/*
---------------------------------------------------------------------------
Open Asset Import Library (assimp)
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  following disclaimer.

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*/

/** @file  B3DImporter.cpp
 *  @brief Implementation of the b3d importer class
 */

#ifndef ASSIMP_BUILD_NO_B3D_IMPORTER

// internal headers
#include "B3DImporter.h"
#include "PostProcessing/ConvertToLHProcess.h"
#include "PostProcessing/TextureTransform.h"

#include <assimp/StringUtils.h>
#include <assimp/anim.h>
#include <assimp/importerdesc.h>
#include <assimp/scene.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/IOSystem.hpp>

#include <memory>

namespace Assimp {
using namespace std;

static constexpr aiImporterDesc desc = {
    "BlitzBasic 3D Importer",
    "",
    "",
    "http://www.blitzbasic.com/",
    aiImporterFlags_SupportBinaryFlavour,
    0,
    0,
    0,
    0,
    "b3d"
};

#ifdef _MSC_VER
#pragma warning(disable : 4018)
#endif

// #define DEBUG_B3D

template <typename T>
void DeleteAllBarePointers(std::vector<T> &x) {
    for (auto p : x) {
        delete p;
    }
}

B3DImporter::~B3DImporter() = default;

// ------------------------------------------------------------------------------------------------
bool B3DImporter::CanRead(const std::string &pFile, IOSystem * /*pIOHandler*/, bool /*checkSig*/) const {
    size_t pos = pFile.find_last_of('.');
    if (pos == string::npos) {
        return false;
    }

    string ext = pFile.substr(pos + 1);
    if (ext.size() != 3) {
        return false;
    }

    return (ext[0] == 'b' || ext[0] == 'B') && (ext[1] == '3') && (ext[2] == 'd' || ext[2] == 'D');
}

// ------------------------------------------------------------------------------------------------
// Loader meta information
const aiImporterDesc *B3DImporter::GetInfo() const {
    return &desc;
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {
    std::unique_ptr<IOStream> file(pIOHandler->Open(pFile));

    // Check whether we can read from the file
    if (file == nullptr) {
        throw DeadlyImportError("Failed to open B3D file ", pFile, ".");
    }

    // check whether the .b3d file is large enough to contain
    // at least one chunk.
    size_t fileSize = file->FileSize();
    if (fileSize < 8) {
        throw DeadlyImportError("B3D File is too small.");
    }

    _pos = 0;
    _buf.resize(fileSize);
    file->Read(&_buf[0], 1, fileSize);
    _stack.clear();

    ReadBB3D(pScene);
}

// ------------------------------------------------------------------------------------------------
AI_WONT_RETURN void B3DImporter::Oops() {
    throw DeadlyImportError("B3D Importer - INTERNAL ERROR");
}

// ------------------------------------------------------------------------------------------------
AI_WONT_RETURN void B3DImporter::Fail(const string &str) {
#ifdef DEBUG_B3D
    ASSIMP_LOG_ERROR("Error in B3D file data: ", str);
#endif
    throw DeadlyImportError("B3D Importer - error in B3D file data: ", str);
}

// ------------------------------------------------------------------------------------------------
int B3DImporter::ReadByte() {
    if (_pos >= _buf.size()) {
        Fail("EOF");
    }

    return _buf[_pos++];
}

// ------------------------------------------------------------------------------------------------
int B3DImporter::ReadInt() {
    if (_pos + 4 > _buf.size()) {
        Fail("EOF");
    }

    int n;
    memcpy(&n, &_buf[_pos], 4);
    _pos += 4;

    return n;
}

// ------------------------------------------------------------------------------------------------
float B3DImporter::ReadFloat() {
    if (_pos + 4 > _buf.size()) {
        Fail("EOF");
    }

    float n;
    memcpy(&n, &_buf[_pos], 4);
    _pos += 4;

    return n;
}

// ------------------------------------------------------------------------------------------------
aiVector2D B3DImporter::ReadVec2() {
    float x = ReadFloat();
    float y = ReadFloat();
    return aiVector2D(x, y);
}

// ------------------------------------------------------------------------------------------------
aiVector3D B3DImporter::ReadVec3() {
    float x = ReadFloat();
    float y = ReadFloat();
    float z = ReadFloat();
    return aiVector3D(x, y, z);
}

