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/** @file  USDLoader.cpp
 *  @brief Implementation of the USD importer class
 */

#ifndef ASSIMP_BUILD_NO_USD_IMPORTER

#include "USDLoaderImplTinyusdz.h"
#include "USDLoaderImplTinyusdzHelper.h"
#include "USDLoaderUtil.h"
#include "USDPreprocessor.h"
#include "io-util.hh" // namespace tinyusdz::io
#include "tydra/scene-access.hh"
#include "tydra/shader-network.hh"

#include <memory>
#include <sstream>

// internal headers
#include "assimp/MemoryIOWrapper.h"
#include <assimp/CreateAnimMesh.h>
#include <assimp/DefaultIOSystem.h>
#include <assimp/IOStreamBuffer.h>
#include <assimp/StreamReader.h>
#include <assimp/StringUtils.h>
#include <assimp/ai_assert.h>
#include <assimp/anim.h>
#include <assimp/fast_atof.h>
#include <assimp/importerdesc.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/IOSystem.hpp>
#include <assimp/Importer.hpp>


#include "../../../contrib/tinyusdz/assimp_tinyusdz_logging.inc"

namespace {
    static constexpr char TAG[] = "tinyusdz loader";
}

namespace Assimp {

using Assimp::tinyUsdzMat4ToAiMat4;
using Assimp::tinyusdzNodeTypeFor;
using tinyusdz::tydra::NodeType;
using namespace tinyusdz::tydra;

void USDImporterImplTinyusdz::InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {
    // Grab filename for logging purposes
    size_t pos = pFile.find_last_of('/');
    std::string basePath = pFile.substr(0, pos);
    std::string nameWExt = pFile.substr(pos + 1);
    std::stringstream ss;
    ss.str("");
    ss << "InternReadFile(): model" << nameWExt;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());

    bool is_load_from_mem{ pFile.substr(0, AI_MEMORYIO_MAGIC_FILENAME_LENGTH) == AI_MEMORYIO_MAGIC_FILENAME };
    std::vector<uint8_t> in_mem_data;
    if (is_load_from_mem) {
        auto stream_closer = [pIOHandler](IOStream *pStream) {
            pIOHandler->Close(pStream);
        };
        std::unique_ptr<IOStream, decltype(stream_closer)> file_stream(pIOHandler->Open(pFile, "rb"), stream_closer);
        if (!file_stream) {
            throw DeadlyImportError("Failed to open file ", pFile, ".");
        }
        size_t file_size{ file_stream->FileSize() };
        in_mem_data.resize(file_size);
        file_stream->Read(in_mem_data.data(), 1, file_size);
    }

    bool ret{ false };
    tinyusdz::USDLoadOptions options;
    tinyusdz::Stage stage;
    std::string warn, err;
    bool is_usdz{ false };
    if (isUsdc(pFile)) {
        ret = is_load_from_mem ? LoadUSDCFromMemory(in_mem_data.data(), in_mem_data.size(), pFile, &stage, &warn, &err, options) :
                                 LoadUSDCFromFile(pFile, &stage, &warn, &err, options);
        ss.str("");
        ss << "InternReadFile(): LoadUSDCFromFile() result: " << ret;
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    } else if (isUsda(pFile)) {
        ret = is_load_from_mem ? LoadUSDAFromMemory(in_mem_data.data(), in_mem_data.size(), pFile, &stage, &warn, &err, options) :
                                 LoadUSDAFromFile(pFile, &stage, &warn, &err, options);
        ss.str("");
        ss << "InternReadFile(): LoadUSDAFromFile() result: " << ret;
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    } else if (isUsdz(pFile)) {
        ret = is_load_from_mem ? LoadUSDZFromMemory(in_mem_data.data(), in_mem_data.size(), pFile, &stage, &warn, &err, options) :
                                 LoadUSDZFromFile(pFile, &stage, &warn, &err, options);
        is_usdz = true;
        ss.str("");
        ss << "InternReadFile(): LoadUSDZFromFile() result: " << ret;
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    } else if (isUsd(pFile)) {
        ret = is_load_from_mem ? LoadUSDFromMemory(in_mem_data.data(), in_mem_data.size(), pFile, &stage, &warn, &err, options) :
                                 LoadUSDFromFile(pFile, &stage, &warn, &err, options);
        ss.str("");
        ss << "InternReadFile(): LoadUSDFromFile() result: " << ret;
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    }
    if (warn.empty() && err.empty()) {
        ss.str("");
        ss << "InternReadFile(): load free of warnings/errors";
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    } else {
        if (!warn.empty()) {
            ss.str("");
            ss << "InternReadFile(): WARNING reported: " << warn;
            TINYUSDZLOGW(TAG, "%s", ss.str().c_str());
        }
        if (!err.empty()) {
            ss.str("");
            ss << "InternReadFile(): ERROR reported: " << err;
            TINYUSDZLOGE(TAG, "%s", ss.str().c_str());
        }
    }
    if (!ret) {
        ss.str("");
        ss << "InternReadFile(): ERROR: load failed! ret: " << ret;
        TINYUSDZLOGE(TAG, "%s", ss.str().c_str());
        return;
    }
    
    RenderScene render_scene;
    RenderSceneConverter converter;
    RenderSceneConverterEnv env(stage);
    std::string usd_basedir = tinyusdz::io::GetBaseDir(pFile);
    env.set_search_paths({ usd_basedir }); // {} needed to convert to vector of char

