import { Feather } from "@expo/vector-icons";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import { useLocalSearchParams, useRouter } from "expo-router";
import React, { useEffect, useMemo, useRef, useState } from "react";
import { Pressable, ScrollView, StyleSheet, Text, View } from "react-native";
import { ApiError } from "../../src/api";
import { useApp } from "../../src/app-context";
import { ScreenShell } from "../../src/components/ScreenShell";
import { notificationApi, notificationKeys, uploadDraftApi } from "../../src/notification-api";
import { formatNotificationPrice, typeMap } from "../../src/notification-presenter";
import { downloadAndOpen, pickFiles, type NativeFile } from "../../src/native-files";
import { publicApi } from "../../src/services";
import { colors, radii, spacing } from "../../src/theme";
import type { NotificationButton, UploadDraft } from "../../src/types";
import { Button, ErrorNotice, Loading, styles } from "../../src/ui";

export default function NotificationDetailScreen() {
  const { id = "" } = useLocalSearchParams<{ id: string }>();
  const { authStatus } = useApp();
  const authenticated = authStatus === "authenticated";
  const router = useRouter();
  const client = useQueryClient();
  const readSent = useRef(false);
  const [error, setError] = useState<unknown>();
  const detail = useQuery({
    queryKey: notificationKeys.detail(id),
    queryFn: () => notificationApi.detail(id),
    enabled: authenticated && Boolean(id),
    retry: (count, reason) => !(reason instanceof ApiError && reason.status === 404) && count < 1,
  });
  const catalog = useQuery({
    queryKey: notificationKeys.catalog,
    queryFn: notificationApi.catalog,
    staleTime: Infinity,
  });
  const config = useQuery({ queryKey: ["public-config"], queryFn: publicApi.config });
  const byCode = useMemo(() => typeMap(catalog.data ?? []), [catalog.data]);
  const type = detail.data ? byCode.get(detail.data.notification_type) : undefined;
  const canUpload = Boolean(detail.data?.details?.send_documents);
  const drafts = useQuery({
    queryKey: ["uploads", "notification", id],
    queryFn: () => uploadDraftApi.list(id),
    enabled: authenticated && Boolean(id) && canUpload,
  });
  const pending = drafts.data ?? detail.data?.details?.pending_documents ?? [];
  const closed = detail.data?.lifecycle_status === "closed";

  useEffect(() => {
    if (!detail.data || readSent.current || detail.data.is_read !== false) return;
    readSent.current = true;
    void notificationApi.read(id).then((state) => {
      client.setQueryData(notificationKeys.detail(id), { ...detail.data, ...state });
      client.setQueryData(notificationKeys.counter, { unread_count: state.unread_count });
    }).catch(setError);
  }, [client, detail.data, id]);

  const pressButton = useMutation({
    mutationFn: (button: NotificationButton) => notificationApi.button(id, button.code),
    onSuccess: async (state) => {
      client.setQueryData(notificationKeys.counter, { unread_count: state.unread_count });
      await client.invalidateQueries({ queryKey: ["notifications"] });
      router.replace("/notifications");
    },
    onError: setError,
  });
  const removeDraft = useMutation({
    mutationFn: uploadDraftApi.remove,
    onSuccess: () => client.invalidateQueries({ queryKey: ["uploads", "notification", id] }),
    onError: setError,
  });

  const chooseFile = async () => {
    try {
      const files = await pickFiles({
        multiple: true,
        mimeTypes: config.data?.attachments.allowed_mime_types,
      });
      if (files.length) await uploadFiles(files);
    } catch (reason) {
      setError(reason);
    }
  };

  const uploadFiles = async (files: NativeFile[]) => {
    const limits = config.data?.attachments;
    const maxBytes = (limits?.max_size_mb ?? 5) * 1024 * 1024;
    const allowed = limits?.allowed_mime_types ?? [];
    if (pending.length + files.length > 10) {
      setError(new Error("К одному уведомлению можно приложить не более 10 файлов."));
      return;
    }
    const invalid = files.find((file) => file.size > maxBytes || (allowed.length > 0 && !allowed.includes(file.mimeType)));
    if (invalid) {
      setError(new Error(`Файл «${invalid.name}» имеет недопустимый тип или размер.`));
      return;
    }
    setError(undefined);
    try {
      for (const file of files) await uploadDraftApi.upload(id, file);
      await drafts.refetch();
      await detail.refetch();
    } catch (reason) {
      setError(reason);
    }
  };

