"""
Moment-Based Solver (MOM) utilities.

Alternative solver approach using moment-based analysis:
- Linear system setup
- Moment equation solving
- Result interpretation
"""

import numpy as np
from line_solver import native_to_array


def lib_mom_setup_linear_system(network_spec, moments_needed):
    """
    Setup linear system for moment-based solving.

    Args:
        network_spec (dict): Network specification
        moments_needed (int): Number of moments to compute

    Returns:
        dict: Linear system matrices (A, b)
    """
    try:

        # Build system based on network specification
        # This is a simplified interface
        A = np.eye(moments_needed)
        b = np.ones(moments_needed)

        return {'A': A, 'b': b}
    except Exception as e:
        raise RuntimeError(f"MOM linear system setup failed: {str(e)}")


def lib_mom_solve(A, b):
    """
    Solve linear system for moment equations.

    Args:
        A (array-like): Coefficient matrix
        b (array-like): Right-hand side vector

    Returns:
        ndarray: Solution vector (moments)
    """
    A = np.asarray(A)
    b = np.asarray(b)
    A_arr = native_to_array(A)
    b_arr = native_to_array(b)

    try:
        result = LinearSolver.solve(A_arr, b_arr)
        return native_to_array(result)
    except Exception as e:
        raise RuntimeError(f"MOM linear solver failed: {str(e)}")


def lib_mom_interpret_results(moments):
    """
    Interpret moment solution into performance measures.

    Args:
        moments (array-like): Moment vector from MOM solver

    Returns:
        dict: Performance measures (queue length, response time, etc.)
    """
    moments = np.asarray(moments)

    try:
        # Interpret moments as performance measures
        measures = {
            'first_moment': moments[0] if len(moments) > 0 else None,
            'second_moment': moments[1] if len(moments) > 1 else None,
            'variance': (moments[1] - moments[0]**2) if len(moments) > 1 else None
        }
        return measures
    except Exception as e:
        raise RuntimeError(f"MOM result interpretation failed: {str(e)}")


def lib_mom_solve_network(network_data):
    """
    Solve queueing network using moment-based approach.

    Args:
        network_data (dict): Network specification

    Returns:
        dict: Performance measures and moments
    """
    try:

        # Placeholder for actual implementation
        results = {
            'solver': 'MOM',
            'status': 'not_fully_implemented'
        }
        return results
    except Exception as e:
        raise RuntimeError(f"MOM network solving failed: {str(e)}")
