/* SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup imbdds
 */

/*
 * This file is based on a similar file from the NVIDIA texture tools
 * (http://nvidia-texture-tools.googlecode.com/)
 *
 * Original license from NVIDIA follows.
 */

/* Copyright NVIDIA Corporation 2007 -- Ignacio Castano <icastano@nvidia.com>
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE. */

#pragma once

#include <Color.h>
#include <ColorBlock.h>
#include <Common.h>
#include <Stream.h>

/** DXT1 block. */
struct BlockDXT1 {
  Color16 col0;
  Color16 col1;
  union {
    uint8 row[4];
    uint indices;
  };

  bool isFourColorMode() const;

  uint evaluatePalette(Color32 color_array[4]) const;
  uint evaluatePaletteNV5x(Color32 color_array[4]) const;

  /** Evaluate palette assuming 3 color block. */
  void evaluatePalette3(Color32 color_array[4]) const;
  /** Evaluate palette assuming 4 color block. */
  void evaluatePalette4(Color32 color_array[4]) const;

  void decodeBlock(ColorBlock *block) const;
  void decodeBlockNV5x(ColorBlock *block) const;

  void setIndices(const int *idx);

  /** Flip DXT1 block vertically. */
  void flip4();
  /** Flip half DXT1 block vertically. */
  void flip2();
};

/** Return true if the block uses four color mode, false otherwise. */
inline bool BlockDXT1::isFourColorMode() const
{
  return col0.u > col1.u;
}

/** DXT3 alpha block with explicit alpha. */
struct AlphaBlockDXT3 {
  union {
    struct {
      uint alpha0 : 4;
      uint alpha1 : 4;
      uint alpha2 : 4;
      uint alpha3 : 4;
      uint alpha4 : 4;
      uint alpha5 : 4;
      uint alpha6 : 4;
      uint alpha7 : 4;
      uint alpha8 : 4;
      uint alpha9 : 4;
      uint alphaA : 4;
      uint alphaB : 4;
      uint alphaC : 4;
      uint alphaD : 4;
      uint alphaE : 4;
      uint alphaF : 4;
    };
    uint16 row[4];
  };

  void decodeBlock(ColorBlock *block) const;

  /** Flip DXT3 alpha block vertically. */
  void flip4();
  /** Flip half DXT3 alpha block vertically. */
  void flip2();
};

/** DXT3 block. */
struct BlockDXT3 {
  AlphaBlockDXT3 alpha;
  BlockDXT1 color;

  void decodeBlock(ColorBlock *block) const;
  void decodeBlockNV5x(ColorBlock *block) const;

  /** Flip DXT3 block vertically. */
  void flip4();
  /** Flip half DXT3 block vertically. */
  void flip2();
};

