data/examples/signal_processing/evaluator.py

"""
Evaluator for the Real-Time Adaptive Signal Processing Algorithm

This evaluator implements the multi-objective optimization function defined in the specification:
J(θ) = α₁·S(θ) + α₂·L_recent(θ) + α₃·L_avg(θ) + α₄·R(θ)

Where:
- S(θ): Slope change penalty - counts directional reversals
- L_recent(θ): Instantaneous lag error - |y[n] - x[n]|
- L_avg(θ): Average tracking error over window
- R(θ): False reversal penalty - mismatched trend changes
- α₁=0.3, α₂=α₃=0.2, α₄=0.3: Weighting coefficients
"""

import importlib.util
import numpy as np
import time
import concurrent.futures
import traceback
from scipy import signal
from scipy.stats import pearsonr


def run_with_timeout(func, args=(), kwargs={}, timeout_seconds=30):
    """
    Run a function with a timeout using concurrent.futures
    """
    with concurrent.futures.ThreadPoolExecutor(max_workers=1) as executor:
        future = executor.submit(func, *args, **kwargs)
        try:
            result = future.result(timeout=timeout_seconds)
            return result
        except concurrent.futures.TimeoutError:
            raise TimeoutError(f"Function timed out after {timeout_seconds} seconds")


def safe_float(value):
    """Convert a value to float safely"""
    try:
        if np.isnan(value) or np.isinf(value):
            return 0.0
        return float(value)
    except (TypeError, ValueError):
        return 0.0


def calculate_slope_changes(signal_data):
    """
    Calculate slope change penalty S(θ) - counts directional reversals

    Args:
        signal_data: 1D array of signal values

    Returns:
        Number of slope changes (directional reversals)
    """
    if len(signal_data) < 3:
        return 0

    # Calculate differences
    diffs = np.diff(signal_data)

    # Count sign changes in consecutive differences
    sign_changes = 0
    for i in range(1, len(diffs)):
        if np.sign(diffs[i]) != np.sign(diffs[i - 1]) and diffs[i - 1] != 0:
            sign_changes += 1

    return sign_changes


def calculate_lag_error(filtered_signal, original_signal, window_size):
    """
    Calculate instantaneous lag error L_recent(θ) = |y[n] - x[n]|

    Args:
        filtered_signal: Output of the filter
        original_signal: Original input signal
        window_size: Size of the processing window

    Returns:
        Instantaneous lag error at the most recent sample
    """
    if len(filtered_signal) == 0:
        return 1.0  # Maximum penalty

    # Account for processing delay
    delay = window_size - 1
    if len(original_signal) <= delay:
        return 1.0

    # Compare the last filtered sample with the corresponding original sample
    recent_filtered = filtered_signal[-1]
    recent_original = original_signal[delay + len(filtered_signal) - 1]

    return abs(recent_filtered - recent_original)


def calculate_average_tracking_error(filtered_signal, original_signal, window_size):
    """
    Calculate average tracking error L_avg(θ) over the window

    Args:
        filtered_signal: Output of the filter
        original_signal: Original input signal
        window_size: Size of the processing window

    Returns:
        Average absolute error over the processed samples
    """
    if len(filtered_signal) == 0:
        return 1.0  # Maximum penalty

    # Account for processing delay
    delay = window_size - 1
    if len(original_signal) <= delay:
        return 1.0

    # Align signals
    aligned_original = original_signal[delay : delay + len(filtered_signal)]

    # Ensure same length
    min_length = min(len(filtered_signal), len(aligned_original))
    if min_length == 0:
        return 1.0

    filtered_aligned = filtered_signal[:min_length]
    original_aligned = aligned_original[:min_length]

    # Calculate mean absolute error
    return np.mean(np.abs(filtered_aligned - original_aligned))


def calculate_false_reversal_penalty(filtered_signal, clean_signal, window_size):
    """
    Calculate false reversal penalty R(θ) - mismatched trend changes

    Args:
        filtered_signal: Output of the filter
        clean_signal: Ground truth clean signal
        window_size: Size of the processing window

    Returns:
        Penalty for trend changes that don't match the clean signal
    """
    if len(filtered_signal) < 3 or len(clean_signal) < 3:
        return 0

