/*
Copyright (c) 2013. The YARA Authors. All Rights Reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors
may be used to endorse or promote products derived from this software without
specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#ifndef YR_RE_H
#define YR_RE_H

#include <ctype.h>

#include "arena.h"
#include "sizedstr.h"

#define RE_NODE_LITERAL             1
#define RE_NODE_MASKED_LITERAL      2
#define RE_NODE_ANY                 3
#define RE_NODE_CONCAT              4
#define RE_NODE_ALT                 5
#define RE_NODE_RANGE               6
#define RE_NODE_STAR                7
#define RE_NODE_PLUS                8
#define RE_NODE_CLASS               9
#define RE_NODE_WORD_CHAR           10
#define RE_NODE_NON_WORD_CHAR       11
#define RE_NODE_SPACE               12
#define RE_NODE_NON_SPACE           13
#define RE_NODE_DIGIT               14
#define RE_NODE_NON_DIGIT           15
#define RE_NODE_EMPTY               16
#define RE_NODE_ANCHOR_START        17
#define RE_NODE_ANCHOR_END          18
#define RE_NODE_WORD_BOUNDARY       19
#define RE_NODE_NON_WORD_BOUNDARY   20
#define RE_NODE_RANGE_ANY           21


#define RE_OPCODE_ANY                   0xA0
#define RE_OPCODE_ANY_EXCEPT_NEW_LINE   0xA1
#define RE_OPCODE_LITERAL               0xA2
#define RE_OPCODE_MASKED_LITERAL        0xA4
#define RE_OPCODE_CLASS                 0xA5
#define RE_OPCODE_WORD_CHAR             0xA7
#define RE_OPCODE_NON_WORD_CHAR         0xA8
#define RE_OPCODE_SPACE                 0xA9
#define RE_OPCODE_NON_SPACE             0xAA
#define RE_OPCODE_DIGIT                 0xAB
#define RE_OPCODE_NON_DIGIT             0xAC
#define RE_OPCODE_MATCH                 0xAD

#define RE_OPCODE_MATCH_AT_END          0xB0
#define RE_OPCODE_MATCH_AT_START        0xB1
#define RE_OPCODE_WORD_BOUNDARY         0xB2
#define RE_OPCODE_NON_WORD_BOUNDARY     0xB3
#define RE_OPCODE_REPEAT_ANY_GREEDY     0xB4
#define RE_OPCODE_REPEAT_ANY_UNGREEDY   0xB5

#define RE_OPCODE_SPLIT_A               0xC0
#define RE_OPCODE_SPLIT_B               0xC1
#define RE_OPCODE_JUMP                  0xC2
#define RE_OPCODE_REPEAT_START_GREEDY   0xC3
#define RE_OPCODE_REPEAT_END_GREEDY     0xC4
#define RE_OPCODE_REPEAT_START_UNGREEDY 0xC5
#define RE_OPCODE_REPEAT_END_UNGREEDY   0xC6


#define RE_FLAGS_FAST_REGEXP            0x02
#define RE_FLAGS_BACKWARDS              0x04
#define RE_FLAGS_EXHAUSTIVE             0x08
#define RE_FLAGS_WIDE                   0x10
#define RE_FLAGS_NO_CASE                0x20
#define RE_FLAGS_SCAN                   0x40
#define RE_FLAGS_DOT_ALL                0x80
#define RE_FLAGS_GREEDY                0x400
#define RE_FLAGS_UNGREEDY              0x800


typedef struct RE RE;
typedef struct RE_AST RE_AST;
typedef struct RE_NODE RE_NODE;
typedef struct RE_ERROR RE_ERROR;

typedef uint8_t RE_SPLIT_ID_TYPE;


struct RE_NODE
{
    int type;

    union
    {
        int value;
        int count;
        int start;
    };

    union
    {
        int mask;
        int end;
    };

    int greedy;

    uint8_t* class_vector;

    RE_NODE* left;
    RE_NODE* right;

    uint8_t* forward_code;
    uint8_t* backward_code;
};


struct RE_AST
{
    uint32_t flags;
    RE_NODE* root_node;
};


// Disable warning due to zero length array in Microsoft's compiler

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable:4200)
#endif

struct RE
{
    uint32_t flags;
    uint8_t code[0];
};

#ifdef _MSC_VER
#pragma warning(pop)
#endif


struct RE_ERROR
{
    char message[512];
};


typedef int RE_MATCH_CALLBACK_FUNC(
    uint8_t* match,
    int match_length,
    int flags,
    void* args);


int yr_re_ast_create(
    RE_AST** re_ast);

void yr_re_ast_destroy(
    RE_AST* re_ast);

void yr_re_ast_print(
    RE_AST* re_ast);

SIZED_STRING* yr_re_ast_extract_literal(
    RE_AST* re_ast);


int yr_re_ast_contains_dot_star(
    RE_AST* re_ast);


int yr_re_ast_split_at_chaining_point(
    RE_AST* re_ast,
    RE_AST** result_re_ast,
    RE_AST** remainder_re_ast,
    int32_t* min_gap,
    int32_t* max_gap);


int yr_re_ast_emit_code(
    RE_AST* re_ast,
    YR_ARENA* arena,
    int backwards_code);


RE_NODE* yr_re_node_create(
    int type,
    RE_NODE* left,
    RE_NODE* right);


void yr_re_node_destroy(
    RE_NODE* node);


int yr_re_exec(
    uint8_t* re_code,
    uint8_t* input,
    size_t input_forwards_size,
    size_t input_backwards_size,
    int flags,
    RE_MATCH_CALLBACK_FUNC callback,
    void* callback_args,
    int* matches);


int yr_re_fast_exec(
    uint8_t* code,
    uint8_t* input_data,
    size_t input_forwards_size,
    size_t input_backwards_size,
    int flags,
    RE_MATCH_CALLBACK_FUNC callback,
    void* callback_args,
    int* matches);


int yr_re_parse(
    const char* re_string,
    RE_AST** re_ast,
    RE_ERROR* error);


int yr_re_parse_hex(
    const char* hex_string,
    RE_AST** re_ast,
    RE_ERROR* error);


int yr_re_compile(
    const char* re_string,
    int flags,
    YR_ARENA* code_arena,
    RE** re,
    RE_ERROR* error);


int yr_re_match(
    RE* re,
    const char* target);


int yr_re_initialize(void);


int yr_re_finalize(void);


int yr_re_finalize_thread(void);

#endif
