// -*- c++ -*-

#ifndef LEMON_LIST_GRAPH_H

#define LEMON_LIST_GRAPH_H

#include <lemon/erasable_graph_extender.h>

#include <lemon/clearable_graph_extender.h>

#include <lemon/extendable_graph_extender.h>

#include <lemon/idmappable_graph_extender.h>

#include <lemon/iterable_graph_extender.h>

#include <lemon/alteration_observer_registry.h>

#include <lemon/default_map.h>

namespace lemon {

  class ListGraphBase {

    struct NodeT {

      int first_in,first_out;

      int prev, next;

    };

    struct EdgeT {

      int head, tail;

      int prev_in, prev_out;

      int next_in, next_out;

    };

    std::vector<NodeT> nodes;

    int first_node;

    int first_free_node;

    std::vector<EdgeT> edges;

    int first_free_edge;

  public:

    typedef ListGraphBase Graph;

    class Node {

      friend class Graph;

    protected:

      int id;

      Node(int pid) { id = pid;}

    public:

      Node() {}

      Node (Invalid) { id = -1; }

      bool operator==(const Node& node) const {return id == node.id;}

      bool operator!=(const Node& node) const {return id != node.id;}

      bool operator<(const Node& node) const {return id < node.id;}

    };

    class Edge {

      friend class Graph;

    protected:

      int id;

      Edge(int pid) { id = pid;}

    public:

      Edge() {}

      Edge (Invalid) { id = -1; }

      bool operator==(const Edge& edge) const {return id == edge.id;}

      bool operator!=(const Edge& edge) const {return id != edge.id;}

      bool operator<(const Edge& edge) const {return id < edge.id;}

    };

    ListGraphBase()

      : nodes(), first_node(-1),

	first_free_node(-1), edges(), first_free_edge(-1) {}

    ///it possible to avoid the superfluous memory allocation.

    void reserveEdge(int n) { edges.reserve(n); };

    /// Maximum node ID.

    /// Maximum node ID.

    ///\sa id(Node)

    int maxNodeId() const { return nodes.size()-1; } 

    /// Maximum edge ID.

    /// Maximum edge ID.

    ///\sa id(Edge)

    int maxEdgeId() const { return edges.size()-1; }

    Node tail(Edge e) const { return edges[e.id].tail; }

    Node head(Edge e) const { return edges[e.id].head; }

    void first(Node& node) const { 

      node.id = first_node;

    }

    void next(Node& node) const {

      node.id = nodes[node.id].next;

    }

    void first(Edge& e) const { 

      int n;

      for(n = first_node; 

	  n!=-1 && nodes[n].first_in == -1; 

	  n = nodes[n].next);

      e.id = (n == -1) ? -1 : nodes[n].first_in;

    }

    void next(Edge& edge) const {

      if (edges[edge.id].next_in != -1) {

	edge.id = edges[edge.id].next_in;

      } else {

	int n;

	for(n = nodes[edges[edge.id].head].next;

	  n!=-1 && nodes[n].first_in == -1; 

	  n = nodes[n].next);

	edge.id = (n == -1) ? -1 : nodes[n].first_in;

      }      

    }

    void firstOut(Edge &e, const Node& v) const {

      e.id = nodes[v.id].first_out;

    }

    void nextOut(Edge &e) const {

      e.id=edges[e.id].next_out;

    }

    void firstIn(Edge &e, const Node& v) const {

      e.id = nodes[v.id].first_in;

    }

    void nextIn(Edge &e) const {

      e.id=edges[e.id].next_in;

    }

    static int id(Node v) { return v.id; }

    static int id(Edge e) { return e.id; }

    /// Adds a new node to the graph.

    /// \warning It adds the new node to the front of the list.

    /// (i.e. the lastly added node becomes the first.)

    Node addNode() {     

      int n;

      if(first_free_node==-1) {

	n = nodes.size();

	nodes.push_back(NodeT());

      } else {

	n = first_free_node;

	first_free_node = nodes[n].next;

      }

      nodes[n].next = first_node;

      if(first_node != -1) nodes[first_node].prev = n;

      first_node = n;

      nodes[n].prev = -1;

      nodes[n].first_in = nodes[n].first_out = -1;

      return Node(n);

    }

    Edge addEdge(Node u, Node v) {

      int n;      

      if (first_free_edge == -1) {

	n = edges.size();

	edges.push_back(EdgeT());

      } else {

	n = first_free_edge;

	first_free_edge = edges[n].next_in;

      }

      edges[n].tail = u.id; 

      edges[n].head = v.id;

      edges[n].next_out = nodes[u.id].first_out;

      if(nodes[u.id].first_out != -1) {

	edges[nodes[u.id].first_out].prev_out = n;

      }

      edges[n].next_in = nodes[v.id].first_in;

      if(nodes[v.id].first_in != -1) {

	edges[nodes[v.id].first_in].prev_in = n;

      }

      edges[n].prev_in = edges[n].prev_out = -1;

      nodes[u.id].first_out = nodes[v.id].first_in = n;

      return Edge(n);

    }

    void erase(const Node& node) {

      int n = node.id;

      if(nodes[n].next != -1) {

	nodes[nodes[n].next].prev = nodes[n].prev;

      }

      if(nodes[n].prev != -1) {

	nodes[nodes[n].prev].next = nodes[n].next;

      } else {

	first_node = nodes[n].next;

      }

      nodes[n].next = first_free_node;

      first_free_node = n;

    }

    void erase(const Edge& edge) {

      int n = edge.id;

      if(edges[n].next_in!=-1) {

	edges[edges[n].next_in].prev_in = edges[n].prev_in;

      }

      if(edges[n].prev_in!=-1) {

	edges[edges[n].prev_in].next_in = edges[n].next_in;

      } else {

	nodes[edges[n].head].first_in = edges[n].next_in;

      }

      if(edges[n].next_out!=-1) {

	edges[edges[n].next_out].prev_out = edges[n].prev_out;

      } 

      if(edges[n].prev_out!=-1) {

	edges[edges[n].prev_out].next_out = edges[n].next_out;

      } else {

	nodes[edges[n].tail].first_out = edges[n].next_out;

      }

      edges[n].next_in = first_free_edge;

      first_free_edge = n;      

    }

    void clear() {

      edges.clear();

      nodes.clear();

      first_node = first_free_node = first_free_edge = -1;

    }

  };

  typedef AlterableGraphExtender<ListGraphBase> AlterableListGraphBase;

  typedef IterableGraphExtender<AlterableListGraphBase> IterableListGraphBase;

  typedef IdMappableGraphExtender<IterableListGraphBase> IdMappableListGraphBase;

  typedef DefaultMappableGraphExtender<IdMappableListGraphBase> MappableListGraphBase;

  typedef ExtendableGraphExtender<MappableListGraphBase> ExtendableListGraphBase;

  typedef ClearableGraphExtender<ExtendableListGraphBase> ClearableListGraphBase;

  typedef ErasableGraphExtender<ClearableListGraphBase> ErasableListGraphBase;

  typedef ErasableListGraphBase ListGraph;

}

#endif