import { useLocalSearchParams, useRouter } from "expo-router";
import React, { useEffect, useRef, useState } from "react";
import { Text, View } from "react-native";
import { clearPendingConsents, loadPendingConsents, useApp } from "../../src/app-context";
import { AuthLoadingView } from "../../src/components/AuthLoadingView";
import { ScreenShell } from "../../src/components/ScreenShell";
import { pendingDialogKey, restorePendingIntents } from "../../src/pending-intent";
import { spacing } from "../../src/theme";
import { Button, ErrorNotice, styles } from "../../src/ui";

export default function AuthCallbackScreen() {
  const params = useLocalSearchParams<{ code?: string; state?: string; error?: string }>();
  const app = useApp();
  const router = useRouter();
  const [error, setError] = useState<unknown>();
  const completionStarted = useRef(false);

  const complete = async () => {
    if (!params.code || !params.state) return;
    const consents = await loadPendingConsents();
    if (!consents) throw new Error("Не найдены локально принятые согласия. Начните вход заново.");
    setError(undefined);
    await app.finishCallback(params.code, params.state, consents);
    await clearPendingConsents();
    await restorePendingIntents();

    if (pendingDialogKey()) {
      router.replace("/dialogs?pending=1");
      return;
    }

    router.replace("/");
  };

  useEffect(() => {
    if (completionStarted.current) return;
    if (params.error) {
      completionStarted.current = true;
      setError(new Error("Авторизация отменена или отклонена."));
      return;
    }
    if (!params.code || !params.state) return;
    completionStarted.current = true;
    void complete().catch(setError);
  }, [params.code, params.state, params.error]);

  return (
    <ScreenShell>
      {!error ? (
        <AuthLoadingView />
      ) : (
        <View style={{ flex: 1, justifyContent: "center", padding: spacing.lg, gap: spacing.lg }}>
          <Text accessibilityRole="header" style={styles.title}>Не удалось завершить вход</Text>
          <>
            <ErrorNotice error={error} />
            <Button title="Повторить" onPress={() => void complete().catch(setError)} />
            <Button title="На главную" secondary onPress={() => router.replace("/")} />
          </>
        </View>
      )}
    </ScreenShell>
  );
}