_frame_ms      The length of the audio processing can be 10ms, 20ms, 30ms, default: 30.
 *
 * @return
 *         - NULL: Create failed
 *         - Others: The instance of VAD
 */
vad_handle_t vad_create(vad_mode_t vad_mode, int sample_rate_hz, int one_frame_ms);

/**
 * @brief Feed samples of an audio stream to the VAD and check if there is someone speaking.
 *
 * @param inst      The instance of VAD.
 *
 * @param data      An array of 16-bit signed audio samples.
 *
 * @return
 *         - VAD_SILENCE if no voice
 *         - VAD_SPEECH  if voice is detected
 *
 */
vad_state_t vad_process(vad_handle_t inst, int16_t *data);

/**
 * @brief Free the VAD instance
 *
 * @param inst The instance of VAD.
 *
 * @return None
 *
 */
void vad_destroy(vad_handle_t inst);

/*
* Programming Guide:
*
* @code{c}
* vad_handle_t vad_inst = vad_create(VAD_MODE_3, SAMPLE_RATE_HZ, VAD_FRAME_LENGTH_MS);     // Creates an instance to the VAD structure.
*
* while (1) {
*    //Use buffer to receive the audio data from MIC.
*    vad_state_t vad_state = vad_process(vad_inst, buffer);      // Feed samples to the VAD process and get the result.
* }
*
* vad_destroy(vad_inst);   // Free the VAD instance at the end of whole VAD process
*
* @endcode
*/

#ifdef __cplusplus
extern "C" {
#endif

#endif //_ESP_VAD_H_