Slightly reorganise the project structure

telethon/extensions/binary_reader.py

@@ -0,0 +1,168 @@
+import os
+from datetime import datetime
+from io import BufferedReader, BytesIO
+from struct import unpack
+
+from ..errors import InvalidParameterError, TypeNotFoundError
+from ..tl.all_tlobjects import tlobjects
+
+
+class BinaryReader:
+    """
+    Small utility class to read binary data.
+    Also creates a "Memory Stream" if necessary
+    """
+
+    def __init__(self, data=None, stream=None):
+        if data:
+            self.stream = BytesIO(data)
+        elif stream:
+            self.stream = stream
+        else:
+            raise InvalidParameterError(
+                'Either bytes or a stream must be provided')
+
+        self.reader = BufferedReader(self.stream)
+
+    # region Reading
+
+    # "All numbers are written as little endian." |> Source: https://core.telegram.org/mtproto
+    def read_byte(self):
+        """Reads a single byte value"""
+        return self.read(1)[0]
+
+    def read_int(self, signed=True):
+        """Reads an integer (4 bytes) value"""
+        return int.from_bytes(self.read(4), byteorder='little', signed=signed)
+
+    def read_long(self, signed=True):
+        """Reads a long integer (8 bytes) value"""
+        return int.from_bytes(self.read(8), byteorder='little', signed=signed)
+
+    def read_float(self):
+        """Reads a real floating point (4 bytes) value"""
+        return unpack('<f', self.read(4))[0]
+
+    def read_double(self):
+        """Reads a real floating point (8 bytes) value"""
+        return unpack('<d', self.read(8))[0]
+
+    def read_large_int(self, bits, signed=True):
+        """Reads a n-bits long integer value"""
+        return int.from_bytes(
+            self.read(bits // 8), byteorder='little', signed=signed)
+
+    def read(self, length):
+        """Read the given amount of bytes"""
+        result = self.reader.read(length)
+        if len(result) != length:
+            raise BufferError(
+                'Trying to read outside the data bounds (no more data left to read)')
+
+        return result
+
+    def get_bytes(self):
+        """Gets the byte array representing the current buffer as a whole"""
+        return self.stream.getvalue()
+
+    # endregion
+
+    # region Telegram custom reading
+
+    def tgread_bytes(self):
+        """Reads a Telegram-encoded byte array, without the need of specifying its length"""
+        first_byte = self.read_byte()
+        if first_byte == 254:
+            length = self.read_byte() | (self.read_byte() << 8) | (
+                self.read_byte() << 16)
+            padding = length % 4
+        else:
+            length = first_byte
+            padding = (length + 1) % 4
+
+        data = self.read(length)
+        if padding > 0:
+            padding = 4 - padding
+            self.read(padding)
+
+        return data
+
+    def tgread_string(self):
+        """Reads a Telegram-encoded string"""
+        return str(self.tgread_bytes(), encoding='utf-8', errors='replace')
+
+    def tgread_bool(self):
+        """Reads a Telegram boolean value"""
+        value = self.read_int(signed=False)
+        if value == 0x997275b5:  # boolTrue
+            return True
+        elif value == 0xbc799737:  # boolFalse
+            return False
+        else:
+            raise ValueError('Invalid boolean code {}'.format(hex(value)))
+
+    def tgread_date(self):
+        """Reads and converts Unix time (used by Telegram) into a Python datetime object"""
+        value = self.read_int()
+        return None if value == 0 else datetime.fromtimestamp(value)
+
+    def tgread_object(self):
+        """Reads a Telegram object"""
+        constructor_id = self.read_int(signed=False)
+        clazz = tlobjects.get(constructor_id, None)
+        if clazz is None:
+            # The class was None, but there's still a
+            # chance of it being a manually parsed value like bool!
+            value = constructor_id
+            if value == 0x997275b5:  # boolTrue
+                return True
+            elif value == 0xbc799737:  # boolFalse
+                return False
+
+            # If there was still no luck, give up
+            raise TypeNotFoundError(constructor_id)
+
+        # Create an empty instance of the class and
+        # fill it with the read attributes
+        result = clazz.empty()
+        result.on_response(self)
+        return result
+
+    def tgread_vector(self):
+        """Reads a vector (a list) of Telegram objects"""
+        if 0x1cb5c415 != self.read_int(signed=False):
+            raise ValueError('Invalid constructor code, vector was expected')
+
+        count = self.read_int()
+        return [self.tgread_object() for _ in range(count)]
+
+    # endregion
+
+    def close(self):
+        self.reader.close()
+
+    # region Position related
+
+    def tell_position(self):
+        """Tells the current position on the stream"""
+        return self.reader.tell()
+
+    def set_position(self, position):
+        """Sets the current position on the stream"""
+        self.reader.seek(position)
+
+    def seek(self, offset):
+        """Seeks the stream position given an offset from the current position. May be negative"""
+        self.reader.seek(offset, os.SEEK_CUR)
+
+    # endregion
+
+    # region with block
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.close()
+
+    # endregion