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/** @file  UnrealLoader.cpp

 *  @brief Implementation of the UNREAL (*.3D) importer class

 *

 *  Sources:

 *    http://local.wasp.uwa.edu.au/~pbourke/dataformats/unreal/

 */

#ifndef ASSIMP_BUILD_NO_3D_IMPORTER

#include "AssetLib/Unreal/UnrealLoader.h"

#include "PostProcessing/ConvertToLHProcess.h"

#include <assimp/ParsingUtils.h>

#include <assimp/StreamReader.h>

#include <assimp/fast_atof.h>

#include <assimp/importerdesc.h>

#include <assimp/scene.h>

#include <assimp/DefaultLogger.hpp>

#include <assimp/IOSystem.hpp>

#include <assimp/Importer.hpp>

#include <cstdint>

#include <memory>

namespace Assimp {

namespace Unreal {

// Mesh-specific fags.

enum MeshFlags {

    MF_INVALID = -1,            // Not set

    MF_NORMAL_OS = 0,           // Normal one-sided

    MF_NORMAL_TS = 1,           // Normal two-sided

    MF_NORMAL_TRANS_TS = 2,     // Translucent two-sided

    MF_NORMAL_MASKED_TS = 3,    // Masked two-sided

    MF_NORMAL_MOD_TS = 4,       // Modulation blended two-sided

    MF_WEAPON_PLACEHOLDER = 8   // Placeholder triangle for weapon positioning (invisible)

};

// a single triangle

struct Triangle {

    uint16_t mVertex[3];        // Vertex indices

    char mType;                 // James' Mesh Type

    char mColor;                // Color for flat and Gourand Shaded

    unsigned char mTex[3][2];   // Texture UV coordinates

    unsigned char mTextureNum;  // Source texture offset

    char mFlags;                // Unreal Mesh Flags (unused)

    unsigned int matIndex;      // Material index

};

// temporary representation for a material

struct TempMat {

    TempMat() :

            type(MF_NORMAL_OS), tex(), numFaces(0) {}

    explicit TempMat(const Triangle &in) :

            type((Unreal::MeshFlags)in.mType), tex(in.mTextureNum), numFaces(0) {}

    // type of mesh

    Unreal::MeshFlags type;

    // index of texture

    unsigned int tex;

    // number of faces using us

    unsigned int numFaces;

    // for std::find

    bool operator==(const TempMat &o) {

        return (tex == o.tex && type == o.type);

    }

};

// A single vertex in an unsigned int 32 bit

struct Vertex {

    int32_t X : 11;

    int32_t Y : 11;

    int32_t Z : 10;

};

// UNREAL vertex compression

inline void CompressVertex(const aiVector3D &v, uint32_t &out) {

    union {

        Vertex n;

        int32_t t;

    };

    t = 0;

    n.X = (int32_t)v.x;

    n.Y = (int32_t)v.y;

    n.Z = (int32_t)v.z;

    ::memcpy(&out, &t, sizeof(int32_t));

}

// UNREAL vertex decompression

inline void DecompressVertex(aiVector3D &v, int32_t in) {

    union {

        Vertex n;

        int32_t i;

    };

    i = in;

    v.x = (float)n.X;

    v.y = (float)n.Y;

    v.z = (float)n.Z;

}

} // end namespace Unreal

static constexpr aiImporterDesc desc = {

    "Unreal Mesh Importer",

    "",

    "",

    "",

    aiImporterFlags_SupportTextFlavour,

    0,

    0,

    0,

    0,

    "3d uc"

};

// ------------------------------------------------------------------------------------------------

// Constructor to be privately used by Importer

UnrealImporter::UnrealImporter() :

        mConfigFrameID(0), mConfigHandleFlags(true) {

    // empty

}

// ------------------------------------------------------------------------------------------------

// Returns whether the class can handle the format of the given file.

bool UnrealImporter::CanRead(const std::string &filename, IOSystem * /*pIOHandler*/, bool /*checkSig*/) const {

    return SimpleExtensionCheck(filename, "3d", "uc");

}

// ------------------------------------------------------------------------------------------------

// Build a string of all file extensions supported

const aiImporterDesc *UnrealImporter::GetInfo() const {

    return &desc;

}

// ------------------------------------------------------------------------------------------------

// Setup configuration properties for the loader

void UnrealImporter::SetupProperties(const Importer *pImp) {

    // The

    // AI_CONFIG_IMPORT_UNREAL_KEYFRAME option overrides the

    // AI_CONFIG_IMPORT_GLOBAL_KEYFRAME option.

