# Copyright (c) 2023 Amphion.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.

import torch
import librosa

import numpy as np

from torchmetrics.audio.stoi import ShortTimeObjectiveIntelligibility


def extract_stoi(audio_ref, audio_deg, fs=None, extended=False, method="cut"):
    """Compute Short-Time Objective Intelligibility between the predicted and the ground truth audio.
    audio_ref: path to the ground truth audio.
    audio_deg: path to the predicted audio.
    fs: sampling rate.
    method: "dtw" will use dtw algorithm to align the length of the ground truth and predicted audio.
            "cut" will cut both audios into a same length according to the one with the shorter length.
    """
    # Load audio
    if fs != None:
        audio_ref, _ = librosa.load(audio_ref, sr=fs)
        audio_deg, _ = librosa.load(audio_deg, sr=fs)
    else:
        audio_ref, fs = librosa.load(audio_ref)
        audio_deg, fs = librosa.load(audio_deg)

    # Initialize method
    stoi = ShortTimeObjectiveIntelligibility(fs, extended)

    # Audio length alignment
    if len(audio_ref) != len(audio_deg):
        if method == "cut":
            length = min(len(audio_ref), len(audio_deg))
            audio_ref = audio_ref[:length]
            audio_deg = audio_deg[:length]
        elif method == "dtw":
            _, wp = librosa.sequence.dtw(audio_ref, audio_deg, backtrack=True)
            audio_ref_new = []
            audio_deg_new = []
            for i in range(wp.shape[0]):
                ref_index = wp[i][0]
                deg_index = wp[i][1]
                audio_ref_new.append(audio_ref[ref_index])
                audio_deg_new.append(audio_deg[deg_index])
            audio_ref = np.array(audio_ref_new)
            audio_deg = np.array(audio_deg_new)
            assert len(audio_ref) == len(audio_deg)

    # Convert to tensor
    audio_ref = torch.from_numpy(audio_ref)
    audio_deg = torch.from_numpy(audio_deg)

    return stoi(audio_deg, audio_ref).numpy().tolist()