--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/idna/core.py	Sun May 05 23:32:17 2024 -0400
@@ -0,0 +1,395 @@
+from . import idnadata
+import bisect
+import unicodedata
+import re
+from typing import Union, Optional
+from .intranges import intranges_contain
+
+_virama_combining_class = 9
+_alabel_prefix = b'xn--'
+_unicode_dots_re = re.compile('[\u002e\u3002\uff0e\uff61]')
+
+class IDNAError(UnicodeError):
+    """ Base exception for all IDNA-encoding related problems """
+    pass
+
+
+class IDNABidiError(IDNAError):
+    """ Exception when bidirectional requirements are not satisfied """
+    pass
+
+
+class InvalidCodepoint(IDNAError):
+    """ Exception when a disallowed or unallocated codepoint is used """
+    pass
+
+
+class InvalidCodepointContext(IDNAError):
+    """ Exception when the codepoint is not valid in the context it is used """
+    pass
+
+
+def _combining_class(cp: int) -> int:
+    v = unicodedata.combining(chr(cp))
+    if v == 0:
+        if not unicodedata.name(chr(cp)):
+            raise ValueError('Unknown character in unicodedata')
+    return v
+
+def _is_script(cp: str, script: str) -> bool:
+    return intranges_contain(ord(cp), idnadata.scripts[script])
+
+def _punycode(s: str) -> bytes:
+    return s.encode('punycode')
+
+def _unot(s: int) -> str:
+    return 'U+{:04X}'.format(s)
+
+
+def valid_label_length(label: Union[bytes, str]) -> bool:
+    if len(label) > 63:
+        return False
+    return True
+
+
+def valid_string_length(label: Union[bytes, str], trailing_dot: bool) -> bool:
+    if len(label) > (254 if trailing_dot else 253):
+        return False
+    return True
+
+
+def check_bidi(label: str, check_ltr: bool = False) -> bool:
+    # Bidi rules should only be applied if string contains RTL characters
+    bidi_label = False
+    for (idx, cp) in enumerate(label, 1):
+        direction = unicodedata.bidirectional(cp)
+        if direction == '':
+            # String likely comes from a newer version of Unicode
+            raise IDNABidiError('Unknown directionality in label {} at position {}'.format(repr(label), idx))
+        if direction in ['R', 'AL', 'AN']:
+            bidi_label = True
+    if not bidi_label and not check_ltr:
+        return True
+
+    # Bidi rule 1
+    direction = unicodedata.bidirectional(label[0])
+    if direction in ['R', 'AL']:
+        rtl = True
+    elif direction == 'L':
+        rtl = False
+    else:
+        raise IDNABidiError('First codepoint in label {} must be directionality L, R or AL'.format(repr(label)))
+
+    valid_ending = False
+    number_type = None  # type: Optional[str]
+    for (idx, cp) in enumerate(label, 1):
+        direction = unicodedata.bidirectional(cp)
+
+        if rtl:
+            # Bidi rule 2
+            if not direction in ['R', 'AL', 'AN', 'EN', 'ES', 'CS', 'ET', 'ON', 'BN', 'NSM']:
+                raise IDNABidiError('Invalid direction for codepoint at position {} in a right-to-left label'.format(idx))
+            # Bidi rule 3
+            if direction in ['R', 'AL', 'EN', 'AN']:
+                valid_ending = True
+            elif direction != 'NSM':
+                valid_ending = False
+            # Bidi rule 4
+            if direction in ['AN', 'EN']:
+                if not number_type:
+                    number_type = direction
+                else:
+                    if number_type != direction:
+                        raise IDNABidiError('Can not mix numeral types in a right-to-left label')
+        else:
+            # Bidi rule 5
+            if not direction in ['L', 'EN', 'ES', 'CS', 'ET', 'ON', 'BN', 'NSM']:
+                raise IDNABidiError('Invalid direction for codepoint at position {} in a left-to-right label'.format(idx))
+            # Bidi rule 6
+            if direction in ['L', 'EN']:
+                valid_ending = True
+            elif direction != 'NSM':
+                valid_ending = False
+
+    if not valid_ending:
+        raise IDNABidiError('Label ends with illegal codepoint directionality')
+
+    return True
+
+
+def check_initial_combiner(label: str) -> bool:
+    if unicodedata.category(label[0])[0] == 'M':
+        raise IDNAError('Label begins with an illegal combining character')
+    return True
+
+
+def check_hyphen_ok(label: str) -> bool:
+    if label[2:4] == '--':
+        raise IDNAError('Label has disallowed hyphens in 3rd and 4th position')
