// sherpa-onnx/csrc/offline-recognizer-whisper-impl.h
//
// Copyright (c)  2022-2023  Xiaomi Corporation

#ifndef SHERPA_ONNX_CSRC_OFFLINE_RECOGNIZER_WHISPER_IMPL_H_
#define SHERPA_ONNX_CSRC_OFFLINE_RECOGNIZER_WHISPER_IMPL_H_

#include <algorithm>
#include <cmath>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "sherpa-onnx/csrc/offline-model-config.h"
#include "sherpa-onnx/csrc/offline-recognizer-impl.h"
#include "sherpa-onnx/csrc/offline-recognizer.h"
#include "sherpa-onnx/csrc/offline-whisper-decoder.h"
#include "sherpa-onnx/csrc/offline-whisper-greedy-search-decoder.h"
#include "sherpa-onnx/csrc/offline-whisper-model.h"
#include "sherpa-onnx/csrc/symbol-table.h"
#include "sherpa-onnx/csrc/transpose.h"

namespace sherpa_onnx {

static OfflineRecognitionResult Convert(const OfflineWhisperDecoderResult &src,
                                        const SymbolTable &sym_table) {
  OfflineRecognitionResult r;
  r.tokens.reserve(src.tokens.size());

  std::string text;
  for (auto i : src.tokens) {
    if (!sym_table.Contains(i)) {
      continue;
    }

    const auto &s = sym_table[i];
    text += s;
    r.tokens.push_back(s);
  }

  r.text = text;
  r.lang = src.lang;

  return r;
}

class OfflineRecognizerWhisperImpl : public OfflineRecognizerImpl {
 public:
  explicit OfflineRecognizerWhisperImpl(const OfflineRecognizerConfig &config)
      : OfflineRecognizerImpl(config),
        config_(config),
        symbol_table_(config_.model_config.tokens),
        model_(std::make_unique<OfflineWhisperModel>(config.model_config)) {
    Init();
  }

  template <typename Manager>
  OfflineRecognizerWhisperImpl(Manager *mgr,
                               const OfflineRecognizerConfig &config)
      : OfflineRecognizerImpl(mgr, config),
        config_(config),
        symbol_table_(mgr, config_.model_config.tokens),
        model_(
            std::make_unique<OfflineWhisperModel>(mgr, config.model_config)) {
    Init();
  }

  void Init() {
    // tokens.txt from whisper is base64 encoded, so we need to decode it
    symbol_table_.ApplyBase64Decode();

    if (config_.decoding_method == "greedy_search") {
      decoder_ = std::make_unique<OfflineWhisperGreedySearchDecoder>(
          config_.model_config.whisper, model_.get());
    } else {
      SHERPA_ONNX_LOGE(
          "Only greedy_search is supported at present for whisper. Given %s",
          config_.decoding_method.c_str());
      exit(-1);
    }
  }

  std::unique_ptr<OfflineStream> CreateStream() const override {
    WhisperTag tag;
    tag.dim = model_->FeatureDim();
    return std::make_unique<OfflineStream>(tag);
  }

  void DecodeStreams(OfflineStream **ss, int32_t n) const override {
    // batch decoding is not implemented yet
    for (int32_t i = 0; i != n; ++i) {
      DecodeStream(ss[i]);
    }
  }

  void SetConfig(const OfflineRecognizerConfig &config) override {
    config_.model_config.whisper = config.model_config.whisper;
  }

  OfflineRecognizerConfig GetConfig() const override { return config_; }

 private:
  void DecodeStream(OfflineStream *s) const {
    decoder_->SetConfig(config_.model_config.whisper);

    int32_t max_num_frames = 3000;
    auto memory_info =
        Ort::MemoryInfo::CreateCpu(OrtDeviceAllocator, OrtMemTypeDefault);

    int32_t feat_dim = s->FeatureDim();
    std::vector<float> f = s->GetFrames();
    int32_t num_frames = f.size() / feat_dim;

    // we use 50 here so that there will be some zero tail paddings
    if (num_frames >= max_num_frames - 50) {
      SHERPA_ONNX_LOGE(
          "Only waves less than 30 seconds are supported. We process only the "
          "first 30 seconds and discard the remaining data");
      num_frames = max_num_frames - 50;
    }

    model_->NormalizeFeatures(f.data(), num_frames, feat_dim);

    // note that 1000 is an experience-value.
    // You can replace 1000 by other values, say, 100.
    //
    // Since we have removed the 30 seconds constraint, we need
    // tail_padding_frames so that whisper is able to detect the eot token.
    int32_t tail_padding_frames = 1000;

    if (config_.model_config.whisper.tail_paddings > 0) {
      tail_padding_frames = config_.model_config.whisper.tail_paddings;
    }

    int32_t actual_frames =
        std::min(num_frames + tail_padding_frames, max_num_frames);

    std::array<int64_t, 3> shape{1, actual_frames, feat_dim};

    Ort::Value mel = Ort::Value::CreateTensor<float>(
        model_->Allocator(), shape.data(), shape.size());

    float *p_mel = mel.GetTensorMutableData<float>();
    std::copy(f.data(), f.data() + num_frames * feat_dim, p_mel);

    std::fill_n(p_mel + num_frames * feat_dim,
                (actual_frames - num_frames) * feat_dim, 0);

    mel = Transpose12(model_->Allocator(), &mel);

    try {
      auto cross_kv = model_->ForwardEncoder(std::move(mel));

      auto results = decoder_->Decode(std::move(cross_kv.first),
                                      std::move(cross_kv.second));

      auto r = Convert(results[0], symbol_table_);
      r.text = ApplyInverseTextNormalization(std::move(r.text));
      s->SetResult(r);
    } catch (const Ort::Exception &ex) {
      SHERPA_ONNX_LOGE(
          "\n\nCaught exception:\n\n%s\n\nReturn an empty result. Number of "
          "input frames: %d, Current tail "
          "paddings: %d. If you see a lot of such exceptions, please consider "
          "using a larger --whisper-tail-paddings",
          ex.what(), num_frames, tail_padding_frames);
      return;
    }
  }

 private:
  OfflineRecognizerConfig config_;
  SymbolTable symbol_table_;
  std::unique_ptr<OfflineWhisperModel> model_;
  std::unique_ptr<OfflineWhisperDecoder> decoder_;
};

}  // namespace sherpa_onnx

#endif  // SHERPA_ONNX_CSRC_OFFLINE_RECOGNIZER_WHISPER_IMPL_H_