/*
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Open Asset Import Library (assimp)
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*/

/** @file  BaseImporter.cpp
 *  @brief Implementation of BaseImporter
 */

#include "FileSystemFilter.h"
#include "Importer.h"
#include <assimp/BaseImporter.h>
#include <assimp/ByteSwapper.h>
#include <assimp/ParsingUtils.h>
#include <assimp/importerdesc.h>
#include <assimp/postprocess.h>
#include <assimp/scene.h>
#include <assimp/Importer.hpp>

#include <cctype>
#include <ios>
#include <list>
#include <memory>
#include <sstream>

namespace {
// Checks whether the passed string is a gcs version.
bool IsGcsVersion(const std::string &s) {
    if (s.empty()) return false;
    return std::all_of(s.cbegin(), s.cend(), [](const char c) {
        // gcs only permits numeric characters.
        return std::isdigit(static_cast<int>(c));
    });
}

// Removes a possible version hash from a filename, as found for example in
// gcs uris (e.g. `gs://bucket/model.glb#1234`), see also
// https://github.com/GoogleCloudPlatform/gsutil/blob/c80f329bc3c4011236c78ce8910988773b2606cb/gslib/storage_url.py#L39.
std::string StripVersionHash(const std::string &filename) {
    const std::string::size_type pos = filename.find_last_of('#');
    // Only strip if the hash is behind a possible file extension and the part
    // behind the hash is a version string.
    if (pos != std::string::npos && pos > filename.find_last_of('.') &&
        IsGcsVersion(filename.substr(pos + 1))) {
        return filename.substr(0, pos);
    }
    return filename;
}
}  // namespace

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
BaseImporter::BaseImporter() AI_NO_EXCEPT
        : m_progress() {
    // empty
}

void BaseImporter::UpdateImporterScale(Importer *pImp) {
    ai_assert(pImp != nullptr);
    ai_assert(importerScale != 0.0);
    ai_assert(fileScale != 0.0);

    double activeScale = importerScale * fileScale;

    // Set active scaling
    pImp->SetPropertyFloat(AI_CONFIG_APP_SCALE_KEY, static_cast<float>(activeScale));

    ASSIMP_LOG_DEBUG("UpdateImporterScale scale set: ", activeScale);
}

// ------------------------------------------------------------------------------------------------
// Imports the given file and returns the imported data.
aiScene *BaseImporter::ReadFile(Importer *pImp, const std::string &pFile, IOSystem *pIOHandler) {

    m_progress = pImp->GetProgressHandler();
    if (nullptr == m_progress) {
        return nullptr;
    }

    ai_assert(m_progress);

    // Gather configuration properties for this run
    SetupProperties(pImp);

    // Construct a file system filter to improve our success ratio at reading external files
    FileSystemFilter filter(pFile, pIOHandler);

    // create a scene object to hold the data
    std::unique_ptr<aiScene> sc(new aiScene());

    // dispatch importing
    try {
        InternReadFile(pFile, sc.get(), &filter);

        // Calculate import scale hook - required because pImp not available anywhere else
        // passes scale into ScaleProcess
        UpdateImporterScale(pImp);

    } catch( const std::exception &err ) {
        // extract error description
        m_ErrorText = err.what();
        ASSIMP_LOG_ERROR(err.what());
        m_Exception = std::current_exception();
        return nullptr;
    }

    // return what we gathered from the import.
    return sc.release();
}

// ------------------------------------------------------------------------------------------------
void BaseImporter::SetupProperties(const Importer *) {
    // the default implementation does nothing
}

// ------------------------------------------------------------------------------------------------
void BaseImporter::GetExtensionList(std::set<std::string> &extensions) {
    const aiImporterDesc *desc = GetInfo();
    ai_assert(desc != nullptr);

    const char *ext = desc->mFileExtensions;
    ai_assert(ext != nullptr);

    const char *last = ext;
    do {
        if (!*ext || *ext == ' ') {
            extensions.insert(std::string(last, ext - last));
            ai_assert(ext - last > 0);
            last = ext;
            while (*last == ' ') {
                ++last;
            }
        }
    } while (*ext++);
}

