import { useState } from "react";
import {
  View,
  Text,
  FlatList,
  TextInput,
  Pressable,
  KeyboardAvoidingView,
  Platform,
  type ListRenderItemInfo,
} from "react-native";
import { useLocalSearchParams, Stack, useRouter } from "expo-router";
import { useQuery, useMutation } from "convex/react";
import { api } from "../../convex/_generated/api";
import { useAuth } from "../_layout";
import { useTheme } from "../../components/theme";
import { Button } from "../../components/ui/button";
import { Loading } from "../../components/ui/loading";

function formatMessageTime(timestamp: number): string {
  return new Date(timestamp).toLocaleTimeString("mk-MK", {
    hour: "2-digit",
    minute: "2-digit",
  });
}

export default function ChatDetailScreen() {
  const { id } = useLocalSearchParams<{ id: string }>();
  const theme = useTheme();
  const router = useRouter();
  const { token, userId, isAuthenticated } = useAuth();

  const chat = useQuery(
    api.chats.getById,
    isAuthenticated && token && id ? { token, chatId: id as any } : "skip"
  );
  const messages = useQuery(
    api.messages.listByChat,
    isAuthenticated && token && id ? { token, chatId: id as any } : "skip"
  );

  const sendMessage = useMutation(api.messages.send);
  const [text, setText] = useState("");
  const [sending, setSending] = useState(false);

  async function handleSend() {
    const content = text.trim();
    if (!content || !token || !id) return;
    setText("");
    setSending(true);
    try {
      await sendMessage({ token, chatId: id as any, content });
    } catch {
      setText(content);
    } finally {
      setSending(false);
    }
  }

  if (!isAuthenticated) {
    return (
      <>
        <Stack.Screen
          options={{
            title: "Разговор",
            headerShown: true,
            headerBackButtonDisplayMode: "minimal",
          }}
        />
        <View
          style={{
            flex: 1,
            justifyContent: "center",
            alignItems: "center",
            padding: 24,
            backgroundColor: theme.colors.background,
          }}
        >
          <Text
            style={{
              fontSize: 16,
              color: theme.colors.text,
              marginBottom: 16,
              textAlign: "center",
            }}
          >
            Најавете се за да ги видите пораките.
          </Text>
          <Button onPress={() => router.push("/(auth)/login")}>
            Најави се
          </Button>
        </View>
      </>
    );
  }

  if (!chat || !messages) {
    return (
      <>
        <Stack.Screen
          options={{
            title: "Разговор",
            headerShown: true,
            headerBackButtonDisplayMode: "minimal",
          }}
        />
        <View
          style={{
            flex: 1,
            justifyContent: "center",
            alignItems: "center",
            backgroundColor: theme.colors.background,
          }}
        >
          <Loading />
        </View>
      </>
    );
  }

  const otherUserName = chat.otherUser?.name ?? "Непознат";

  return (
    <>
      <Stack.Screen
        options={{
          title: otherUserName,
          headerShown: true,
          headerBackButtonDisplayMode: "minimal",
        }}
      />
      <KeyboardAvoidingView
        behavior={Platform.OS === "ios" ? "padding" : undefined}
        style={{ flex: 1, backgroundColor: theme.colors.background }}
        keyboardVerticalOffset={90}
      >
        {messages.length === 0 ? (
          <View
            style={{
              flex: 1,
              justifyContent: "center",
              alignItems: "center",
              padding: 24,
            }}
          >
            <Text style={{ fontSize: 48, marginBottom: 16 }}>
              {"\uD83D\uDCAC"}
            </Text>
            <Text
              style={{
                fontSize: 16,
                fontWeight: "600",
                color: theme.colors.text,
                marginBottom: 8,
              }}
            >
              Започнете разговор
            </Text>
            <Text
              style={{
                color: theme.colors.textSecondary,
                textAlign: "center",
              }}
            >
              Испратете порака за да започнете разговор.
            </Text>
          </View>
        ) : (
          <FlatList
            data={messages}
            keyExtractor={(item) => item._id}
            inverted
            contentContainerStyle={{
              paddingVertical: 16,
              paddingHorizontal: 16,
            }}
            ItemSeparatorComponent={() => <View style={{ height: 8 }} />}
            renderItem={({
              item,
            }: ListRenderItemInfo<typeof messages[number]>) => {
              const isSelf = item.senderId === userId;
              return (
                <View
                  style={{
                    alignItems: isSelf ? "flex-end" : "flex-start",
                  }}
                >
                  <View
                    style={{
                      maxWidth: "80%",
                      backgroundColor: isSelf
                        ? theme.colors.primary
                        : theme.colors.surface,
                      borderRadius: 16,
                      paddingHorizontal: 14,
                      paddingVertical: 10,
                      borderWidth: isSelf ? 0 : 1,
                      borderColor: theme.colors.border,
                    }}
                  >
                    <Text
                      style={{
                        color: isSelf ? "#FFFFFF" : theme.colors.text,
                        fontSize: 15,
                        lineHeight: 20,
                      }}
                    >
                      {item.content}
                    </Text>
                  </View>
                  <Text
                    style={{
                      fontSize: 11,
                      color: theme.colors.textTertiary,
                      marginTop: 4,
                    }}
                  >
                    {formatMessageTime(item.createdAt)}
                  </Text>
                </View>
              );
            }}
            style={{ flex: 1 }}
          />
        )}
        <View
          style={{
            flexDirection: "row",
            alignItems: "flex-end",
            paddingHorizontal: 16,
            paddingVertical: 12,
            borderTopWidth: 1,
            borderTopColor: theme.colors.border,
            backgroundColor: theme.colors.card,
            gap: 8,
          }}
        >
          <TextInput
            value={text}
            onChangeText={setText}
            placeholder="Напишете порака..."
            placeholderTextColor={theme.colors.textTertiary}
            style={{
              flex: 1,
              backgroundColor: theme.colors.surface,
              borderWidth: 1,
              borderColor: theme.colors.border,
              borderRadius: 20,
              paddingHorizontal: 16,
              paddingVertical: 10,
              fontSize: 16,
              color: theme.colors.text,
              maxHeight: 100,
            }}
            multiline
            maxLength={1000}
          />
          <Pressable
            onPress={handleSend}
            disabled={!text.trim() || sending}
            style={{
              backgroundColor: text.trim()
                ? theme.colors.primary
                : theme.colors.border,
              width: 40,
              height: 40,
              borderRadius: 20,
              alignItems: "center",
              justifyContent: "center",
              opacity: sending ? 0.5 : 1,
            }}
          >
            <Text style={{ color: "#FFFFFF", fontSize: 18 }}>{"\u27A4"}</Text>
          </Pressable>
        </View>
      </KeyboardAvoidingView>
    </>
  );
}