#ifndef MARCI_LIST_GRAPH_HH
#define MARCI_LIST_GRAPH_HH

#include <iostream>

namespace marci {

  class list_graph {
    class node_item;
    class edge_item;
  public:
    class node_iterator;
    class each_node_iterator;
    class edge_iterator;
    class each_edge_iterator;
    class out_edge_iterator;
    class in_edge_iterator;
    class sym_edge_iterator;
  private:
    int node_id;
    int edge_id;
    int _node_num;
    int _edge_num;

    node_item* _first_node;
    node_item* _last_node;

    class node_item {
      friend class list_graph;
      friend class node_iterator;
      friend class each_node_iterator;
      friend class edge_iterator;
      friend class each_edge_iterator;
      friend class out_edge_iterator;
      friend class in_edge_iterator;
      friend class sym_edge_iterator;
      friend std::ostream& operator<<(std::ostream& os, const node_iterator& i);
      friend std::ostream& operator<<(std::ostream& os, const edge_iterator& i);
      list_graph* G;
      int id;
      edge_item* _first_out_edge;
      edge_item* _last_out_edge;
      edge_item* _first_in_edge;
      edge_item* _last_in_edge;
      node_item* _next_node;
      node_item* _prev_node;
    public:
      node_item() { }
    };

    class edge_item {
      friend class list_graph;
      friend class node_iterator;
      friend class each_node_iterator;
      friend class edge_iterator;
      friend class each_edge_iterator;
      friend class out_edge_iterator;
      friend class in_edge_iterator;
      friend class sym_edge_iterator;
      friend std::ostream& operator<<(std::ostream& os, const edge_iterator& i);
      list_graph* G;
      int id;
      node_item* _tail;
      node_item* _head;
      edge_item* _next_out;
      edge_item* _prev_out;
      edge_item* _next_in;
      edge_item* _prev_in;
    public:
      edge_item() { }
    };

    node_item* _add_node() { 
      node_item* p=new node_item;
      p->id=node_id++;
      p->_first_out_edge=0;
      p->_last_out_edge=0;
      p->_first_in_edge=0;
      p->_last_in_edge=0;
      p->_prev_node=_last_node;
      p->_next_node=0;
      if (_last_node) _last_node->_next_node=p;
      _last_node=p;
      if (!_first_node) _first_node=p;
      ++_node_num;
      return p;
    }

    edge_item* _add_edge(node_item* _tail, node_item* _head) {
      edge_item* e=new edge_item;
      e->id=edge_id++;
      e->_tail=_tail;
      e->_head=_head;
      
      e->_prev_out=_tail->_last_out_edge;
      if (_tail->_last_out_edge) (_tail->_last_out_edge)->_next_out=e;
      _tail->_last_out_edge=e;
      if (!_tail->_first_out_edge) _tail->_first_out_edge=e; 
       
      e->_prev_in=_head->_last_in_edge;
      if (_head->_last_in_edge) (_head->_last_in_edge)->_next_in=e;
      _head->_last_in_edge=e;
      if (!_head->_first_in_edge) { _head->_first_in_edge=e; } 
      ++_edge_num;
      return e;
    }

  public:

    /* default constructor */

    list_graph() : node_id(0), edge_id(0), _node_num(0), _edge_num(0), _first_node(0), _last_node(0) { }
    
    int node_num() { return _node_num; }
    int edge_num() { return _edge_num; }

    /* functions to construct iterators from the graph, or from each other */

    each_node_iterator first_node() { return each_node_iterator(_first_node); }
    each_edge_iterator first_edge() { 
      node_item* v=_first_node;
      edge_item* edge=v->_first_out_edge;
      while (v && !edge) { v=v->_next_node; if (v) edge=v->_first_out_edge; }
      return each_edge_iterator(v, edge); 
    }
    
    out_edge_iterator first_out_edge(const node_iterator& v) { 
      return out_edge_iterator(v); 
    }
    in_edge_iterator first_in_edge(const node_iterator& v) { 
      return in_edge_iterator(v); 
    }
    sym_edge_iterator first_sym_edge(const node_iterator& v) { 
      return sym_edge_iterator(v); 
    }
    node_iterator tail(const edge_iterator& e) { return e.tail_node(); }
    node_iterator head(const edge_iterator& e) { return e.head_node(); }

    node_iterator a_node(const out_edge_iterator& e) { return e.a_node(); }
    node_iterator a_node(const in_edge_iterator& e) { return e.a_node(); }
    node_iterator a_node(const sym_edge_iterator& e) { return e.a_node(); }

    node_iterator b_node(const out_edge_iterator& e) { return e.b_node(); }
    node_iterator b_node(const in_edge_iterator& e) { return e.b_node(); }
    node_iterator b_node(const sym_edge_iterator& e) { return e.b_node(); }

