/*
  Copyright (C) 2015-2016, 2018, 2020 cc9cii

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.

  cc9cii cc9c@iinet.net.au

  Much of the information on the data structures are based on the information
  from Tes4Mod:Mod_File_Format and Tes5Mod:File_Formats but also refined by
  trial & error.  See http://en.uesp.net/wiki for details.

*/
#ifndef ESM4_LAND_H
#define ESM4_LAND_H

#include <cstdint>
#include <vector>

#include <components/esm/defs.hpp>
#include <components/esm/formid.hpp>

namespace ESM4
{
    class Reader;

    struct Land
    {
        enum
        {
            LAND_VNML = 1,
            LAND_VHGT = 2,
            LAND_WNAM = 4, // only in TES3?
            LAND_VCLR = 8,
            LAND_VTEX = 16
        };

        // number of vertices per side
        static constexpr unsigned sVertsPerSide = 33;

        // cell terrain size in world coords
        static constexpr unsigned sRealSize = 4096;

        // total number of vertices
        static constexpr unsigned sLandNumVerts = sVertsPerSide * sVertsPerSide;

        static constexpr unsigned sHeightScale = 8;

        // number of textures per side of a land quadrant
        // (for TES4 - based on vanilla observations)
        static constexpr unsigned sQuadTexturePerSide = 6;

#pragma pack(push, 1)
        struct VHGT
        {
            float heightOffset;
            std::int8_t gradientData[sVertsPerSide * sVertsPerSide];
            std::uint16_t unknown1;
            std::uint8_t unknown2;
        };

        struct BTXT
        {
            ESM::FormId32 formId;
            std::uint8_t quadrant; // 0 = bottom left, 1 = bottom right, 2 = top left, 3 = top right
            std::uint8_t unknown1;
            std::uint16_t unknown2;
        };

        struct ATXT
        {
            ESM::FormId32 formId;
            std::uint8_t quadrant; // 0 = bottom left, 1 = bottom right, 2 = top left, 3 = top right
            std::uint8_t unknown;
            std::uint16_t layerIndex; // texture layer, 0..7
        };

        struct VTXT
        {
            std::uint16_t position; // 0..288 (17x17 grid)
            std::uint8_t unknown1;
            std::uint8_t unknown2;
            float opacity;
        };
#pragma pack(pop)

        struct TxtLayer
        {
            ATXT texture;
            std::vector<VTXT> data; // alpha data
        };

        struct Texture
        {
            BTXT base;
            std::vector<TxtLayer> layers;
        };

        ESM::FormId mId; // from the header
        std::uint32_t mFlags; // from the header, see enum type RecordFlag for details

        std::uint32_t mLandFlags; // from DATA subrecord

        // FIXME: lazy loading not yet implemented
        int mDataTypes; // which data types are loaded

        float mHeights[sVertsPerSide * sVertsPerSide]; // Float value of compressed Heightmap
        std::int8_t mVertNorm[sVertsPerSide * sVertsPerSide * 3]; // from VNML subrecord
        std::uint8_t mVertColr[sVertsPerSide * sVertsPerSide * 3]; // from VCLR subrecord
        VHGT mHeightMap;
        Texture mTextures[4]; // 0 = bottom left, 1 = bottom right, 2 = top left, 3 = top right
        std::vector<ESM::FormId> mIds; // land texture (LTEX) formids
        ESM::FormId mCell;

        void load(Reader& reader);

        // void save(Writer& writer) const;

        // void blank();

        static constexpr ESM::RecNameInts sRecordId = ESM::REC_LAND4;
    };
}

#endif // ESM4_LAND_H