import { useEffect, useRef, useState } from "react";
import {
  ActionIcon,
  Avatar,
  Box,
  Center,
  Divider,
  Group,
  ScrollArea,
  Stack,
  Text,
  TextInput,
  Tooltip,
} from "@mantine/core";
import {
  IconSend,
  IconLock,
  IconHash,
  IconDotsVertical,
  IconPaperclip,
} from "@tabler/icons-react";
import type { Message, Room, User } from "./types";

function initials(s: string) {
  return s.replace(/[^a-z0-9]/gi, "").slice(0, 2).toUpperCase() || "?";
}
function timeShort(ts: number) {
  const d = new Date(ts);
  return `${String(d.getHours()).padStart(2, "0")}:${String(
    d.getMinutes(),
  ).padStart(2, "0")}`;
}

function MessageRow({ msg }: { msg: Message }) {
  return (
    <Group align="flex-start" gap="sm" wrap="nowrap">
      <Avatar radius="xl" size={36} color={msg.mine ? "brand" : "gray"}>
        {initials(msg.sender)}
      </Avatar>
      <Box style={{ minWidth: 0 }}>
        <Group gap={8} align="baseline">
          <Text size="sm" fw={600} c={msg.mine ? "brand.4" : undefined}>
            {msg.sender}
          </Text>
          <Text size="xs" c="dimmed">
            {timeShort(msg.ts)}
          </Text>
        </Group>
        <Text size="sm" style={{ wordBreak: "break-word" }}>
          {msg.body}
        </Text>
      </Box>
    </Group>
  );
}

export function ChatPanel({
  room,
  user,
}: {
  room: Room | undefined;
  user: User;
}) {
  const [draft, setDraft] = useState("");
  const [extra, setExtra] = useState<Record<string, Message[]>>({});
  const viewport = useRef<HTMLDivElement>(null);

  const msgs = room ? [...room.messages, ...(extra[room.id] ?? [])] : [];

  useEffect(() => {
    viewport.current?.scrollTo({ top: viewport.current.scrollHeight });
  }, [room?.id, msgs.length]);

  if (!room) {
    return (
      <Center h="100%">
        <Text c="dimmed">Selecciona una conversación</Text>
      </Center>
    );
  }

  const send = () => {
    const body = draft.trim();
    if (!body) return;
    const msg: Message = {
      id: `local-${Date.now()}`,
      sender: user.handle,
      body,
      ts: Date.now(),
      mine: true,
    };
    setExtra((e) => ({ ...e, [room.id]: [...(e[room.id] ?? []), msg] }));
    setDraft("");
  };

  return (
    <Stack h="100vh" gap={0}>
      <Group justify="space-between" px="md" py="xs" wrap="nowrap">
        <Group gap="sm" wrap="nowrap" style={{ minWidth: 0 }}>
          <Avatar radius="md" size={38} color="brand">
            {initials(room.name)}
          </Avatar>
          <Box style={{ minWidth: 0 }}>
            <Group gap={6} wrap="nowrap">
              <Text fw={650} truncate>
                {room.name}
              </Text>
              {room.encrypted ? (
                <Tooltip label="Cifrada de extremo a extremo">
                  <IconLock size={14} style={{ opacity: 0.6 }} />
                </Tooltip>
              ) : (
                <IconHash size={14} style={{ opacity: 0.6 }} />
              )}
            </Group>
            <Text size="xs" c="dimmed">
              {room.encrypted ? "cifrada · E2E" : "abierta · cleartext"}
            </Text>
          </Box>
        </Group>
        <ActionIcon variant="subtle" color="gray">
          <IconDotsVertical size={18} />
        </ActionIcon>
      </Group>
      <Divider color="dark.4" />

      <ScrollArea style={{ flex: 1 }} viewportRef={viewport}>
        <Stack gap="lg" p="md">
          {msgs.map((m) => (
            <MessageRow key={m.id} msg={m} />
          ))}
        </Stack>
      </ScrollArea>

      <Divider color="dark.4" />
      <Group p="sm" gap="xs" wrap="nowrap">
        <ActionIcon variant="subtle" color="gray" size="lg">
          <IconPaperclip size={18} />
        </ActionIcon>
        <TextInput
          style={{ flex: 1 }}
          radius="xl"
          placeholder={`Mensaje a ${room.name}`}
          value={draft}
          onChange={(e) => setDraft(e.currentTarget.value)}
          onKeyDown={(e) => e.key === "Enter" && send()}
        />
        <ActionIcon
          size="lg"
          radius="xl"
          variant="filled"
          color="brand"
          onClick={send}
          disabled={!draft.trim()}
        >
          <IconSend size={18} />
        </ActionIcon>
      </Group>
    </Stack>
  );
}