    mConfigFrameID = pImp->GetPropertyInteger(AI_CONFIG_IMPORT_UNREAL_KEYFRAME, -1);

    if (static_cast<unsigned int>(-1) == mConfigFrameID) {

        mConfigFrameID = pImp->GetPropertyInteger(AI_CONFIG_IMPORT_GLOBAL_KEYFRAME, 0);

    }

    // AI_CONFIG_IMPORT_UNREAL_HANDLE_FLAGS, default is true

    mConfigHandleFlags = (0 != pImp->GetPropertyInteger(AI_CONFIG_IMPORT_UNREAL_HANDLE_FLAGS, 1));

}

// ------------------------------------------------------------------------------------------------

// Imports the given file into the given scene structure.

void UnrealImporter::InternReadFile(const std::string &pFile,

        aiScene *pScene, IOSystem *pIOHandler) {

    // For any of the 3 files being passed get the three correct paths

    // First of all, determine file extension

    std::string::size_type pos = pFile.find_last_of('.');

    std::string extension = GetExtension(pFile);

    std::string d_path, a_path, uc_path;

    if (extension == "3d") {

        // jjjj_d.3d

        // jjjj_a.3d

        pos = pFile.find_last_of('_');

        if (std::string::npos == pos) {

            throw DeadlyImportError("UNREAL: Unexpected naming scheme");

        }

        extension = pFile.substr(0, pos);

    } else {

        extension = pFile.substr(0, pos);

    }

    // build proper paths

    d_path = extension + "_d.3d";

    a_path = extension + "_a.3d";

    uc_path = extension + ".uc";

    ASSIMP_LOG_DEBUG("UNREAL: data file is ", d_path);

    ASSIMP_LOG_DEBUG("UNREAL: aniv file is ", a_path);

    ASSIMP_LOG_DEBUG("UNREAL: uc file is ", uc_path);

    // and open the files ... we can't live without them

    std::unique_ptr<IOStream> p(pIOHandler->Open(d_path));

    if (!p)

        throw DeadlyImportError("UNREAL: Unable to open _d file");

    StreamReaderLE d_reader(pIOHandler->Open(d_path));

    const uint16_t numTris = d_reader.GetI2();

    const uint16_t numVert = d_reader.GetI2();

    d_reader.IncPtr(44);

    if (!numTris || numVert < 3) {

        throw DeadlyImportError("UNREAL: Invalid number of vertices/triangles");

    }

    // maximum texture index

    unsigned int maxTexIdx = 0;

    // collect triangles

    std::vector<Unreal::Triangle> triangles(numTris);

    for (auto &tri : triangles) {

        for (unsigned int i = 0; i < 3; ++i) {

            tri.mVertex[i] = d_reader.GetI2();

            if (tri.mVertex[i] >= numTris) {

                ASSIMP_LOG_WARN("UNREAL: vertex index out of range");

                tri.mVertex[i] = 0;

            }

        }

        tri.mType = d_reader.GetI1();

        // handle mesh flagss?

        if (mConfigHandleFlags) {

            tri.mType = Unreal::MF_NORMAL_OS;

        } else {

            // ignore MOD and MASKED for the moment, treat them as two-sided

            if (tri.mType == Unreal::MF_NORMAL_MOD_TS || tri.mType == Unreal::MF_NORMAL_MASKED_TS)

                tri.mType = Unreal::MF_NORMAL_TS;

        }

        d_reader.IncPtr(1);

        for (unsigned int i = 0; i < 3; ++i) {

            for (unsigned int i2 = 0; i2 < 2; ++i2) {

                tri.mTex[i][i2] = d_reader.GetI1();

            }

        }

        tri.mTextureNum = d_reader.GetI1();

        maxTexIdx = std::max(maxTexIdx, (unsigned int)tri.mTextureNum);

        d_reader.IncPtr(1);

    }

    p.reset(pIOHandler->Open(a_path));

    if (!p) {

        throw DeadlyImportError("UNREAL: Unable to open _a file");

    }

    StreamReaderLE a_reader(pIOHandler->Open(a_path));

    // read number of frames

    const uint32_t numFrames = a_reader.GetI2();

    if (mConfigFrameID >= numFrames) {

        throw DeadlyImportError("UNREAL: The requested frame does not exist");

    }

    // read aniv file length

    if (uint32_t st = a_reader.GetI2(); st != numVert * 4u) {

        throw DeadlyImportError("UNREAL: Unexpected aniv file length");