    // NOTE: Pointer address of usdz_asset must be valid until the call of RenderSceneConverter::ConvertToRenderScene.
    tinyusdz::USDZAsset usdz_asset;
    if (is_usdz) {
        bool is_read_USDZ_asset = is_load_from_mem ? tinyusdz::ReadUSDZAssetInfoFromMemory(in_mem_data.data(), in_mem_data.size(), false, &usdz_asset, &warn, &err) :
                                                     tinyusdz::ReadUSDZAssetInfoFromFile(pFile, &usdz_asset, &warn, &err);
        if (!is_read_USDZ_asset) {
            if (!warn.empty()) {
                ss.str("");
                ss << "InternReadFile(): ReadUSDZAssetInfoFromFile: WARNING reported: " << warn;
                TINYUSDZLOGW(TAG, "%s", ss.str().c_str());
            }
            if (!err.empty()) {
                ss.str("");
                ss << "InternReadFile(): ReadUSDZAssetInfoFromFile: ERROR reported: " << err;
                TINYUSDZLOGE(TAG, "%s", ss.str().c_str());
            }
            ss.str("");
            ss << "InternReadFile(): ReadUSDZAssetInfoFromFile: ERROR!";
            TINYUSDZLOGE(TAG, "%s", ss.str().c_str());
        } else {
            ss.str("");
            ss << "InternReadFile(): ReadUSDZAssetInfoFromFile: OK";
            TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        }

        tinyusdz::AssetResolutionResolver arr;
        if (!tinyusdz::SetupUSDZAssetResolution(arr, &usdz_asset)) {
            ss.str("");
            ss << "InternReadFile(): SetupUSDZAssetResolution: ERROR: load failed! ret: " << ret;
            TINYUSDZLOGE(TAG, "%s", ss.str().c_str());
        } else {
            ss.str("");
            ss << "InternReadFile(): SetupUSDZAssetResolution: OK";
            TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
            env.asset_resolver = arr;
        }
    }

    ret = converter.ConvertToRenderScene(env, &render_scene);
    if (!ret) {
        ss.str("");
        ss << "InternReadFile(): ConvertToRenderScene() failed!";
        TINYUSDZLOGE(TAG, "%s", ss.str().c_str());
        return;
    }

    // sanityCheckNodesRecursive(pScene->mRootNode);
    animations(render_scene, pScene);
    meshes(render_scene, pScene, nameWExt);
    materials(render_scene, pScene, nameWExt);
    textures(render_scene, pScene, nameWExt);
    textureImages(render_scene, pScene, nameWExt);
    buffers(render_scene, pScene, nameWExt);
    pScene->mRootNode = nodesRecursive(nullptr, render_scene.nodes[0], render_scene.skeletons);

    setupBlendShapes(render_scene, pScene, nameWExt);
}

void USDImporterImplTinyusdz::animations(const tinyusdz::tydra::RenderScene &render_scene, aiScene *pScene) {
    if (render_scene.animations.empty()) {
        return;
    }

    pScene->mNumAnimations = unsigned(render_scene.animations.size());
    pScene->mAnimations = new aiAnimation *[pScene->mNumAnimations];

    for (unsigned animationIndex = 0; animationIndex < pScene->mNumAnimations; ++animationIndex) {

        const auto &animation = render_scene.animations[animationIndex];

        auto newAiAnimation = new aiAnimation();
        pScene->mAnimations[animationIndex] = newAiAnimation;

        newAiAnimation->mName = animation.abs_path;

        if (animation.channels_map.empty()) {
            newAiAnimation->mNumChannels = 0;
            continue;
        }

        // each channel affects a node (joint)
        newAiAnimation->mTicksPerSecond = render_scene.meta.framesPerSecond;
        newAiAnimation->mNumChannels = unsigned(animation.channels_map.size());

        newAiAnimation->mChannels = new aiNodeAnim *[newAiAnimation->mNumChannels];
        int channelIndex = 0;
        for (const auto &[jointName, animationChannelMap] : animation.channels_map) {
            auto newAiNodeAnim = new aiNodeAnim();
            newAiAnimation->mChannels[channelIndex] = newAiNodeAnim;
            newAiNodeAnim->mNodeName = jointName;
            newAiAnimation->mDuration = 0;

            std::vector<aiVectorKey> positionKeys;
            std::vector<aiQuatKey> rotationKeys;
            std::vector<aiVectorKey> scalingKeys;

            for (const auto &[channelType, animChannel] : animationChannelMap) {
                switch (channelType) {
                case AnimationChannel::ChannelType::Rotation:
                    if (animChannel.rotations.static_value.has_value()) {
                        rotationKeys.emplace_back(0, tinyUsdzQuatToAiQuat(animChannel.rotations.static_value.value()));
                    }
                    for (const auto &rotationAnimSampler : animChannel.rotations.samples) {
                        if (rotationAnimSampler.t > newAiAnimation->mDuration) {
                            newAiAnimation->mDuration = rotationAnimSampler.t;
                        }

                        rotationKeys.emplace_back(rotationAnimSampler.t, tinyUsdzQuatToAiQuat(rotationAnimSampler.value));
                    }
                    break;
                case AnimationChannel::ChannelType::Scale:
                    if (animChannel.scales.static_value.has_value()) {
                        scalingKeys.emplace_back(0, tinyUsdzScaleOrPosToAssimp(animChannel.scales.static_value.value()));
                    }
                    for (const auto &scaleAnimSampler : animChannel.scales.samples) {
                        if (scaleAnimSampler.t > newAiAnimation->mDuration) {
                            newAiAnimation->mDuration = scaleAnimSampler.t;
                        }
                        scalingKeys.emplace_back(scaleAnimSampler.t, tinyUsdzScaleOrPosToAssimp(scaleAnimSampler.value));
                    }
                    break;
                case AnimationChannel::ChannelType::Transform:
                    if (animChannel.transforms.static_value.has_value()) {
                        aiVector3D position;
                        aiVector3D scale;
                        aiQuaternion rotation;
                        tinyUsdzMat4ToAiMat4(animChannel.transforms.static_value.value().m).Decompose(scale, rotation, position);

