/*
Open Asset Import Library (assimp)
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*/

/** @file  BlenderDNA.cpp
 *  @brief Implementation of the Blender `DNA`, that is its own
 *    serialized set of data structures.
 */

#ifndef ASSIMP_BUILD_NO_BLEND_IMPORTER
#include "BlenderDNA.h"
#include <assimp/StreamReader.h>
#include <assimp/TinyFormatter.h>
#include <assimp/fast_atof.h>

using namespace Assimp;
using namespace Assimp::Blender;
using namespace Assimp::Formatter;

static bool match4(StreamReaderAny &stream, const char *string) {
    ai_assert(nullptr != string);
    char tmp[4];
    tmp[0] = (stream).GetI1();
    tmp[1] = (stream).GetI1();
    tmp[2] = (stream).GetI1();
    tmp[3] = (stream).GetI1();
    return (tmp[0] == string[0] && tmp[1] == string[1] && tmp[2] == string[2] && tmp[3] == string[3]);
}

struct Type {
    size_t size;
    std::string name;
};

// ------------------------------------------------------------------------------------------------
void DNAParser::Parse() {
    StreamReaderAny &stream = *db.reader.get();
    DNA &dna = db.dna;

    if (!match4(stream, "SDNA")) {
        throw DeadlyImportError("BlenderDNA: Expected SDNA chunk");
    }

    // name dictionary
    if (!match4(stream, "NAME")) {
        throw DeadlyImportError("BlenderDNA: Expected NAME field");
    }

    std::vector<std::string> names(stream.GetI4());
    for (std::string &s : names) {
        while (char c = stream.GetI1()) {
            s += c;
        }
    }

    // type dictionary
    for (; stream.GetCurrentPos() & 0x3; stream.GetI1())
        ;
    if (!match4(stream, "TYPE")) {
        throw DeadlyImportError("BlenderDNA: Expected TYPE field");
    }

    std::vector<Type> types(stream.GetI4());
    for (Type &s : types) {
        while (char c = stream.GetI1()) {
            s.name += c;
        }
    }

    // type length dictionary
    for (; stream.GetCurrentPos() & 0x3; stream.GetI1())
        ;
    if (!match4(stream, "TLEN")) {
        throw DeadlyImportError("BlenderDNA: Expected TLEN field");
    }

    for (Type &s : types) {
        s.size = stream.GetI2();
    }

    // structures dictionary
    for (; stream.GetCurrentPos() & 0x3; stream.GetI1())
        ;
    if (!match4(stream, "STRC")) {
        throw DeadlyImportError("BlenderDNA: Expected STRC field");
    }

    size_t end = stream.GetI4(), fields = 0;

    dna.structures.reserve(end);
    for (size_t i = 0; i != end; ++i) {

        uint16_t n = stream.GetI2();
        if (n >= types.size()) {
            throw DeadlyImportError("BlenderDNA: Invalid type index in structure name", n, " (there are only ", types.size(), " entries)");
        }

        // maintain separate indexes
        dna.indices[types[n].name] = dna.structures.size();

        dna.structures.push_back(Structure());
        Structure &s = dna.structures.back();
        s.name = types[n].name;

        n = stream.GetI2();
        s.fields.reserve(n);

        size_t offset = 0;
        for (size_t m = 0; m < n; ++m, ++fields) {

            uint16_t j = stream.GetI2();
            if (j >= types.size()) {
                throw DeadlyImportError("BlenderDNA: Invalid type index in structure field ", j, " (there are only ", types.size(), " entries)");
            }
            s.fields.push_back(Field());
            Field &f = s.fields.back();
            f.offset = offset;

            f.type = types[j].name;
            f.size = types[j].size;

            j = stream.GetI2();
            if (j >= names.size()) {
                throw DeadlyImportError("BlenderDNA: Invalid name index in structure field ", j, " (there are only ", names.size(), " entries)");
            }

            f.name = names[j];
            f.flags = 0u;

            // pointers always specify the size of the pointee instead of their own.
            // The pointer asterisk remains a property of the lookup name.
            if (f.name[0] == '*') {
                f.size = db.i64bit ? 8 : 4;
                f.flags |= FieldFlag_Pointer;
            }

            // arrays, however, specify the size of a single element so we
            // need to parse the (possibly multi-dimensional) array declaration
            // in order to obtain the actual size of the array in the file.
            // Also we need to alter the lookup name to include no array
            // brackets anymore or size fixup won't work (if our size does
            // not match the size read from the DNA).
            if (*f.name.rbegin() == ']') {
                const std::string::size_type rb = f.name.find('[');
                if (rb == std::string::npos) {
                    throw DeadlyImportError("BlenderDNA: Encountered invalid array declaration ", f.name);
                }

                f.flags |= FieldFlag_Array;
                DNA::ExtractArraySize(f.name, f.array_sizes);
                f.name = f.name.substr(0, rb);

                f.size *= f.array_sizes[0] * f.array_sizes[1];
            }

            // maintain separate indexes
            s.indices[f.name] = s.fields.size() - 1;
            offset += f.size;
        }
        s.size = offset;
    }

