import rclpy
from rclpy.node import Node
from sensor_msgs.msg import PointCloud2
import sensor_msgs_py.point_cloud2 as pc2
import numpy as np
import matplotlib.pyplot as plt
import struct
from io import BytesIO

class PointCloudSaver(Node):
    def __init__(self, node_name: str, pointcloud_topic: str, buffer, timeout_ms: int):
        super().__init__(node_name)
        self.subscription = self.create_subscription(
            PointCloud2,
            pointcloud_topic,
            self.callback,
            10
        )
        self.buffer = buffer
        self.points = []
        self.end_time = self.get_clock().now().nanoseconds + (timeout_ms * 1_000_000)
        self.cmap = plt.get_cmap('jet') 

    def callback(self, msg):
        now = self.get_clock().now().nanoseconds
        for p in pc2.read_points(msg, field_names=("x", "y", "z", "intensity"), skip_nans=True):
            self.points.append([p[0], p[1], p[2], p[3]])

        if now > self.end_time:
            if not self.points:
                self.get_logger().warn("No points received!")
                rclpy.shutdown()
                return

            np_points = np.array(self.points, dtype=np.float32)
            intensities = np_points[:, 3]
            norm_int = (intensities - intensities.min()) / (intensities.ptp() + 1e-8)

            # Map normalized intensity to RGB colormap
            colors = self.cmap(norm_int)[:, :3]  # RGB 0-1
            colors = (colors * 255).astype(np.uint8)
            rgb_int = np.left_shift(colors[:,0].astype(np.uint32), 16) | \
                      np.left_shift(colors[:,1].astype(np.uint32), 8)  | \
                      colors[:,2].astype(np.uint32)

            filename = "pointcloud.pcd"
            self.write_pcd_with_intensity_rgb(filename, np_points, rgb_int)
            self.get_logger().info(f"Saved {filename} with intensity (grayscale) and colored RGB")
            rclpy.shutdown()

    def write_pcd_with_intensity_rgb(self, filename, points, rgb_int):
        header = f"""# .PCD v0.7 - Point Cloud Data file format
VERSION 0.7
FIELDS x y z intensity rgb
SIZE 4 4 4 4 4
TYPE F F F F U
COUNT 1 1 1 1 1
WIDTH {points.shape[0]}
HEIGHT 1
VIEWPOINT 0 0 0 1 0 0 0
POINTS {points.shape[0]}
DATA binary
"""
        self.buffer.write(header.encode('ascii'))
        for i in range(points.shape[0]):
            # x, y, z, intensity as float32, rgb as uint32
            f.write(struct.pack('ffffI', points[i,0], points[i,1], points[i,2], points[i,3], rgb_int[i]))

def main():
    rclpy.init()
    with open('/root/velodyne.pcd', "w+") as f:
        node = PointCloudSaver('velodyne_pcd_saver', '/velodyne_points', f, 5000)
    rclpy.spin(node)

if __name__ == "__main__":
    main()