                        positionKeys.emplace_back(0, position);
                        scalingKeys.emplace_back(0, scale);
                        rotationKeys.emplace_back(0, rotation);
                    }
                    for (const auto &transformAnimSampler : animChannel.transforms.samples) {
                        if (transformAnimSampler.t > newAiAnimation->mDuration) {
                            newAiAnimation->mDuration = transformAnimSampler.t;
                        }

                        aiVector3D position;
                        aiVector3D scale;
                        aiQuaternion rotation;
                        tinyUsdzMat4ToAiMat4(transformAnimSampler.value.m).Decompose(scale, rotation, position);

                        positionKeys.emplace_back(transformAnimSampler.t, position);
                        scalingKeys.emplace_back(transformAnimSampler.t, scale);
                        rotationKeys.emplace_back(transformAnimSampler.t, rotation);
                    }
                    break;
                case AnimationChannel::ChannelType::Translation:
                    if (animChannel.translations.static_value.has_value()) {
                        positionKeys.emplace_back(0, tinyUsdzScaleOrPosToAssimp(animChannel.translations.static_value.value()));
                    }
                    for (const auto &translationAnimSampler : animChannel.translations.samples) {
                        if (translationAnimSampler.t > newAiAnimation->mDuration) {
                            newAiAnimation->mDuration = translationAnimSampler.t;
                        }

                        positionKeys.emplace_back(translationAnimSampler.t, tinyUsdzScaleOrPosToAssimp(translationAnimSampler.value));
                    }
                    break;
                default:
                    TINYUSDZLOGW(TAG, "Unsupported animation channel type (%s). Please update the USD importer to support this animation channel.", tinyusdzAnimChannelTypeFor(channelType).c_str());
                }
            }

            newAiNodeAnim->mNumPositionKeys = unsigned(positionKeys.size());
            newAiNodeAnim->mPositionKeys = new aiVectorKey[newAiNodeAnim->mNumPositionKeys];
            std::move(positionKeys.begin(), positionKeys.end(), newAiNodeAnim->mPositionKeys);

            newAiNodeAnim->mNumRotationKeys = unsigned(rotationKeys.size());
            newAiNodeAnim->mRotationKeys = new aiQuatKey[newAiNodeAnim->mNumRotationKeys];
            std::move(rotationKeys.begin(), rotationKeys.end(), newAiNodeAnim->mRotationKeys);

            newAiNodeAnim->mNumScalingKeys = unsigned(scalingKeys.size());
            newAiNodeAnim->mScalingKeys = new aiVectorKey[newAiNodeAnim->mNumScalingKeys];
            std::move(scalingKeys.begin(), scalingKeys.end(), newAiNodeAnim->mScalingKeys);

            ++channelIndex;
        }
    }
}

void USDImporterImplTinyusdz::meshes(
        const tinyusdz::tydra::RenderScene &render_scene,
        aiScene *pScene,
        const std::string &nameWExt) {
    std::stringstream ss;
    pScene->mNumMeshes = static_cast<unsigned int>(render_scene.meshes.size());
    pScene->mMeshes = new aiMesh *[pScene->mNumMeshes]();
    ss.str("");
    ss << "meshes(): pScene->mNumMeshes: " << pScene->mNumMeshes;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());

    // Export meshes
    for (size_t meshIdx = 0; meshIdx < pScene->mNumMeshes; meshIdx++) {
        pScene->mMeshes[meshIdx] = new aiMesh();
        pScene->mMeshes[meshIdx]->mName.Set(render_scene.meshes[meshIdx].prim_name);
        ss.str("");
        ss << "   mesh[" << meshIdx << "]: " << render_scene.meshes[meshIdx].joint_and_weights.jointIndices.size() << " jointIndices, " << render_scene.meshes[meshIdx].joint_and_weights.jointWeights.size() << " jointWeights, elementSize: " << render_scene.meshes[meshIdx].joint_and_weights.elementSize;
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        ss.str("");
        ss << "        skel_id: " << render_scene.meshes[meshIdx].skel_id;
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        if (render_scene.meshes[meshIdx].material_id > -1) {
            pScene->mMeshes[meshIdx]->mMaterialIndex = render_scene.meshes[meshIdx].material_id;
        }
        verticesForMesh(render_scene, pScene, meshIdx, nameWExt);
        facesForMesh(render_scene, pScene, meshIdx, nameWExt);
        // Some models infer normals from faces, but others need them e.g.
        //   - apple "toy car" canopy normals will be wrong
        //   - human "untitled" model (tinyusdz issue #115) will be "splotchy"
        normalsForMesh(render_scene, pScene, meshIdx, nameWExt);
        materialsForMesh(render_scene, pScene, meshIdx, nameWExt);
        uvsForMesh(render_scene, pScene, meshIdx, nameWExt);
    }
}

void USDImporterImplTinyusdz::verticesForMesh(const tinyusdz::tydra::RenderScene &render_scene, 
        aiScene *pScene, size_t meshIdx, const std::string &) {
    const auto numVertices = static_cast<unsigned int>(render_scene.meshes[meshIdx].points.size());
    pScene->mMeshes[meshIdx]->mNumVertices = numVertices;
    pScene->mMeshes[meshIdx]->mVertices = new aiVector3D[pScene->mMeshes[meshIdx]->mNumVertices];

