<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">

  <xacro:macro name="diffbot" params="prefix">

    <!-- Constants for robot dimensions -->
    <xacro:property name="PI" value="3.1415926535897931"/>
    <xacro:property name="base_mass" value="0.3" /> <!-- arbitrary value for base mass -->
    <xacro:property name="base_width" value="0.25" /> <!-- Updated wheel spacing to 25cm -->
    <xacro:property name="base_length" value="0.34" />
    <xacro:property name="base_height" value="0.1" />
    <xacro:property name="wheel_mass" value="0.3" /> <!-- arbitrary value for wheel mass -->
    <xacro:property name="wheel_len" value="0.020" />
    <xacro:property name="wheel_radius" value="0.0625" />
    <xacro:property name="caster_wheel_mass" value="0.1" /> <!-- arbitrary value for caster wheel mass -->
    <xacro:property name="caster_wheel_radius" value="0.04" />
    <xacro:property name="z_offset" value="-${base_height/2}" /> <!-- Space btw top of beam and the each joint -->

    <!-- Base Link -->
    <link name="${prefix}base_link">
      <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
          <box size="${base_length} ${base_width} ${base_height}"/> <!-- Updated base dimensions -->
        </geometry>
      </collision>

      <visual>
        <origin xyz="0 0 ${base_height/2}" rpy="0 0 0"/>
        <geometry>
          <box size="${base_length} ${base_width} ${base_height}"/> <!-- Updated base dimensions -->
        </geometry>
        <material name="orange"/>
      </visual>

      <inertial>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <mass value="${base_mass}"/>
        <inertia
          ixx="${base_mass / 12.0 * (base_length*base_length + base_height*base_height)}" ixy="0.0" ixz="0.0"
          iyy="${base_mass / 12.0 * (base_height*base_height + base_width*base_width)}" iyz="0.0"
          izz="${base_mass / 12.0 * (base_width*base_width + base_length*base_length)}"/>
      </inertial>
    </link>

    <joint name="${prefix}left_wheel_joint" type="continuous">
      <parent link="${prefix}base_link"/>
      <child link="${prefix}left_wheel"/>
      <origin xyz="${base_length/2} 0 ${z_offset}" rpy="0 0 0"/> <!-- Updated wheel position -->
      <axis xyz="0 1 0"/>
      <dynamics damping="0.2"/>
    </joint>

    <!-- left wheel Link -->
    <link name="${prefix}left_wheel">
      <collision>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <geometry>
          <cylinder length="${wheel_len}" radius="${wheel_radius}"/>
        </geometry>
      </collision>

      <visual>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <geometry>
          <cylinder length="${wheel_len}" radius="${wheel_radius}"/>
        </geometry>
        <material name="black"/>
      </visual>

      <inertial>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <mass value="${wheel_mass}"/>
        <inertia
          ixx="${wheel_mass / 12.0 * (3*wheel_radius + wheel_len*wheel_len)}" ixy="0.0" ixz="0.0"
          iyy="${wheel_mass / 12.0 * wheel_radius*wheel_radius}" iyz="0.0"
          izz="${wheel_mass / 12.0 * wheel_radius*wheel_radius}"/>
      </inertial>
    </link>

    <joint name="${prefix}right_wheel_joint" type="continuous">
      <parent link="${prefix}base_link"/>
      <child link="${prefix}right_wheel"/>
      <origin xyz="${base_length/2} 0 ${z_offset}" rpy="0 0 0"/> <!-- Updated wheel position -->
      <axis xyz="0 -1 0"/>
      <dynamics damping="0.2"/>
    </joint>

    <!-- right wheel Link -->
    <link name="${prefix}right_wheel">
      <collision>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <geometry>
          <cylinder length="${wheel_len}" radius="${wheel_radius}"/>
        </geometry>
      </collision>

      <visual>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <geometry>
          <cylinder length="${wheel_len}" radius="${wheel_radius}"/>
        </geometry>
        <material name="black"/>
      </visual>