    # Account for processing delay
    delay = window_size - 1
    if len(clean_signal) <= delay:
        return 1.0

    # Align signals
    aligned_clean = clean_signal[delay : delay + len(filtered_signal)]
    min_length = min(len(filtered_signal), len(aligned_clean))

    if min_length < 3:
        return 0

    filtered_aligned = filtered_signal[:min_length]
    clean_aligned = aligned_clean[:min_length]

    # Calculate trend changes for both signals
    filtered_diffs = np.diff(filtered_aligned)
    clean_diffs = np.diff(clean_aligned)

    # Count mismatched trend changes
    false_reversals = 0
    for i in range(1, len(filtered_diffs)):
        # Check if there's a trend change in filtered signal
        filtered_change = (
            np.sign(filtered_diffs[i]) != np.sign(filtered_diffs[i - 1])
            and filtered_diffs[i - 1] != 0
        )

        # Check if there's a corresponding trend change in clean signal
        clean_change = (
            np.sign(clean_diffs[i]) != np.sign(clean_diffs[i - 1]) and clean_diffs[i - 1] != 0
        )

        # Count as false reversal if filtered has change but clean doesn't
        if filtered_change and not clean_change:
            false_reversals += 1

    return false_reversals


def calculate_composite_score(S, L_recent, L_avg, R, alpha=[0.3, 0.2, 0.2, 0.3]):
    """
    Calculate the composite metric J(θ) = α₁·S(θ) + α₂·L_recent(θ) + α₃·L_avg(θ) + α₄·R(θ)

    All metrics are normalized and converted to penalties (higher = worse)
    The final score is converted to a maximization problem (higher = better)
    """
    # Normalize slope changes (typical range 0-100)
    S_norm = min(S / 50.0, 2.0)

    # Lag errors are already in reasonable range (0-10 typically)
    L_recent_norm = min(L_recent, 2.0)
    L_avg_norm = min(L_avg, 2.0)

    # Normalize false reversals (typical range 0-50)
    R_norm = min(R / 25.0, 2.0)

    # Calculate weighted penalty
    penalty = (
        alpha[0] * S_norm + alpha[1] * L_recent_norm + alpha[2] * L_avg_norm + alpha[3] * R_norm
    )

    # Convert to maximization score (higher is better)
    score = 1.0 / (1.0 + penalty)

    return score


def generate_test_signals(num_signals=5):
    """
    Generate multiple test signals with different characteristics
    """
    test_signals = []

    for i in range(num_signals):
        np.random.seed(42 + i)  # Different seed for each signal
        length = 500 + i * 100  # Varying lengths
        noise_level = 0.2 + i * 0.1  # Varying noise levels

        t = np.linspace(0, 10, length)

        # Different signal characteristics
        if i == 0:
            # Smooth sinusoidal with trend
            clean = 2 * np.sin(2 * np.pi * 0.5 * t) + 0.1 * t
        elif i == 1:
            # Multiple frequency components
            clean = (
                np.sin(2 * np.pi * 0.5 * t)
                + 0.5 * np.sin(2 * np.pi * 2 * t)
                + 0.2 * np.sin(2 * np.pi * 5 * t)
            )
        elif i == 2:
            # Non-stationary with changing frequency
            clean = np.sin(2 * np.pi * (0.5 + 0.2 * t) * t)
        elif i == 3:
            # Step changes
            clean = np.concatenate(
                [
                    np.ones(length // 3),
                    2 * np.ones(length // 3),
                    0.5 * np.ones(length - 2 * (length // 3)),
                ]
            )
        else:
            # Random walk with trend
            clean = np.cumsum(np.random.randn(length) * 0.1) + 0.05 * t

        # Add noise
        noise = np.random.normal(0, noise_level, length)
        noisy = clean + noise

        test_signals.append((noisy, clean))

    return test_signals


def evaluate(program_path):
    """
    Main evaluation function that tests the signal processing algorithm
    on multiple test signals and calculates the composite performance metric.
    """
    try:
        # Load the program
        spec = importlib.util.spec_from_file_location("program", program_path)
        program = importlib.util.module_from_spec(spec)
        spec.loader.exec_module(program)

        # Check if required function exists
        if not hasattr(program, "run_signal_processing"):
            return {"composite_score": 0.0, "error": "Missing run_signal_processing function"}

