/*
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*/

/** @file A helper class that processes texture transformations */


#include <assimp/Importer.hpp>
#include <assimp/postprocess.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/scene.h>

#include "TextureTransform.h"
#include "StringUtils.h"

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
TextureTransformStep::TextureTransformStep() :
    configFlags()
{
    // nothing to do here
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
TextureTransformStep::~TextureTransformStep()
{
    // nothing to do here
}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool TextureTransformStep::IsActive( unsigned int pFlags) const
{
    return  (pFlags & aiProcess_TransformUVCoords) != 0;
}

// ------------------------------------------------------------------------------------------------
// Setup properties
void TextureTransformStep::SetupProperties(const Importer* pImp)
{
    configFlags = pImp->GetPropertyInteger(AI_CONFIG_PP_TUV_EVALUATE,AI_UVTRAFO_ALL);
}

// ------------------------------------------------------------------------------------------------
void TextureTransformStep::PreProcessUVTransform(STransformVecInfo& info)
{
    /*  This function tries to simplify the input UV transformation.
     *  That's very important as it allows us to reduce the number
     *  of output UV channels. The oder in which the transformations
     *  are applied is - as always - scaling, rotation, translation.
     */

    char szTemp[512];
    int rounded = 0;


    /* Optimize the rotation angle. That's slightly difficult as
     * we have an inprecise floating-point number (when comparing
     * UV transformations we'll take that into account by using
     * an epsilon of 5 degrees). If there is a rotation value, we can't
     * perform any further optimizations.
     */
    if (info.mRotation)
    {
        float out = info.mRotation;
        if ((rounded = (int)(info.mRotation / (float)AI_MATH_TWO_PI)))
        {
            out -= rounded*(float)AI_MATH_PI;

            ai_snprintf(szTemp, 512, "Texture coordinate rotation %f can be simplified to %f",info.mRotation,out);
            DefaultLogger::get()->info(szTemp);
        }

        // Next step - convert negative rotation angles to positives
        if (out < 0.f)
            out = (float)AI_MATH_TWO_PI * 2 + out;

        info.mRotation = out;
        return;
    }


    /* Optimize UV translation in the U direction. To determine whether
     * or not we can optimize we need to look at the requested mapping
     * type (e.g. if mirroring is active there IS a difference between
     * offset 2 and 3)
     */
    if ((rounded  = (int)info.mTranslation.x))  {
        float out = 0.0f;
        szTemp[0] = 0;
        if (aiTextureMapMode_Wrap == info.mapU) {
            // Wrap - simple take the fraction of the field
            out = info.mTranslation.x-(float)rounded;
			ai_snprintf(szTemp, 512, "[w] UV U offset %f can be simplified to %f", info.mTranslation.x, out);
        }
        else if (aiTextureMapMode_Mirror == info.mapU && 1 != rounded)  {
            // Mirror
            if (rounded % 2)
                rounded--;
            out = info.mTranslation.x-(float)rounded;

            ai_snprintf(szTemp,512,"[m/d] UV U offset %f can be simplified to %f",info.mTranslation.x,out);
        }
        else if (aiTextureMapMode_Clamp == info.mapU || aiTextureMapMode_Decal == info.mapU)    {
            // Clamp - translations beyond 1,1 are senseless
            ai_snprintf(szTemp,512,"[c] UV U offset %f can be clamped to 1.0f",info.mTranslation.x);

            out = 1.f;
        }
        if (szTemp[0])      {
            DefaultLogger::get()->info(szTemp);
            info.mTranslation.x = out;
        }
    }

    /* Optimize UV translation in the V direction. To determine whether
     * or not we can optimize we need to look at the requested mapping
     * type (e.g. if mirroring is active there IS a difference between
     * offset 2 and 3)
     */
    if ((rounded  = (int)info.mTranslation.y))  {
        float out = 0.0f;
        szTemp[0] = 0;
        if (aiTextureMapMode_Wrap == info.mapV) {
            // Wrap - simple take the fraction of the field
            out = info.mTranslation.y-(float)rounded;
            ::ai_snprintf(szTemp,512,"[w] UV V offset %f can be simplified to %f",info.mTranslation.y,out);
        }
        else if (aiTextureMapMode_Mirror == info.mapV  && 1 != rounded) {
            // Mirror
            if (rounded % 2)
                rounded--;
            out = info.mTranslation.x-(float)rounded;

            ::ai_snprintf(szTemp,512,"[m/d] UV V offset %f can be simplified to %f",info.mTranslation.y,out);
        }
        else if (aiTextureMapMode_Clamp == info.mapV || aiTextureMapMode_Decal == info.mapV)    {
            // Clamp - translations beyond 1,1 are senseless
            ::ai_snprintf(szTemp,512,"[c] UV V offset %f canbe clamped to 1.0f",info.mTranslation.y);

            out = 1.f;
        }
        if (szTemp[0])  {
            DefaultLogger::get()->info(szTemp);
            info.mTranslation.y = out;
        }
    }
    return;
}