// ------------------------------------------------------------------------------------------------
aiQuaternion B3DImporter::ReadQuat() {
    // (aramis_acg) Fix to adapt the loader to changed quat orientation
    float w = -ReadFloat();
    float x = ReadFloat();
    float y = ReadFloat();
    float z = ReadFloat();
    return aiQuaternion(w, x, y, z);
}

// ------------------------------------------------------------------------------------------------
string B3DImporter::ReadString() {
    if (_pos > _buf.size()) {
        Fail("EOF");
    }
    string str;
    while (_pos < _buf.size()) {
        char c = (char)ReadByte();
        if (!c) {
            return str;
        }
        str += c;
    }
    return string();
}

// ------------------------------------------------------------------------------------------------
string B3DImporter::ReadChunk() {
    string tag;
    for (int i = 0; i < 4; ++i) {
        tag += char(ReadByte());
    }
#ifdef DEBUG_B3D
    ASSIMP_LOG_DEBUG("ReadChunk: ", tag);
#endif
    unsigned sz = (unsigned)ReadInt();
    _stack.push_back(_pos + sz);
    return tag;
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ExitChunk() {
    _pos = _stack.back();
    _stack.pop_back();
}

// ------------------------------------------------------------------------------------------------
size_t B3DImporter::ChunkSize() {
    return _stack.back() - _pos;
}
// ------------------------------------------------------------------------------------------------

template <class T>
T *B3DImporter::to_array(const vector<T> &v) {
    if (v.empty()) {
        return nullptr;
    }
    T *p = new T[v.size()];
    for (size_t i = 0; i < v.size(); ++i) {
        p[i] = v[i];
    }
    return p;
}

// ------------------------------------------------------------------------------------------------
template <class T>
T **unique_to_array(vector<std::unique_ptr<T>> &v) {
    if (v.empty()) {
        return nullptr;
    }
    T **p = new T *[v.size()];
    for (size_t i = 0; i < v.size(); ++i) {
        p[i] = v[i].release();
    }
    return p;
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadTEXS() {
    while (ChunkSize()) {
        string name = ReadString();
        /*int flags=*/ReadInt();
        /*int blend=*/ReadInt();
        /*aiVector2D pos=*/ReadVec2();
        /*aiVector2D scale=*/ReadVec2();
        /*float rot=*/ReadFloat();

        _textures.push_back(name);
    }
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadBRUS() {
    int n_texs = ReadInt();
    if (n_texs < 0 || n_texs > 8) {
        Fail("Bad texture count");
    }
    while (ChunkSize()) {
        string name = ReadString();
        aiVector3D color = ReadVec3();
        float alpha = ReadFloat();
        float shiny = ReadFloat();
        /*int blend=**/ ReadInt();
        int fx = ReadInt();

        std::unique_ptr<aiMaterial> mat(new aiMaterial);

        // Name
        aiString ainame(name);
        mat->AddProperty(&ainame, AI_MATKEY_NAME);

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

        // Opacity
        mat->AddProperty(&alpha, 1, AI_MATKEY_OPACITY);

        // Specular color
        aiColor3D speccolor(shiny, shiny, shiny);
        mat->AddProperty(&speccolor, 1, AI_MATKEY_COLOR_SPECULAR);

        // Specular power
        float specpow = shiny * 128;
        mat->AddProperty(&specpow, 1, AI_MATKEY_SHININESS);

        // Double sided
        if (fx & 0x10) {
            int i = 1;
            mat->AddProperty(&i, 1, AI_MATKEY_TWOSIDED);
        }

