[cleanup, utils] Split into submodules (#7090)

Closes https://github.com/yt-dlp/yt-dlp/pull/2173

Authored by: pukkandan, coletdjnz
Co-authored-by: pukkandan <pukkandan.ytdlp@gmail.com>

yt_dlp/utils/_legacy.py

@@ -0,0 +1,163 @@
+"""No longer used and new code should not use. Exists only for API compat."""
+
+import platform
+import struct
+import sys
+import urllib.parse
+import zlib
+
+from ._utils import decode_base_n, preferredencoding
+from .traversal import traverse_obj
+from ..dependencies import certifi, websockets
+
+has_certifi = bool(certifi)
+has_websockets = bool(websockets)
+
+
+def load_plugins(name, suffix, namespace):
+    from ..plugins import load_plugins
+    ret = load_plugins(name, suffix)
+    namespace.update(ret)
+    return ret
+
+
+def traverse_dict(dictn, keys, casesense=True):
+    return traverse_obj(dictn, keys, casesense=casesense, is_user_input=True, traverse_string=True)
+
+
+def decode_base(value, digits):
+    return decode_base_n(value, table=digits)
+
+
+def platform_name():
+    """ Returns the platform name as a str """
+    return platform.platform()
+
+
+def get_subprocess_encoding():
+    if sys.platform == 'win32' and sys.getwindowsversion()[0] >= 5:
+        # For subprocess calls, encode with locale encoding
+        # Refer to http://stackoverflow.com/a/9951851/35070
+        encoding = preferredencoding()
+    else:
+        encoding = sys.getfilesystemencoding()
+    if encoding is None:
+        encoding = 'utf-8'
+    return encoding
+
+
+# UNUSED
+# Based on png2str() written by @gdkchan and improved by @yokrysty
+# Originally posted at https://github.com/ytdl-org/youtube-dl/issues/9706
+def decode_png(png_data):
+    # Reference: https://www.w3.org/TR/PNG/
+    header = png_data[8:]
+
+    if png_data[:8] != b'\x89PNG\x0d\x0a\x1a\x0a' or header[4:8] != b'IHDR':
+        raise OSError('Not a valid PNG file.')
+
+    int_map = {1: '>B', 2: '>H', 4: '>I'}
+    unpack_integer = lambda x: struct.unpack(int_map[len(x)], x)[0]
+
+    chunks = []
+
+    while header:
+        length = unpack_integer(header[:4])
+        header = header[4:]
+
+        chunk_type = header[:4]
+        header = header[4:]
+
+        chunk_data = header[:length]
+        header = header[length:]
+
+        header = header[4:]  # Skip CRC
+
+        chunks.append({
+            'type': chunk_type,
+            'length': length,
+            'data': chunk_data
+        })
+
+    ihdr = chunks[0]['data']
+
+    width = unpack_integer(ihdr[:4])
+    height = unpack_integer(ihdr[4:8])
+
+    idat = b''
+
+    for chunk in chunks:
+        if chunk['type'] == b'IDAT':
+            idat += chunk['data']
+
+    if not idat:
+        raise OSError('Unable to read PNG data.')
+
+    decompressed_data = bytearray(zlib.decompress(idat))
+
+    stride = width * 3
+    pixels = []
+
+    def _get_pixel(idx):
+        x = idx % stride
+        y = idx // stride
+        return pixels[y][x]
+
+    for y in range(height):
+        basePos = y * (1 + stride)
+        filter_type = decompressed_data[basePos]
+
+        current_row = []
+
+        pixels.append(current_row)
+
+        for x in range(stride):
+            color = decompressed_data[1 + basePos + x]
+            basex = y * stride + x
+            left = 0
+            up = 0
+
+            if x > 2:
+                left = _get_pixel(basex - 3)
+            if y > 0:
+                up = _get_pixel(basex - stride)
+
+            if filter_type == 1:  # Sub
+                color = (color + left) & 0xff
+            elif filter_type == 2:  # Up
+                color = (color + up) & 0xff
+            elif filter_type == 3:  # Average
+                color = (color + ((left + up) >> 1)) & 0xff
+            elif filter_type == 4:  # Paeth
+                a = left
+                b = up
+                c = 0
+
+                if x > 2 and y > 0:
+                    c = _get_pixel(basex - stride - 3)
+
+                p = a + b - c
+
+                pa = abs(p - a)
+                pb = abs(p - b)
+                pc = abs(p - c)
+
+                if pa <= pb and pa <= pc:
+                    color = (color + a) & 0xff
+                elif pb <= pc:
+                    color = (color + b) & 0xff
+                else:
+                    color = (color + c) & 0xff
+
+            current_row.append(color)
+
+    return width, height, pixels
+
+
+def register_socks_protocols():
+    # "Register" SOCKS protocols
+    # In Python < 2.6.5, urlsplit() suffers from bug https://bugs.python.org/issue7904
+    # URLs with protocols not in urlparse.uses_netloc are not handled correctly
+    for scheme in ('socks', 'socks4', 'socks4a', 'socks5'):
+        if scheme not in urllib.parse.uses_netloc:
+            urllib.parse.uses_netloc.append(scheme)