Implement mining

pytchat/paramgen/arcparam_mining.py

@@ -0,0 +1,133 @@
+from base64 import urlsafe_b64encode as b64enc
+from functools import reduce
+import math
+import random
+import urllib.parse
+
+'''
+Generate continuation parameter of youtube replay chat.
+
+Author: taizan-hokuto (2019) @taizan205
+
+ver 0.0.1 2019.10.05
+'''
+
+def _gen_vid_long(video_id):
+    """generate video_id parameter.
+    Parameter
+    ---------
+        video_id : str
+
+    Return
+    ---------
+    byte[] : base64 encoded video_id parameter.
+    """
+    header_magic = b'\x0A\x0F\x1A\x0D\x0A'
+    header_id =  video_id.encode()
+    header_sep_1 = b'\x1A\x13\xEA\xA8\xDD\xB9\x01\x0D\x0A\x0B'
+    header_terminator = b'\x20\x01'
+
+    item = [
+        header_magic,
+        _nval(len(header_id)),
+        header_id,
+        header_sep_1,
+        header_id,
+        header_terminator
+    ]
+
+    return urllib.parse.quote(
+        b64enc(reduce(lambda x, y: x+y, item)).decode()
+    ).encode()
+
+def _gen_vid(video_id):
+    """generate video_id parameter.
+    Parameter
+    ---------
+        video_id : str
+
+    Return
+    ---------
+        bytes : base64 encoded video_id parameter.
+    """
+    header_magic = b'\x0A\x0F\x1A\x0D\x0A'
+    header_id =  video_id.encode()
+    header_terminator = b'\x20\x01'
+
+    item = [
+        header_magic,
+        _nval(len(header_id)),
+        header_id,
+        header_terminator
+    ]
+
+    return urllib.parse.quote(
+        b64enc(reduce(lambda x, y: x+y, item)).decode()
+    ).encode()
+
+def _nval(val):
+    """convert value to byte array"""
+    if val<0: raise ValueError
+    buf = b''
+    while val >> 7:
+        m = val & 0xFF | 0x80
+        buf += m.to_bytes(1,'big')
+        val >>= 7
+    buf += val.to_bytes(1,'big')
+    return buf
+
+def _build(video_id, seektime, topchat_only):
+    switch_01 = b'\x04' if topchat_only else b'\x01'
+    if seektime < 0:
+        raise ValueError("seektime must be greater than or equal to zero.")
+    if seektime == 0:
+        times = b''
+    else:
+        times =_nval(int(seektime*1000))
+    if seektime > 0:
+        _len_time = ( b'\x5A'
+                    + (len(times)+1).to_bytes(1,'big')
+                    + b'\x10')
+    else:
+        _len_time = b''
+    
+    header_magic = b'\xA2\x9D\xB0\xD3\x04'
+    sep_0        = b'\x1A'
+    vid          = _gen_vid(video_id)
+    _tag         = b'\x40\x01'
+    timestamp1   = times
+    sep_1        = b'\x60\x04\x72\x02\x08'
+    terminator   = b'\x78\x01'
+
+    body = [
+        sep_0,
+        _nval(len(vid)),
+        vid,
+        _tag,
+        _len_time,
+        timestamp1,
+        sep_1,
+        switch_01,
+        terminator
+    ]
+
+    body = reduce(lambda x, y: x+y, body)
+    
+    return  urllib.parse.quote(
+                b64enc( header_magic +
+                        _nval(len(body)) +
+                        body
+                ).decode()
+            )
+
+def getparam(video_id, seektime = 0.0, topchat_only = False):
+    '''
+    Parameter
+    ---------
+    seektime : int
+        unit:seconds
+        start position of fetching chat data.
+    topchat_only : bool
+        if True, fetch only 'top chat'
+    '''
+    return _build(video_id, seektime, topchat_only)