    //node_iterator invalid_node() { return node_iterator(); }
    //edge_iterator invalid_edge() { return edge_iterator(); }
    //out_edge_iterator invalid_out_edge() { return out_edge_iterator(); }
    //in_edge_iterator invalid_in_edge() { return in_edge_iterator(); }
    //sym_edge_iterator invalid_sym_edge() { return sym_edge_iterator(); }

    /* same methods in other style */
    /* for experimental purpose */

    void get_first(each_node_iterator& v) { v=each_node_iterator(_first_node); }
    void get_first(each_edge_iterator& e) { e=first_edge(); }
    void get_first(out_edge_iterator& e, const node_iterator& v) { 
      e=out_edge_iterator(v); 
    }
    void get_first(in_edge_iterator& e, const node_iterator& v) { 
      e=in_edge_iterator(v); 
    }
    void get_first(sym_edge_iterator& e, const node_iterator& v) { 
      e=sym_edge_iterator(v); 
    }
    void get_tail(node_iterator& n, const edge_iterator& e) { n=tail(e); }
    void get_head(node_iterator& n, const edge_iterator& e) { n=head(e); }

    void get_a_node(node_iterator& n, const out_edge_iterator& e) { n=e.a_node(); }
    void get_a_node(node_iterator& n, const in_edge_iterator& e) { n=e.a_node(); }
    void get_a_node(node_iterator& n, const sym_edge_iterator& e) { n=e.a_node(); }
    void get_b_node(node_iterator& n, const out_edge_iterator& e) { n=e.b_node(); }
    void get_b_node(node_iterator& n, const in_edge_iterator& e) { n=e.b_node(); }
    void get_b_node(node_iterator& n, const sym_edge_iterator& e) { n=e.b_node(); }
    //void get_invalid(node_iterator& n) { n=node_iterator(); }
    //void get_invalid(edge_iterator& e) { e=edge_iterator(); }
    //void get_invalid(out_edge_iterator& e) { e=out_edge_iterator(); }
    //void get_invalid(in_edge_iterator& e) { e=in_edge_iterator(); }
    //void get_invalid(sym_edge_iterator& e) { e=sym_edge_iterator(); }


    /* for getting id's of graph objects */
    /* these are important for the implementation of property vectors */

    int id(const node_iterator& v) { return v.node->id; }
    int id(const edge_iterator& e) { return e.edge->id; }

    /* adding nodes and edges */

    node_iterator add_node() { return node_iterator(_add_node()); }
    edge_iterator add_edge(const node_iterator& u, const node_iterator& v) {
      return edge_iterator(_add_edge(u.node, v.node)); 
    }

    /* stream operations, for testing purpose */

    friend std::ostream& operator<<(std::ostream& os, const node_iterator& i) { 
      os << i.node->id; return os; 
    }
    friend std::ostream& operator<<(std::ostream& os, const edge_iterator& i) { 
      os << "(" << i.edge->_tail->id << "--" << i.edge->id << "->" << i.edge->_head->id << ")"; 
      return os; 
    }

    class node_iterator {
      friend class list_graph;

      friend class edge_iterator;
      friend class out_edge_iterator;
      friend class in_edge_iterator;
      friend class sym_edge_iterator;
    protected:
      node_item* node;
      friend int list_graph::id(const node_iterator& v); 
    public:
      node_iterator() : node(0) { }
      node_iterator(node_item* _node) : node(_node) { }
      bool valid() { return (node!=0); }
      void make_invalid() { node=0; }
      friend bool operator==(const node_iterator& u, const node_iterator& v) { 
	return v.node==u.node; 
      } 
      friend bool operator!=(const node_iterator& u, const node_iterator& v) { 
	return v.node!=u.node; 
      } 
      friend std::ostream& operator<<(std::ostream& os, const node_iterator& i);
    };
    
