// sherpa-onnx/c-api/c-api.h
//
// Copyright (c)  2023  Xiaomi Corporation

// C API for sherpa-onnx
//
// Please refer to
// https://github.com/k2-fsa/sherpa-onnx/blob/master/c-api-examples/decode-file-c-api.c
// for usages.
//

#ifndef SHERPA_ONNX_C_API_C_API_H_
#define SHERPA_ONNX_C_API_C_API_H_

#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

/// Please refer to
/// https://k2-fsa.github.io/sherpa/onnx/pretrained_models/index.html
/// to download pre-trained models. That is, you can find encoder-xxx.onnx
/// decoder-xxx.onnx, joiner-xxx.onnx, and tokens.txt for this struct
/// from there.
typedef struct SherpaOnnxOnlineTransducerModelConfig {
  const char *encoder;
  const char *decoder;
  const char *joiner;
  const char *tokens;
  int32_t num_threads;
  int32_t debug;  // true to print debug information of the model
} SherpaOnnxOnlineTransducerModelConfig;

/// It expects 16 kHz 16-bit single channel wave format.
typedef struct SherpaOnnxFeatureConfig {
  /// Sample rate of the input data. MUST match the one expected
  /// by the model. For instance, it should be 16000 for models provided
  /// by us.
  int32_t sample_rate;

  /// Feature dimension of the model.
  /// For instance, it should be 80 for models provided by us.
  int32_t feature_dim;
} SherpaOnnxFeatureConfig;

typedef struct SherpaOnnxOnlineRecognizerConfig {
  SherpaOnnxFeatureConfig feat_config;
  SherpaOnnxOnlineTransducerModelConfig model_config;

  /// 0 to disable endpoint detection.
  /// A non-zero value to enable endpoint detection.
  int32_t enable_endpoint;

  /// An endpoint is detected if trailing silence in seconds is larger than
  /// this value even if nothing has been decoded.
  /// Used only when enable_endpoint is not 0.
  float rule1_min_trailing_silence;

  /// An endpoint is detected if trailing silence in seconds is larger than
  /// this value after something that is not blank has been decoded.
  /// Used only when enable_endpoint is not 0.
  float rule2_min_trailing_silence;

  /// An endpoint is detected if the utterance in seconds is larger than
  /// this value.
  /// Used only when enable_endpoint is not 0.
  float rule3_min_utterance_length;
} SherpaOnnxOnlineRecognizerConfig;

typedef struct SherpaOnnxOnlineRecognizerResult {
  const char *text;
  // TODO(fangjun): Add more fields
} SherpaOnnxOnlineRecognizerResult;

/// Note: OnlineRecognizer here means StreamingRecognizer.
/// It does not need to access the Internet during recognition.
/// Everything is run locally.
typedef struct SherpaOnnxOnlineRecognizer SherpaOnnxOnlineRecognizer;
typedef struct SherpaOnnxOnlineStream SherpaOnnxOnlineStream;

/// @param config  Config for the recongizer.
/// @return Return a pointer to the recognizer. The user has to invoke
//          DestroyOnlineRecognizer() to free it to avoid memory leak.
SherpaOnnxOnlineRecognizer *CreateOnlineRecognizer(
    const SherpaOnnxOnlineRecognizerConfig *config);

/// Free a pointer returned by CreateOnlineRecognizer()
///
/// @param p A pointer returned by CreateOnlineRecognizer()
void DestroyOnlineRecognizer(SherpaOnnxOnlineRecognizer *recognizer);

/// Create an online stream for accepting wave samples.
///
/// @param recognizer  A pointer returned by CreateOnlineRecognizer()
/// @return Return a pointer to an OnlineStream. The user has to invoke
///         DestoryOnlineStream() to free it to avoid memory leak.
SherpaOnnxOnlineStream *CreateOnlineStream(
    const SherpaOnnxOnlineRecognizer *recognizer);

/// Destory an online stream.
///
/// @param stream A pointer returned by CreateOnlineStream()
void DestoryOnlineStream(SherpaOnnxOnlineStream *stream);

