#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;

    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;

      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; } 

      return e;

    }

  public:

    /* default constructor */

    list_graph() : node_id(0), edge_id(0), _first_node(0), _last_node(0) { }

    /* 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 is_valid() { return (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 is_valid() { return (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