/*

Copyright (c) 2013, Project OSRM, Dennis Luxen, others
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list
of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this
list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

#ifndef DYNAMICGRAPH_H_INCLUDED
#define DYNAMICGRAPH_H_INCLUDED

#include "../DataStructures/DeallocatingVector.h"

#include <boost/assert.hpp>
#include <boost/integer.hpp>

#include <algorithm>
#include <limits>
#include <vector>

template< typename EdgeDataT>
class DynamicGraph {
    public:
        typedef EdgeDataT EdgeData;
        typedef uint32_t NodeIterator;
        typedef uint32_t EdgeIterator;

        class InputEdge {
            public:
                NodeIterator source;
                NodeIterator target;
                EdgeDataT data;
                bool operator<( const InputEdge& right ) const {
                    if ( source != right.source )
                        return source < right.source;
                    return target < right.target;
                }
        };

        //Constructs an empty graph with a given number of nodes.
        DynamicGraph( int32_t nodes ) : m_numNodes(nodes), m_numEdges(0) {
            m_nodes.reserve( m_numNodes );
            m_nodes.resize( m_numNodes );

            m_edges.reserve( m_numNodes * 1.1 );
            m_edges.resize( m_numNodes );
        }

        template<class ContainerT>
        DynamicGraph( const int32_t nodes, const ContainerT &graph ) {
            m_numNodes = nodes;
            m_numEdges = ( EdgeIterator ) graph.size();
            m_nodes.reserve( m_numNodes +1);
            m_nodes.resize( m_numNodes +1);
            EdgeIterator edge = 0;
            EdgeIterator position = 0;
            for ( NodeIterator node = 0; node < m_numNodes; ++node ) {
                EdgeIterator lastEdge = edge;
                while ( edge < m_numEdges && graph[edge].source == node ) {
                    ++edge;
                }
                m_nodes[node].firstEdge = position;
                m_nodes[node].edges = edge - lastEdge;
                position += m_nodes[node].edges;
            }
            m_nodes.back().firstEdge = position;
            m_edges.reserve( position * 1.1 );
            m_edges.resize( position );
            edge = 0;
            for ( NodeIterator node = 0; node < m_numNodes; ++node ) {
                for ( EdgeIterator i = m_nodes[node].firstEdge, e = m_nodes[node].firstEdge + m_nodes[node].edges; i != e; ++i ) {
                    m_edges[i].target = graph[edge].target;
                    m_edges[i].data = graph[edge].data;
                    BOOST_ASSERT_MSG(
                        graph[edge].data.distance > 0,
                        "edge distance invalid"
                    );
                    ++edge;
                }
            }
        }

        ~DynamicGraph(){ }

        uint32_t GetNumberOfNodes() const {
            return m_numNodes;
        }

        uint32_t GetNumberOfEdges() const {
            return m_numEdges;
        }

        uint32_t GetOutDegree( const NodeIterator n ) const {
            return m_nodes[n].edges;
        }

        NodeIterator GetTarget( const EdgeIterator e ) const {
            return NodeIterator( m_edges[e].target );
        }

        EdgeDataT &GetEdgeData( const EdgeIterator e ) {
            return m_edges[e].data;
        }

        const EdgeDataT &GetEdgeData( const EdgeIterator e ) const {
            return m_edges[e].data;
        }

        EdgeIterator BeginEdges( const NodeIterator n ) const {
            return EdgeIterator( m_nodes[n].firstEdge );
        }

        EdgeIterator EndEdges( const NodeIterator n ) const {
            return EdgeIterator( m_nodes[n].firstEdge + m_nodes[n].edges );
        }

        //adds an edge. Invalidates edge iterators for the source node
        EdgeIterator InsertEdge( const NodeIterator from, const NodeIterator to, const EdgeDataT &data ) {
            Node &node = m_nodes[from];
            EdgeIterator newFirstEdge = node.edges + node.firstEdge;
            if ( newFirstEdge >= m_edges.size() || !isDummy( newFirstEdge ) ) {
                if ( node.firstEdge != 0 && isDummy( node.firstEdge - 1 ) ) {
                    node.firstEdge--;
                    m_edges[node.firstEdge] = m_edges[node.firstEdge + node.edges];
                } else {
                    EdgeIterator newFirstEdge = ( EdgeIterator ) m_edges.size();
                    uint32_t newSize = node.edges * 1.1 + 2;
                    EdgeIterator requiredCapacity = newSize + m_edges.size();
                    EdgeIterator oldCapacity = m_edges.capacity();
                    if ( requiredCapacity >= oldCapacity ) {
                        m_edges.reserve( requiredCapacity * 1.1 );
                    }
                    m_edges.resize( m_edges.size() + newSize );
                    for ( EdgeIterator i = 0; i < node.edges; ++i ) {
                        m_edges[newFirstEdge + i ] = m_edges[node.firstEdge + i];
                        makeDummy( node.firstEdge + i );
                    }
                    for ( EdgeIterator i = node.edges + 1; i < newSize; ++i )
                        makeDummy( newFirstEdge + i );
                    node.firstEdge = newFirstEdge;
                }
            }
            Edge &edge = m_edges[node.firstEdge + node.edges];
            edge.target = to;
            edge.data = data;
            ++m_numEdges;
            ++node.edges;
            return EdgeIterator( node.firstEdge + node.edges );
        }

        //removes an edge. Invalidates edge iterators for the source node
        void DeleteEdge( const NodeIterator source, const EdgeIterator e ) {
            Node &node = m_nodes[source];
            --m_numEdges;
            --node.edges;
            const uint32_t last = node.firstEdge + node.edges;
            //swap with last edge
            m_edges[e] = m_edges[last];
            makeDummy( last );
        }

        //removes all edges (source,target)
        int32_t DeleteEdgesTo( const NodeIterator source, const NodeIterator target ) {
            int32_t deleted = 0;
            for ( EdgeIterator i = BeginEdges( source ), iend = EndEdges( source ); i < iend - deleted; ++i ) {
                if ( m_edges[i].target == target ) {
                    do {
                        deleted++;
                        m_edges[i] = m_edges[iend - deleted];
                        makeDummy( iend - deleted );
                    } while ( i < iend - deleted && m_edges[i].target == target );
                }
            }

            #pragma omp atomic
            m_numEdges -= deleted;
            m_nodes[source].edges -= deleted;

            return deleted;
        }

        //searches for a specific edge
        EdgeIterator FindEdge( const NodeIterator from, const NodeIterator to ) const {
            for ( EdgeIterator i = BeginEdges( from ), iend = EndEdges( from ); i != iend; ++i ) {
                if ( to == m_edges[i].target ) {
                    return i;
                }
            }
            return EndEdges( from );
        }

    protected:

        bool isDummy( const EdgeIterator edge ) const {
            return m_edges[edge].target == (std::numeric_limits< NodeIterator >::max)();
        }

        void makeDummy( const EdgeIterator edge ) {
            m_edges[edge].target = (std::numeric_limits< NodeIterator >::max)();
        }

        struct Node {
            //index of the first edge
            EdgeIterator firstEdge;
            //amount of edges
            uint32_t edges;
        };

        struct Edge {
            NodeIterator target;
            EdgeDataT data;
        };

        NodeIterator m_numNodes;
        EdgeIterator m_numEdges;

        std::vector< Node > m_nodes;
        DeallocatingVector< Edge > m_edges;
};

#endif // DYNAMICGRAPH_H_INCLUDED