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import sys
import re
import warnings
import types
import keyword
import functools
from shibokensupport.signature.mapping import (type_map, update_mapping,
    namespace, typing, _NotCalled, ResultVariable, ArrayLikeVariable)
from shibokensupport.signature.lib.tool import (SimpleNamespace,
    build_brace_pattern)

_DEBUG = False
LIST_KEYWORDS = False

"""
parser.py

This module parses the signature text and creates properties for the
signature objects.

PySide has a new function 'CppGenerator::writeSignatureInfo()'
that extracts the gathered information about the function arguments
and defaults as good as it can. But what PySide generates is still
very C-ish and has many constants that Python doesn't understand.

The function 'try_to_guess()' below understands a lot of PySide's
peculiar way to assume local context. If it is able to do the guess,
then the result is inserted into the dict, so the search happens
not again. For everything that is not covered by these automatic
guesses, we provide an entry in 'type_map' that resolves it.

In effect, 'type_map' maps text to real Python objects.
"""

def dprint(*args, **kw):
    if _DEBUG:
        import pprint
        for arg in args:
            pprint.pprint(arg)
            sys.stdout.flush()


_cache = {}

def _parse_arglist(argstr):
    # The following is a split re. The string is broken into pieces which are
    # between the recognized strings. Because the re has groups, both the
    # strings and the separators are returned, where the strings are not
    # interesting at all: They are just the commata.
    key = "_parse_arglist"
    if key not in _cache:
        regex = build_brace_pattern(level=3, separators=",")
        _cache[key] = re.compile(regex, flags=re.VERBOSE)
    split = _cache[key].split
    # Note: this list is interspersed with "," and surrounded by ""
    return [x.strip() for x in split(argstr) if x.strip() not in ("", ",")]


def _parse_line(line):
    line_re = r"""
        ((?P<multi> ([0-9]+)) : )?    # the optional multi-index
        (?P<funcname> \w+(\.\w+)*)    # the function name
        \( (?P<arglist> .*?) \)       # the argument list
        ( -> (?P<returntype> .*) )?   # the optional return type
        $
        """
    ret = SimpleNamespace(**re.match(line_re, line, re.VERBOSE).groupdict())
    # PYSIDE-1095: Handle arbitrary default expressions
    argstr = ret.arglist.replace("->", ".deref.")
    arglist = _parse_arglist(argstr)
    args = []
    for idx, arg in enumerate(arglist):
        tokens = arg.split(":")
        if len(tokens) < 2:
            if idx == 0 and tokens[0] == "self":
                tokens = 2 * tokens     # "self: self"
            else:
                # This should never happen again (but who knows?)
                raise SystemError(f'Invalid argument "{arg}" in "{line}".')
        name, ann = tokens
        if name in keyword.kwlist:
            if LIST_KEYWORDS:
                print("KEYWORD", ret)
            name = name + "_"
        if "=" in ann:
            ann, default = ann.split("=", 1)
            tup = name, ann, default
        else:
            tup = name, ann
        args.append(tup)
    ret.arglist = args
    multi = ret.multi
    if multi is not None:
        ret.multi = int(multi)
    funcname = ret.funcname
    parts = funcname.split(".")
    if parts[-1] in keyword.kwlist:
        ret.funcname = funcname + "_"
    return vars(ret)


def make_good_value(thing, valtype):
    try:
        if thing.endswith("()"):
            thing = f'Default("{thing[:-2]}")'
        else:
            ret = eval(thing, namespace)
            if valtype and repr(ret).startswith("<"):
                thing = f'Instance("{thing}")'
        return eval(thing, namespace)
    except Exception:
        pass


def try_to_guess(thing, valtype):
    if "." not in thing and "(" not in thing:
        text = f"{valtype}.{thing}"
        ret = make_good_value(text, valtype)
        if ret is not None:
            return ret
    typewords = valtype.split(".")
    valwords = thing.split(".")
    braceless = valwords[0]    # Yes, not -1. Relevant is the overlapped word.
    if "(" in braceless:
        braceless = braceless[:braceless.index("(")]
    for idx, w in enumerate(typewords):
        if w == braceless:
            text = ".".join(typewords[:idx] + valwords)
            ret = make_good_value(text, valtype)
            if ret is not None:
                return ret
    return None

def get_name(thing):
    if isinstance(thing, type):
        return getattr(thing, "__qualname__", thing.__name__)
    else:
        return thing.__name__

def _resolve_value(thing, valtype, line):
    if thing in ("0", "None") and valtype:
        if valtype.startswith("PySide6.") or valtype.startswith("typing."):
            return None
        map = type_map[valtype]
        # typing.Any: '_SpecialForm' object has no attribute '__name__'
        name = get_name(map) if hasattr(map, "__name__") else str(map)
        thing = f"zero({name})"
    if thing in type_map:
        return type_map[thing]
    res = make_good_value(thing, valtype)
    if res is not None:
        type_map[thing] = res
        return res
    res = try_to_guess(thing, valtype) if valtype else None
    if res is not None:
        type_map[thing] = res
        return res
    warnings.warn(f"""pyside_type_init:

