// Copyright 2014 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#ifndef CORE_FXCODEC_LGIF_FX_GIF_H_
#define CORE_FXCODEC_LGIF_FX_GIF_H_

#include <memory>
#include <vector>

class CGifContext;

#define GIF_SIGNATURE "GIF"
#define GIF_SIG_EXTENSION 0x21
#define GIF_SIG_IMAGE 0x2C
#define GIF_SIG_TRAILER 0x3B
#define GIF_BLOCK_GCE 0xF9
#define GIF_BLOCK_PTE 0x01
#define GIF_BLOCK_CE 0xFE
#define GIF_BLOCK_AE 0xFF
#define GIF_BLOCK_TERMINAL 0x00
#define GIF_MAX_LZW_CODE 4096
#define GIF_DATA_BLOCK 255
#define GIF_MAX_ERROR_SIZE 256
#define GIF_D_STATUS_SIG 0x01
#define GIF_D_STATUS_TAIL 0x02
#define GIF_D_STATUS_EXT 0x03
#define GIF_D_STATUS_EXT_AE 0x04
#define GIF_D_STATUS_EXT_CE 0x05
#define GIF_D_STATUS_EXT_GCE 0x06
#define GIF_D_STATUS_EXT_PTE 0x07
#define GIF_D_STATUS_EXT_UNE 0x08
#define GIF_D_STATUS_IMG_INFO 0x09
#define GIF_D_STATUS_IMG_DATA 0x0A
#pragma pack(1)
typedef struct tagGifGF {
  uint8_t pal_bits : 3;
  uint8_t sort_flag : 1;
  uint8_t color_resolution : 3;
  uint8_t global_pal : 1;
} GifGF;
typedef struct tagGifLF {
  uint8_t pal_bits : 3;
  uint8_t reserved : 2;
  uint8_t sort_flag : 1;
  uint8_t interlace : 1;
  uint8_t local_pal : 1;
} GifLF;
typedef struct tagGifHeader {
  char signature[3];
  char version[3];
} GifHeader;
typedef struct tagGifLSD {
  uint16_t width;
  uint16_t height;
  uint8_t global_flag;
  uint8_t bc_index;
  uint8_t pixel_aspect;
} GifLSD;
typedef struct tagGifImageInfo {
  uint16_t left;
  uint16_t top;
  uint16_t width;
  uint16_t height;

  uint8_t local_flag;
} GifImageInfo;
typedef struct tagGifCEF {
  uint8_t transparency : 1;
  uint8_t user_input : 1;
  uint8_t disposal_method : 3;
  uint8_t reserved : 3;
} GifCEF;
typedef struct tagGifGCE {
  uint8_t block_size;
  uint8_t gce_flag;
  uint16_t delay_time;
  uint8_t trans_index;
} GifGCE;
typedef struct tagGifPTE {
  uint8_t block_size;
  uint16_t grid_left;
  uint16_t grid_top;
  uint16_t grid_width;
  uint16_t grid_height;

  uint8_t char_width;
  uint8_t char_height;

  uint8_t fc_index;
  uint8_t bc_index;
} GifPTE;
typedef struct tagGifAE {
  uint8_t block_size;
  uint8_t app_identify[8];
  uint8_t app_authentication[3];
} GifAE;
typedef struct tagGifPalette { uint8_t r, g, b; } GifPalette;
#pragma pack()

enum class GifDecodeStatus {
  Error,
  Success,
  Unfinished,
  InsufficientDestSize,  // Only used internally by CGifLZWDecoder::Decode()
};

class GifImage {
 public:
  GifImage();
  ~GifImage();

  std::unique_ptr<GifGCE> m_ImageGCE;
  std::vector<GifPalette> m_LocalPalettes;
  std::vector<uint8_t> m_ImageRowBuf;
  GifImageInfo m_ImageInfo;
  uint8_t image_code_size;
  uint32_t image_data_pos;
  int32_t image_row_num;
};

class CGifLZWDecoder {
 public:
  struct tag_Table {
    uint16_t prefix;
    uint8_t suffix;
  };

  explicit CGifLZWDecoder(char* error_ptr);
  ~CGifLZWDecoder();

  void InitTable(uint8_t code_len);
  GifDecodeStatus Decode(uint8_t* des_buf, uint32_t* des_size);
  void Input(uint8_t* src_buf, uint32_t src_size);
  uint32_t GetAvailInput();

 private:
  void ClearTable();
  void AddCode(uint16_t prefix_code, uint8_t append_char);
  bool DecodeString(uint16_t code);

  uint8_t code_size;
  uint8_t code_size_cur;
  uint16_t code_clear;
  uint16_t code_end;
  uint16_t code_next;
  uint8_t code_first;
  uint8_t stack[GIF_MAX_LZW_CODE];
  uint16_t stack_size;
  tag_Table code_table[GIF_MAX_LZW_CODE];
  uint16_t code_old;

  uint8_t* next_in;
  uint32_t avail_in;

  uint8_t bits_left;
  uint32_t code_store;

  char* err_msg_ptr;
};

static const int32_t s_gif_interlace_step[4] = {8, 8, 4, 2};

GifDecodeStatus gif_read_header(CGifContext* gif_ptr);
GifDecodeStatus gif_get_frame(CGifContext* gif_ptr);
int32_t gif_get_frame_num(CGifContext* gif_ptr);
GifDecodeStatus gif_load_frame(CGifContext* gif_ptr, int32_t frame_num);
void gif_input_buffer(CGifContext* gif_ptr,
                      uint8_t* src_buf,
                      uint32_t src_size);
uint32_t gif_get_avail_input(CGifContext* gif_ptr, uint8_t** avail_buf_ptr);

#endif  // CORE_FXCODEC_LGIF_FX_GIF_H_