import functools
from collections import defaultdict, namedtuple
from textwrap import dedent

from prompt_toolkit.completion import NestedCompleter

from site_tools.console import Console

COMMANDS = defaultdict(dict)

Command = namedtuple("Commmand", "prompt,handler,usage,completer")

def register_command(handler, usage, completer=None):
    prompt = handler.__qualname__.split(".", -1)[0]
    cmd = handler.__name__
    if cmd not in COMMANDS[prompt]:
        COMMANDS[prompt][cmd] = Command(
            prompt=prompt,
            handler=handler,
            usage=usage,
            completer=completer,
        )

def command(usage, completer=None, binding=None):
    def decorator(func):
        register_command(func, usage, completer)

        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            return func(*args, **kwargs)
        return wrapper
    return decorator

class BasePrompt(NestedCompleter):
    def __init__(self, cache={}):
        super(BasePrompt, self).__init__(self._nested_completer_map())
        self._prompt = ""
        self._console = None
        self._theme = None
        self._toolbar = None
        self._key_bindings = None
        self._subshells = {}
        self._cache = cache
        self._name = "Interactive Shell"
    def _register_subshells(self):
        for subclass in BasePrompt.__subclasses__():
            if subclass.__name__ == self.__class__.__name__:
                continue
            self._subshells[subclass.__name__] = subclass(parent=self)
    def _nested_completer_map(self):
        return dict((cmd_name, cmd.completer) for (cmd_name, cmd) in COMMANDS[self.__class__.__name__].items())
    def _get_help(self, cmd=None):
        try:
            return dedent(COMMANDS[self.__class__.__name__][cmd].usage)
        except KeyError:
            return self.usage
    @property
    def name(self):
        return self._name
    @property
    def cache(self):
        return self._cache
    @property
    def key_bindings(self):
        return self._key_bindings
    @property
    def usage(self):
        text = dedent(f"""
        [title]{self.name}[/title]

        Available commands are listed below. Try 'help COMMAND' for detailed help.

        [title]COMMANDS[/title]

        """)
        for name, cmd in sorted(self.commands.items()):
            text += f"    [b]{name:10s}[/b]    {cmd.handler.__doc__.strip()}\n"
        return text
    @property
    def commands(self):
        return COMMANDS[self.__class__.__name__]
    @property
    def console(self):
        if not self._console:
            self._console = Console(color_system="truecolor")
        return self._console
    @property
    def prompt(self):
        return self._prompt
    @property
    def autocomplete_values(self):
        return list(self.commands.keys())
    @property
    def toolbar(self):
        return self._toolbar
    @property
    def key_bindings(self):
        return self._key_bindings
    def help(self, parts):
        attr = None
        if parts:
            attr = parts[0]
        self.console.print(self._get_help(attr))
        return True
    def process(self, cmd, *parts):
        if cmd in self.commands:
            return self.commands[cmd].handler(self, parts)
        self.console.error(f"Command {cmd} not understood; try 'help' for help.")
    def start(self, cmd=None):
        while True:
            if not cmd:
                cmd = self.console.prompt(
                    self.prompt, completer=self, bottom_toolbar=self.toolbar, key_bindings=self.key_bindings
                )
            if cmd:
                cmd, *parts = cmd.split()
                self.process(cmd, *parts)
            cmd = None