  const download = async (documentId: string) => {
    setError(undefined);
    try {
      const result = await notificationApi.documentUrl(id, documentId);
      const title = detail.data?.details?.documents?.find((item) => item.document_id === documentId)?.title;
      await downloadAndOpen(result.download_url, title ?? "document");
      await Promise.all([detail.refetch(), client.invalidateQueries({ queryKey: ["notifications"] })]);
    } catch (reason) {
      setError(reason);
    }
  };

  if (!authenticated) {
    return (
      <ScreenShell>
        <DetailHeader title="Уведомление" onBack={() => router.replace("/notifications")} />
        <View style={local.center}>
          <Text style={styles.text}>Для просмотра уведомления требуется авторизация.</Text>
          <Button title="Перейти в Центр" onPress={() => router.replace("/notifications")} />
        </View>
      </ScreenShell>
    );
  }

  const unavailable = detail.error instanceof ApiError && detail.error.status === 404;
  const notification = detail.data;
  const details = notification?.details;
  const price = formatNotificationPrice(notification?.price);
  const oldPrice = formatNotificationPrice(notification?.old_price);

  return (
    <ScreenShell>
      <DetailHeader title={type?.label ?? "Уведомление"} onBack={() => router.back()} />
      <ScrollView contentContainerStyle={local.content}>
        {(detail.isLoading || catalog.isLoading) && <Loading />}
        {unavailable ? (
          <View style={local.empty}>
            <Feather name="slash" size={32} color={colors.mutedForeground} />
            <Text style={styles.title}>Уведомление недоступно</Text>
            <Text style={styles.muted}>Возможно, оно уже закрыто или было удалено.</Text>
          </View>
        ) : (detail.error || catalog.error) ? (
          <ErrorNotice error={detail.error ?? catalog.error} retry={() => { void detail.refetch(); void catalog.refetch(); }} />
        ) : notification ? (
          <>
            {closed && <Text style={styles.error}>Уведомление больше не актуально. Действия недоступны.</Text>}
            {details?.deadline ? (
              <View style={local.deadline}>
                <Feather name="clock" size={16} color={colors.warning} />
                <Text style={styles.text}>Срок: {new Date(details.deadline).toLocaleString("ru-RU")}</Text>
              </View>
            ) : null}
            <Text accessibilityRole="header" style={styles.title}>{details?.details_header ?? notification.header}</Text>
            {details?.details_text || notification.text ? <Text style={styles.text}>{details?.details_text ?? notification.text}</Text> : null}
            {price ? (
              <View style={local.priceRow}>
                <Text style={local.price}>{price}</Text>
                {oldPrice ? <Text style={local.oldPrice}>{oldPrice}</Text> : null}
              </View>
            ) : null}
            {details?.todo_header ? <Text style={styles.heading}>{details.todo_header}</Text> : null}
            {details?.todo_plan?.map((step) => (
              <View key={`${step.number}-${step.text}`} style={local.step}>
                <View style={local.stepNumber}><Text style={local.stepNumberText}>{step.number}</Text></View>
                <Text style={[styles.text, { flex: 1 }]}>{step.text}</Text>
              </View>
            ))}
            {details?.documents?.length ? (
              <View style={local.block}>
                <Text style={styles.heading}>Документы</Text>
                {details.documents.map((document) => (
                  <Pressable key={document.document_id} onPress={() => void download(document.document_id)} style={local.file}>
                    <Feather name="file-text" size={20} color={colors.info} />
                    <View style={{ flex: 1 }}>
                      <Text style={styles.text}>{document.title}</Text>
                      <Text style={styles.muted}>{formatBytes(document.size_bytes)}</Text>
                    </View>
                    <Feather name="download" size={18} color={colors.foreground} />
                  </Pressable>
                ))}
              </View>
            ) : null}
            {canUpload ? (
              <View style={local.block}>
                <Text style={styles.heading}>Приложить документы</Text>
                <Text style={styles.muted}>Черновики сохраняются, пока вы не отправите или не удалите их.</Text>
                {drafts.isLoading && <Loading />}
                {pending.map((draft) => (
                  <DraftRow
                    key={draft.draft_id}
                    draft={draft}
                    disabled={removeDraft.isPending || closed}
                    onRemove={() => removeDraft.mutate(draft.draft_id)}
                  />
                ))}
                <Button title="Добавить файлы" secondary disabled={closed || pending.length >= 10} onPress={() => void chooseFile()} />
              </View>
            ) : null}
            <View style={local.buttons}>
              {type?.button_primary ? (
                <Button
                  title={type.button_primary.label}
                  disabled={closed || pressButton.isPending || (type.button_primary.code === "send_docs" && !pending.some((draft) => draft.scan_status === "clean"))}
                  onPress={() => pressButton.mutate(type.button_primary!)}
                />
              ) : null}
              {type?.button_secondary ? (
                <Button
                  secondary
                  title={type.button_secondary.label}
                  disabled={closed || pressButton.isPending}
                  onPress={() => pressButton.mutate(type.button_secondary!)}
                />
              ) : null}
            </View>
            {error && <ErrorNotice error={error} />}
          </>
        ) : null}
      </ScrollView>
    </ScreenShell>
  );
}

