# Copyright (C) 2013 Simon Feltman <sfeltman@gnome.org>
#
#   docstring.py: documentation string generator for gi.
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
# USA

from ._gi import (
    VFuncInfo,
    FunctionInfo,
    CallableInfo,
    ObjectInfo,
    StructInfo,
    Direction,
    TypeTag,
)


#: Module storage for currently registered doc string generator function.
_generate_doc_string_func = None


def set_doc_string_generator(func):
    """Set doc string generator function.

    :param callable func:
        Callable which takes a GIInfoStruct and returns documentation for it.
    """
    global _generate_doc_string_func
    _generate_doc_string_func = func


def get_doc_string_generator():
    """Returns the currently registered doc string generator."""
    return _generate_doc_string_func


def generate_doc_string(info):
    """Generate a doc string given a GIInfoStruct.

    :param gi.types.BaseInfo info:
        GI info instance to generate documentation for.
    :returns:
        Generated documentation as a string.
    :rtype: str

    This passes the info struct to the currently registered doc string
    generator and returns the result.
    """
    return _generate_doc_string_func(info)


_type_tag_to_py_type = {
    TypeTag.BOOLEAN: bool,
    TypeTag.INT8: int,
    TypeTag.UINT8: int,
    TypeTag.INT16: int,
    TypeTag.UINT16: int,
    TypeTag.INT32: int,
    TypeTag.UINT32: int,
    TypeTag.INT64: int,
    TypeTag.UINT64: int,
    TypeTag.FLOAT: float,
    TypeTag.DOUBLE: float,
    TypeTag.GLIST: list,
    TypeTag.GSLIST: list,
    TypeTag.ARRAY: list,
    TypeTag.GHASH: dict,
    TypeTag.UTF8: str,
    TypeTag.FILENAME: str,
    TypeTag.UNICHAR: str,
    TypeTag.INTERFACE: None,
    TypeTag.GTYPE: None,
    TypeTag.ERROR: None,
    TypeTag.VOID: None,
}


def _get_pytype_hint(gi_type):
    type_tag = gi_type.get_tag()
    py_type = _type_tag_to_py_type.get(type_tag)

    if py_type and hasattr(py_type, "__name__"):
        return py_type.__name__
    if type_tag == TypeTag.INTERFACE:
        iface = gi_type.get_interface()

        info_name = iface.get_name()
        if not info_name:
            return gi_type.get_tag_as_string()

        return f"{iface.get_namespace()}.{info_name}"

    return gi_type.get_tag_as_string()


def _generate_callable_info_doc(info):
    in_args_strs = []
    if isinstance(info, VFuncInfo) or (
        isinstance(info, FunctionInfo) and info.is_method()
    ):
        in_args_strs = ["self"]

    args = info.get_arguments()
    hint_blacklist = ("void",)

    # Build lists of indices prior to adding the docs because it is possible
    # the index retrieved comes before input arguments being used.
    ignore_indices = {info.get_return_type().get_array_length_index()}
    user_data_indices = set()
    for arg in args:
        ignore_indices.add(arg.get_destroy_index())
        ignore_indices.add(arg.get_type_info().get_array_length_index())
        user_data_indices.add(arg.get_closure_index())

    # Build input argument strings
    for i, arg in enumerate(args):
        if arg.get_direction() == Direction.OUT:
            continue  # skip exclusively output args
        if i in ignore_indices:
            continue
        argstr = arg.get_name()
        hint = _get_pytype_hint(arg.get_type_info())
        if hint not in hint_blacklist:
            argstr += ":" + hint
        if arg.may_be_null() or i in user_data_indices:
            # allow-none or user_data from a closure
            argstr += "=None"
        elif arg.is_optional():
            argstr += "=<optional>"
        in_args_strs.append(argstr)
    in_args_str = ", ".join(in_args_strs)

    # Build return + output argument strings
    out_args_strs = []
    return_hint = _get_pytype_hint(info.get_return_type())
    if not info.skip_return() and return_hint and return_hint not in hint_blacklist:
        argstr = return_hint
        if info.may_return_null():
            argstr += " or None"
        out_args_strs.append(argstr)

    for i, arg in enumerate(args):
        if arg.get_direction() == Direction.IN:
            continue  # skip exclusively input args
        if i in ignore_indices:
            continue
        argstr = arg.get_name()
        hint = _get_pytype_hint(arg.get_type_info())
        if hint not in hint_blacklist:
            argstr += ":" + hint
        out_args_strs.append(argstr)

    if out_args_strs:
        return f"{info.__name__}({in_args_str}) -> {', '.join(out_args_strs)}"
    return f"{info.__name__}({in_args_str})"


def _generate_class_info_doc(info):
    header = "\n:Constructors:\n\n::\n\n"  # start with \n to avoid auto indent of other lines
    doc = ""

    if isinstance(info, StructInfo):
        # Don't show default constructor for disguised (0 length) structs
        if info.get_size() > 0:
            doc += "    " + info.get_name() + "()\n"
    else:
        doc += "    " + info.get_name() + "(**properties)\n"

    for method_info in info.get_methods():
        if method_info.is_constructor():
            doc += "    " + _generate_callable_info_doc(method_info) + "\n"

    if doc:
        return header + doc
    return ""


def _generate_doc_dispatch(info):
    if isinstance(info, (ObjectInfo, StructInfo)):
        return _generate_class_info_doc(info)

    if isinstance(info, CallableInfo):
        return _generate_callable_info_doc(info)

    return ""


set_doc_string_generator(_generate_doc_dispatch)