#!/usr/bin/env python3
"""
Generate an animation GIF of a single KdV-Burgers sample time evolution.
"""

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from burgers_dataset import KdvBurgersDataset

def create_kdv_burgers_animation(sample, save_path="sample_animation.gif", fps=10):
    """Create an animation GIF from a KdV-Burgers sample"""
    # Extract data
    spatial_coordinates = sample['spatial_coordinates']
    u_initial = sample['u_initial']
    u_trajectory = sample['u_trajectory']
    time_coordinates = sample['time_coordinates']
    
    # Set up the figure and axis
    fig, ax = plt.subplots(figsize=(10, 6))
    ax.set_xlim(0, spatial_coordinates[-1])
    
    # Determine y-axis limits based on data range
    u_min = np.min(u_trajectory)
    u_max = np.max(u_trajectory)
    u_range = u_max - u_min
    ax.set_ylim(u_min - 0.1 * u_range, u_max + 0.1 * u_range)
    
    ax.set_xlabel('x')
    ax.set_ylabel('u(x,t)')
    ax.grid(True, alpha=0.3)
    
    # Initialize empty line
    line, = ax.plot([], [], 'b-', linewidth=2)
    time_text = ax.text(0.02, 0.95, '', transform=ax.transAxes, 
                       bbox=dict(boxstyle="round", facecolor='white', alpha=0.8))
    
    def animate(frame):
        """Animation function"""
        line.set_data(spatial_coordinates, u_trajectory[frame])
        time_text.set_text(f'Time: {time_coordinates[frame]:.3f}')
        return line, time_text
    
    # Create animation
    anim = animation.FuncAnimation(
        fig, animate, frames=len(time_coordinates),
        interval=1000/fps, blit=True, repeat=True
    )
    
    # Save as GIF
    anim.save(save_path, writer='pillow', fps=fps)
    plt.close()
    
    print(f"Animation saved to {save_path}")

if __name__ == "__main__":
    # Set random seed for reproducibility
    np.random.seed(42)
    
    # Create dataset
    dataset = KdvBurgersDataset()
    
    # Generate a single sample
    sample = next(iter(dataset))
    
    print("Creating animation...")
    print(f"Time steps: {len(sample['time_coordinates'])}")
    print(f"Spatial points: {len(sample['spatial_coordinates'])}")
    
    # Create animation
    create_kdv_burgers_animation(sample)