    // Check if this is a skinned mesh
    if (int skeleton_id = render_scene.meshes[meshIdx].skel_id; skeleton_id > -1) {
        // Recursively iterate to collect all the joints in the hierarchy into a flattened array
        std::vector<const tinyusdz::tydra::SkelNode *> skeletonNodes;
        skeletonNodes.push_back(&render_scene.skeletons[skeleton_id].root_node);
        for (int i = 0; i < skeletonNodes.size(); ++i) {
            for (const auto &child : skeletonNodes[i]->children) {
                skeletonNodes.push_back(&child);
            }
        }

        // Convert USD skeleton joints to Assimp bones
        const unsigned int numBones = unsigned(skeletonNodes.size());
        pScene->mMeshes[meshIdx]->mNumBones = numBones;
        pScene->mMeshes[meshIdx]->mBones = new aiBone *[numBones];

        for (unsigned int i = 0; i < numBones; ++i) {
            const tinyusdz::tydra::SkelNode *skeletonNode = skeletonNodes[i];
            const int boneIndex = skeletonNode->joint_id;

            // Sorted so that Assimp bone ids align with USD joint id
            auto outputBone = new aiBone();
            outputBone->mName = aiString(skeletonNode->joint_name);
            outputBone->mOffsetMatrix = tinyUsdzMat4ToAiMat4(skeletonNode->bind_transform.m).Inverse();
            pScene->mMeshes[meshIdx]->mBones[boneIndex] = outputBone;
        }

        // Vertex weights
        std::vector<std::vector<aiVertexWeight>> aiBonesVertexWeights;
        aiBonesVertexWeights.resize(numBones);

        const std::vector<int> &jointIndices = render_scene.meshes[meshIdx].joint_and_weights.jointIndices;
        const std::vector<float> &jointWeightIndices = render_scene.meshes[meshIdx].joint_and_weights.jointWeights;
        const int numWeightsPerVertex = render_scene.meshes[meshIdx].joint_and_weights.elementSize;

        for (unsigned int vertexIndex = 0; vertexIndex < numVertices; ++vertexIndex) {
            for (int weightIndex = 0; weightIndex < numWeightsPerVertex; ++weightIndex) {
                const unsigned int index = vertexIndex * numWeightsPerVertex + weightIndex;
                const float jointWeight = jointWeightIndices[index];

                if (jointWeight > 0) {
                    const int jointIndex = jointIndices[index];
                    aiBonesVertexWeights[jointIndex].emplace_back(vertexIndex, jointWeight);
                }
            }
        }

        for (unsigned boneIndex = 0; boneIndex < numBones; ++boneIndex) {
            const auto numWeightsForBone = unsigned(aiBonesVertexWeights[boneIndex].size());
            pScene->mMeshes[meshIdx]->mBones[boneIndex]->mWeights = new aiVertexWeight[numWeightsForBone];
            pScene->mMeshes[meshIdx]->mBones[boneIndex]->mNumWeights = numWeightsForBone;

            std::swap_ranges(aiBonesVertexWeights[boneIndex].begin(), aiBonesVertexWeights[boneIndex].end(), pScene->mMeshes[meshIdx]->mBones[boneIndex]->mWeights);
        }
    } // Skinned mesh end

    for (size_t j = 0; j < pScene->mMeshes[meshIdx]->mNumVertices; ++j) {
        pScene->mMeshes[meshIdx]->mVertices[j].x = render_scene.meshes[meshIdx].points[j][0];
        pScene->mMeshes[meshIdx]->mVertices[j].y = render_scene.meshes[meshIdx].points[j][1];
        pScene->mMeshes[meshIdx]->mVertices[j].z = render_scene.meshes[meshIdx].points[j][2];
    }
}

void USDImporterImplTinyusdz::facesForMesh(const RenderScene &render_scene, aiScene *pScene, 
        size_t meshIdx, const std::string &) {
    pScene->mMeshes[meshIdx]->mNumFaces = static_cast<unsigned int>(render_scene.meshes[meshIdx].faceVertexCounts().size());
    pScene->mMeshes[meshIdx]->mFaces = new aiFace[pScene->mMeshes[meshIdx]->mNumFaces]();
    size_t faceVertIdxOffset = 0;
    for (size_t faceIdx = 0; faceIdx < pScene->mMeshes[meshIdx]->mNumFaces; ++faceIdx) {
        pScene->mMeshes[meshIdx]->mFaces[faceIdx].mNumIndices = render_scene.meshes[meshIdx].faceVertexCounts()[faceIdx];
        pScene->mMeshes[meshIdx]->mFaces[faceIdx].mIndices = new unsigned int[pScene->mMeshes[meshIdx]->mFaces[faceIdx].mNumIndices];
        for (size_t j = 0; j < pScene->mMeshes[meshIdx]->mFaces[faceIdx].mNumIndices; ++j) {
            pScene->mMeshes[meshIdx]->mFaces[faceIdx].mIndices[j] =
                    render_scene.meshes[meshIdx].faceVertexIndices()[j + faceVertIdxOffset];
        }
        faceVertIdxOffset += pScene->mMeshes[meshIdx]->mFaces[faceIdx].mNumIndices;
    }
}

