import { useMutation, useQueryClient } from '@tanstack/react-query';
import { useEffect, useRef, useState } from 'react';
import { useTranslation } from 'react-i18next';

import {
  deleteGuildAppearance,
  guildQueryKey,
  updateGuildAccent,
  uploadGuildAppearance,
  type GuildAppearanceKind,
} from '@/api/guilds';
import { myGuildsQueryKey } from '@/api/users';
import { Avatar } from '@/components/ui/Avatar';
import { Button } from '@/components/ui/primitives';
import { avatarUrl } from '@/lib/identity';
import { revokeObjectUrl, safeObjectUrl } from '@/lib/objectUrl';
import { useApiErrorMessage } from '@/lib/useApiErrorMessage';
import { useSessionStore } from '@/stores/session';
import { SettingsSection } from '@/pages/settings/SettingsSection';
import type { Guild } from '@/api/types';

/** Пресеты акцентного цвета: 0 — цвет темы. */
const ACCENT_PRESETS: { value: number; labelKey: string }[] = [
  { value: 0, labelKey: 'settings.servers.appearance.accentDefault' },
  { value: 0x5865f2, labelKey: 'settings.servers.appearance.accentBlurple' },
  { value: 0x2ecc71, labelKey: 'settings.servers.appearance.accentGreen' },
  { value: 0xe67e22, labelKey: 'settings.servers.appearance.accentOrange' },
  { value: 0xe74c3c, labelKey: 'settings.servers.appearance.accentRed' },
  { value: 0x9b59b6, labelKey: 'settings.servers.appearance.accentPurple' },
];

/** Максимальный размер файла оформления: сервер отвечает `file.too_large`. */
export const GUILD_IMAGE_MAX_BYTES = 8 * 1024 * 1024;

interface GuildAppearanceSectionProps {
  guild: Guild;
  canEdit: boolean;
}

/**
 * «Оформление»: иконка, баннер, splash для страницы приглашения и акцентный
 * цвет сервера (AGENT.md 7.4). Анимированные GIF/APNG/WebP не перекодируются,
 * поэтому показываются с анимацией как есть.
 */
export function GuildAppearanceSection({ guild, canEdit }: GuildAppearanceSectionProps) {
  const { t } = useTranslation();
  const describeError = useApiErrorMessage();
  const queryClient = useQueryClient();
  const [previews, setPreviews] = useState<Partial<Record<GuildAppearanceKind, string>>>({});
  const [error, setError] = useState<unknown>(null);
  // Три отдельных ref: правило react-hooks/refs запрещает читать их из объекта
  // во время рендера.
  const iconInput = useRef<HTMLInputElement | null>(null);
  const bannerInput = useRef<HTMLInputElement | null>(null);
  const splashInput = useRef<HTMLInputElement | null>(null);
  // Зеркало превью: нужно, чтобы освобождать object URL при закрытии настроек.
  const previewsRef = useRef<Partial<Record<GuildAppearanceKind, string>>>({});

  useEffect(
    () => () => {
      for (const url of Object.values(previewsRef.current)) {
        revokeObjectUrl(url);
      }
      previewsRef.current = {};
    },
    [],
  );

  /** Меняет превью вида, освобождая предыдущую ссылку на локальный файл. */
  const putPreview = (kind: GuildAppearanceKind, url: string | null): void => {
    revokeObjectUrl(previewsRef.current[kind]);
    const next = { ...previewsRef.current };
    if (url === null) {
      delete next[kind];
    } else {
      next[kind] = url;
    }
    previewsRef.current = next;
    setPreviews(next);
  };

  const applyGuild = (updated: Guild): void => {
    // Карточка сервера, рейка и шапка обновляются сразу: рейка берёт иконку из
    // session-store, а не из запроса, поэтому обновляем оба места (AGENT.md 11.6).
    queryClient.setQueryData(guildQueryKey(guild.id), updated);
    useSessionStore.getState().applyGuildAppearance(guild.id, {
      icon_file_id: updated.icon_file_id ?? '',
      banner_file_id: updated.banner_file_id ?? '',
      splash_file_id: updated.splash_file_id ?? '',
      accent_color: updated.accent_color ?? 0,
    });
    void queryClient.invalidateQueries({ queryKey: myGuildsQueryKey });
  };