// ------------------------------------------------------------------------------------------------
/*static*/ bool BaseImporter::SearchFileHeaderForToken(IOSystem *pIOHandler,
        const std::string &pFile,
        const char **tokens,
        std::size_t numTokens,
        unsigned int searchBytes /* = 200 */,
        bool tokensSol /* false */,
        bool noGraphBeforeTokens /* false */) {
    ai_assert(nullptr != tokens);
    ai_assert(0 != numTokens);
    ai_assert(0 != searchBytes);

    if (nullptr == pIOHandler) {
        return false;
    }

    std::unique_ptr<IOStream> pStream(pIOHandler->Open(pFile));
    if (pStream) {
        // read 200 characters from the file
        std::unique_ptr<char[]> _buffer(new char[searchBytes + 1 /* for the '\0' */]);
        char *buffer(_buffer.get());
        const size_t read(pStream->Read(buffer, 1, searchBytes));
        if (0 == read) {
            return false;
        }

        for (size_t i = 0; i < read; ++i) {
            buffer[i] = static_cast<char>(::tolower((unsigned char)buffer[i]));
        }

        // It is not a proper handling of unicode files here ...
        // ehm ... but it works in most cases.
        char *cur = buffer, *cur2 = buffer, *end = &buffer[read];
        while (cur != end) {
            if (*cur) {
                *cur2++ = *cur;
            }
            ++cur;
        }
        *cur2 = '\0';

        std::string token;
        for (unsigned int i = 0; i < numTokens; ++i) {
            ai_assert(nullptr != tokens[i]);
            const size_t len(strlen(tokens[i]));
            token.clear();
            const char *ptr(tokens[i]);
            for (size_t tokIdx = 0; tokIdx < len; ++tokIdx) {
                token.push_back(static_cast<char>(tolower(static_cast<unsigned char>(*ptr))));
                ++ptr;
            }
            const char *r = strstr(buffer, token.c_str());
            if (!r) {
                continue;
            }
            // We need to make sure that we didn't accidentally identify the end of another token as our token,
            // e.g. in a previous version the "gltf " present in some gltf files was detected as "f ", or a
            // Blender-exported glb file containing "Khronos glTF Blender I/O " was detected as "o "
            if (noGraphBeforeTokens && (r != buffer && isgraph(static_cast<unsigned char>(r[-1])))) {
                continue;
            }
            // We got a match, either we don't care where it is, or it happens to
            // be in the beginning of the file / line
            if (!tokensSol || r == buffer || r[-1] == '\r' || r[-1] == '\n') {
                ASSIMP_LOG_DEBUG("Found positive match for header keyword: ", tokens[i]);
                return true;
            }
        }
    }

    return false;
}

// ------------------------------------------------------------------------------------------------
// Simple check for file extension
/*static*/ bool BaseImporter::SimpleExtensionCheck(const std::string &pFile,
        const char *ext0,
        const char *ext1,
        const char *ext2) {
    std::set<std::string> extensions;
    for (const char* ext : {ext0, ext1, ext2}) {
        if (ext == nullptr) continue;
        extensions.emplace(ext);
    }
    return HasExtension(pFile, extensions);
}

// ------------------------------------------------------------------------------------------------
// Check for file extension
/*static*/ bool BaseImporter::HasExtension(const std::string &pFile, const std::set<std::string> &extensions) {
    const std::string file = StripVersionHash(pFile);
    // CAUTION: Do not just search for the extension!
    // GetExtension() returns the part after the *last* dot, but some extensions
    // have dots inside them, e.g. ogre.mesh.xml. Compare the entire end of the
    // string.
    for (const std::string& ext : extensions) {
        // Yay for C++<20 not having std::string::ends_with()
        const std::string dotExt = "." + ext;
        if (dotExt.length() > file.length()) continue;
        // Possible optimization: Fetch the lowercase filename!
        if (0 == ASSIMP_stricmp(file.c_str() + file.length() - dotExt.length(), dotExt.c_str())) {
            return true;
        }
    }
    return false;
}