void USDImporterImplTinyusdz::normalsForMesh(const RenderScene &render_scene, aiScene *pScene,
        size_t meshIdx, const std::string &) {
    pScene->mMeshes[meshIdx]->mNormals = new aiVector3D[pScene->mMeshes[meshIdx]->mNumVertices];
    const float *floatPtr = reinterpret_cast<const float *>(render_scene.meshes[meshIdx].normals.get_data().data());
    for (size_t vertIdx = 0, fpj = 0; vertIdx < pScene->mMeshes[meshIdx]->mNumVertices; ++vertIdx, fpj += 3) {
        pScene->mMeshes[meshIdx]->mNormals[vertIdx].x = floatPtr[fpj];
        pScene->mMeshes[meshIdx]->mNormals[vertIdx].y = floatPtr[fpj + 1];
        pScene->mMeshes[meshIdx]->mNormals[vertIdx].z = floatPtr[fpj + 2];
    }
}

void USDImporterImplTinyusdz::materialsForMesh(const RenderScene&, aiScene*,
        size_t, const std::string&) {
    // todo
}

void USDImporterImplTinyusdz::uvsForMesh(
        const tinyusdz::tydra::RenderScene &render_scene,
        aiScene *pScene,
        size_t meshIdx,
        const std::string&) {
    const size_t uvSlotsCount = render_scene.meshes[meshIdx].texcoords.size();
    if (uvSlotsCount < 1) {
        return;
    }
    pScene->mMeshes[meshIdx]->mTextureCoords[0] = new aiVector3D[pScene->mMeshes[meshIdx]->mNumVertices];
    pScene->mMeshes[meshIdx]->mNumUVComponents[0] = 2; // U and V stored in "x", "y" of aiVector3D.
    for (unsigned int uvSlotIdx = 0; uvSlotIdx < uvSlotsCount; ++uvSlotIdx) {
        const auto uvsForSlot = render_scene.meshes[meshIdx].texcoords.at(uvSlotIdx);
        if (uvsForSlot.get_data().size() == 0) {
            continue;
        }
        const float *floatPtr = reinterpret_cast<const float *>(uvsForSlot.get_data().data());
        for (size_t vertIdx = 0, fpj = 0; vertIdx < pScene->mMeshes[meshIdx]->mNumVertices; ++vertIdx, fpj += 2) {
            pScene->mMeshes[meshIdx]->mTextureCoords[uvSlotIdx][vertIdx].x = floatPtr[fpj];
            pScene->mMeshes[meshIdx]->mTextureCoords[uvSlotIdx][vertIdx].y = floatPtr[fpj + 1];
        }
    }
}

static std::string nameForTextureWithId(const RenderScene &render_scene, const int targetId) {
    std::stringstream ss;
    std::string texName;
    for (const auto &image : render_scene.images) {
        if (image.buffer_id == targetId) {
            texName = image.asset_identifier;
            ss.str("");
            ss << "nameForTextureWithId(): found texture " << texName << " with target id " << targetId;
            TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
            break;
        }
    }
    ss.str("");
    ss << "nameForTextureWithId(): ERROR!  Failed to find texture with target id " << targetId;
    TINYUSDZLOGE(TAG, "%s", ss.str().c_str());
    return texName;
}

static void assignTexture(
        const RenderScene &render_scene,
        const RenderMaterial &,
        aiMaterial *mat,
        const int textureId,
        const int aiTextureType) {
    std::string name = nameForTextureWithId(render_scene, textureId);
    aiString texName;
    texName.Set(name);
    std::stringstream ss;
    ss.str("");
    ss << "assignTexture(): name: " << name;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    // TODO: verify hard-coded '0' index is correct
    mat->AddProperty(&texName, _AI_MATKEY_TEXTURE_BASE, aiTextureType, 0);
}

void USDImporterImplTinyusdz::materials(
        const tinyusdz::tydra::RenderScene &render_scene,
        aiScene *pScene,
        const std::string &nameWExt) {
    const size_t numMaterials{ render_scene.materials.size() };
    std::stringstream ss;
    ss.str("");
    ss << "materials(): model" << nameWExt << ", numMaterials: " << numMaterials;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    pScene->mNumMaterials = 0;
    if (render_scene.materials.empty()) {
        return;
    }

    pScene->mMaterials = new aiMaterial *[render_scene.materials.size()];
    for (const auto &material : render_scene.materials) {
        ss.str("");
        ss << "    material[" << pScene->mNumMaterials << "]: name: |" << material.name << "|, disp name: |" << material.display_name << "|";
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        aiMaterial *mat = new aiMaterial;

        aiString materialName;
        materialName.Set(material.name);
        mat->AddProperty(materialName, AI_MATKEY_NAME);

        mat->AddProperty(
                reinterpret_cast<const aiColor3D *>(material.surfaceShader.diffuseColor.value.data()),
                1, AI_MATKEY_COLOR_DIFFUSE);
        mat->AddProperty(
                reinterpret_cast<const aiColor3D *>(material.surfaceShader.specularColor.value.data()),
                1, AI_MATKEY_COLOR_SPECULAR);
        mat->AddProperty(
                reinterpret_cast<const aiColor3D *>(material.surfaceShader.emissiveColor.value.data()),
                1, AI_MATKEY_COLOR_EMISSIVE);