    }

    // skip to our frame

    a_reader.IncPtr(mConfigFrameID * numVert * 4);

    // collect vertices

    std::vector<aiVector3D> vertices(numVert);

    for (auto &vertex : vertices) {

        int32_t val = a_reader.GetI4();

        Unreal::DecompressVertex(vertex, val);

    }

    // list of textures.

    std::vector<std::pair<unsigned int, std::string>> textures;

    // allocate the output scene

    aiNode *nd = pScene->mRootNode = new aiNode();

    nd->mName.Set("<UnrealRoot>");

    // we can live without the uc file if necessary

    std::unique_ptr<IOStream> pb(pIOHandler->Open(uc_path));

    if (pb) {

        std::vector<char> _data;

        TextFileToBuffer(pb.get(), _data);

        const char *data = &_data[0];

        const char *end = &_data[_data.size() - 1] + 1;

        std::vector<std::pair<std::string, std::string>> tempTextures;

        // do a quick search in the UC file for some known, usually texture-related, tags

        for (; *data; ++data) {

            if (TokenMatchI(data, "#exec", 5)) {

                SkipSpacesAndLineEnd(&data, end);

                // #exec TEXTURE IMPORT [...] NAME=jjjjj [...] FILE=jjjj.pcx [...]

                if (TokenMatchI(data, "TEXTURE", 7)) {

                    SkipSpacesAndLineEnd(&data, end);

                    if (TokenMatchI(data, "IMPORT", 6)) {

                        tempTextures.emplace_back();

                        std::pair<std::string, std::string> &me = tempTextures.back();

                        for (; !IsLineEnd(*data); ++data) {

                            if (!ASSIMP_strincmp(data, "NAME=", 5)) {

                                const char *d = data += 5;

                                for (; !IsSpaceOrNewLine(*data); ++data)

                                    ;

                                me.first = std::string(d, (size_t)(data - d));

                            } else if (!ASSIMP_strincmp(data, "FILE=", 5)) {

                                const char *d = data += 5;

                                for (; !IsSpaceOrNewLine(*data); ++data)

                                    ;

                                me.second = std::string(d, (size_t)(data - d));

                            }

                        }

                        if (!me.first.length() || !me.second.length()) {

                            tempTextures.pop_back();

                        }

                    }

                }

                // #exec MESHMAP SETTEXTURE MESHMAP=box NUM=1 TEXTURE=Jtex1

                // #exec MESHMAP SCALE MESHMAP=box X=0.1 Y=0.1 Z=0.2

                else if (TokenMatchI(data, "MESHMAP", 7)) {

                    SkipSpacesAndLineEnd(&data, end);

                    if (TokenMatchI(data, "SETTEXTURE", 10)) {

                        textures.emplace_back();

                        std::pair<unsigned int, std::string> &me = textures.back();

                        for (; !IsLineEnd(*data); ++data) {

                            if (!ASSIMP_strincmp(data, "NUM=", 4)) {

                                data += 4;

                                me.first = strtoul10(data, &data);

                            } else if (!ASSIMP_strincmp(data, "TEXTURE=", 8)) {

                                data += 8;

                                const char *d = data;

                                for (; !IsSpaceOrNewLine(*data); ++data);

                                me.second = std::string(d, (size_t)(data - d));

                                // try to find matching path names, doesn't care if we don't find them

                                for (std::vector<std::pair<std::string, std::string>>::const_iterator it = tempTextures.begin();

                                        it != tempTextures.end(); ++it) {

                                    if ((*it).first == me.second) {

                                        me.second = (*it).second;

                                        break;

                                    }

                                }

                            }

                        }

                    } else if (TokenMatchI(data, "SCALE", 5)) {

                        for (; !IsLineEnd(*data); ++data) {

                            if (data[0] == 'X' && data[1] == '=') {

                                data = fast_atoreal_move<float>(data + 2, (float &)nd->mTransformation.a1);

                            } else if (data[0] == 'Y' && data[1] == '=') {

                                data = fast_atoreal_move<float>(data + 2, (float &)nd->mTransformation.b2);

                            } else if (data[0] == 'Z' && data[1] == '=') {

                                data = fast_atoreal_move<float>(data + 2, (float &)nd->mTransformation.c3);

                            }

                        }

                    }

                }

            }

        }

    } else {

        ASSIMP_LOG_ERROR("Unable to open .uc file");

    }

    std::vector<Unreal::TempMat> materials;

    materials.reserve(textures.size() * 2 + 5);

