#
#  Copyright © 2010—2023 Andrey Mikhaylenko and contributors
#
#  This file is part of Argh.
#
#  Argh is free software under terms of the GNU Lesser
#  General Public License version 3 (LGPLv3) as published by the Free
#  Software Foundation. See the file README.rst for copying conditions.
#
"""
Assembling
~~~~~~~~~~

Functions and classes to properly assemble your commands in a parser.
"""
import warnings
from collections import OrderedDict

from argh.completion import COMPLETION_ENABLED
from argh.constants import (
    ATTR_ALIASES,
    ATTR_ARGS,
    ATTR_EXPECTS_NAMESPACE_OBJECT,
    ATTR_NAME,
    DEFAULT_ARGUMENT_TEMPLATE,
    DEST_FUNCTION,
    PARSER_FORMATTER,
)
from argh.exceptions import AssemblingError
from argh.utils import get_arg_spec, get_subparsers

__all__ = [
    "SUPPORTS_ALIASES",
    "set_default_command",
    "add_commands",
    "add_subcommands",
]


# TODO: remove in v.0.30.
SUPPORTS_ALIASES = True
"""
.. deprecated:: 0.28.0

    This constant will be removed in Argh v.0.30.

    It's not relevant anymore because it's always `True` for all Python
    versions currently supported by Argh.

"""


def _get_args_from_signature(function):
    if getattr(function, ATTR_EXPECTS_NAMESPACE_OBJECT, False):
        return

    spec = get_arg_spec(function)

    defaults = dict(zip(*[reversed(x) for x in (spec.args, spec.defaults or [])]))
    defaults.update(getattr(spec, "kwonlydefaults", None) or {})

    kwonly = getattr(spec, "kwonlyargs", [])

    annotations = dict(
        (k, v) for k, v in function.__annotations__.items() if isinstance(v, str)
    )

    # define the list of conflicting option strings
    # (short forms, i.e. single-character ones)
    chars = [a[0] for a in spec.args + kwonly]
    char_counts = dict((char, chars.count(char)) for char in set(chars))
    conflicting_opts = tuple(char for char in char_counts if 1 < char_counts[char])

    for name in spec.args + kwonly:
        flags = []  # name_or_flags
        akwargs = {}  # keyword arguments for add_argument()

        # TODO: remove this in v.0.30.
        if name in annotations:
            # help message:  func(a : "b")  ->  add_argument("a", help="b")
            value = annotations.get(name)
            if isinstance(value, str):
                warnings.warn(
                    "Defining argument help messages via annotations is "
                    + "deprecated and will be removed in Argh 0.30.  Please "
                    + 'replace `f(a:"foo")` with `@arg("-a", help="foo")(a)`.',
                    DeprecationWarning,
                )
                akwargs.update(help=value)

        if name in defaults or name in kwonly:
            if name in defaults:
                akwargs.update(default=defaults.get(name))
            else:
                akwargs.update(required=True)
            flags = ("-{0}".format(name[0]), "--{0}".format(name))
            if name.startswith(conflicting_opts):
                # remove short name
                flags = flags[1:]

        else:
            # positional argument
            flags = (name,)

        # cmd(foo_bar)  ->  add_argument('foo-bar')
        flags = tuple(x.replace("_", "-") if x.startswith("-") else x for x in flags)

        yield dict(option_strings=flags, **akwargs)

    if spec.varargs:
        # *args
        yield dict(option_strings=[spec.varargs], nargs="*")


def _guess(kwargs):
    """
    Adds types, actions, etc. to given argument specification.
    For example, ``default=3`` implies ``type=int``.

    :param arg: a :class:`argh.utils.Arg` instance
    """
    guessed = {}

    # Parser actions that accept argument 'type'
    TYPE_AWARE_ACTIONS = "store", "append"

    # guess type/action from default value
    value = kwargs.get("default")
    if value is not None:
        if isinstance(value, bool):
            if kwargs.get("action") is None:
                # infer action from default value
                guessed["action"] = "store_false" if value else "store_true"
        elif kwargs.get("type") is None:
            # infer type from default value
            # (make sure that action handler supports this keyword)
            if kwargs.get("action", "store") in TYPE_AWARE_ACTIONS:
                guessed["type"] = type(value)

    # guess type from choices (first item)
    if kwargs.get("choices") and "type" not in list(guessed) + list(kwargs):
        guessed["type"] = type(kwargs["choices"][0])

    return dict(kwargs, **guessed)


def _is_positional(args, prefix_chars="-"):
    if not args or not args[0]:
        raise ValueError("Expected at least one argument")
    if args[0][0].startswith(tuple(prefix_chars)):
        return False
    else:
        return True


def _get_parser_param_kwargs(parser, argspec):
    argspec = argspec.copy()  # parser methods modify source data
    args = argspec["option_strings"]

    if _is_positional(args, prefix_chars=parser.prefix_chars):
        get_kwargs = parser._get_positional_kwargs
    else:
        get_kwargs = parser._get_optional_kwargs

    kwargs = get_kwargs(*args, **argspec)

    kwargs["dest"] = kwargs["dest"].replace("-", "_")

    return kwargs


def _get_dest(parser, argspec):
    kwargs = _get_parser_param_kwargs(parser, argspec)
    return kwargs["dest"]


def set_default_command(parser, function):
    """
    Sets default command (i.e. a function) for given parser.

