from __future__ import annotations

import typing
from dataclasses import dataclass, field

import pygame

from config import WIDTH, HEIGHT, DARK_BLUE, WHITE, GREY, BLUE, font


@dataclass
class ChatSelector:
    """
    The widget with the list of chats.
    It's a dataclass, it should be initialized using the `from_chats` classmethod

    Attributes:
        chats (List[dc.Chat]): list of all chats, where each chat is a native Rust struct Chat
        active_chat (int): the index of the current selected chat
        hovered_chat (int or None): the index of the current hovered chat
        width (int): the width of this widget
        height (int): the height of this widget
        chat_height (int): height of one chat
    """
    chats: typing.List['dc.Chat'] = field(default_factory=list)
    active_chat: int = 0
    hovered_chat: typing.Optional[int] = None
    width: int = WIDTH // 3
    height: int = HEIGHT
    chat_height: int = HEIGHT // 4

    def render(self) -> pygame.Surface:
        """
        Creates a pygame surface and draws the list of chats on it
        :return: the surface with the chat selector
        """
        surface: pygame.Surface = pygame.Surface((self.width, self.chat_height * len(self.chats)))
        for i, chat in enumerate(self.chats):
            bg_color, text_color = DARK_BLUE, WHITE
            if i == self.hovered_chat:
                bg_color = GREY
            if i == self.active_chat:
                bg_color = BLUE
            title_surface: pygame.Surface = font.render(chat.profile.name, True, text_color)
            pygame.draw.rect(surface, bg_color, (0, i * self.chat_height + 1, self.width, self.chat_height - 2))
            surface.blit(title_surface, (i * self.chat_height + 10))
        return surface

    def process_event(self, event: pygame.event.Event):
        """
        Process a click: select the necessary chat if this click is in the widget
        :param event: a pygame event
        """
        if event.type == pygame.MOUSEBUTTONUP and event.pos[0] < self.width:
            self.active_chat = event.pos[1] // self.chat_height
            self.hovered_chat = None
        if event.type == pygame.MOUSEMOTION:
            if 0 < event.pos[0] < self.width \
                    and 0 < event.pos[1] < min(self.height, len(self.chats) * self.chat_height) - 2:
                self.hovered_chat = event.pos[1] // self.chat_height
            else:
                self.hovered_chat = None

    @classmethod
    def from_chats(cls, chats: typing.List['dc.Chat'], **kwargs) -> ChatSelector:
        return cls(chats, **kwargs)