import cv2
import numpy as np
import matplotlib.pyplot as plt
import sys

def plot_barcode_segment(image_path: str, pixels: int = 1000, height: int = 400):
    # Load image in grayscale
    img = cv2.imread(image_path, cv2.IMREAD_GRAYSCALE)
    if img is None:
        print("❌ Could not open image")
        sys.exit(1)

    h, w = img.shape
    print(f"Loaded {w}x{h} image")

    # Crop the first N pixels (widthwise)
    cropped = img[:, :min(pixels, w)]

    # Stretch vertically for visualization
    scaled = cv2.resize(cropped, (cropped.shape[1], height), interpolation=cv2.INTER_NEAREST)

    # Display
    plt.figure(figsize=(12, 4))
    plt.imshow(scaled, cmap="gray", aspect="auto")
    plt.title(f"First {pixels} pixels of barcode (height scaled to {height}px)")
    plt.axis("off")
    plt.savefig("barcode_segment.png", bbox_inches="tight", dpi=150)


if __name__ == "__main__":
    if len(sys.argv) < 2:
        print("Usage: python plot_barcode_segment.py <barcode_image>")
        sys.exit(1)

    plot_barcode_segment(sys.argv[1])