        // Textures
        for (int i = 0; i < n_texs; ++i) {
            int texid = ReadInt();
            if (texid < -1 || (texid >= 0 && texid >= static_cast<int>(_textures.size()))) {
                Fail("Bad texture id");
            }
            if (i == 0 && texid >= 0) {
                aiString texname(_textures[texid]);
                mat->AddProperty(&texname, AI_MATKEY_TEXTURE_DIFFUSE(0));
            }
        }
        _materials.emplace_back(std::move(mat));
    }
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadVRTS() {
    _vflags = ReadInt();
    _tcsets = ReadInt();
    _tcsize = ReadInt();
    if (_tcsets < 0 || _tcsets > 4 || _tcsize < 0 || _tcsize > 4) {
        Fail("Bad texcoord data");
    }

    int sz = 12 + (_vflags & 1 ? 12 : 0) + (_vflags & 2 ? 16 : 0) + (_tcsets * _tcsize * 4);
    size_t n_verts = ChunkSize() / sz;

    int v0 = static_cast<int>(_vertices.size());
    _vertices.resize(v0 + n_verts);

    for (unsigned int i = 0; i < n_verts; ++i) {
        Vertex &v = _vertices[v0 + i];

        memset(v.bones, 0, sizeof(v.bones));
        memset(v.weights, 0, sizeof(v.weights));

        v.vertex = ReadVec3();

        if (_vflags & 1) {
            v.normal = ReadVec3();
        }

        if (_vflags & 2) {
            ReadQuat(); // skip v 4bytes...
        }

        for (int j = 0; j < _tcsets; ++j) {
            float t[4] = { 0, 0, 0, 0 };
            for (int k = 0; k < _tcsize; ++k) {
                t[k] = ReadFloat();
            }
            t[1] = 1 - t[1];
            if (!j) {
                v.texcoords = aiVector3D(t[0], t[1], t[2]);
            }
        }
    }
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadTRIS(int v0) {
    int matid = ReadInt();
    if (matid == -1) {
        matid = 0;
    } else if (matid < 0 || matid >= (int)_materials.size()) {
#ifdef DEBUG_B3D
        ASSIMP_LOG_ERROR("material id=", matid);
#endif
        Fail("Bad material id");
    }

    std::unique_ptr<aiMesh> mesh(new aiMesh);

    mesh->mMaterialIndex = matid;
    mesh->mNumFaces = 0;
    mesh->mPrimitiveTypes = aiPrimitiveType_TRIANGLE;

    size_t n_tris = ChunkSize() / 12;
    aiFace *face = mesh->mFaces = new aiFace[n_tris];

    for (unsigned int i = 0; i < n_tris; ++i) {
        int i0 = ReadInt() + v0;
        int i1 = ReadInt() + v0;
        int i2 = ReadInt() + v0;
        if (i0 < 0 || i0 >= (int)_vertices.size() || i1 < 0 || i1 >= (int)_vertices.size() || i2 < 0 || i2 >= (int)_vertices.size()) {
#ifdef DEBUG_B3D
            ASSIMP_LOG_ERROR("Bad triangle index: i0=", i0, ", i1=", i1, ", i2=", i2);
#endif
            Fail("Bad triangle index");
        }
        face->mNumIndices = 3;
        face->mIndices = new unsigned[3];
        face->mIndices[0] = i0;
        face->mIndices[1] = i1;
        face->mIndices[2] = i2;
        ++mesh->mNumFaces;
        ++face;
    }

    _meshes.emplace_back(std::move(mesh));
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadMESH() {
    /*int matid=*/ReadInt();

    int v0 = static_cast<int>(_vertices.size());

    while (ChunkSize()) {
        string t = ReadChunk();
        if (t == "VRTS") {
            ReadVRTS();
        } else if (t == "TRIS") {
            ReadTRIS(v0);
        }
        ExitChunk();
    }
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadBONE(int id) {
    while (ChunkSize()) {
        int vertex = ReadInt();
        float weight = ReadFloat();
        if (vertex < 0 || vertex >= (int)_vertices.size()) {
            Fail("Bad vertex index");
        }

        Vertex &v = _vertices[vertex];
        for (int i = 0; i < 4; ++i) {
            if (!v.weights[i]) {
                v.bones[i] = static_cast<unsigned char>(id);
                v.weights[i] = weight;
                break;
            }
        }
    }
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadKEYS(AnimKeys& keys) {
    vector<aiVectorKey>& trans = keys.positionKeys;
    vector<aiVectorKey>& scale = keys.scalingKeys;
    vector<aiQuatKey>& rot = keys.rotationKeys;

    int flags = ReadInt();
    while (ChunkSize()) {
        int frame = ReadInt();
        if (flags & 1) {
            trans.emplace_back(frame, ReadVec3());
        }
        if (flags & 2) {
            scale.emplace_back(frame, ReadVec3());
        }
        if (flags & 4) {
            rot.emplace_back(frame, ReadQuat());
        }
    }
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadANIM() {
    /*int flags=*/ReadInt();
    int frames = ReadInt();
    float fps = ReadFloat();

    std::unique_ptr<aiAnimation> anim(new aiAnimation);

    anim->mDuration = frames;
    anim->mTicksPerSecond = fps;
    _animations.emplace_back(std::move(anim));
}