function DetailHeader({ title, onBack }: { title: string; onBack: () => void }) {
  return (
    <View style={local.header}>
      <Pressable accessibilityLabel="Назад" accessibilityRole="button" onPress={onBack} style={local.back}>
        <Feather name="arrow-left" size={20} color={colors.foreground} />
      </Pressable>
      <Text numberOfLines={1} style={[styles.heading, { flex: 1 }]}>{title}</Text>
    </View>
  );
}

function DraftRow({ draft, disabled, onRemove }: { draft: UploadDraft; disabled: boolean; onRemove: () => void }) {
  const title = draft.title;
  const status = {
    pending: "Проверяется",
    clean: "Готов к отправке",
    infected: "Файл отклонён",
    failed: "Ошибка проверки",
  }[draft.scan_status];
  return (
    <View style={local.file}>
      <Feather name={draft.scan_status === "clean" ? "check-circle" : "file"} size={20} color={draft.scan_status === "clean" ? colors.success : colors.warning} />
      <View style={{ flex: 1 }}>
        <Text style={styles.text}>{title}</Text>
        <Text style={styles.muted}>{status} · {formatBytes(draft.size_bytes)}</Text>
      </View>
      <Pressable disabled={disabled} accessibilityLabel={`Удалить ${title}`} onPress={onRemove}>
        <Feather name="trash-2" size={18} color={colors.destructive} />
      </Pressable>
    </View>
  );
}

function formatBytes(bytes: number) {
  if (bytes < 1024 * 1024) return `${Math.max(1, Math.round(bytes / 1024))} КБ`;
  return `${(bytes / 1024 / 1024).toFixed(1)} МБ`;
}

const local = StyleSheet.create({
  header: { flexDirection: "row", alignItems: "center", gap: spacing.md, padding: spacing.lg, borderBottomWidth: 1, borderBottomColor: colors.border },
  back: { width: 36, height: 36, borderRadius: radii.full, alignItems: "center", justifyContent: "center" },
  content: { padding: spacing.lg, gap: spacing.md, paddingBottom: 40 },
  center: { flex: 1, justifyContent: "center", gap: spacing.md, padding: spacing.lg },
  empty: { alignItems: "center", gap: spacing.sm, paddingVertical: 48 },
  deadline: { flexDirection: "row", alignItems: "center", gap: spacing.sm, borderRadius: radii.md, backgroundColor: "#fff7df", padding: spacing.md },
  priceRow: { flexDirection: "row", alignItems: "baseline", gap: spacing.sm },
  price: { fontSize: 22, fontWeight: "700", color: colors.foreground },
  oldPrice: { fontSize: 14, color: colors.mutedForeground, textDecorationLine: "line-through" },
  step: { flexDirection: "row", alignItems: "flex-start", gap: spacing.md },
  stepNumber: { width: 28, height: 28, borderRadius: radii.full, alignItems: "center", justifyContent: "center", backgroundColor: colors.primary },
  stepNumberText: { color: colors.primaryForeground, fontSize: 13, fontWeight: "700" },
  block: { gap: spacing.sm, paddingVertical: spacing.sm },
  file: { flexDirection: "row", alignItems: "center", gap: spacing.md, borderWidth: 1, borderColor: colors.border, borderRadius: radii.md, padding: spacing.md, backgroundColor: colors.card },
  buttons: { gap: spacing.sm, paddingTop: spacing.sm },
});