    If `parser.description` is empty and the function has a docstring,
    it is used as the description.

    .. note::

       If there are both explicitly declared arguments (e.g. via
       :func:`~argh.decorators.arg`) and ones inferred from the function
       signature, declared ones will be merged into inferred ones.
       If an argument does not conform to the function signature,
       `AssemblingError` is raised.

    .. note::

       If the parser was created with ``add_help=True`` (which is by default),
       option name ``-h`` is silently removed from any argument.

    """
    spec = get_arg_spec(function)

    declared_args = getattr(function, ATTR_ARGS, [])
    inferred_args = list(_get_args_from_signature(function))

    if inferred_args and declared_args:
        # We've got a mixture of declared and inferred arguments

        # a mapping of "dest" strings to argument declarations.
        #
        # * a "dest" string is a normalized form of argument name, i.e.:
        #
        #     '-f', '--foo' → 'foo'
        #     'foo-bar'     → 'foo_bar'
        #
        # * argument declaration is a dictionary representing an argument;
        #   it is obtained either from _get_args_from_signature() or from
        #   an @arg decorator (as is).
        #
        dests = OrderedDict()

        for argspec in inferred_args:
            dest = _get_parser_param_kwargs(parser, argspec)["dest"]
            dests[dest] = argspec

        for declared_kw in declared_args:
            # an argument is declared via decorator
            dest = _get_dest(parser, declared_kw)
            if dest in dests:
                # the argument is already known from function signature
                #
                # now make sure that this declared arg conforms to the function
                # signature and therefore only refines an inferred arg:
                #
                #      @arg('my-foo')    maps to  func(my_foo)
                #      @arg('--my-bar')  maps to  func(my_bar=...)

                # either both arguments are positional or both are optional
                decl_positional = _is_positional(declared_kw["option_strings"])
                infr_positional = _is_positional(dests[dest]["option_strings"])
                if decl_positional != infr_positional:
                    kinds = {True: "positional", False: "optional"}
                    raise AssemblingError(
                        '{func}: argument "{dest}" declared as {kind_i} '
                        "(in function signature) and {kind_d} (via decorator)".format(
                            func=function.__name__,
                            dest=dest,
                            kind_i=kinds[infr_positional],
                            kind_d=kinds[decl_positional],
                        )
                    )

                # merge explicit argument declaration into the inferred one
                # (e.g. `help=...`)
                dests[dest].update(**declared_kw)
            else:
                # the argument is not in function signature
                varkw = getattr(spec, "varkw", getattr(spec, "keywords", []))
                if varkw:
                    # function accepts **kwargs; the argument goes into it
                    dests[dest] = declared_kw
                else:
                    # there's no way we can map the argument declaration
                    # to function signature
                    xs = (dests[x]["option_strings"] for x in dests)
                    raise AssemblingError(
                        "{func}: argument {flags} does not fit "
                        "function signature: {sig}".format(
                            flags=", ".join(declared_kw["option_strings"]),
                            func=function.__name__,
                            sig=", ".join("/".join(x) for x in xs),
                        )
                    )

        # pack the modified data back into a list
        inferred_args = dests.values()

    command_args = inferred_args or declared_args

    # add types, actions, etc. (e.g. default=3 implies type=int)
    command_args = [_guess(x) for x in command_args]

    for draft in command_args:
        draft = draft.copy()
        if "help" not in draft:
            draft.update(help=DEFAULT_ARGUMENT_TEMPLATE)
        dest_or_opt_strings = draft.pop("option_strings")
        if parser.add_help and "-h" in dest_or_opt_strings:
            dest_or_opt_strings = [x for x in dest_or_opt_strings if x != "-h"]
        completer = draft.pop("completer", None)
        try:
            action = parser.add_argument(*dest_or_opt_strings, **draft)
            if COMPLETION_ENABLED and completer:
                action.completer = completer
        except Exception as e:
            raise type(e)(
                "{func}: cannot add arg {args}: {msg}".format(
                    args="/".join(dest_or_opt_strings), func=function.__name__, msg=e
                )
            )

    if function.__doc__ and not parser.description:
        parser.description = function.__doc__
    parser.set_defaults(
        **{
            DEST_FUNCTION: function,
        }
    )


def add_commands(
    parser,
    functions,
    namespace=None,
    namespace_kwargs=None,
    func_kwargs=None,
    # deprecated args:
    title=None,
    description=None,
    help=None,
):
    """
    Adds given functions as commands to given parser.

    :param parser:

        an :class:`argparse.ArgumentParser` instance.

    :param functions:

        a list of functions. A subparser is created for each of them.
        If the function is decorated with :func:`~argh.decorators.arg`, the
        arguments are passed to :meth:`argparse.ArgumentParser.add_argument`.
        See also :func:`~argh.dispatching.dispatch` for requirements
        concerning function signatures. The command name is inferred from the
        function name. Note that the underscores in the name are replaced with
        hyphens, i.e. function name "foo_bar" becomes command name "foo-bar".

