/// Functions used to read raw binary data from .nif files

#ifndef OPENMW_COMPONENTS_NIF_NIFSTREAM_HPP
#define OPENMW_COMPONENTS_NIF_NIFSTREAM_HPP

#include <cassert>
#include <istream>
#include <stdexcept>
#include <stdint.h>
#include <type_traits>
#include <vector>

#include <components/files/istreamptr.hpp>
#include <components/misc/endianness.hpp>
#include <components/misc/float16.hpp>

#include <osg/Quat>
#include <osg/Vec3f>
#include <osg/Vec4f>

#include "niftypes.hpp"

namespace Nif
{

    class Reader;

    template <class T>
    struct is_arithmetic
        : std::integral_constant<bool, std::is_arithmetic_v<T> || std::is_same<T, Misc::float16_t>::value>
    {
    };

    template <std::size_t numInstances, typename T>
    inline void readLittleEndianBufferOfType(Files::IStreamPtr& pIStream, T* dest)
    {
        static_assert(is_arithmetic<T>(), "Buffer element type is not arithmetic");
        pIStream->read((char*)dest, numInstances * sizeof(T));
        if (pIStream->bad())
            throw std::runtime_error("Failed to read little endian typed (" + std::string(typeid(T).name())
                + ") buffer of " + std::to_string(numInstances) + " instances");
        if constexpr (Misc::IS_BIG_ENDIAN)
            for (std::size_t i = 0; i < numInstances; i++)
                Misc::swapEndiannessInplace(dest[i]);
    }

    template <typename T>
    inline void readLittleEndianDynamicBufferOfType(Files::IStreamPtr& pIStream, T* dest, std::size_t numInstances)
    {
        static_assert(is_arithmetic<T>(), "Buffer element type is not arithmetic");
        pIStream->read((char*)dest, numInstances * sizeof(T));
        if (pIStream->bad())
            throw std::runtime_error(
                "Failed to read little endian dynamic buffer of " + std::to_string(numInstances) + " instances");
        if constexpr (Misc::IS_BIG_ENDIAN)
            for (std::size_t i = 0; i < numInstances; i++)
                Misc::swapEndiannessInplace(dest[i]);
    }
    template <typename type>
    type inline readLittleEndianType(Files::IStreamPtr& pIStream)
    {
        type val;
        readLittleEndianBufferOfType<1, type>(pIStream, &val);
        return val;
    }

    class NIFStream
    {
        const Reader& file;

        /// Input stream
        Files::IStreamPtr inp;

    public:
        explicit NIFStream(const Reader& file, Files::IStreamPtr&& inp)
            : file(file)
            , inp(std::move(inp))
        {
        }

        const Reader& getFile() const { return file; }

        void skip(size_t size) { inp->ignore(size); }

        template <class T>
        void read(T& data)
        {
            data = readLittleEndianType<T>(inp);
        }

        void read(osg::Vec2f& data) { readLittleEndianBufferOfType<2, float>(inp, data._v); }
        void read(osg::Vec3f& data) { readLittleEndianBufferOfType<3, float>(inp, data._v); }
        void read(osg::Vec4f& data) { readLittleEndianBufferOfType<4, float>(inp, data._v); }

        template <class T>
        T get()
        {
            return readLittleEndianType<T>(inp);
        }

        template <class T>
        void readVector(std::vector<T>& vec, size_t size)
        {
            vec.resize(size);
            readLittleEndianDynamicBufferOfType<T>(inp, vec.data(), size);
        }

        template <class T, size_t size>
        void readArray(std::array<T, size>& arr)
        {
            readLittleEndianDynamicBufferOfType<T>(inp, arr.data(), size);
        }

        // DEPRECATED: Use read() or get() whenever relevant
        char getChar() { return readLittleEndianType<char>(inp); }

        // DEPRECATED: Use read() or get() whenever relevant
        short getShort() { return readLittleEndianType<short>(inp); }

        // DEPRECATED: Use read() or get() whenever relevant
        unsigned short getUShort() { return readLittleEndianType<unsigned short>(inp); }

        // DEPRECATED: Use read() or get() whenever relevant
        int getInt() { return readLittleEndianType<int>(inp); }

        // DEPRECATED: Use read() or get() whenever relevant
        unsigned int getUInt() { return readLittleEndianType<unsigned int>(inp); }

        // DEPRECATED: Use read() or get() whenever relevant
        float getFloat() { return readLittleEndianType<float>(inp); }

        osg::Vec2f getVector2()
        {
            osg::Vec2f vec;
            readLittleEndianBufferOfType<2, float>(inp, vec._v);
            return vec;
        }

        // DEPRECATED: Use read() whenever relevant
        osg::Vec3f getVector3()
        {
            osg::Vec3f vec;
            readLittleEndianBufferOfType<3, float>(inp, vec._v);
            return vec;
        }

        osg::Vec4f getVector4()
        {
            osg::Vec4f vec;
            readLittleEndianBufferOfType<4, float>(inp, vec._v);
            return vec;
        }

