/*++

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Abstract:

NMR_ResourcDependencySorter resolves the dependencies between resources by
sorting them topologically.
--*/

#include "Model/Writer/v100/NMR_ResourceDependencySorter.h"

#include <algorithm>

#include "Common/Graph/DirectedGraph.h"
#include "Common/Graph/GraphAlgorithms.h"
#include "Model/Classes/NMR_Model.h"
#include "Model/Classes/NMR_ModelResource.h"

namespace NMR
{

    CResourceDependencySorter::CResourceDependencySorter(CModel* pModel)
        : m_pModel(pModel)
    {
        buildIndexMaps();
    }

    TopologicalSortResult CResourceDependencySorter::sort()
    {
        // gather list of resources that are standalone
        TopologicalSortResult sortedResources;

        for(nfUint32 i = 0; i < m_pModel->getResourceCount(); i++)
        {
            auto pResource = m_pModel->getResource(i);
            if(pResource->getDependencies().empty())
            {
                sortedResources.push_back(
                    pResource->getPackageResourceID());
            }
        }

        auto graph = buildGraph();
        if (common::graph::isCyclic(graph))
        {
            throw CNMRException(NMR_ERROR_INVALIDPARAM, "Cyclic dependency between resources detected");
        }
        auto sortedIndices = common::graph::topologicalSort(
            buildGraph());  // only contains resources that have or are a
                            // dependency

        for (auto index : sortedIndices)
        {
            
            auto modelResourceID = indexToModelResourceID(index);
            if (std::find(sortedResources.begin(), sortedResources.end(), modelResourceID) == sortedResources.end()) {
                sortedResources.push_back(modelResourceID);
            }
        }
        return sortedResources;
    }

    common::graph::DirectedGraph CResourceDependencySorter::buildGraph()
    {
        common::graph::DirectedGraph graph(m_pModel->getResourceCount());

        for(nfUint32 i = 0; i < m_pModel->getResourceCount(); i++)
        {
            auto pResource = m_pModel->getResource(i);
            auto dependencies = pResource->getDependencies();
            for(auto dependency : dependencies)
            {
                auto dependencyIndex = modelResourceIDToIndex(dependency);
                graph.addDependency(i, dependencyIndex);
            }
        }

        return graph;
    }

    void CResourceDependencySorter::buildIndexMaps()
    {
        for(nfUint32 i = 0; i < m_pModel->getResourceCount(); i++)
        {
            auto pResource = m_pModel->getResource(i);
            m_indexToResourceID[i] =
                pResource->getPackageResourceID();
            m_resourceIDToIndex[pResource->getPackageResourceID()] = i;
        }
    }

    PPackageResourceID CResourceDependencySorter::indexToModelResourceID(
        size_t index) const
    {
        return m_indexToResourceID.at(index);
    }

    size_t CResourceDependencySorter::modelResourceIDToIndex(
        PPackageResourceID resourceID) const
    {
        return m_resourceIDToIndex.at(resourceID);
    }

}  // namespace NMR