    :param namespace:

        an optional string representing the group of commands. For example, if
        a command named "hello" is added without the namespace, it will be
        available as "prog.py hello"; if the namespace if specified as "greet",
        then the command will be accessible as "prog.py greet hello". The
        namespace itself is not callable, so "prog.py greet" will fail and only
        display a help message.

    :param func_kwargs:

        a `dict` of keyword arguments to be passed to each nested ArgumentParser
        instance created per command (i.e. per function).  Members of this
        dictionary have the highest priority, so a function's docstring is
        overridden by a `help` in `func_kwargs` (if present).

    :param namespace_kwargs:

        a `dict` of keyword arguments to be passed to the nested ArgumentParser
        instance under given `namespace`.

    Deprecated params that should be moved into `namespace_kwargs`:

    :param title:

        .. deprecated:: 0.26.0

           This argument will be removed in Argh v.0.30.
           Please use `namespace_kwargs` instead.

    :param description:

        .. deprecated:: 0.26.0

           This argument will be removed in Argh v.0.30.
           Please use `namespace_kwargs` instead.

    :param help:

        .. deprecated:: 0.26.0

           This argument will be removed in Argh v.0.30.
           Please use `namespace_kwargs` instead.

    .. note::

        This function modifies the parser object. Generally side effects are
        bad practice but we don't seem to have any choice as ArgumentParser is
        pretty opaque.
        You may prefer :meth:`~argh.helpers.ArghParser.add_commands` for a bit
        more predictable API.

    .. note::

       An attempt to add commands to a parser which already has a default
       function (e.g. added with :func:`~argh.assembling.set_default_command`)
       results in `AssemblingError`.

    """
    # FIXME "namespace" is a correct name but it clashes with the "namespace"
    # that represents arguments (argparse.Namespace and our ArghNamespace).
    # We should rename the argument here.
    namespace_kwargs = namespace_kwargs or {}

    # TODO remove this in 0.30
    #
    if title:
        warnings.warn(
            "Argument `title` is deprecated in add_commands(), "
            + "it will be removed in Argh 0.30. "
            + "Please use `parser_kwargs` instead.",
            DeprecationWarning,
        )
        namespace_kwargs["description"] = title
    if help:
        warnings.warn(
            "Argument `help` is deprecated in add_commands(), "
            + "it will be removed in Argh 0.30. "
            + "Please use `parser_kwargs` instead.",
            DeprecationWarning,
        )
        namespace_kwargs["help"] = help
    if description:
        warnings.warn(
            "Argument `description` is deprecated in add_commands(), "
            + "it will be removed in Argh 0.30. "
            + "Please use `parser_kwargs` instead.",
            DeprecationWarning,
        )
        namespace_kwargs["description"] = description
    #
    # /

    subparsers_action = get_subparsers(parser, create=True)

    if namespace:
        # Make a nested parser and init a deeper _SubParsersAction under it.

        # Create a named group of commands.  It will be listed along with
        # root-level commands in ``app.py --help``; in that context its `title`
        # can be used as a short description on the right side of its name.
        # Normally `title` is shown above the list of commands
        # in ``app.py my-namespace --help``.
        subsubparser_kw = {
            "help": namespace_kwargs.get("title"),
        }
        subsubparser = subparsers_action.add_parser(namespace, **subsubparser_kw)
        subparsers_action = subsubparser.add_subparsers(**namespace_kwargs)
    else:
        if namespace_kwargs:
            raise ValueError("`parser_kwargs` only makes sense " "with `namespace`.")

    for func in functions:
        cmd_name, func_parser_kwargs = _extract_command_meta_from_func(func)

        # override any computed kwargs by manually supplied ones
        if func_kwargs:
            func_parser_kwargs.update(func_kwargs)

        # create and set up the parser for this command
        command_parser = subparsers_action.add_parser(cmd_name, **func_parser_kwargs)
        set_default_command(command_parser, func)


def _extract_command_meta_from_func(func):
    # use explicitly defined name; if none, use function name (a_b → a-b)
    cmd_name = getattr(func, ATTR_NAME, func.__name__.replace("_", "-"))

    func_parser_kwargs = {
        # add command help from function's docstring
        "help": func.__doc__,
        # set default formatter
        "formatter_class": PARSER_FORMATTER,
    }

    # add aliases for command name
    func_parser_kwargs["aliases"] = getattr(func, ATTR_ALIASES, [])

    return cmd_name, func_parser_kwargs


def add_subcommands(parser, namespace, functions, **namespace_kwargs):
    """
    A wrapper for :func:`add_commands`.

    These examples are equivalent::

        add_commands(parser, [get, put], namespace='db',
                     namespace_kwargs={
                         'title': 'database commands',
                         'help': 'CRUD for our silly database'
                     })

        add_subcommands(parser, 'db', [get, put],
                        title='database commands',
                        help='CRUD for our silly database')

    """
    add_commands(
        parser, functions, namespace=namespace, namespace_kwargs=namespace_kwargs
    )
