"""Quantum machine learning module."""

from typing import Dict, List, Optional, Tuple

import numpy as np


class QuantumML:
    """Quantum machine learning implementation."""

    def __init__(self, n_qubits: int = 4, n_layers: int = 2):
        """Initialize quantum ML.

        Args:
            n_qubits: Number of qubits
            n_layers: Number of layers
        """
        self.n_qubits = n_qubits
        self.n_layers = n_layers
        self.parameters = self._initialize_parameters()

    def _initialize_parameters(self) -> np.ndarray:
        """Initialize model parameters.

        Returns:
            np.ndarray: Initial parameters
        """
        # Stub implementation
        return np.random.uniform(
            -np.pi, np.pi, size=(self.n_qubits * self.n_layers * 3)
        )

    def forward(self, x: np.ndarray) -> np.ndarray:
        """Forward pass through quantum ML model.

        Args:
            x: Input data

        Returns:
            np.ndarray: Model output
        """
        # Stub implementation
        return np.random.random(size=(x.shape[0], 1))

    def backward(
        self, x: np.ndarray, grad: np.ndarray
    ) -> Tuple[np.ndarray, np.ndarray]:
        """Backward pass through quantum ML model.

        Args:
            x: Input data
            grad: Gradient from next layer

        Returns:
            Tuple[np.ndarray, np.ndarray]: Input and parameter gradients
        """
        # Stub implementation
        return np.zeros_like(x), np.zeros_like(self.parameters)

    def train(self, x: np.ndarray, y: np.ndarray, epochs: int = 100) -> List[float]:
        """Train the quantum ML model.

        Args:
            x: Training data
            y: Training labels
            epochs: Number of training epochs

        Returns:
            List[float]: Training loss history
        """
        # Stub implementation
        return [0.1] * epochs

    def predict(self, x: np.ndarray) -> np.ndarray:
        """Make predictions with the trained model.

        Args:
            x: Input data

        Returns:
            np.ndarray: Predictions
        """
        # Stub implementation
        return self.forward(x)