        UNRECOGNIZED:   {thing!r}
        OFFENDING LINE: {line!r}
        """, RuntimeWarning)
    return thing


def _resolve_arraytype(thing, line):
    search = re.search(r"\[(\d*)\]$", thing)
    thing = thing[:search.start()]
    if thing.endswith("]"):
        thing = _resolve_arraytype(thing, line)
    if search.group(1):
        # concrete array, use a tuple
        nelem = int(search.group(1))
        thing = ", ".join([thing] * nelem)
        thing = "Tuple[" + thing + "]"
    else:
        thing = "QList[" + thing + "]"
    return thing


def to_string(thing):
    if isinstance(thing, str):
        return thing
    if hasattr(thing, "__name__"):
        dot = "." in str(thing)
        name = get_name(thing)
        return thing.__module__ + "." + name if dot else name
    # Note: This captures things from the typing module:
    return str(thing)


matrix_pattern = "PySide6.QtGui.QGenericMatrix"

def handle_matrix(arg):
    n, m, typstr = tuple(map(lambda x:x.strip(), arg.split(",")))
    assert typstr == "float"
    result = f"PySide6.QtGui.QMatrix{n}x{m}"
    return eval(result, namespace)


debugging_aid = """
from inspect import currentframe

def lno(level):
    lineno = currentframe().f_back.f_lineno
    spaces = level * "  "
    return f"{lineno}{spaces}"
"""


def _resolve_type(thing, line, level, var_handler):
    # Capture total replacements, first. Happens in
    # "PySide6.QtCore.QCborStreamReader.StringResult[PySide6.QtCore.QByteArray]"
    if thing in type_map:
        return type_map[thing]
    # Now the nested structures are handled.
    if "[" in thing:
        # handle primitive arrays
        if re.search(r"\[\d*\]$", thing):
            thing = _resolve_arraytype(thing, line)
        # Handle a container return type. (see PYSIDE-921 in cppgenerator.cpp)
        contr, thing = re.match(r"(.*?)\[(.*?)\]$", thing).groups()
        # Special case: Handle the generic matrices.
        if contr == matrix_pattern:
            return handle_matrix(thing)
        contr = var_handler(_resolve_type(contr, line, level+1, var_handler))
        if isinstance(contr, _NotCalled):
            raise SystemError("Container types must exist:", repr(contr))
        contr = to_string(contr)
        pieces = []
        for part in _parse_arglist(thing):
            part = var_handler(_resolve_type(part, line, level+1, var_handler))
            if isinstance(part, _NotCalled):
                # fix the tag (i.e. "Missing") by repr
                part = repr(part)
            pieces.append(to_string(part))
        thing = ", ".join(pieces)
        result = f"{contr}[{thing}]"
        return eval(result, namespace)
    return _resolve_value(thing, None, line)


def _handle_generic(obj, repl):
    """
    Assign repl if obj is an ArrayLikeVariable

    This is a neat trick. Example:

        obj                     repl        result
        ----------------------  --------    ---------
        ArrayLikeVariable       List        List
        ArrayLikeVariable(str)  List        List[str]
        ArrayLikeVariable       Sequence    Sequence
        ArrayLikeVariable(str)  Sequence    Sequence[str]
    """
    if isinstance(obj, ArrayLikeVariable):
        return repl[obj.type]
    if isinstance(obj, type) and issubclass(obj, ArrayLikeVariable):
        # was "if obj is ArrayLikeVariable"
        return repl
    return obj


def handle_argvar(obj):
    """
    Decide how array-like variables are resolved in arguments

    Currently, the best approximation is types.Sequence.
    We want to change that to types.Iterable in the near future.
    """
    return _handle_generic(obj, typing.Sequence)


def handle_retvar(obj):
    """
    Decide how array-like variables are resolved in results

