//========= Copyright Valve Corporation, All rights reserved. ============//
//
//	LZSS Codec. Designed for fast cheap gametime encoding/decoding.
//Compression results
//	are	not aggresive as other alogrithms, but gets 2:1 on most
//arbitrary uncompressed data.
//
//=====================================================================================//

#ifndef _LZSS_H
#define _LZSS_H
#pragma once

#define LZSS_ID uint32(BigLong(('L' << 24) | ('Z' << 16) | ('S' << 8) | ('S')))
#define SNAPPY_ID \
    uint32(BigLong(('S' << 24) | ('N' << 16) | ('A' << 8) | ('P')))

// bind the buffer for correct identification
struct lzss_header_t {
    unsigned int id;
    unsigned int actualSize;  // always little endian
};

class CUtlBuffer;

#define DEFAULT_LZSS_WINDOW_SIZE 4096

class CLZSS {
   public:
    unsigned char *Compress(const unsigned char *pInput, int inputlen,
                            unsigned int *pOutputSize);
    unsigned char *CompressNoAlloc(const unsigned char *pInput, int inputlen,
                                   unsigned char *pOutput,
                                   unsigned int *pOutputSize);
    unsigned int Uncompress(const unsigned char *pInput,
                            unsigned char *pOutput);
    // unsigned int	Uncompress( unsigned char *pInput, CUtlBuffer &buf );
    unsigned int SafeUncompress(const unsigned char *pInput,
                                unsigned char *pOutput, unsigned int unBufSize);

    static bool IsCompressed(const unsigned char *pInput);
    static unsigned int GetActualSize(const unsigned char *pInput);

    // windowsize must be a power of two.
    FORCEINLINE CLZSS(int nWindowSize = DEFAULT_LZSS_WINDOW_SIZE);

   private:
    // expected to be sixteen bytes
    struct lzss_node_t {
        const unsigned char *pData;
        lzss_node_t *pPrev;
        lzss_node_t *pNext;
        char empty[4];
    };

    struct lzss_list_t {
        lzss_node_t *pStart;
        lzss_node_t *pEnd;
    };

    void BuildHash(const unsigned char *pData);
    lzss_list_t *m_pHashTable;
    lzss_node_t *m_pHashTarget;
    int m_nWindowSize;
};

FORCEINLINE CLZSS::CLZSS(int nWindowSize) { m_nWindowSize = nWindowSize; }
#endif