    class each_node_iterator : public node_iterator {
      friend class list_graph;
    public:
      each_node_iterator() : node_iterator() { }
      each_node_iterator(node_item* v) : node_iterator(v) { }
      each_node_iterator& operator++() { node=node->_next_node; return *this; }
    };

    class edge_iterator {
      friend class list_graph;
      
      friend class node_iterator;
      friend class each_node_iterator;
    protected:
      edge_item* edge;
      friend int list_graph::id(const edge_iterator& e);
    public:
      edge_iterator() : edge(0) { }
      edge_iterator(edge_item* _edge) : edge(_edge) { }
      bool valid() { return (edge!=0); }
      void make_invalid() { edge=0; }
      friend bool operator==(const edge_iterator& u, const edge_iterator& v) { 
	return v.edge==u.edge; 
      } 
      friend bool operator!=(const edge_iterator& u, const edge_iterator& v) { 
	return v.edge!=u.edge; 
      } 
    protected:
      node_iterator tail_node() const { return node_iterator(edge->_tail); }
      node_iterator head_node() const { return node_iterator(edge->_head); }
    public:
      friend std::ostream& operator<<(std::ostream& os, const edge_iterator& i);
    };
    
    class each_edge_iterator : public edge_iterator {
      friend class list_graph;
      node_item* v;
    public:
      each_edge_iterator() : edge_iterator(), v(0) { }
      each_edge_iterator(node_item* _v, edge_item* _e) : edge_iterator(_e), v(_v) { }
      each_edge_iterator& operator++() { 
	edge=edge->_next_out; 
	while (v && !edge) { v=v->_next_node; if (v) edge=v->_first_out_edge; }
	return *this;
      }
    };
    
    class out_edge_iterator : public edge_iterator {
      friend class list_graph;
      node_item* v;
    public:
      out_edge_iterator() : edge_iterator(), v(0) { }
    protected:
      out_edge_iterator(const node_iterator& _v) : v(_v.node) { edge=v->_first_out_edge; }
    public:
      out_edge_iterator& operator++() { edge=edge->_next_out; return *this; }
    protected:
      node_iterator a_node() const { return node_iterator(v); }
      node_iterator b_node() const { 
	return (edge->_tail==v) ? node_iterator(edge->_head) : node_iterator(edge->_tail); }
    };
    
    class in_edge_iterator : public edge_iterator {
      friend class list_graph;
      node_item* v;
    public:
      in_edge_iterator() : edge_iterator(), v(0) { }
    protected:
      in_edge_iterator(const node_iterator& _v) : v(_v.node) { 
	edge=v->_first_in_edge; 
      }
    public:
      in_edge_iterator& operator++() { edge=edge->_next_in; return *this; }
    protected:
      node_iterator a_node() const { return node_iterator(v); }
      node_iterator b_node() const { 
	return (edge->_tail==v) ? node_iterator(edge->_head) : node_iterator(edge->_tail); }
    };

    class sym_edge_iterator : public edge_iterator {
      friend class list_graph;
      bool out_or_in; //1 iff out, 0 iff in
      node_item* v;
    public:
      sym_edge_iterator() : edge_iterator(), v(0) { }
    protected:
      sym_edge_iterator(const node_iterator& _v) : v(_v.node) { 
	out_or_in=1;
	edge=v->_first_out_edge; 
	if (!edge) { edge=v->_first_in_edge; out_or_in=0; }
      }
    public:
      sym_edge_iterator& operator++() { 
	if (out_or_in) { 
	  edge=edge->_next_out; 
	  if (!edge) { out_or_in=0; edge=v->_first_in_edge; }
	} else {
	  edge=edge->_next_in; 
	}
	return *this;
      }
    protected:
      node_iterator a_node() const { return node_iterator(v); }
      node_iterator b_node() const { 
	return (edge->_tail==v) ? node_iterator(edge->_head) : node_iterator(edge->_tail); }
    };

  };



} //namespace marci

#endif //MARCI_LIST_GRAPH_HH