    This will probably stay typing.List forever.
    """
    return _handle_generic(obj, typing.List)


def calculate_props(line):
    parsed = SimpleNamespace(**_parse_line(line.strip()))
    arglist = parsed.arglist
    annotations = {}
    _defaults = []
    for idx, tup in enumerate(arglist):
        name, ann = tup[:2]
        if ann == "...":
            name = "*args" if name.startswith("arg_") else "*" + name
            # copy the pathed fields back
            ann = 'nullptr'     # maps to None
            tup = name, ann
            arglist[idx] = tup
        annotations[name] = _resolve_type(ann, line, 0, handle_argvar)
        if len(tup) == 3:
            default = _resolve_value(tup[2], ann, line)
            _defaults.append(default)
    defaults = tuple(_defaults)
    returntype = parsed.returntype
    # PYSIDE-1383: We need to handle `None` explicitly.
    annotations["return"] = (_resolve_type(returntype, line, 0, handle_retvar)
                             if returntype is not None else None)
    props = SimpleNamespace()
    props.defaults = defaults
    props.kwdefaults = {}
    props.annotations = annotations
    props.varnames = varnames = tuple(tup[0] for tup in arglist)
    funcname = parsed.funcname
    shortname = funcname[funcname.rindex(".")+1:]
    props.name = shortname
    props.multi = parsed.multi
    fix_variables(props, line)
    return vars(props)


def fix_variables(props, line):
    annos = props.annotations
    if not any(isinstance(ann, (ResultVariable, ArrayLikeVariable))
               for ann in annos.values()):
        return
    retvar = annos.get("return", None)
    if retvar and isinstance(retvar, (ResultVariable, ArrayLikeVariable)):
        # Special case: a ResultVariable which is the result will always be an array!
        annos["return"] = retvar = typing.List[retvar.type]
    varnames = list(props.varnames)
    defaults = list(props.defaults)
    diff = len(varnames) - len(defaults)

    safe_annos = annos.copy()
    retvars = [retvar] if retvar else []
    deletions = []
    for idx, name in enumerate(varnames):
        ann = safe_annos[name]
        if isinstance(ann, ArrayLikeVariable):
            ann = typing.Sequence[ann.type]
            annos[name] = ann
        if not isinstance(ann, ResultVariable):
            continue
        # We move the variable to the end and remove it.
        retvars.append(ann.type)
        deletions.append(idx)
        del annos[name]
    for idx in reversed(deletions):
        # varnames:  0 1 2 3 4 5 6 7
        # defaults:        0 1 2 3 4
        # diff: 3
        del varnames[idx]
        if idx >= diff:
            del defaults[idx - diff]
        else:
            diff -= 1
    if retvars:
        rvs = []
        retvars = list(handle_retvar(rv) if isinstance(rv, ArrayLikeVariable) else rv
                       for rv in retvars)
        if len(retvars) == 1:
            returntype = retvars[0]
        else:
            retvars_str = ", ".join(map(to_string, retvars))
            typestr = f"typing.Tuple[{retvars_str}]"
            returntype = eval(typestr, namespace)
        props.annotations["return"] = returntype
    props.varnames = tuple(varnames)
    props.defaults = tuple(defaults)


def fixup_multilines(lines):
    """
    Multilines can collapse when certain distinctions between C++ types
    vanish after mapping to Python.
    This function fixes this by re-computing multiline-ness.
    """
    res = []
    multi_lines = []
    for line in lines:
        multi = re.match(r"([0-9]+):", line)
        if multi:
            idx, rest = int(multi.group(1)), line[multi.end():]
            multi_lines.append(rest)
            if idx > 0:
                continue
            # remove duplicates
            multi_lines = sorted(set(multi_lines))
            # renumber or return a single line
            nmulti = len(multi_lines)
            if nmulti > 1:
                for idx, line in enumerate(multi_lines):
                    res.append(f"{nmulti-idx-1}:{line}")
            else:
                res.append(multi_lines[0])
            multi_lines = []
        else:
            res.append(line)
    return res


def pyside_type_init(type_key, sig_strings):
    dprint()
    dprint(f"Initialization of type key '{type_key}'")
    update_mapping()
    lines = fixup_multilines(sig_strings)
    ret = {}
    multi_props = []
    for line in lines:
        props = calculate_props(line)
        shortname = props["name"]
        multi = props["multi"]
        if multi is None:
            ret[shortname] = props
            dprint(props)
        else:
            multi_props.append(props)
            if multi > 0:
                continue
            multi_props = {"multi": multi_props}
            ret[shortname] = multi_props
            dprint(multi_props)
            multi_props = []
    return ret

# end of file
