# /// script
# requires-python = ">=3.10"
# dependencies = ["numpy"]
# ///
"""
@effect contrast
@version 1.0.0
@author artdag

@description
Adjusts contrast by scaling pixel values around the midpoint (128).
Higher values increase contrast, lower values flatten the image.

@param factor float
  @range 0 3
  @default 1.0
  Contrast multiplier. 0.5 = low contrast, 1 = unchanged, 2 = high contrast.

@example
  (effect contrast :factor 1.5)

@example
  ;; Dramatic contrast on energy peaks
  (effect contrast :factor (bind energy :range [1.0 2.0]))
"""

import numpy as np


def process_frame(frame: np.ndarray, params: dict, state: dict) -> tuple:
    """
    Adjust contrast of a video frame.

    Args:
        frame: Input frame as numpy array (H, W, 3) RGB uint8
        params: Effect parameters
            - factor: contrast multiplier (default 1.0)
        state: Persistent state dict (unused)

    Returns:
        Tuple of (processed_frame, new_state)
    """
    factor = params.get("factor", 1.0)

    if factor == 1.0:
        return frame, state

    # Adjust contrast around midpoint (128)
    img_float = frame.astype(np.float32)
    result = 128 + factor * (img_float - 128)

    return np.clip(result, 0, 255).astype(np.uint8), state