/** DXT5 alpha block. */
struct AlphaBlockDXT5 {
  /* uint64 unions do not compile on all platforms */
#if 0
  union {
    struct {
      uint64 alpha0 : 8;  /* 8 */
      uint64 alpha1 : 8;  /* 16 */
      uint64 bits0 : 3;   /* 3 - 19 */
      uint64 bits1 : 3;   /* 6 - 22 */
      uint64 bits2 : 3;   /* 9 - 25 */
      uint64 bits3 : 3;   /* 12 - 28 */
      uint64 bits4 : 3;   /* 15 - 31 */
      uint64 bits5 : 3;   /* 18 - 34 */
      uint64 bits6 : 3;   /* 21 - 37 */
      uint64 bits7 : 3;   /* 24 - 40 */
      uint64 bits8 : 3;   /* 27 - 43 */
      uint64 bits9 : 3;   /* 30 - 46 */
      uint64 bitsA : 3;   /* 33 - 49 */
      uint64 bitsB : 3;   /* 36 - 52 */
      uint64 bitsC : 3;   /* 39 - 55 */
      uint64 bitsD : 3;   /* 42 - 58 */
      uint64 bitsE : 3;   /* 45 - 61 */
      uint64 bitsF : 3;   /* 48 - 64 */
    };
    uint64 u;
  };
#endif
  uint64 u;
  uint8 alpha0() const
  {
    return u & 0xffLL;
  }
  uint8 alpha1() const
  {
    return (u >> 8) & 0xffLL;
  }
  uint8 bits0() const
  {
    return (u >> 16) & 0x7LL;
  }
  uint8 bits1() const
  {
    return (u >> 19) & 0x7LL;
  }
  uint8 bits2() const
  {
    return (u >> 22) & 0x7LL;
  }
  uint8 bits3() const
  {
    return (u >> 25) & 0x7LL;
  }
  uint8 bits4() const
  {
    return (u >> 28) & 0x7LL;
  }
  uint8 bits5() const
  {
    return (u >> 31) & 0x7LL;
  }
  uint8 bits6() const
  {
    return (u >> 34) & 0x7LL;
  }
  uint8 bits7() const
  {
    return (u >> 37) & 0x7LL;
  }
  uint8 bits8() const
  {
    return (u >> 40) & 0x7LL;
  }
  uint8 bits9() const
  {
    return (u >> 43) & 0x7LL;
  }
  uint8 bitsA() const
  {
    return (u >> 46) & 0x7LL;
  }
  uint8 bitsB() const
  {
    return (u >> 49) & 0x7LL;
  }
  uint8 bitsC() const
  {
    return (u >> 52) & 0x7LL;
  }
  uint8 bitsD() const
  {
    return (u >> 55) & 0x7LL;
  }
  uint8 bitsE() const
  {
    return (u >> 58) & 0x7LL;
  }
  uint8 bitsF() const
  {
    return (u >> 61) & 0x7LL;
  }

  void evaluatePalette(uint8 alpha[8]) const;
  void evaluatePalette8(uint8 alpha[8]) const;
  void evaluatePalette6(uint8 alpha[8]) const;
  void indices(uint8 index_array[16]) const;

  uint index(uint index) const;
  void setIndex(uint index, uint value);

  void decodeBlock(ColorBlock *block) const;

  void flip4();
  void flip2();
};

/** DXT5 block. */
struct BlockDXT5 {
  AlphaBlockDXT5 alpha;
  BlockDXT1 color;

  void decodeBlock(ColorBlock *block) const;
  void decodeBlockNV5x(ColorBlock *block) const;

  /** Flip DXT5 block vertically. */
  void flip4();
  /** Flip half DXT5 block vertically. */
  void flip2();
};

/** ATI1 block. */
struct BlockATI1 {
  AlphaBlockDXT5 alpha;

  /** Decode ATI1 block. */
  void decodeBlock(ColorBlock *block) const;

  /** Flip ATI1 block vertically. */
  void flip4();
  /** Flip half ATI1 block vertically. */
  void flip2();
};

/** ATI2 block. */
struct BlockATI2 {
  AlphaBlockDXT5 x;
  AlphaBlockDXT5 y;

  /** Decode ATI2 block. */
  void decodeBlock(ColorBlock *block) const;

  /** Flip ATI2 block vertically. */
  void flip4();
  /** Flip half ATI2 block vertically. */
  void flip2();
};

/** CTX1 block. */
struct BlockCTX1 {
  uint8 col0[2];
  uint8 col1[2];
  union {
    uint8 row[4];
    uint indices;
  };

  void evaluatePalette(Color32 color_array[4]) const;
  void setIndices(const int *idx);

  void decodeBlock(ColorBlock *block) const;

  /** Flip CTX1 block vertically. */
  void flip4();
  /** Flip half CTX1 block vertically. */
  void flip2();
};

void mem_read(Stream &mem, BlockDXT1 &block);
void mem_read(Stream &mem, AlphaBlockDXT3 &block);
void mem_read(Stream &mem, BlockDXT3 &block);
void mem_read(Stream &mem, AlphaBlockDXT5 &block);
void mem_read(Stream &mem, BlockDXT5 &block);
void mem_read(Stream &mem, BlockATI1 &block);
void mem_read(Stream &mem, BlockATI2 &block);
void mem_read(Stream &mem, BlockCTX1 &block);