from __future__ import annotations

import sys
from typing import Any, MutableMapping, cast

import click
from prompt_toolkit.history import InMemoryHistory

from ._completer import ClickCompleter
from .core import ReplContext
from .exceptions import ClickExit  # type: ignore[attr-defined]
from .exceptions import CommandLineParserError, ExitReplException, InvalidGroupFormat
from .globals_ import ISATTY, get_current_repl_ctx
from .utils import (
    _execute_internal_and_sys_cmds,
    _get_protected_args,
    _set_protected_args,
)

__all__ = ["bootstrap_prompt", "register_repl", "repl"]


def bootstrap_prompt(
    group: click.MultiCommand,
    prompt_kwargs: dict[str, Any],
    ctx: click.Context,
) -> dict[str, Any]:
    """
    Bootstrap prompt_toolkit kwargs or use user defined values.

    :param group: click.MultiCommand object
    :param prompt_kwargs: The user specified prompt kwargs.
    """

    defaults = {
        "history": InMemoryHistory(),
        "completer": ClickCompleter(group, ctx=ctx),
        "message": "> ",
    }

    defaults.update(prompt_kwargs)
    return defaults


def repl(
    old_ctx: click.Context,
    prompt_kwargs: dict[str, Any] = {},
    allow_system_commands: bool = True,
    allow_internal_commands: bool = True,
) -> None:
    """
    Start an interactive shell. All subcommands are available in it.

    :param old_ctx: The current Click context.
    :param prompt_kwargs: Parameters passed to
        :py:func:`prompt_toolkit.PromptSession`.

    If stdin is not a TTY, no prompt will be printed, but only commands read
    from stdin.
    """

    group_ctx = old_ctx
    # Switching to the parent context that has a Group as its command
    # as a Group acts as a CLI for all of its subcommands
    if old_ctx.parent is not None and not isinstance(
        old_ctx.command, click.MultiCommand
    ):
        group_ctx = old_ctx.parent

    group = cast(click.MultiCommand, group_ctx.command)

    # An Optional click.Argument in the CLI Group, that has no value
    # will consume the first word from the REPL input, causing issues in
    # executing the command
    # So, if there's an empty Optional Argument
    for param in group.params:
        if (
            isinstance(param, click.Argument)
            and group_ctx.params[param.name] is None  # type: ignore[index]
            and not param.required
        ):
            raise InvalidGroupFormat(
                f"{type(group).__name__} '{group.name}' requires value for "
                f"an optional argument '{param.name}' in REPL mode"
            )

    # Delete the REPL command from those available, as we don't want to allow
    # nesting REPLs (note: pass `None` to `pop` as we don't want to error if
    # REPL command already not present for some reason).
    repl_command_name = old_ctx.command.name

    available_commands: MutableMapping[str, click.Command] = {}

    if isinstance(group, click.CommandCollection):
        available_commands = {
            cmd_name: source.get_command(group_ctx, cmd_name)  # type: ignore[misc]
            for source in group.sources
            for cmd_name in source.list_commands(group_ctx)
        }

    elif isinstance(group, click.Group):
        available_commands = group.commands

    original_command = available_commands.pop(repl_command_name, None)  # type: ignore

    repl_ctx = ReplContext(
        group_ctx,
        bootstrap_prompt(group, prompt_kwargs, group_ctx),
        get_current_repl_ctx(silent=True),
    )

    if ISATTY:
        # If stdin is a TTY, prompt the user for input using PromptSession.
        def get_command() -> str:
            return repl_ctx.session.prompt()  # type: ignore

    else:
        # If stdin is not a TTY, read input from stdin directly.
        def get_command() -> str:
            inp = sys.stdin.readline().strip()
            repl_ctx._history.append(inp)
            return inp

    with repl_ctx:
        while True:
            try:
                command = get_command()
            except KeyboardInterrupt:
                continue
            except EOFError:
                break

            if not command:
                if ISATTY:
                    continue
                else:
                    break

            try:
                args = _execute_internal_and_sys_cmds(
                    command, allow_internal_commands, allow_system_commands
                )
                if args is None:
                    continue

            except CommandLineParserError:
                continue

            except ExitReplException:
                break

            try:
                # The group command will dispatch based on args.
                old_protected_args = _get_protected_args(group_ctx)
                try:
                    _set_protected_args(group_ctx, args)
                    group.invoke(group_ctx)
                finally:
                    _set_protected_args(group_ctx, old_protected_args)
            except click.ClickException as e:
                e.show()
            except (ClickExit, SystemExit):
                pass

            except ExitReplException:
                break

    if original_command is not None:
        available_commands[repl_command_name] = original_command  # type: ignore[index]


def register_repl(group: click.Group, name="repl") -> None:
    """Register :func:`repl()` as sub-command *name* of *group*."""
    group.command(name=name)(click.pass_context(repl))