// ------------------------------------------------------------------------------------------------
// Get file extension from path
std::string BaseImporter::GetExtension(const std::string &pFile) {
    const std::string file = StripVersionHash(pFile);
    std::string::size_type pos = file.find_last_of('.');

    // no file extension at all
    if (pos == std::string::npos) {
        return std::string();
    }

    // thanks to Andy Maloney for the hint
    std::string ret = file.substr(pos + 1);
    ret = ai_tolower(ret);

    return ret;
}


// ------------------------------------------------------------------------------------------------
// Check for magic bytes at the beginning of the file.
/* static */ bool BaseImporter::CheckMagicToken(IOSystem *pIOHandler, const std::string &pFile,
        const void *_magic, std::size_t num, unsigned int offset, unsigned int size) {
    ai_assert(size <= 16);
    ai_assert(_magic);

    if (!pIOHandler) {
        return false;
    }
    const char *magic = reinterpret_cast<const char *>(_magic);
    std::unique_ptr<IOStream> pStream(pIOHandler->Open(pFile));
    if (pStream) {

        // skip to offset
        pStream->Seek(offset, aiOrigin_SET);

        // read 'size' characters from the file
        union {
            char data[16];
            uint16_t data_u16[8];
            uint32_t data_u32[4];
        };
        if (size != pStream->Read(data, 1, size)) {
            return false;
        }

        for (unsigned int i = 0; i < num; ++i) {
            // also check against big endian versions of tokens with size 2,4
            // that's just for convenience, the chance that we cause conflicts
            // is quite low and it can save some lines and prevent nasty bugs
            if (2 == size) {
                uint16_t magic_u16;
                memcpy(&magic_u16, magic, 2);
                if (data_u16[0] == magic_u16 || data_u16[0] == ByteSwap::Swapped(magic_u16)) {
                    return true;
                }
            } else if (4 == size) {
                uint32_t magic_u32;
                memcpy(&magic_u32, magic, 4);
                if (data_u32[0] == magic_u32 || data_u32[0] == ByteSwap::Swapped(magic_u32)) {
                    return true;
                }
            } else {
                // any length ... just compare
                if (!memcmp(magic, data, size)) {
                    return true;
                }
            }
            magic += size;
        }
    }
    return false;
}

#include "utf8.h"

// ------------------------------------------------------------------------------------------------
// Convert to UTF8 data
void BaseImporter::ConvertToUTF8(std::vector<char> &data) {
    //ConversionResult result;
    if (data.size() < 8) {
        throw DeadlyImportError("File is too small");
    }

    // UTF 8 with BOM
    if ((uint8_t)data[0] == 0xEF && (uint8_t)data[1] == 0xBB && (uint8_t)data[2] == 0xBF) {
        ASSIMP_LOG_DEBUG("Found UTF-8 BOM ...");

        std::copy(data.begin() + 3, data.end(), data.begin());
        data.resize(data.size() - 3);
        return;
    }

    // UTF 32 BE with BOM
    if (*((uint32_t *)&data.front()) == 0xFFFE0000) {

        // swap the endianness ..
        for (uint32_t *p = (uint32_t *)&data.front(), *end = (uint32_t *)&data.back(); p <= end; ++p) {
            AI_SWAP4P(p);
        }
    }

    // UTF 32 LE with BOM
    if (*((uint32_t *)&data.front()) == 0x0000FFFE) {
        ASSIMP_LOG_DEBUG("Found UTF-32 BOM ...");

        std::vector<char> output;
        int *ptr = (int *)&data[0];
        int *end = ptr + (data.size() / sizeof(int)) + 1;
        utf8::utf32to8(ptr, end, back_inserter(output));
        return;
    }