        ss.str("");
        if (material.surfaceShader.diffuseColor.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.diffuseColor.texture_id, aiTextureType_DIFFUSE);
            ss << "    material[" << pScene->mNumMaterials << "]: diff tex id " << material.surfaceShader.diffuseColor.texture_id << "\n";
        }
        if (material.surfaceShader.specularColor.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.specularColor.texture_id, aiTextureType_SPECULAR);
            ss << "    material[" << pScene->mNumMaterials << "]: spec tex id " << material.surfaceShader.specularColor.texture_id << "\n";
        }
        if (material.surfaceShader.normal.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.normal.texture_id, aiTextureType_NORMALS);
            ss << "    material[" << pScene->mNumMaterials << "]: normal tex id " << material.surfaceShader.normal.texture_id << "\n";
        }
        if (material.surfaceShader.emissiveColor.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.emissiveColor.texture_id, aiTextureType_EMISSIVE);
            ss << "    material[" << pScene->mNumMaterials << "]: emissive tex id " << material.surfaceShader.emissiveColor.texture_id << "\n";
        }
        if (material.surfaceShader.occlusion.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.occlusion.texture_id, aiTextureType_LIGHTMAP);
            ss << "    material[" << pScene->mNumMaterials << "]: lightmap (occlusion) tex id " << material.surfaceShader.occlusion.texture_id << "\n";
        }
        if (material.surfaceShader.metallic.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.metallic.texture_id, aiTextureType_METALNESS);
            ss << "    material[" << pScene->mNumMaterials << "]: metallic tex id " << material.surfaceShader.metallic.texture_id << "\n";
        }
        if (material.surfaceShader.roughness.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.roughness.texture_id, aiTextureType_DIFFUSE_ROUGHNESS);
            ss << "    material[" << pScene->mNumMaterials << "]: roughness tex id " << material.surfaceShader.roughness.texture_id << "\n";
        }
        if (material.surfaceShader.clearcoat.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.clearcoat.texture_id, aiTextureType_CLEARCOAT);
            ss << "    material[" << pScene->mNumMaterials << "]: clearcoat tex id " << material.surfaceShader.clearcoat.texture_id << "\n";
        }
        if (material.surfaceShader.opacity.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.opacity.texture_id, aiTextureType_OPACITY);
            ss << "    material[" << pScene->mNumMaterials << "]: opacity tex id " << material.surfaceShader.opacity.texture_id << "\n";
        }
        if (material.surfaceShader.displacement.is_texture()) {
            assignTexture(render_scene, material, mat, material.surfaceShader.displacement.texture_id, aiTextureType_DISPLACEMENT);
            ss << "    material[" << pScene->mNumMaterials << "]: displacement tex id " << material.surfaceShader.displacement.texture_id << "\n";
        }
        if (material.surfaceShader.clearcoatRoughness.is_texture()) {
            ss << "    material[" << pScene->mNumMaterials << "]: clearcoatRoughness tex id " << material.surfaceShader.clearcoatRoughness.texture_id << "\n";
        }
        if (material.surfaceShader.opacityThreshold.is_texture()) {
            ss << "    material[" << pScene->mNumMaterials << "]: opacityThreshold tex id " << material.surfaceShader.opacityThreshold.texture_id << "\n";
        }
        if (material.surfaceShader.ior.is_texture()) {
            ss << "    material[" << pScene->mNumMaterials << "]: ior tex id " << material.surfaceShader.ior.texture_id << "\n";
        }
        if (!ss.str().empty()) {
            TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        }

        pScene->mMaterials[pScene->mNumMaterials] = mat;
        ++pScene->mNumMaterials;
    }
}

void USDImporterImplTinyusdz::textures(
        const tinyusdz::tydra::RenderScene &render_scene,
        aiScene*,
        const std::string &nameWExt) {
    const size_t numTextures{ render_scene.textures.size() };
    std::stringstream ss;
    ss.str("");
    ss << "textures(): model" << nameWExt << ", numTextures: " << numTextures;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    size_t i{ 0 };
    
    for (const auto &texture : render_scene.textures) {
        ss.str("");
        ss << "    texture[" << i << "]: id: " << texture.texture_image_id << ", disp name: |" << texture.display_name << "|, varname_uv: " << texture.varname_uv << ", prim_name: |" << texture.prim_name << "|, abs_path: |" << texture.abs_path << "|";
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        ++i;
    }
}

/**
 * "owned" as in, used "new" to allocate and aiScene now responsible for "delete"
 *
 * @param render_scene  renderScene object
 * @param image         textureImage object
 * @param nameWExt      filename w/ext (use to extract file type hint)
 * @return              aiTexture ptr
 */
static aiTexture *ownedEmbeddedTextureFor(const RenderScene &render_scene, const TextureImage &image,
        const std::string&) {
    std::stringstream ss;
    aiTexture *tex = new aiTexture();
    size_t pos = image.asset_identifier.find_last_of('/');
    std::string embTexName{ image.asset_identifier.substr(pos + 1) };
    tex->mFilename.Set(image.asset_identifier.c_str());
    tex->mHeight = image.height;

    tex->mWidth = image.width;
    if (tex->mHeight == 0) {
        pos = embTexName.find_last_of('.');
        strncpy(tex->achFormatHint, embTexName.substr(pos + 1).c_str(), 3);
        const size_t imageBytesCount{ render_scene.buffers[image.buffer_id].data.size() };
        tex->pcData = (aiTexel *)new char[imageBytesCount];
        memcpy(tex->pcData, &render_scene.buffers[image.buffer_id].data[0], imageBytesCount);
    } else {
        std::string formatHint{ "rgba8888" };
        strncpy(tex->achFormatHint, formatHint.c_str(), 8);
        const size_t imageTexelsCount{ tex->mWidth * tex->mHeight };
        tex->pcData = (aiTexel *)new char[imageTexelsCount * image.channels];
        const float *floatPtr = reinterpret_cast<const float *>(&render_scene.buffers[image.buffer_id].data[0]);
        ss.str("");
        ss << "ownedEmbeddedTextureFor(): manual fill...";
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        for (size_t i = 0, fpi = 0; i < imageTexelsCount; ++i, fpi += 4) {
            tex->pcData[i].b = static_cast<uint8_t>(floatPtr[fpi] * 255);
            tex->pcData[i].g = static_cast<uint8_t>(floatPtr[fpi + 1] * 255);
            tex->pcData[i].r = static_cast<uint8_t>(floatPtr[fpi + 2] * 255);
            tex->pcData[i].a = static_cast<uint8_t>(floatPtr[fpi + 3] * 255);
        }
        ss.str("");
        ss << "ownedEmbeddedTextureFor(): imageTexelsCount: " << imageTexelsCount << ", channels: " << image.channels;
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    }
    return tex;
}