    ASSIMP_LOG_DEBUG_F("BlenderDNA: Got ", dna.structures.size(), " structures with totally ", fields, " fields");

#ifdef ASSIMP_BUILD_BLENDER_DEBUG
    dna.DumpToFile();
#endif

    dna.AddPrimitiveStructures();
    dna.RegisterConverters();
}

#ifdef ASSIMP_BUILD_BLENDER_DEBUG

#include <fstream>
// ------------------------------------------------------------------------------------------------
void DNA ::DumpToFile() {
    // we don't bother using the VFS here for this is only for debugging.
    // (and all your bases are belong to us).

    std::ofstream f("dna.txt");
    if (f.fail()) {
        ASSIMP_LOG_ERROR("Could not dump dna to dna.txt");
        return;
    }
    f << "Field format: type name offset size"
      << "\n";
    f << "Structure format: name size"
      << "\n";

    for (const Structure &s : structures) {
        f << s.name << " " << s.size << "\n\n";
        for (const Field &ff : s.fields) {
            f << "\t" << ff.type << " " << ff.name << " " << ff.offset << " " << ff.size << "\n";
        }
        f << "\n";
    }
    f << std::flush;

    ASSIMP_LOG_INFO("BlenderDNA: Dumped dna to dna.txt");
}
#endif

// ------------------------------------------------------------------------------------------------
/*static*/ void DNA ::ExtractArraySize(
        const std::string &out,
        size_t array_sizes[2]) {
    array_sizes[0] = array_sizes[1] = 1;
    std::string::size_type pos = out.find('[');
    if (pos++ == std::string::npos) {
        return;
    }
    array_sizes[0] = strtoul10(&out[pos]);

    pos = out.find('[', pos);
    if (pos++ == std::string::npos) {
        return;
    }
    array_sizes[1] = strtoul10(&out[pos]);
}

// ------------------------------------------------------------------------------------------------
std::shared_ptr<ElemBase> DNA ::ConvertBlobToStructure(
        const Structure &structure,
        const FileDatabase &db) const {
    std::map<std::string, FactoryPair>::const_iterator it = converters.find(structure.name);
    if (it == converters.end()) {
        return std::shared_ptr<ElemBase>();
    }

    std::shared_ptr<ElemBase> ret = (structure.*((*it).second.first))();
    (structure.*((*it).second.second))(ret, db);

    return ret;
}

// ------------------------------------------------------------------------------------------------
DNA::FactoryPair DNA ::GetBlobToStructureConverter(
        const Structure &structure,
        const FileDatabase & /*db*/
) const {
    std::map<std::string, FactoryPair>::const_iterator it = converters.find(structure.name);
    return it == converters.end() ? FactoryPair() : (*it).second;
}

// basing on http://www.blender.org/development/architecture/notes-on-sdna/
// ------------------------------------------------------------------------------------------------
void DNA ::AddPrimitiveStructures() {
    // NOTE: these are just dummies. Their presence enforces
    // Structure::Convert<target_type> to be called on these
    // empty structures. These converters are special
    // overloads which scan the name of the structure and
    // perform the required data type conversion if one
    // of these special names is found in the structure
    // in question.

    indices["int"] = structures.size();
    structures.push_back(Structure());
    structures.back().name = "int";
    structures.back().size = 4;

    indices["short"] = structures.size();
    structures.push_back(Structure());
    structures.back().name = "short";
    structures.back().size = 2;

    indices["char"] = structures.size();
    structures.push_back(Structure());
    structures.back().name = "char";
    structures.back().size = 1;

    indices["float"] = structures.size();
    structures.push_back(Structure());
    structures.back().name = "float";
    structures.back().size = 4;

    indices["double"] = structures.size();
    structures.push_back(Structure());
    structures.back().name = "double";
    structures.back().size = 8;

    // no long, seemingly.
}

// ------------------------------------------------------------------------------------------------
void SectionParser ::Next() {
    stream.SetCurrentPos(current.start + current.size);

    const char tmp[] = {
        (const char)stream.GetI1(),
        (const char)stream.GetI1(),
        (const char)stream.GetI1(),
        (const char)stream.GetI1()
    };
    current.id = std::string(tmp, tmp[3] ? 4 : tmp[2] ? 3 : tmp[1] ? 2 : 1);

    current.size = stream.GetI4();
    current.address.val = ptr64 ? stream.GetU8() : stream.GetU4();

    current.dna_index = stream.GetI4();
    current.num = stream.GetI4();

    current.start = stream.GetCurrentPos();
    if (stream.GetRemainingSizeToLimit() < current.size) {
        throw DeadlyImportError("BLEND: invalid size of file block");
    }

#ifdef ASSIMP_BUILD_BLENDER_DEBUG
    ASSIMP_LOG_VERBOSE_DEBUG(current.id);
#endif
}

#endif
