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  /* Author: Wim Meeussen */
  
  #ifndef URDF_INTERFACE_MODEL_H
  #define URDF_INTERFACE_MODEL_H
  
  #include <string>
  #include <map>
  #include <boost/function.hpp>
  #include <urdf_model/link.h>
  #include <urdf_model/types.h>
  #include <urdf_exception/exception.h>
  
  namespace urdf {
  
  class ModelInterface
  {
  public:
    LinkConstSharedPtr getRoot(void) const{return this->root_link_;};
    LinkConstSharedPtr getLink(const std::string& name) const
    {
      LinkConstSharedPtr ptr;
      if (this->links_.find(name) == this->links_.end())
        ptr.reset();
      else
        ptr = this->links_.find(name)->second;
      return ptr;
    };
    
    JointConstSharedPtr getJoint(const std::string& name) const
    {
      JointConstSharedPtr ptr;
      if (this->joints_.find(name) == this->joints_.end())
        ptr.reset();
      else
        ptr = this->joints_.find(name)->second;
      return ptr;
    };
    
    
    const std::string& getName() const {return name_;};
    void getLinks(std::vector<LinkSharedPtr >& links) const
    {
      for (std::map<std::string,LinkSharedPtr>::const_iterator link = this->links_.begin();link != this->links_.end(); link++)
      {
        links.push_back(link->second);
      }
    };
    
    void clear()
    {
      name_.clear();
      this->links_.clear();
      this->joints_.clear();
      this->materials_.clear();
      this->root_link_.reset();
    };
    
    /// non-const getLink()
    void getLink(const std::string& name, LinkSharedPtr &link) const
    {
      LinkSharedPtr ptr;
      if (this->links_.find(name) == this->links_.end())
        ptr.reset();
      else
        ptr = this->links_.find(name)->second;
      link = ptr;
    };
    
    /// non-const getMaterial()
    MaterialSharedPtr getMaterial(const std::string& name) const
    {
      MaterialSharedPtr ptr;
      if (this->materials_.find(name) == this->materials_.end())
        ptr.reset();
      else
        ptr = this->materials_.find(name)->second;
      return ptr;
    };
    
    void initTree(std::map<std::string, std::string> &parent_link_tree)
    {
      // loop through all joints, for every link, assign children links and children joints
      for (std::map<std::string, JointSharedPtr>::iterator joint = this->joints_.begin();joint != this->joints_.end(); joint++)
      {
        std::string parent_link_name = joint->second->parent_link_name;
        std::string child_link_name = joint->second->child_link_name;
        
        if (parent_link_name.empty() || child_link_name.empty())
        {
          throw ParseError("Joint [" + joint->second->name + "] is missing a parent and/or child link specification.");
        }
        else
        {
          // find child and parent links
          LinkSharedPtr child_link, parent_link;
          this->getLink(child_link_name, child_link);
          if (!child_link)
          {
            throw ParseError("child link [" + child_link_name + "] of joint [" + joint->first + "] not found");
          }
          this->getLink(parent_link_name, parent_link);
          if (!parent_link)
          {
            throw ParseError("parent link [" + parent_link_name + "] of joint [" + joint->first + "] not found.  This is not valid according to the URDF spec. Every link you refer to from a joint needs to be explicitly defined in the robot description. To fix this problem you can either remove this joint [" + joint->first + "] from your urdf file, or add \"<link name=\"" + parent_link_name + "\" />\" to your urdf file.");
          }
          
          //set parent link for child link
          child_link->setParent(parent_link);
  
          //set parent joint for child link        
          child_link->parent_joint = joint->second;
          
          //set child joint for parent link
          parent_link->child_joints.push_back(joint->second);
  
          //set child link for parent link
          parent_link->child_links.push_back(child_link);
  
          // fill in child/parent string map
          parent_link_tree[child_link->name] = parent_link_name;
        }
      }
    }
    
    void initRoot(const std::map<std::string, std::string> &parent_link_tree)
    { 
      this->root_link_.reset();
      
      // find the links that have no parent in the tree
      for (std::map<std::string, LinkSharedPtr>::const_iterator l=this->links_.begin(); l!=this->links_.end(); l++)
      {
        std::map<std::string, std::string >::const_iterator parent = parent_link_tree.find(l->first);
        if (parent == parent_link_tree.end())
        {
          // store root link
          if (!this->root_link_)
          {
            getLink(l->first, this->root_link_);
          }
          // we already found a root link
          else
          {
            throw ParseError("Two root links found: [" + this->root_link_->name + "] and [" + l->first + "]");
          }
        }
      }
      if (!this->root_link_)
      {
        throw ParseError("No root link found. The robot xml is not a valid tree.");
      }
    }
    
    
    /// \brief complete list of Links
    std::map<std::string, LinkSharedPtr> links_;
    /// \brief complete list of Joints
    std::map<std::string, JointSharedPtr> joints_;
    /// \brief complete list of Materials
    std::map<std::string, MaterialSharedPtr> materials_;
  
    /// \brief The name of the robot model
    std::string name_;
  
    /// \brief The root is always a link (the parent of the tree describing the robot)
    LinkSharedPtr root_link_;
  
  
  
  };
  
  }
  
  #endif
  