void USDImporterImplTinyusdz::textureImages(const RenderScene &render_scene, aiScene *pScene, const std::string &nameWExt) {
    std::stringstream ss;
    const size_t numTextureImages{ render_scene.images.size() };
    ss.str("");
    ss << "textureImages(): model" << nameWExt << ", numTextureImages: " << numTextureImages;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    pScene->mTextures = nullptr; // Need to iterate over images before knowing if valid textures available
    pScene->mNumTextures = 0;
    for (const auto &image : render_scene.images) {
        ss.str("");
        ss << "    image[" << pScene->mNumTextures << "]: |" << image.asset_identifier << "| w: " 
            << image.width << ", h: " << image.height << ", channels: " << image.channels << ", miplevel: " 
            << image.miplevel << ", buffer id: " << image.buffer_id << "\n"
            << "    buffers.size(): " << render_scene.buffers.size() << ", data empty? " 
            << render_scene.buffers[image.buffer_id].data.empty();
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        if (image.buffer_id > -1 &&
                image.buffer_id < static_cast<long int>(render_scene.buffers.size()) &&
                !render_scene.buffers[image.buffer_id].data.empty()) {
            aiTexture *tex = ownedEmbeddedTextureFor(
                    render_scene,
                    image,
                    nameWExt);
            if (pScene->mTextures == nullptr) {
                ss.str("");
                ss << "    Init pScene->mTextures[" << render_scene.images.size() << "]";
                TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
                pScene->mTextures = new aiTexture *[render_scene.images.size()];
            }
            ss.str("");
            ss << "    pScene->mTextures[" << pScene->mNumTextures << "] name: |" << tex->mFilename.C_Str() 
                << "|, w: " << tex->mWidth << ", h: " << tex->mHeight << ", hint: " << tex->achFormatHint;
            TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
            pScene->mTextures[pScene->mNumTextures++] = tex;
        }
    }
}

void USDImporterImplTinyusdz::buffers(
        const RenderScene &render_scene, aiScene*, const std::string &nameWExt) {
    const size_t numBuffers{ render_scene.buffers.size() };
    std::stringstream ss;
    ss.str("");
    ss << "buffers(): model" << nameWExt << ", numBuffers: " << numBuffers;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    size_t i = 0;
    for (const auto &buffer : render_scene.buffers) {
        ss.str("");
        ss << "    buffer[" << i << "]: count: " << buffer.data.size() << ", type: " << to_string(buffer.componentType);
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        ++i;
    }
}

aiNode *USDImporterImplTinyusdz::nodesRecursive(aiNode *pNodeParent, const tinyusdz::tydra::Node &node,
        const std::vector<SkelHierarchy> &skeletons) {
    std::stringstream ss;
    aiNode *cNode = new aiNode();
    cNode->mParent = pNodeParent;
    cNode->mName.Set(node.prim_name);
    cNode->mTransformation = tinyUsdzMat4ToAiMat4(node.local_matrix.m);

    if (node.nodeType == NodeType::Mesh) {
        cNode->mNumMeshes = 1;
        cNode->mMeshes = new unsigned int[cNode->mNumMeshes];
        cNode->mMeshes[0] = node.id;
    }

    ss.str("");
    ss << "nodesRecursive(): node " << cNode->mName.C_Str() << " type: |" 
        << tinyusdzNodeTypeFor(node.nodeType) 
        << "|, disp " << node.display_name << ", abs " << node.abs_path;
    if (cNode->mParent != nullptr) {
        ss << " (parent " << cNode->mParent->mName.C_Str() << ")";
    }
    ss << " has " << node.children.size() << " children";
    if (node.nodeType == NodeType::Mesh) {
        ss << "\n    node mesh id: " << node.id << " (node type: " << tinyusdzNodeTypeFor(node.nodeType) << ")";
    }
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());

    unsigned int numChildren = unsigned(node.children.size());

    // Find any tinyusdz skeletons which might begin at this node
    // Add the skeleton bones as child nodes
    const tinyusdz::tydra::SkelNode *skelNode = nullptr;
    for (const auto &skeleton : skeletons) {
        if (skeleton.abs_path == node.abs_path) {
            // Add this skeleton's bones as child nodes
            ++numChildren;
            skelNode = &skeleton.root_node;
            break;
        }
    }

    cNode->mNumChildren = numChildren;