        Matrix3 getMatrix3()
        {
            Matrix3 mat;
            readLittleEndianBufferOfType<9, float>(inp, (float*)&mat.mValues);
            return mat;
        }

        osg::Quat getQuaternion();

        Transformation getTrafo();

        bool getBoolean();

        std::string getString();

        unsigned int getVersion() const;
        unsigned int getUserVersion() const;
        unsigned int getBethVersion() const;

        // Convert human-readable version numbers into a number that can be compared.
        static constexpr uint32_t generateVersion(uint8_t major, uint8_t minor, uint8_t patch, uint8_t rev)
        {
            return (major << 24) + (minor << 16) + (patch << 8) + rev;
        }

        /// Read in a string of the given length
        std::string getSizedString(size_t length)
        {
            std::string str(length, '\0');
            inp->read(str.data(), length);
            if (inp->bad())
                throw std::runtime_error("Failed to read sized string of " + std::to_string(length) + " chars");
            size_t end = str.find('\0');
            if (end != std::string::npos)
                str.erase(end);
            return str;
        }
        /// Read in a string of the length specified in the file
        std::string getSizedString()
        {
            size_t size = readLittleEndianType<uint32_t>(inp);
            return getSizedString(size);
        }

        /// Specific to Bethesda headers, uses a byte for length
        std::string getExportString()
        {
            size_t size = static_cast<size_t>(readLittleEndianType<uint8_t>(inp));
            return getSizedString(size);
        }

        /// This is special since the version string doesn't start with a number, and ends with "\n"
        std::string getVersionString()
        {
            std::string result;
            std::getline(*inp, result);
            if (inp->bad())
                throw std::runtime_error("Failed to read version string");
            return result;
        }

        /// Read a sequence of null-terminated strings
        std::string getStringPalette()
        {
            size_t size = readLittleEndianType<uint32_t>(inp);
            std::string str(size, '\0');
            inp->read(str.data(), size);
            if (inp->bad())
                throw std::runtime_error("Failed to read string palette of " + std::to_string(size) + " chars");
            return str;
        }

        // DEPRECATED: Use readVector()
        void getChars(std::vector<char>& vec, size_t size)
        {
            vec.resize(size);
            readLittleEndianDynamicBufferOfType<char>(inp, vec.data(), size);
        }

        // DEPRECATED: Use readVector()
        void getUChars(std::vector<unsigned char>& vec, size_t size)
        {
            vec.resize(size);
            readLittleEndianDynamicBufferOfType<unsigned char>(inp, vec.data(), size);
        }

        // DEPRECATED: Use readVector()
        void getUShorts(std::vector<unsigned short>& vec, size_t size)
        {
            vec.resize(size);
            readLittleEndianDynamicBufferOfType<unsigned short>(inp, vec.data(), size);
        }

        // DEPRECATED: Use readVector()
        void getFloats(std::vector<float>& vec, size_t size)
        {
            vec.resize(size);
            readLittleEndianDynamicBufferOfType<float>(inp, vec.data(), size);
        }

        // DEPRECATED: Use readVector()
        void getInts(std::vector<int>& vec, size_t size)
        {
            vec.resize(size);
            readLittleEndianDynamicBufferOfType<int>(inp, vec.data(), size);
        }

        // DEPRECATED: Use readVector()
        void getUInts(std::vector<unsigned int>& vec, size_t size)
        {
            vec.resize(size);
            readLittleEndianDynamicBufferOfType<unsigned int>(inp, vec.data(), size);
        }

        void getVector2s(std::vector<osg::Vec2f>& vec, size_t size)
        {
            vec.resize(size);
            /* The packed storage of each Vec2f is 2 floats exactly */
            readLittleEndianDynamicBufferOfType<float>(inp, (float*)vec.data(), size * 2);
        }

        void getVector3s(std::vector<osg::Vec3f>& vec, size_t size)
        {
            vec.resize(size);
            /* The packed storage of each Vec3f is 3 floats exactly */
            readLittleEndianDynamicBufferOfType<float>(inp, (float*)vec.data(), size * 3);
        }

        void getVector4s(std::vector<osg::Vec4f>& vec, size_t size)
        {
            vec.resize(size);
            /* The packed storage of each Vec4f is 4 floats exactly */
            readLittleEndianDynamicBufferOfType<float>(inp, (float*)vec.data(), size * 4);
        }

        void getQuaternions(std::vector<osg::Quat>& quat, size_t size)
        {
            quat.resize(size);
            for (size_t i = 0; i < quat.size(); i++)
                quat[i] = getQuaternion();
        }

        void getStrings(std::vector<std::string>& vec, size_t size)
        {
            vec.resize(size);
            for (size_t i = 0; i < vec.size(); i++)
                vec[i] = getString();
        }
        /// We need to use this when the string table isn't actually initialized.
        void getSizedStrings(std::vector<std::string>& vec, size_t size)
        {
            vec.resize(size);
            for (size_t i = 0; i < vec.size(); i++)
                vec[i] = getSizedString();
        }
    };

}

#endif