# Copyright (c) ONNX Project Contributors
#
# SPDX-License-Identifier: Apache-2.0

import numpy as np

import onnx
from onnx.backend.test.case.base import Base
from onnx.backend.test.case.node import expect


class STFT(Base):
    @staticmethod
    def export() -> None:
        signal = np.arange(0, 128, dtype=np.float32).reshape(1, 128, 1)
        length = np.array(16).astype(np.int64)
        onesided_length = (length >> 1) + 1
        step = np.array(8).astype(np.int64)

        no_window = ""  # optional input, not supplied
        node = onnx.helper.make_node(
            "STFT",
            inputs=["signal", "frame_step", no_window, "frame_length"],
            outputs=["output"],
        )

        nstfts = ((signal.shape[1] - length) // step) + 1
        # [batch_size][frames][frame_length][2]
        output = np.empty([1, nstfts, onesided_length, 2], dtype=np.float32)
        for i in range(nstfts):
            start = i * step
            stop = i * step + length
            complex_out = np.fft.fft(signal[0, start:stop, 0])[0:onesided_length]
            output[0, i] = np.stack((complex_out.real, complex_out.imag), axis=1)

        expect(node, inputs=[signal, step, length], outputs=[output], name="test_stft")

        node = onnx.helper.make_node(
            "STFT",
            inputs=["signal", "frame_step", "window"],
            outputs=["output"],
        )

        # Test with window
        a0 = 0.5
        a1 = 0.5
        window = a0 + a1 * np.cos(
            2 * 3.1415 * np.arange(0, length, 1, dtype=np.float32) / length
        )
        nstfts = 1 + (signal.shape[1] - window.shape[0]) // step

        # [batch_size][frames][frame_length][2]
        output = np.empty([1, nstfts, onesided_length, 2], dtype=np.float32)
        for i in range(nstfts):
            start = i * step
            stop = i * step + length
            complex_out = np.fft.fft(signal[0, start:stop, 0] * window)[
                0:onesided_length
            ]
            output[0, i] = np.stack((complex_out.real, complex_out.imag), axis=1)
        expect(
            node,
            inputs=[signal, step, window],
            outputs=[output],
            name="test_stft_with_window",
        )