+    if label[0] == '-' or label[-1] == '-':
+        raise IDNAError('Label must not start or end with a hyphen')
+    return True
+
+
+def check_nfc(label: str) -> None:
+    if unicodedata.normalize('NFC', label) != label:
+        raise IDNAError('Label must be in Normalization Form C')
+
+
+def valid_contextj(label: str, pos: int) -> bool:
+    cp_value = ord(label[pos])
+
+    if cp_value == 0x200c:
+
+        if pos > 0:
+            if _combining_class(ord(label[pos - 1])) == _virama_combining_class:
+                return True
+
+        ok = False
+        for i in range(pos-1, -1, -1):
+            joining_type = idnadata.joining_types.get(ord(label[i]))
+            if joining_type == ord('T'):
+                continue
+            elif joining_type in [ord('L'), ord('D')]:
+                ok = True
+                break
+            else:
+                break
+
+        if not ok:
+            return False
+
+        ok = False
+        for i in range(pos+1, len(label)):
+            joining_type = idnadata.joining_types.get(ord(label[i]))
+            if joining_type == ord('T'):
+                continue
+            elif joining_type in [ord('R'), ord('D')]:
+                ok = True
+                break
+            else:
+                break
+        return ok
+
+    if cp_value == 0x200d:
+
+        if pos > 0:
+            if _combining_class(ord(label[pos - 1])) == _virama_combining_class:
+                return True
+        return False
+
+    else:
+
+        return False
+
+
+def valid_contexto(label: str, pos: int, exception: bool = False) -> bool:
+    cp_value = ord(label[pos])
+
+    if cp_value == 0x00b7:
+        if 0 < pos < len(label)-1:
+            if ord(label[pos - 1]) == 0x006c and ord(label[pos + 1]) == 0x006c:
+                return True
+        return False
+
+    elif cp_value == 0x0375:
+        if pos < len(label)-1 and len(label) > 1:
+            return _is_script(label[pos + 1], 'Greek')
+        return False
+
+    elif cp_value == 0x05f3 or cp_value == 0x05f4:
+        if pos > 0:
+            return _is_script(label[pos - 1], 'Hebrew')
+        return False
+
+    elif cp_value == 0x30fb:
+        for cp in label:
+            if cp == '\u30fb':
+                continue
+            if _is_script(cp, 'Hiragana') or _is_script(cp, 'Katakana') or _is_script(cp, 'Han'):
+                return True
+        return False
+
+    elif 0x660 <= cp_value <= 0x669:
+        for cp in label:
+            if 0x6f0 <= ord(cp) <= 0x06f9:
+                return False
+        return True
+
+    elif 0x6f0 <= cp_value <= 0x6f9:
+        for cp in label:
+            if 0x660 <= ord(cp) <= 0x0669:
+                return False
+        return True
+
+    return False
+
+
+def check_label(label: Union[str, bytes, bytearray]) -> None:
+    if isinstance(label, (bytes, bytearray)):
+        label = label.decode('utf-8')
+    if len(label) == 0:
+        raise IDNAError('Empty Label')
+
+    check_nfc(label)
+    check_hyphen_ok(label)
+    check_initial_combiner(label)
+
+    for (pos, cp) in enumerate(label):
+        cp_value = ord(cp)
+        if intranges_contain(cp_value, idnadata.codepoint_classes['PVALID']):
+            continue
+        elif intranges_contain(cp_value, idnadata.codepoint_classes['CONTEXTJ']):
+            if not valid_contextj(label, pos):
+                raise InvalidCodepointContext('Joiner {} not allowed at position {} in {}'.format(
+                    _unot(cp_value), pos+1, repr(label)))
+        elif intranges_contain(cp_value, idnadata.codepoint_classes['CONTEXTO']):
+            if not valid_contexto(label, pos):
+                raise InvalidCodepointContext('Codepoint {} not allowed at position {} in {}'.format(_unot(cp_value), pos+1, repr(label)))
+        else:
+            raise InvalidCodepoint('Codepoint {} at position {} of {} not allowed'.format(_unot(cp_value), pos+1, repr(label)))
+
+    check_bidi(label)
+
+
+def alabel(label: str) -> bytes:
+    try:
+        label_bytes = label.encode('ascii')
+        ulabel(label_bytes)
+        if not valid_label_length(label_bytes):
+            raise IDNAError('Label too long')
+        return label_bytes
+    except UnicodeEncodeError:
+        pass
+
+    check_label(label)
+    label_bytes = _alabel_prefix + _punycode(label)
+
+    if not valid_label_length(label_bytes):