    // find out how many output meshes and materials we'll have and build material indices

    for (auto &tri : triangles) {

        Unreal::TempMat mat(tri);

        auto nt = std::find(materials.begin(), materials.end(), mat);

        if (nt == materials.end()) {

            // add material

            tri.matIndex = static_cast<unsigned int>(materials.size());

            mat.numFaces = 1;

            materials.push_back(mat);

            ++pScene->mNumMeshes;

        } else {

            tri.matIndex = static_cast<unsigned int>(nt - materials.begin());

            ++nt->numFaces;

        }

    }

    if (!pScene->mNumMeshes) {

        throw DeadlyImportError("UNREAL: Unable to find valid mesh data");

    }

    // allocate meshes and bind them to the node graph

    pScene->mMeshes = new aiMesh *[pScene->mNumMeshes];

    pScene->mMaterials = new aiMaterial *[pScene->mNumMaterials = pScene->mNumMeshes];

    nd->mNumMeshes = pScene->mNumMeshes;

    nd->mMeshes = new unsigned int[nd->mNumMeshes];

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

        aiMesh *m = pScene->mMeshes[i] = new aiMesh();

        m->mPrimitiveTypes = aiPrimitiveType_TRIANGLE;

        const unsigned int num = materials[i].numFaces;

        m->mFaces = new aiFace[num];

        m->mVertices = new aiVector3D[num * 3];

        m->mTextureCoords[0] = new aiVector3D[num * 3];

        nd->mMeshes[i] = i;

        // create materials, too

        aiMaterial *mat = new aiMaterial();

        pScene->mMaterials[i] = mat;

        // all white by default - texture rulez

        aiColor3D color(1.f, 1.f, 1.f);

        aiString s;

        ::ai_snprintf(s.data, AI_MAXLEN, "mat%u_tx%u_", i, materials[i].tex);

        // set the two-sided flag

        if (materials[i].type == Unreal::MF_NORMAL_TS) {

            const int twosided = 1;

            mat->AddProperty(&twosided, 1, AI_MATKEY_TWOSIDED);

            ::strcat(s.data, "ts_");

        } else

            ::strcat(s.data, "os_");

        // make TRANS faces 90% opaque that RemRedundantMaterials won't catch us

        if (materials[i].type == Unreal::MF_NORMAL_TRANS_TS) {

            const float opac = 0.9f;

            mat->AddProperty(&opac, 1, AI_MATKEY_OPACITY);

            ::strcat(s.data, "tran_");

        } else

            ::strcat(s.data, "opaq_");

        // a special name for the weapon attachment point

        if (materials[i].type == Unreal::MF_WEAPON_PLACEHOLDER) {

            s.length = ::ai_snprintf(s.data, AI_MAXLEN, "$WeaponTag$");

            color = aiColor3D(0.f, 0.f, 0.f);

        }

        // set color and name

        mat->AddProperty(&color, 1, AI_MATKEY_COLOR_DIFFUSE);

        s.length = static_cast<ai_uint32>(::strlen(s.data));

        mat->AddProperty(&s, AI_MATKEY_NAME);

        // set texture, if any

        const unsigned int tex = materials[i].tex;

        for (auto it = textures.begin(); it != textures.end(); ++it) {

            if ((*it).first == tex) {

                s.Set((*it).second);

                mat->AddProperty(&s, AI_MATKEY_TEXTURE_DIFFUSE(0));

                break;

            }

        }

    }

    // fill them.

    for (const Unreal::Triangle &tri : triangles) {

        Unreal::TempMat mat(tri);

        auto nt = std::find(materials.begin(), materials.end(), mat);

        aiMesh *mesh = pScene->mMeshes[nt - materials.begin()];

        aiFace &f = mesh->mFaces[mesh->mNumFaces++];

        f.mIndices = new unsigned int[f.mNumIndices = 3];

        for (unsigned int i = 0; i < 3; ++i, mesh->mNumVertices++) {

            f.mIndices[i] = mesh->mNumVertices;

            mesh->mVertices[mesh->mNumVertices] = vertices[tri.mVertex[i]];

            mesh->mTextureCoords[0][mesh->mNumVertices] = aiVector3D(tri.mTex[i][0] / 255.f, 1.f - tri.mTex[i][1] / 255.f, 0.f);

        }

    }

    // convert to RH

    MakeLeftHandedProcess hero;

    hero.Execute(pScene);

    FlipWindingOrderProcess flipper;

    flipper.Execute(pScene);

}

} // namespace Assimp

#endif // !! ASSIMP_BUILD_NO_3D_IMPORTER