// ------------------------------------------------------------------------------------------------
aiNode *B3DImporter::ReadNODE(aiNode *parent) {

    string name = ReadString();
    aiVector3D t = ReadVec3();
    aiVector3D s = ReadVec3();
    aiQuaternion r = ReadQuat();

    aiMatrix4x4 trans, scale, rot;

    aiMatrix4x4::Translation(t, trans);
    aiMatrix4x4::Scaling(s, scale);
    rot = aiMatrix4x4(r.GetMatrix());

    aiMatrix4x4 tform = trans * rot * scale;

    int nodeid = static_cast<int>(_nodes.size());

    aiNode *node = new aiNode(name);
    _nodes.push_back(node);

    node->mParent = parent;
    node->mTransformation = tform;

    std::unique_ptr<aiNodeAnim> nodeAnim;
    vector<unsigned> meshes;
    vector<aiNode *> children;
    AnimKeys keys;

    while (ChunkSize()) {
        const string chunk = ReadChunk();
        if (chunk == "MESH") {
            unsigned int n = static_cast<unsigned int>(_meshes.size());
            ReadMESH();
            for (unsigned int i = n; i < static_cast<unsigned int>(_meshes.size()); ++i) {
                meshes.push_back(i);
            }
        } else if (chunk == "BONE") {
            ReadBONE(nodeid);
        } else if (chunk == "ANIM") {
            ReadANIM();
        } else if (chunk == "KEYS") {
            if (!nodeAnim) {
                nodeAnim.reset(new aiNodeAnim);
                nodeAnim->mNodeName = node->mName;
            }
            ReadKEYS(keys);
        } else if (chunk == "NODE") {
            aiNode *child = ReadNODE(node);
            children.push_back(child);
        }
        ExitChunk();
    }

    if (nodeAnim) {
        if (!keys.positionKeys.empty()) {
            nodeAnim->mNumPositionKeys = static_cast<unsigned int>(keys.positionKeys.size());
            nodeAnim->mPositionKeys = to_array(keys.positionKeys);
        }

        if (!keys.scalingKeys.empty()) {
            nodeAnim->mNumScalingKeys = static_cast<unsigned int>(keys.scalingKeys.size());
            nodeAnim->mScalingKeys = to_array(keys.scalingKeys);
        }

        if (!keys.rotationKeys.empty()) {
            nodeAnim->mNumRotationKeys = static_cast<unsigned int>(keys.rotationKeys.size());
            nodeAnim->mRotationKeys = to_array(keys.rotationKeys);
        }

        _nodeAnims.emplace_back(std::move(nodeAnim));
    }

    node->mNumMeshes = static_cast<unsigned int>(meshes.size());
    node->mMeshes = to_array(meshes);

    node->mNumChildren = static_cast<unsigned int>(children.size());
    node->mChildren = to_array(children);

    return node;
}

// ------------------------------------------------------------------------------------------------
void B3DImporter::ReadBB3D(aiScene *scene) {

    _textures.clear();

    _materials.clear();

    _vertices.clear();

    _meshes.clear();

    DeleteAllBarePointers(_nodes);
    _nodes.clear();

    _nodeAnims.clear();