    // Done. No more children.
    if (numChildren == 0) {
        return cNode;
    }

    cNode->mChildren = new aiNode *[cNode->mNumChildren];

    size_t i{ 0 };
    for (const auto &childNode : node.children) {
        cNode->mChildren[i] = nodesRecursive(cNode, childNode, skeletons);
        ++i;
    }

    if (skelNode != nullptr) {
        // Convert USD skeleton into an Assimp node and make it the last child
        cNode->mChildren[cNode->mNumChildren - 1] = skeletonNodesRecursive(cNode, *skelNode);
    }

    return cNode;
}

aiNode *USDImporterImplTinyusdz::skeletonNodesRecursive(
        aiNode *pNodeParent,
        const SkelNode &joint) {
    auto *cNode = new aiNode(joint.joint_path);
    cNode->mParent = pNodeParent;
    cNode->mNumMeshes = 0; // not a mesh node
    cNode->mTransformation = tinyUsdzMat4ToAiMat4(joint.rest_transform.m);

    // Done. No more children.
    if (joint.children.empty()) {
        return cNode;
    }

    cNode->mNumChildren = static_cast<unsigned int>(joint.children.size());
    cNode->mChildren = new aiNode *[cNode->mNumChildren];

    for (unsigned i = 0; i < cNode->mNumChildren; ++i) {
        const SkelNode &childJoint = joint.children[i];
        cNode->mChildren[i] = skeletonNodesRecursive(cNode, childJoint);
    }

    return cNode;
}

void USDImporterImplTinyusdz::sanityCheckNodesRecursive(
        aiNode *cNode) {
    std::stringstream ss;
    ss.str("");
    ss << "sanityCheckNodesRecursive(): node " << cNode->mName.C_Str();
    if (cNode->mParent != nullptr) {
        ss << " (parent " << cNode->mParent->mName.C_Str() << ")";
    }
    ss << " has " << cNode->mNumChildren << " children";
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    for (size_t i = 0; i < cNode->mNumChildren; ++i) {
        sanityCheckNodesRecursive(cNode->mChildren[i]);
    }
}

void USDImporterImplTinyusdz::setupBlendShapes(const RenderScene &render_scene, aiScene *pScene, 
        const std::string &nameWExt) {
    std::stringstream ss;
    ss.str("");
    ss << "setupBlendShapes(): iterating over " << pScene->mNumMeshes << " meshes for model" << nameWExt;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    for (size_t meshIdx = 0; meshIdx < pScene->mNumMeshes; meshIdx++) {
        blendShapesForMesh(render_scene, pScene, meshIdx, nameWExt);
    }
}

void USDImporterImplTinyusdz::blendShapesForMesh(
        const tinyusdz::tydra::RenderScene &render_scene,
        aiScene *pScene,
        size_t meshIdx,
        const std::string &) {
    std::stringstream ss;
    const unsigned int numBlendShapeTargets{ static_cast<unsigned int>(render_scene.meshes[meshIdx].targets.size()) };
    UNUSED(numBlendShapeTargets); // Ignore unused variable when -Werror enabled
    ss.str("");
    ss << "    blendShapesForMesh(): mesh[" << meshIdx << "], numBlendShapeTargets: " << numBlendShapeTargets;
    TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
    if (numBlendShapeTargets > 0) {
        pScene->mMeshes[meshIdx]->mNumAnimMeshes = numBlendShapeTargets;
        pScene->mMeshes[meshIdx]->mAnimMeshes = new aiAnimMesh *[pScene->mMeshes[meshIdx]->mNumAnimMeshes];
    }
    auto mapIter = render_scene.meshes[meshIdx].targets.begin();
    size_t animMeshIdx{ 0 };
    for (; mapIter != render_scene.meshes[meshIdx].targets.end(); ++mapIter) {
        const std::string name{ mapIter->first };
        const tinyusdz::tydra::ShapeTarget shapeTarget{ mapIter->second };
        pScene->mMeshes[meshIdx]->mAnimMeshes[animMeshIdx] = aiCreateAnimMesh(pScene->mMeshes[meshIdx]);
        ss.str("");
        ss << "        mAnimMeshes[" << animMeshIdx << "]: mNumVertices: " << pScene->mMeshes[meshIdx]->mAnimMeshes[animMeshIdx]->mNumVertices << ", target: " << shapeTarget.pointIndices.size() << " pointIndices, " << shapeTarget.pointOffsets.size() << " pointOffsets, " << shapeTarget.normalOffsets.size() << " normalOffsets";
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        for (size_t iVert = 0; iVert < shapeTarget.pointOffsets.size(); ++iVert) {
            pScene->mMeshes[meshIdx]->mAnimMeshes[animMeshIdx]->mVertices[shapeTarget.pointIndices[iVert]] +=
                    tinyUsdzScaleOrPosToAssimp(shapeTarget.pointOffsets[iVert]);
        }
        for (size_t iVert = 0; iVert < shapeTarget.normalOffsets.size(); ++iVert) {
            pScene->mMeshes[meshIdx]->mAnimMeshes[animMeshIdx]->mNormals[shapeTarget.pointIndices[iVert]] +=
                    tinyUsdzScaleOrPosToAssimp(shapeTarget.normalOffsets[iVert]);
        }
        ss.str("");
        ss << "        target[" << animMeshIdx << "]: name: " << name << ", prim_name: " << shapeTarget.prim_name << ", abs_path: " << shapeTarget.abs_path << ", display_name: " << shapeTarget.display_name << ", " << shapeTarget.pointIndices.size() << " pointIndices, " << shapeTarget.pointOffsets.size() << " pointOffsets, " << shapeTarget.normalOffsets.size() << " normalOffsets, " << shapeTarget.inbetweens.size() << " inbetweens";
        TINYUSDZLOGD(TAG, "%s", ss.str().c_str());
        ++animMeshIdx;
    }
}

} // namespace Assimp

#endif // !! ASSIMP_BUILD_NO_USD_IMPORTER