        # Generate test signals
        test_signals = generate_test_signals(5)

        # Collect metrics across all test signals
        all_scores = []
        all_metrics = []
        successful_runs = 0

        for i, (noisy_signal, clean_signal) in enumerate(test_signals):
            try:
                # Run the algorithm with timeout
                start_time = time.time()

                # Call the program's main function
                result = run_with_timeout(
                    program.run_signal_processing,
                    kwargs={
                        "signal_length": len(noisy_signal),
                        "noise_level": 0.3,
                        "window_size": 20,
                    },
                    timeout_seconds=10,
                )

                execution_time = time.time() - start_time

                # Validate result format
                if not isinstance(result, dict):
                    print(f"Signal {i}: Invalid result format")
                    continue

                if "filtered_signal" not in result:
                    print(f"Signal {i}: Missing filtered_signal in result")
                    continue

                filtered_signal = result["filtered_signal"]

                if len(filtered_signal) == 0:
                    print(f"Signal {i}: Empty filtered signal")
                    continue

                # Convert to numpy arrays
                filtered_signal = np.array(filtered_signal)

                # Calculate metrics using the generated test signal
                window_size = 20

                # Calculate all penalty components
                S = calculate_slope_changes(filtered_signal)
                L_recent = calculate_lag_error(filtered_signal, noisy_signal, window_size)
                L_avg = calculate_average_tracking_error(filtered_signal, noisy_signal, window_size)
                R = calculate_false_reversal_penalty(filtered_signal, clean_signal, window_size)

                # Calculate composite score
                composite_score = calculate_composite_score(S, L_recent, L_avg, R)

                # Additional quality metrics
                correlation = 0.0
                noise_reduction = 0.0

                try:
                    # Calculate correlation with clean signal
                    delay = window_size - 1
                    aligned_clean = clean_signal[delay : delay + len(filtered_signal)]
                    min_length = min(len(filtered_signal), len(aligned_clean))

                    if min_length > 1:
                        corr_result = pearsonr(
                            filtered_signal[:min_length], aligned_clean[:min_length]
                        )
                        correlation = corr_result[0] if not np.isnan(corr_result[0]) else 0.0

                    # Calculate noise reduction
                    aligned_noisy = noisy_signal[delay : delay + len(filtered_signal)]
                    aligned_noisy = aligned_noisy[:min_length]
                    aligned_clean = aligned_clean[:min_length]

                    if min_length > 0:
                        noise_before = np.var(aligned_noisy - aligned_clean)
                        noise_after = np.var(filtered_signal[:min_length] - aligned_clean)
                        noise_reduction = (
                            (noise_before - noise_after) / noise_before if noise_before > 0 else 0
                        )
                        noise_reduction = max(0, noise_reduction)  # Ensure non-negative

                except Exception as e:
                    print(f"Signal {i}: Error calculating additional metrics: {e}")

                # Store metrics
                metrics = {
                    "slope_changes": safe_float(S),
                    "lag_error": safe_float(L_recent),
                    "avg_error": safe_float(L_avg),
                    "false_reversals": safe_float(R),
                    "composite_score": safe_float(composite_score),
                    "correlation": safe_float(correlation),
                    "noise_reduction": safe_float(noise_reduction),
                    "execution_time": safe_float(execution_time),
                    "signal_length": len(filtered_signal),
                }

                all_scores.append(composite_score)
                all_metrics.append(metrics)
                successful_runs += 1

            except TimeoutError:
                print(f"Signal {i}: Timeout")
                continue
            except Exception as e:
                print(f"Signal {i}: Error - {str(e)}")
                continue

        # If no successful runs, return minimal scores
        if successful_runs == 0:
            return {
                "composite_score": 0.0,
                "slope_changes": 100.0,
                "lag_error": 1.0,
                "avg_error": 1.0,
                "false_reversals": 50.0,
                "correlation": 0.0,
                "noise_reduction": 0.0,
                "success_rate": 0.0,
                "error": "All test signals failed",
            }