    // UTF 16 BE with BOM
    if (*((uint16_t *)&data.front()) == 0xFFFE) {
        // Check to ensure no overflow can happen
        if(data.size() % 2 != 0) {
            return;
        }
        // swap the endianness ..
        for (uint16_t *p = (uint16_t *)&data.front(), *end = (uint16_t *)&data.back(); p <= end; ++p) {
            ByteSwap::Swap2(p);
        }
    }

    // UTF 16 LE with BOM
    if (*((uint16_t *)&data.front()) == 0xFEFF) {
        ASSIMP_LOG_DEBUG("Found UTF-16 BOM ...");

        std::vector<unsigned char> output;
        utf8::utf16to8(data.begin(), data.end(), back_inserter(output));
        return;
    }
}

// ------------------------------------------------------------------------------------------------
// Convert to UTF8 data to ISO-8859-1
void BaseImporter::ConvertUTF8toISO8859_1(std::string &data) {
    size_t size = data.size();
    size_t i = 0, j = 0;

    while (i < size) {
        if ((unsigned char)data[i] < (size_t)0x80) {
            data[j] = data[i];
        } else if (i < size - 1) {
            if ((unsigned char)data[i] == 0xC2) {
                data[j] = data[++i];
            } else if ((unsigned char)data[i] == 0xC3) {
                data[j] = ((unsigned char)data[++i] + 0x40);
            } else {
                std::stringstream stream;
                stream << "UTF8 code " << std::hex << data[i] << data[i + 1] << " can not be converted into ISA-8859-1.";
                ASSIMP_LOG_ERROR(stream.str());

                data[j++] = data[i++];
                data[j] = data[i];
            }
        } else {
            ASSIMP_LOG_ERROR("UTF8 code but only one character remaining");

            data[j] = data[i];
        }

        i++;
        j++;
    }

    data.resize(j);
}

// ------------------------------------------------------------------------------------------------
void BaseImporter::TextFileToBuffer(IOStream *stream,
        std::vector<char> &data,
        TextFileMode mode) {
    ai_assert(nullptr != stream);

    const size_t fileSize = stream->FileSize();
    if (mode == FORBID_EMPTY) {
        if (!fileSize) {
            throw DeadlyImportError("File is empty");
        }
    }

    data.reserve(fileSize + 1);
    data.resize(fileSize);
    if (fileSize > 0) {
        if (fileSize != stream->Read(&data[0], 1, fileSize)) {
            throw DeadlyImportError("File read error");
        }

        ConvertToUTF8(data);
    }

    // append a binary zero to simplify string parsing
    data.push_back(0);
}

// ------------------------------------------------------------------------------------------------
namespace Assimp {
// Represents an import request
struct LoadRequest {
    LoadRequest(const std::string &_file, unsigned int _flags, const BatchLoader::PropertyMap *_map, unsigned int _id) :
            file(_file),
            flags(_flags),
            refCnt(1),
            scene(nullptr),
            loaded(false),
            id(_id) {
        if (_map) {
            map = *_map;
        }
    }

    bool operator==(const std::string &f) const {
        return file == f;
    }

    const std::string file;
    unsigned int flags;
    unsigned int refCnt;
    aiScene *scene;
    bool loaded;
    BatchLoader::PropertyMap map;
    unsigned int id;
};
} // namespace Assimp

// ------------------------------------------------------------------------------------------------
// BatchLoader::pimpl data structure
struct Assimp::BatchData {
    BatchData(IOSystem *pIO, bool validate) :
            pIOSystem(pIO), pImporter(nullptr), next_id(0xffff), validate(validate) {
        ai_assert(nullptr != pIO);

        pImporter = new Importer();
        pImporter->SetIOHandler(pIO);
    }

    ~BatchData() {
        pImporter->SetIOHandler(nullptr); /* get pointer back into our possession */
        delete pImporter;
    }