// ------------------------------------------------------------------------------------------------
void UpdateUVIndex(const std::list<TTUpdateInfo>& l, unsigned int n)
{
    // Don't set if == 0 && wasn't set before
    for (std::list<TTUpdateInfo>::const_iterator it = l.begin();it != l.end(); ++it) {
        const TTUpdateInfo& info = *it;

        if (info.directShortcut)
            *info.directShortcut = n;
        else if (!n)
        {
            info.mat->AddProperty<int>((int*)&n,1,AI_MATKEY_UVWSRC(info.semantic,info.index));
        }
    }
}

// ------------------------------------------------------------------------------------------------
inline const char* MappingModeToChar(aiTextureMapMode map)
{
    if (aiTextureMapMode_Wrap == map)
        return "-w";

    if (aiTextureMapMode_Mirror == map)
        return "-m";

    return "-c";
}

// ------------------------------------------------------------------------------------------------
void TextureTransformStep::Execute( aiScene* pScene)
{
    DefaultLogger::get()->debug("TransformUVCoordsProcess begin");


    /*  We build a per-mesh list of texture transformations we'll need
     *  to apply. To achieve this, we iterate through all materials,
     *  find all textures and get their transformations and UV indices.
     *  Then we search for all meshes using this material.
     */
    typedef std::list<STransformVecInfo> MeshTrafoList;
    std::vector<MeshTrafoList> meshLists(pScene->mNumMeshes);

    for (unsigned int i = 0; i < pScene->mNumMaterials;++i) {

        aiMaterial* mat = pScene->mMaterials[i];
        for (unsigned int a = 0; a < mat->mNumProperties;++a)   {

            aiMaterialProperty* prop = mat->mProperties[a];
            if (!::strcmp( prop->mKey.data, "$tex.file"))   {
                STransformVecInfo info;

                // Setup a shortcut structure to allow for a fast updating
                // of the UV index later
                TTUpdateInfo update;
                update.mat = (aiMaterial*) mat;
                update.semantic = prop->mSemantic;
                update.index = prop->mIndex;

                // Get textured properties and transform
                for (unsigned int a2 = 0; a2 < mat->mNumProperties;++a2)  {
                    aiMaterialProperty* prop2 = mat->mProperties[a2];
                    if (prop2->mSemantic != prop->mSemantic || prop2->mIndex != prop->mIndex) {
                        continue;
                    }

                    if ( !::strcmp( prop2->mKey.data, "$tex.uvwsrc")) {
                        info.uvIndex = *((int*)prop2->mData);

                        // Store a direct pointer for later use
                        update.directShortcut = (unsigned int*) prop2->mData;
                    }

                    else if ( !::strcmp( prop2->mKey.data, "$tex.mapmodeu")) {
                        info.mapU = *((aiTextureMapMode*)prop2->mData);
                    }
                    else if ( !::strcmp( prop2->mKey.data, "$tex.mapmodev")) {
                        info.mapV = *((aiTextureMapMode*)prop2->mData);
                    }
                    else if ( !::strcmp( prop2->mKey.data, "$tex.uvtrafo"))  {
                        // ValidateDS should check this
                        ai_assert(prop2->mDataLength >= 20);
                        ::memcpy(&info.mTranslation.x,prop2->mData,sizeof(float)*5);

                        // Directly remove this property from the list
                        mat->mNumProperties--;
                        for (unsigned int a3 = a2; a3 < mat->mNumProperties;++a3) {
                            mat->mProperties[a3] = mat->mProperties[a3+1];
                        }

                        delete prop2;

                        // Warn: could be an underflow, but this does not invoke undefined behaviour
                        --a2;
                    }
                }

                // Find out which transformations are to be evaluated
                if (!(configFlags & AI_UVTRAFO_ROTATION)) {
                    info.mRotation = 0.f;
                }
                if (!(configFlags & AI_UVTRAFO_SCALING)) {
                    info.mScaling = aiVector2D(1.f,1.f);
                }
                if (!(configFlags & AI_UVTRAFO_TRANSLATION)) {
                    info.mTranslation = aiVector2D(0.f,0.f);
                }

                // Do some preprocessing
                PreProcessUVTransform(info);
                info.uvIndex = std::min(info.uvIndex,AI_MAX_NUMBER_OF_TEXTURECOORDS -1u);