      <inertial>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <mass value="${wheel_mass}"/>
        <inertia
          ixx="${wheel_mass / 12.0 * (3*wheel_radius + wheel_len*wheel_len)}" ixy="0.0" ixz="0.0"
          iyy="${wheel_mass / 12.0 * wheel_radius*wheel_radius}" iyz="0.0"
          izz="${wheel_mass / 12.0 * wheel_radius*wheel_radius}"/>
      </inertial>
    </link>

    <joint name="${prefix}caster_wheel_joint" type="fixed">
      <parent link="${prefix}base_link"/>
      <child link="${prefix}caster_wheel"/>
      <origin xyz="${-base_length/2} 0 ${z_offset}" rpy="0 0 0"/> <!-- Updated caster wheel position -->
    </joint>

    <!-- caster wheel Link -->
    <link name="${prefix}caster_wheel">
      <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
          <sphere radius="${caster_wheel_radius}"/>
        </geometry>
      </collision>

      <visual>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
          <sphere radius="${caster_wheel_radius}"/>
        </geometry>
        <material name="white"/>
      </visual>

      <inertial>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <mass value="${caster_wheel_mass}"/>
        <inertia
              ixx="${2.0/5.0 * caster_wheel_mass * caster_wheel_radius * caster_wheel_radius}"
              ixy="0.0" ixz="0.0"
              iyy="${2.0/5.0 * caster_wheel_mass * caster_wheel_radius * caster_wheel_radius}"
              iyz="0.0"
              izz="${2.0/5.0 * caster_wheel_mass * caster_wheel_radius * caster_wheel_radius}"/>
      </inertial>
      </link>

      <!-- laser_link -->
      <link name="${prefix}laser_link">
        <collision>
          <origin xyz="${base_length/2} 0 ${base_height}" rpy="0 0 0"/>
          <geometry>
            <box size="0.1 0.1 0.1"/>
          </geometry>
        </collision>

        <visual>
          <origin xyz="${base_length/2} 0 ${base_height}" rpy="0 0 0"/>
          <geometry>
            <box size="0.1 0.1 0.1"/>
          </geometry>
          <material name="green"/>
        </visual>

        <inertial>
          <origin xyz="${base_length/2} 0 ${base_height}" rpy="0 0 0"/>
          <mass value="0.1"/>
          <inertia
            ixx="0.001" ixy="0.0" ixz="0.0"
            iyy="0.001" iyz="0.0"
            izz="0.001"/>
        </inertial>
      </link>

      <!-- camera_link -->
      <link name="${prefix}camera_link">
        <collision>
          <origin xyz="${base_length/2} 0 0" rpy="0 0 0"/>
          <geometry>
            <box size="0.1 0.1 0.1"/>
          </geometry>
        </collision>

        <visual>
          <origin xyz="${base_length/2} 0 0" rpy="0 0 0"/>
          <geometry>
            <box size="0.1 0.1 0.1"/>
          </geometry>
          <material name="blue"/>
        </visual>

        <inertial>
          <origin xyz="${base_length/2} 0 0" rpy="0 0 0"/>
          <mass value="0.1"/>
          <inertia
            ixx="0.001" ixy="0.0" ixz="0.0"
            iyy="0.001" iyz="0.0"
            izz="0.001"/>
        </inertial>
      </link>

      <!-- Base Joint -->
      <joint name="${prefix}base_joint" type="fixed">
        <parent link="${prefix}base_link"/>
        <child link="${prefix}laser_link"/>
        <origin xyz="0 0 ${base_height}" rpy="0 0 0"/>
      </joint>

      <!-- Front Joint -->
      <joint name="${prefix}front_joint" type="fixed">
        <parent link="${prefix}laser_link"/>
        <child link="${prefix}camera_link"/>
        <origin xyz="${base_length/2} 0 ${base_height}" rpy="0 0 0"/>
      </joint>

  </xacro:macro>
</robot>