    // IO system to be used for all imports
    IOSystem *pIOSystem;

    // Importer used to load all meshes
    Importer *pImporter;

    // List of all imports
    std::list<LoadRequest> requests;

    // Base path
    std::string pathBase;

    // Id for next item
    unsigned int next_id;

    // Validation enabled state
    bool validate;
};

typedef std::list<LoadRequest>::iterator LoadReqIt;

// ------------------------------------------------------------------------------------------------
BatchLoader::BatchLoader(IOSystem *pIO, bool validate) {
    ai_assert(nullptr != pIO);

    m_data = new BatchData(pIO, validate);
}

// ------------------------------------------------------------------------------------------------
BatchLoader::~BatchLoader() {
    // delete all scenes what have not been polled by the user
    for (LoadReqIt it = m_data->requests.begin(); it != m_data->requests.end(); ++it) {
        delete (*it).scene;
    }
    delete m_data;
}

// ------------------------------------------------------------------------------------------------
void BatchLoader::setValidation(bool enabled) {
    m_data->validate = enabled;
}

// ------------------------------------------------------------------------------------------------
bool BatchLoader::getValidation() const {
    return m_data->validate;
}

// ------------------------------------------------------------------------------------------------
unsigned int BatchLoader::AddLoadRequest(const std::string &file,
        unsigned int steps /*= 0*/, const PropertyMap *map /*= nullptr*/) {
    ai_assert(!file.empty());

    // check whether we have this loading request already
    for (LoadReqIt it = m_data->requests.begin(); it != m_data->requests.end(); ++it) {
        // Call IOSystem's path comparison function here
        if (m_data->pIOSystem->ComparePaths((*it).file, file)) {
            if (map) {
                if (!((*it).map == *map)) {
                    continue;
                }
            } else if (!(*it).map.empty()) {
                continue;
            }

            (*it).refCnt++;
            return (*it).id;
        }
    }

    // no, we don't have it. So add it to the queue ...
    m_data->requests.emplace_back(file, steps, map, m_data->next_id);
    return m_data->next_id++;
}

// ------------------------------------------------------------------------------------------------
aiScene *BatchLoader::GetImport(unsigned int which) {
    for (LoadReqIt it = m_data->requests.begin(); it != m_data->requests.end(); ++it) {
        if ((*it).id == which && (*it).loaded) {
            aiScene *sc = (*it).scene;
            if (!(--(*it).refCnt)) {
                m_data->requests.erase(it);
            }
            return sc;
        }
    }
    return nullptr;
}

// ------------------------------------------------------------------------------------------------
void BatchLoader::LoadAll() {
    // no threaded implementation for the moment
    for (LoadReqIt it = m_data->requests.begin(); it != m_data->requests.end(); ++it) {
        // force validation in debug builds
        unsigned int pp = (*it).flags;
        if (m_data->validate) {
            pp |= aiProcess_ValidateDataStructure;
        }

        // setup config properties if necessary
        ImporterPimpl *pimpl = m_data->pImporter->Pimpl();
        pimpl->mFloatProperties = (*it).map.floats;
        pimpl->mIntProperties = (*it).map.ints;
        pimpl->mStringProperties = (*it).map.strings;
        pimpl->mMatrixProperties = (*it).map.matrices;

        if (!DefaultLogger::isNullLogger()) {
            ASSIMP_LOG_INFO("%%% BEGIN EXTERNAL FILE %%%");
            ASSIMP_LOG_INFO("File: ", (*it).file);
        }
        m_data->pImporter->ReadFile((*it).file, pp);
        (*it).scene = m_data->pImporter->GetOrphanedScene();
        (*it).loaded = true;

        ASSIMP_LOG_INFO("%%% END EXTERNAL FILE %%%");
    }
}