                // Find out whether this material is used by more than
                // one mesh. This will make our task much, much more difficult!
                unsigned int cnt = 0;
                for (unsigned int n = 0; n < pScene->mNumMeshes;++n)    {
                    if (pScene->mMeshes[n]->mMaterialIndex == i)
                        ++cnt;
                }

                if (!cnt)
                    continue;
                else if (1 != cnt)  {
                    // This material is referenced by more than one mesh!
                    // So we need to make sure the UV index for the texture
                    // is identical for each of it ...
                    info.lockedPos = AI_TT_UV_IDX_LOCK_TBD;
                }

                // Get all corresponding meshes
                for (unsigned int n = 0; n < pScene->mNumMeshes;++n)    {
                    aiMesh* mesh = pScene->mMeshes[n];
                    if (mesh->mMaterialIndex != i || !mesh->mTextureCoords[0])
                        continue;

                    unsigned int uv = info.uvIndex;
                    if (!mesh->mTextureCoords[uv])  {
                        // If the requested UV index is not available, take the first one instead.
                        uv = 0;
                    }

                    if (mesh->mNumUVComponents[info.uvIndex] >= 3){
                        DefaultLogger::get()->warn("UV transformations on 3D mapping channels are not supported");
                        continue;
                    }

                    MeshTrafoList::iterator it;

                    // Check whether we have this transform setup already
                    for (it = meshLists[n].begin();it != meshLists[n].end(); ++it)  {

                        if ((*it) == info && (*it).uvIndex == uv)   {
                            (*it).updateList.push_back(update);
                            break;
                        }
                    }

                    if (it == meshLists[n].end())   {
                        meshLists[n].push_back(info);
                        meshLists[n].back().uvIndex = uv;
                        meshLists[n].back().updateList.push_back(update);
                    }
                }
            }
        }
    }

    char buffer[1024]; // should be sufficiently large
    unsigned int outChannels = 0, inChannels = 0, transformedChannels = 0;

    // Now process all meshes. Important: we don't remove unreferenced UV channels.
    // This is a job for the RemoveUnreferencedData-Step.
    for (unsigned int q = 0; q < pScene->mNumMeshes;++q)    {

        aiMesh* mesh = pScene->mMeshes[q];
        MeshTrafoList& trafo =  meshLists[q];

        inChannels += mesh->GetNumUVChannels();

        if (!mesh->mTextureCoords[0] || trafo.empty() ||  (trafo.size() == 1 && trafo.begin()->IsUntransformed())) {
            outChannels += mesh->GetNumUVChannels();
            continue;
        }

        // Move untransformed UV channels to the first position in the list ....
        // except if we need a new locked index which should be as small as possible
        bool veto = false, need = false;
        unsigned int cnt = 0;
        unsigned int untransformed = 0;

        MeshTrafoList::iterator it,it2;
        for (it = trafo.begin();it != trafo.end(); ++it,++cnt)  {

            if (!(*it).IsUntransformed()) {
                need = true;
            }

            if ((*it).lockedPos == AI_TT_UV_IDX_LOCK_TBD)   {
                // Lock this index and make sure it won't be changed
                (*it).lockedPos = cnt;
                veto = true;
                continue;
            }

            if (!veto && it != trafo.begin() && (*it).IsUntransformed())    {
                for (it2 = trafo.begin();it2 != it; ++it2) {
                    if (!(*it2).IsUntransformed())
                        break;
                }
                trafo.insert(it2,*it);
                trafo.erase(it);
                break;
            }
        }
        if (!need)
            continue;

        // Find all that are not at their 'locked' position and move them to it.
        // Conflicts are possible but quite unlikely.
        cnt = 0;
        for (it = trafo.begin();it != trafo.end(); ++it,++cnt) {
            if ((*it).lockedPos != AI_TT_UV_IDX_LOCK_NONE && (*it).lockedPos != cnt) {
                it2 = trafo.begin();unsigned int t = 0;
                while (t != (*it).lockedPos)
                    ++it2;

                if ((*it2).lockedPos != AI_TT_UV_IDX_LOCK_NONE) {
                    DefaultLogger::get()->error("Channel mismatch, can't compute all transformations properly [design bug]");
                    continue;
                }

                std::swap(*it2,*it);
                if ((*it).lockedPos == untransformed)
                    untransformed = cnt;
            }
        }

        // ... and add dummies for all unreferenced channels
        // at the end of the list
        bool ref[AI_MAX_NUMBER_OF_TEXTURECOORDS];
        for (unsigned int n = 0; n < AI_MAX_NUMBER_OF_TEXTURECOORDS;++n)
            ref[n] = (!mesh->mTextureCoords[n] ? true : false);

        for (it = trafo.begin();it != trafo.end(); ++it)
            ref[(*it).uvIndex] = true;

        for (unsigned int n = 0; n < AI_MAX_NUMBER_OF_TEXTURECOORDS;++n) {
            if (ref[n])
                continue;
            trafo.push_back(STransformVecInfo());
            trafo.back().uvIndex = n;
        }