+        raise IDNAError('Label too long')
+
+    return label_bytes
+
+
+def ulabel(label: Union[str, bytes, bytearray]) -> str:
+    if not isinstance(label, (bytes, bytearray)):
+        try:
+            label_bytes = label.encode('ascii')
+        except UnicodeEncodeError:
+            check_label(label)
+            return label
+    else:
+        label_bytes = label
+
+    label_bytes = label_bytes.lower()
+    if label_bytes.startswith(_alabel_prefix):
+        label_bytes = label_bytes[len(_alabel_prefix):]
+        if not label_bytes:
+            raise IDNAError('Malformed A-label, no Punycode eligible content found')
+        if label_bytes.decode('ascii')[-1] == '-':
+            raise IDNAError('A-label must not end with a hyphen')
+    else:
+        check_label(label_bytes)
+        return label_bytes.decode('ascii')
+
+    try:
+        label = label_bytes.decode('punycode')
+    except UnicodeError:
+        raise IDNAError('Invalid A-label')
+    check_label(label)
+    return label
+
+
+def uts46_remap(domain: str, std3_rules: bool = True, transitional: bool = False) -> str:
+    """Re-map the characters in the string according to UTS46 processing."""
+    from .uts46data import uts46data
+    output = ''
+
+    for pos, char in enumerate(domain):
+        code_point = ord(char)
+        try:
+            uts46row = uts46data[code_point if code_point < 256 else
+                bisect.bisect_left(uts46data, (code_point, 'Z')) - 1]
+            status = uts46row[1]
+            replacement = None  # type: Optional[str]
+            if len(uts46row) == 3:
+                replacement = uts46row[2]
+            if (status == 'V' or
+                    (status == 'D' and not transitional) or
+                    (status == '3' and not std3_rules and replacement is None)):
+                output += char
+            elif replacement is not None and (status == 'M' or
+                    (status == '3' and not std3_rules) or
+                    (status == 'D' and transitional)):
+                output += replacement
+            elif status != 'I':
+                raise IndexError()
+        except IndexError:
+            raise InvalidCodepoint(
+                'Codepoint {} not allowed at position {} in {}'.format(
+                _unot(code_point), pos + 1, repr(domain)))
+
+    return unicodedata.normalize('NFC', output)
+
+
+def encode(s: Union[str, bytes, bytearray], strict: bool = False, uts46: bool = False, std3_rules: bool = False, transitional: bool = False) -> bytes:
+    if not isinstance(s, str):
+        try:
+            s = str(s, 'ascii')
+        except UnicodeDecodeError:
+            raise IDNAError('should pass a unicode string to the function rather than a byte string.')
+    if uts46:
+        s = uts46_remap(s, std3_rules, transitional)
+    trailing_dot = False
+    result = []
+    if strict:
+        labels = s.split('.')
+    else:
+        labels = _unicode_dots_re.split(s)
+    if not labels or labels == ['']:
+        raise IDNAError('Empty domain')
+    if labels[-1] == '':
+        del labels[-1]
+        trailing_dot = True
+    for label in labels:
+        s = alabel(label)
+        if s:
+            result.append(s)
+        else:
+            raise IDNAError('Empty label')
+    if trailing_dot:
+        result.append(b'')
+    s = b'.'.join(result)
+    if not valid_string_length(s, trailing_dot):
+        raise IDNAError('Domain too long')
+    return s
+
+
+def decode(s: Union[str, bytes, bytearray], strict: bool = False, uts46: bool = False, std3_rules: bool = False) -> str:
+    try:
+        if not isinstance(s, str):
+            s = str(s, 'ascii')
+    except UnicodeDecodeError:
+        raise IDNAError('Invalid ASCII in A-label')
+    if uts46:
+        s = uts46_remap(s, std3_rules, False)
+    trailing_dot = False
+    result = []
+    if not strict:
+        labels = _unicode_dots_re.split(s)
+    else:
+        labels = s.split('.')
+    if not labels or labels == ['']:
+        raise IDNAError('Empty domain')
+    if not labels[-1]:
+        del labels[-1]
+        trailing_dot = True
+    for label in labels:
+        s = ulabel(label)
+        if s:
+            result.append(s)
+        else:
+            raise IDNAError('Empty label')
+    if trailing_dot:
+        result.append('')
+    return '.'.join(result)