/// Accept input audio samples and compute the features.
/// The user has to invoke DecodeOnlineStream() to run the neural network and
/// decoding.
///
/// @param stream  A pointer returned by CreateOnlineStream().
/// @param sample_rate  Sampler rate of the input samples. It has to be 16 kHz
///                     for models from icefall.
/// @param samples A pointer to a 1-D array containing audio samples.
///                The range of samples has to be normalized to [-1, 1].
/// @param n  Number of elements in the samples array.
void AcceptWaveform(SherpaOnnxOnlineStream *stream, float sample_rate,
                    const float *samples, int32_t n);

/// Return 1 if there are enough number of feature frames for decoding.
/// Return 0 otherwise.
///
/// @param recognizer  A pointer returned by CreateOnlineRecognizer
/// @param stream  A pointer returned by CreateOnlineStream
int32_t IsOnlineStreamReady(SherpaOnnxOnlineRecognizer *recognizer,
                            SherpaOnnxOnlineStream *stream);

/// Call this function to run the neural network model and decoding.
//
/// Precondition for this function: IsOnlineStreamReady() MUST return 1.
///
/// Usage example:
///
///  while (IsOnlineStreamReady(recognizer, stream)) {
///     DecodeOnlineStream(recognizer, stream);
///  }
///
void DecodeOnlineStream(SherpaOnnxOnlineRecognizer *recognizer,
                        SherpaOnnxOnlineStream *stream);

/// This function is similar to DecodeOnlineStream(). It decodes multiple
/// OnlineStream in parallel.
///
/// Caution: The caller has to ensure each OnlineStream is ready, i.e.,
/// IsOnlineStreamReady() for that stream should return 1.
///
/// @param recognizer  A pointer returned by CreateOnlineRecognizer()
/// @param streams  A pointer array containing pointers returned by
///                 CreateOnlineRecognizer()
/// @param n  Number of elements in the given streams array.
void DecodeMultipleOnlineStreams(SherpaOnnxOnlineRecognizer *recognizer,
                                 SherpaOnnxOnlineStream **streams, int32_t n);

/// Get the decoding results so far for an OnlineStream.
///
/// @param recognizer A pointer returned by CreateOnlineRecognizer().
/// @param stream A pointer returned by CreateOnlineStream().
/// @return A pointer containing the result. The user has to invoke
///         DestroyOnlineRecognizerResult() to free the returned pointer to
///         avoid memory leak.
SherpaOnnxOnlineRecognizerResult *GetOnlineStreamResult(
    SherpaOnnxOnlineRecognizer *recognizer, SherpaOnnxOnlineStream *stream);

/// Destroy the pointer returned by GetOnlineStreamResult().
///
/// @param r A pointer returned by GetOnlineStreamResult()
void DestroyOnlineRecognizerResult(const SherpaOnnxOnlineRecognizerResult *r);

/// Reset an OnlineStream , which clears the neural network model state
/// and the state for decoding.
///
/// @param recognizer A pointer returned by CreateOnlineRecognizer().
/// @param stream A pointer returned by CreateOnlineStream
void Reset(SherpaOnnxOnlineRecognizer *recognizer,
           SherpaOnnxOnlineStream *stream);

/// Signal that no more audio samples would be available.
/// After this call, you cannot call AcceptWaveform() any more.
///
/// @param stream A pointer returned by CreateOnlineStream()
void InputFinished(SherpaOnnxOnlineStream *stream);

/// Return 1 if an endpoint has been detected.
///
/// @param recognizer A pointer returned by CreateOnlineRecognizer()
/// @param stream A pointer returned by CreateOnlineStream()
/// @return Return 1 if an endpoint is detected. Return 0 otherwise.
int32_t IsEndpoint(SherpaOnnxOnlineRecognizer *recognizer,
                   SherpaOnnxOnlineStream *stream);

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif  // SHERPA_ONNX_C_API_C_API_H_