        // Then check whether this list breaks the channel limit.
        // The unimportant ones are at the end of the list, so
        // it shouldn't be too worse if we remove them.
        unsigned int size = (unsigned int)trafo.size();
        if (size > AI_MAX_NUMBER_OF_TEXTURECOORDS) {

            if (!DefaultLogger::isNullLogger()) {
                ::ai_snprintf(buffer,1024,"%u UV channels required but just %u available",
                    static_cast<unsigned int>(trafo.size()),AI_MAX_NUMBER_OF_TEXTURECOORDS);

                DefaultLogger::get()->error(buffer);
            }
            size = AI_MAX_NUMBER_OF_TEXTURECOORDS;
        }


        aiVector3D* old[AI_MAX_NUMBER_OF_TEXTURECOORDS];
        for (unsigned int n = 0; n < AI_MAX_NUMBER_OF_TEXTURECOORDS;++n)
            old[n] = mesh->mTextureCoords[n];

        // Now continue and generate the output channels. Channels
        // that we're not going to need later can be overridden.
        it = trafo.begin();
        for (unsigned int n = 0; n < trafo.size();++n,++it) {

            if (n >= size)  {
                // Try to use an untransformed channel for all channels we threw over board
                UpdateUVIndex((*it).updateList,untransformed);
                continue;
            }

            outChannels++;

            // Write to the log
            if (!DefaultLogger::isNullLogger()) {
                ::ai_snprintf(buffer,1024,"Mesh %u, channel %u: t(%.3f,%.3f), s(%.3f,%.3f), r(%.3f), %s%s",
                    q,n,
                    (*it).mTranslation.x,
                    (*it).mTranslation.y,
                    (*it).mScaling.x,
                    (*it).mScaling.y,
                    AI_RAD_TO_DEG( (*it).mRotation),
                    MappingModeToChar ((*it).mapU),
                    MappingModeToChar ((*it).mapV));

                DefaultLogger::get()->info(buffer);
            }

            // Check whether we need a new buffer here
            if (mesh->mTextureCoords[n])    {

                it2 = it;++it2;
                for (unsigned int m = n+1; m < size;++m, ++it2) {

                    if ((*it2).uvIndex == n){
                        it2 = trafo.begin();
                        break;
                    }
                }
                if (it2 == trafo.begin()){
                    mesh->mTextureCoords[n] = new aiVector3D[mesh->mNumVertices];
                }
            }
            else mesh->mTextureCoords[n] = new aiVector3D[mesh->mNumVertices];

            aiVector3D* src = old[(*it).uvIndex];
            aiVector3D* dest, *end;
            dest = mesh->mTextureCoords[n];

            ai_assert(NULL != src);

            // Copy the data to the destination array
            if (dest != src)
                ::memcpy(dest,src,sizeof(aiVector3D)*mesh->mNumVertices);

            end = dest + mesh->mNumVertices;

            // Build a transformation matrix and transform all UV coords with it
            if (!(*it).IsUntransformed()) {
                const aiVector2D& trl = (*it).mTranslation;
                const aiVector2D& scl = (*it).mScaling;

                // fixme: simplify ..
                ++transformedChannels;
                aiMatrix3x3 matrix;

                aiMatrix3x3 m2,m3,m4,m5;

                m4.a1 = scl.x;
                m4.b2 = scl.y;

                m2.a3 = m2.b3 = 0.5f;
                m3.a3 = m3.b3 = -0.5f;

                if ((*it).mRotation > AI_TT_ROTATION_EPSILON )
                    aiMatrix3x3::RotationZ((*it).mRotation,matrix);

                m5.a3 += trl.x; m5.b3 += trl.y;
                matrix = m2 * m4 * matrix * m3 * m5;

                for (src = dest; src != end; ++src) { /* manual homogenious divide */
                    src->z = 1.f;
                    *src = matrix * *src;
                    src->x /= src->z;
                    src->y /= src->z;
                    src->z = 0.f;
                }
            }

            // Update all UV indices
            UpdateUVIndex((*it).updateList,n);
        }
    }

    // Print some detailed statistics into the log
    if (!DefaultLogger::isNullLogger()) {

        if (transformedChannels)    {
            ::ai_snprintf(buffer,1024,"TransformUVCoordsProcess end: %u output channels (in: %u, modified: %u)",
                outChannels,inChannels,transformedChannels);

            DefaultLogger::get()->info(buffer);
        }
        else DefaultLogger::get()->debug("TransformUVCoordsProcess finished");
    }
}