    _animations.clear();

    string t = ReadChunk();
    if (t == "BB3D") {
        int version = ReadInt();

        if (!DefaultLogger::isNullLogger()) {
            char dmp[128];
            ai_snprintf(dmp, 128, "B3D file format version: %i", version);
            ASSIMP_LOG_INFO(dmp);
        }

        while (ChunkSize()) {
            const string chunk = ReadChunk();
            if (chunk == "TEXS") {
                ReadTEXS();
            } else if (chunk == "BRUS") {
                ReadBRUS();
            } else if (chunk == "NODE") {
                ReadNODE(nullptr);
            }
            ExitChunk();
        }
    }
    ExitChunk();

    if (!_nodes.size()) {
        Fail("No nodes");
    }

    if (!_meshes.size()) {
        Fail("No meshes");
    }

    // Fix nodes/meshes/bones
    for (size_t i = 0; i < _nodes.size(); ++i) {
        aiNode *node = _nodes[i];

        for (size_t j = 0; j < node->mNumMeshes; ++j) {
            aiMesh *mesh = _meshes[node->mMeshes[j]].get();

            int n_tris = mesh->mNumFaces;
            int n_verts = mesh->mNumVertices = n_tris * 3;

            aiVector3D *mv = mesh->mVertices = new aiVector3D[n_verts], *mn = nullptr, *mc = nullptr;
            if (_vflags & 1) {
                mn = mesh->mNormals = new aiVector3D[n_verts];
            }
            if (_tcsets) {
                mc = mesh->mTextureCoords[0] = new aiVector3D[n_verts];
            }

            aiFace *face = mesh->mFaces;

            vector<vector<aiVertexWeight>> vweights(_nodes.size());

            for (int vertIdx = 0; vertIdx < n_verts; vertIdx += 3) {
                for (int faceIndex = 0; faceIndex < 3; ++faceIndex) {
                    Vertex &v = _vertices[face->mIndices[faceIndex]];

                    *mv++ = v.vertex;
                    if (mn) *mn++ = v.normal;
                    if (mc) *mc++ = v.texcoords;

                    face->mIndices[faceIndex] = vertIdx + faceIndex;

                    for (int k = 0; k < 4; ++k) {
                        if (!v.weights[k])
                            break;

                        int bone = v.bones[k];
                        float weight = v.weights[k];

                        vweights[bone].emplace_back(vertIdx + faceIndex, weight);
                    }
                }
                ++face;
            }

            vector<aiBone *> bones;
            for (size_t weightIndx = 0; weightIndx < vweights.size(); ++weightIndx) {
                vector<aiVertexWeight> &weights = vweights[weightIndx];
                if (!weights.size()) {
                    continue;
                }

                aiBone *bone = new aiBone;
                bones.push_back(bone);

                aiNode *bnode = _nodes[weightIndx];

                bone->mName = bnode->mName;
                bone->mNumWeights = static_cast<unsigned int>(weights.size());
                bone->mWeights = to_array(weights);

                aiMatrix4x4 mat = bnode->mTransformation;
                while (bnode->mParent) {
                    bnode = bnode->mParent;
                    mat = bnode->mTransformation * mat;
                }
                bone->mOffsetMatrix = mat.Inverse();
            }
            mesh->mNumBones = static_cast<unsigned int>(bones.size());
            mesh->mBones = to_array(bones);
        }
    }

    // nodes
    scene->mRootNode = _nodes[0];
    _nodes.clear(); // node ownership now belongs to scene

    // material
    if (!_materials.size()) {
        _materials.emplace_back(std::unique_ptr<aiMaterial>(new aiMaterial));
    }
    scene->mNumMaterials = static_cast<unsigned int>(_materials.size());
    scene->mMaterials = unique_to_array(_materials);

    // meshes
    scene->mNumMeshes = static_cast<unsigned int>(_meshes.size());
    scene->mMeshes = unique_to_array(_meshes);

    // animations
    if (_animations.size() == 1 && _nodeAnims.size()) {

        aiAnimation *anim = _animations.back().get();
        anim->mNumChannels = static_cast<unsigned int>(_nodeAnims.size());
        anim->mChannels = unique_to_array(_nodeAnims);

        scene->mNumAnimations = static_cast<unsigned int>(_animations.size());
        scene->mAnimations = unique_to_array(_animations);
    }

    // convert to RH
    MakeLeftHandedProcess makeleft;
    makeleft.Execute(scene);

    FlipWindingOrderProcess flip;
    flip.Execute(scene);
}

} // namespace Assimp

#endif // !! ASSIMP_BUILD_NO_B3D_IMPORTER