        # Calculate aggregate metrics
        avg_composite_score = np.mean(all_scores)
        avg_slope_changes = np.mean([m["slope_changes"] for m in all_metrics])
        avg_lag_error = np.mean([m["lag_error"] for m in all_metrics])
        avg_avg_error = np.mean([m["avg_error"] for m in all_metrics])
        avg_false_reversals = np.mean([m["false_reversals"] for m in all_metrics])
        avg_correlation = np.mean([m["correlation"] for m in all_metrics])
        avg_noise_reduction = np.mean([m["noise_reduction"] for m in all_metrics])
        avg_execution_time = np.mean([m["execution_time"] for m in all_metrics])
        success_rate = successful_runs / len(test_signals)

        # Calculate additional derived scores
        smoothness_score = 1.0 / (1.0 + avg_slope_changes / 20.0)  # Higher is better
        responsiveness_score = 1.0 / (1.0 + avg_lag_error)  # Higher is better
        accuracy_score = max(0, avg_correlation)  # 0-1, higher is better
        efficiency_score = min(1.0, 1.0 / max(0.001, avg_execution_time))  # Speed bonus

        # Overall score combining multiple factors
        overall_score = (
            0.4 * avg_composite_score  # Primary metric
            + 0.2 * smoothness_score  # Smoothness
            + 0.2 * accuracy_score  # Correlation with clean signal
            + 0.1 * avg_noise_reduction  # Noise reduction capability
            + 0.1 * success_rate  # Reliability
        )

        return {
            "composite_score": safe_float(avg_composite_score),
            "overall_score": safe_float(overall_score),  # Primary selection metric
            "slope_changes": safe_float(avg_slope_changes),
            "lag_error": safe_float(avg_lag_error),
            "avg_error": safe_float(avg_avg_error),
            "false_reversals": safe_float(avg_false_reversals),
            "correlation": safe_float(avg_correlation),
            "noise_reduction": safe_float(avg_noise_reduction),
            "smoothness_score": safe_float(smoothness_score),
            "responsiveness_score": safe_float(responsiveness_score),
            "accuracy_score": safe_float(accuracy_score),
            "efficiency_score": safe_float(efficiency_score),
            "execution_time": safe_float(avg_execution_time),
            "success_rate": safe_float(success_rate),
        }

    except Exception as e:
        print(f"Evaluation failed: {str(e)}")
        print(traceback.format_exc())
        return {"composite_score": 0.0, "overall_score": 0.0, "error": str(e)}


def evaluate_stage1(program_path):
    """
    Stage 1 evaluation: Quick validation that the program runs without errors
    """
    try:
        # Load the program
        spec = importlib.util.spec_from_file_location("program", program_path)
        program = importlib.util.module_from_spec(spec)
        spec.loader.exec_module(program)

        # Check if required function exists
        if not hasattr(program, "run_signal_processing"):
            return {"runs_successfully": 0.0, "error": "Missing run_signal_processing function"}

        # Quick test with small signal
        try:
            result = run_with_timeout(
                program.run_signal_processing,
                kwargs={"signal_length": 100, "noise_level": 0.3, "window_size": 10},
                timeout_seconds=5,
            )

            if isinstance(result, dict) and "filtered_signal" in result:
                filtered_signal = result["filtered_signal"]
                if len(filtered_signal) > 0:
                    # Quick quality check
                    composite_score = 0.5  # Baseline score for working programs

                    # Bonus for reasonable output length
                    expected_length = 100 - 10 + 1  # signal_length - window_size + 1
                    if len(filtered_signal) == expected_length:
                        composite_score += 0.2

                    return {
                        "runs_successfully": 1.0,
                        "composite_score": composite_score,
                        "output_length": len(filtered_signal),
                    }
                else:
                    return {"runs_successfully": 0.5, "error": "Empty filtered signal"}
            else:
                return {"runs_successfully": 0.3, "error": "Invalid result format"}

        except TimeoutError:
            return {"runs_successfully": 0.0, "error": "Timeout in stage 1"}
        except Exception as e:
            return {"runs_successfully": 0.0, "error": f"Stage 1 error: {str(e)}"}

    except Exception as e:
        return {"runs_successfully": 0.0, "error": f"Stage 1 failed: {str(e)}"}


def evaluate_stage2(program_path):
    """
    Stage 2 evaluation: Full evaluation with all test signals
    """
    return evaluate(program_path)