Module refinery.lib.rtfc

"""
Compressed Rich Text Format (RTF) compression and decompression, see also the
official [Microsoft documentation][MS].
This code is derived from the [Python package by Dmitry Alimov][DA].

The original work is copyright (c) 2016 Dmitry Alimov.

The source code has been modified to fit the code requirements of this project.

The original implementation is covered by an MIT license. Regardless of the
license used for the binary refinery, this code file is also subject to the
terms and conditions of the MIT license, which is included here:

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.

[MS]: https://msdn.microsoft.com/en-us/library/cc463890(v=exchg.80).aspx
[DA]: https://github.com/delimitry/compressed_rtf
"""
from __future__ import annotations

from io import BytesIO

__all__ = ['compress', 'decompress']

_INIT_DICT = (
    b'{\\rtf1\\ansi\\mac\\deff0\\deftab720{\\fonttbl;}{\\f0\\fnil \\froman '
    b'\\fswiss \\fmodern \\fscript \\fdecor MS Sans SerifSymbolArialTimes N'
    b'ew RomanCourier{\\colortbl\\red0\\green0\\blue0\r\n\\par \\pard\\plai'
    b'n\\f0\\fs20\\b\\i\\u\\tab\\tx')

_INIT_DICT_SIZE = len(_INIT_DICT)
_MAX_DICT_SIZE = 4096

_COMPRESSED = b'LZFu'
_UNCOMPRESSED = b'MELA'

_CRC32_TABLE = [
    0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
    0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
    0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
    0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
    0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
    0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
    0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
    0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
    0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
    0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
    0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
    0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
    0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
    0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
    0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
    0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
    0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
    0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
    0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
    0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
    0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
    0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
    0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
    0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
    0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
    0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
    0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
    0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
    0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
    0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
    0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
    0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D,
]


def _crc32(data: bytes | bytearray | memoryview) -> int:
    crc = 0x00000000
    for b in data:
        crc = _CRC32_TABLE[(crc ^ b) & 0xFF] ^ (crc >> 8)
    return crc


def _make_dict() -> list[int]:
    d = list(_INIT_DICT) + [0x20] * (_MAX_DICT_SIZE - _INIT_DICT_SIZE)
    return d


def _find_longest_match(
    dictionary: list[int],
    stream: BytesIO,
    write_offset: int,
) -> tuple[int, int, int]:
    char = stream.read(1)
    if not char:
        return 0, 0, write_offset
    prev_write_offset = write_offset
    dict_index = 0
    match_len = 0
    longest_match_len = 0
    dict_offset = 0
    while True:
        if dictionary[dict_index % _MAX_DICT_SIZE] == char[0]:
            match_len += 1
            if match_len <= 17 and match_len > longest_match_len:
                dict_offset = dict_index - match_len + 1
                dictionary[write_offset] = char[0]
                write_offset = (write_offset + 1) % _MAX_DICT_SIZE
                longest_match_len = match_len
            char = stream.read(1)
            if not char:
                stream.seek(stream.tell() - match_len, 0)
                return dict_offset, longest_match_len, write_offset
        else:
            stream.seek(stream.tell() - match_len - 1, 0)
            match_len = 0
            char = stream.read(1)
            if not char:
                break
        dict_index += 1
        if dict_index >= prev_write_offset + longest_match_len:
            break
    stream.seek(stream.tell() - match_len - 1, 0)
    return dict_offset, longest_match_len, write_offset


def compress(data: bytes | bytearray | memoryview, compressed: bool = True) -> bytes:
    output = bytearray()

    if compressed:
        comp_type = _COMPRESSED
        dictionary = _make_dict()
        write_offset = _INIT_DICT_SIZE
        in_stream = BytesIO(bytes(data))
        control_byte = 0
        control_bit = 1
        token_offset = 0
        token_buffer = bytearray()

        while True:
            dict_offset, longest_match, write_offset = _find_longest_match(
                dictionary, in_stream, write_offset)
            char = in_stream.read(longest_match if longest_match > 1 else 1)
            if not char:
                control_byte |= 1 << (control_bit - 1)
                control_bit += 1
                token_offset += 2
                dict_ref = (write_offset & 0xFFF) << 4
                token_buffer.append((dict_ref >> 8) & 0xFF)
                token_buffer.append(dict_ref & 0xFF)
                output.append(control_byte)
                output.extend(token_buffer[:token_offset])
                break
            else:
                if longest_match > 1:
                    control_byte |= 1 << (control_bit - 1)
                    control_bit += 1
                    token_offset += 2
                    dict_ref = (dict_offset & 0xFFF) << 4 | (longest_match - 2) & 0xF
                    token_buffer.append((dict_ref >> 8) & 0xFF)
                    token_buffer.append(dict_ref & 0xFF)
                else:
                    if longest_match == 0:
                        dictionary[write_offset] = char[0]
                        write_offset = (write_offset + 1) % _MAX_DICT_SIZE
                    control_bit += 1
                    token_offset += 1
                    token_buffer.extend(char)
                longest_match = 0
                if control_bit > 8:
                    output.append(control_byte)
                    output.extend(token_buffer[:token_offset])
                    control_byte = 0
                    control_bit = 1
                    token_offset = 0
                    token_buffer = bytearray()

        crc_value = _crc32(output)
    else:
        comp_type = _UNCOMPRESSED
        output.extend(data)
        crc_value = 0x00000000

    comp_size = (len(output) + 12).to_bytes(4, 'little')
    raw_size = len(data).to_bytes(4, 'little')
    crc_bytes = crc_value.to_bytes(4, 'little')
    return comp_size + raw_size + comp_type + crc_bytes + bytes(output)


def decompress(data: bytes | bytearray | memoryview) -> bytes:
    if len(data) < 16:
        raise ValueError('Data must be at least 16 bytes long')

    mv = memoryview(data)

    comp_size = int.from_bytes(mv[0:4], 'little')
    raw_size = int.from_bytes(mv[4:8], 'little')
    comp_type = bytes(mv[8:12])
    crc_value = int.from_bytes(mv[12:16], 'little')

    contents = mv[16:comp_size + 4]

    if comp_type == _COMPRESSED:
        if crc_value != _crc32(contents):
            raise ValueError('CRC is invalid! The file is corrupt!')

        dictionary = _make_dict()
        write_offset = _INIT_DICT_SIZE
        output = bytearray()
        pos = 0
        end = len(contents)

        while pos < end:
            control = contents[pos]
            pos += 1
            for i in range(8):
                if pos >= end:
                    break
                if control & (1 << i):
                    if pos + 1 >= end:
                        break
                    token = (contents[pos] << 8) | contents[pos + 1]
                    pos += 2
                    offset = (token >> 4) & 0xFFF
                    length = (token & 0xF) + 2
                    if write_offset == offset:
                        return bytes(output)
                    for step in range(length):
                        read_offset = (offset + step) % _MAX_DICT_SIZE
                        val = dictionary[read_offset]
                        output.append(val)
                        dictionary[write_offset] = val
                        write_offset = (write_offset + 1) % _MAX_DICT_SIZE
                else:
                    val = contents[pos]
                    pos += 1
                    output.append(val)
                    dictionary[write_offset] = val
                    write_offset = (write_offset + 1) % _MAX_DICT_SIZE

        return bytes(output)

    elif comp_type == _UNCOMPRESSED:
        if crc_value != 0x00000000:
            raise ValueError('CRC is invalid! Must be 0x00000000!')
        return bytes(contents[:raw_size])

    else:
        raise ValueError('Unknown type of RTF compression!')