  const upload = useMutation({
    mutationFn: ({ kind, file }: { kind: GuildAppearanceKind; file: File }) =>
      uploadGuildAppearance(guild.id, kind, file),
    onSuccess: (updated, variables) => {
      setError(null);
      // Превью заменяет ответ сервера: локальная ссылка больше не нужна.
      putPreview(variables.kind, null);
      applyGuild(updated);
    },
    onError: (cause) => setError(cause),
  });

  const remove = useMutation({
    mutationFn: (kind: GuildAppearanceKind) => deleteGuildAppearance(guild.id, kind),
    onSuccess: (updated, kind) => {
      setError(null);
      putPreview(kind, null);
      applyGuild(updated);
    },
    onError: (cause) => setError(cause),
  });

  const accent = useMutation({
    mutationFn: (value: number) => updateGuildAccent(guild.id, value),
    onSuccess: (updated) => {
      setError(null);
      applyGuild(updated);
    },
    onError: (cause) => setError(cause),
  });

  if (!canEdit) {
    return null;
  }

  const pick = (kind: GuildAppearanceKind, file: File | undefined): void => {
    if (file === undefined) {
      return;
    }
    if (!file.type.startsWith('image/')) {
      setError(new Error(t('settings.servers.appearance.notImage')));
      return;
    }
    if (file.size > GUILD_IMAGE_MAX_BYTES) {
      setError(new Error(t('settings.servers.appearance.tooLarge')));
      return;
    }
    putPreview(kind, safeObjectUrl(file));
    upload.mutate({ kind, file });
  };

  const pending = upload.isPending || remove.isPending || accent.isPending;

  return (
    <SettingsSection
      title={t('settings.servers.appearance.title')}
      description={t('settings.servers.appearance.description')}
    >
      <div className="mt-4 flex flex-col gap-4" data-testid="guild-appearance">
        <AppearanceRow
          testId="appearance-icon"
          label={t('settings.servers.appearance.icon')}
          hint={t('settings.servers.appearance.iconHint')}
          fileId={guild.icon_file_id}
          preview={previews.icon}
          name={guild.name}
          seed={guild.id}
          shape="square"
          disabled={pending}
          onPick={() => iconInput.current?.click()}
          onRemove={() => remove.mutate('icon')}
        />
        <input
          ref={iconInput}
          type="file"
          accept="image/*"
          className="hidden"
          data-testid="appearance-icon-input"
          onChange={(event) => {
            pick('icon', event.target.files?.[0]);
            event.target.value = '';
          }}
        />

        <AppearanceRow
          testId="appearance-banner"
          label={t('settings.servers.appearance.banner')}
          hint={t('settings.servers.appearance.bannerHint')}
          fileId={guild.banner_file_id}
          preview={previews.banner}
          name={guild.name}
          seed={`${guild.id}-banner`}
          shape="wide"
          disabled={pending}
          onPick={() => bannerInput.current?.click()}
          onRemove={() => remove.mutate('banner')}
        />
        <input
          ref={bannerInput}
          type="file"
          accept="image/*"
          className="hidden"
          data-testid="appearance-banner-input"
          onChange={(event) => {
            pick('banner', event.target.files?.[0]);
            event.target.value = '';
          }}
        />

        <AppearanceRow
          testId="appearance-splash"
          label={t('settings.servers.appearance.splash')}
          hint={t('settings.servers.appearance.splashHint')}
          fileId={guild.splash_file_id}
          preview={previews.splash}
          name={guild.name}
          seed={`${guild.id}-splash`}
          shape="wide"
          disabled={pending}
          onPick={() => splashInput.current?.click()}
          onRemove={() => remove.mutate('splash')}
        />
        <input
          ref={splashInput}
          type="file"
          accept="image/*"
          className="hidden"
          data-testid="appearance-splash-input"
          onChange={(event) => {
            pick('splash', event.target.files?.[0]);
            event.target.value = '';
          }}
        />

        <div>
          <p className="text-sm font-medium">{t('settings.servers.appearance.accent')}</p>
          <p className="text-xs text-fg-muted">{t('settings.servers.appearance.accentHint')}</p>
          <div className="mt-2 flex flex-wrap items-center gap-2" data-testid="appearance-accent">
            {ACCENT_PRESETS.map((preset) => {
              const selected = (guild.accent_color ?? 0) === preset.value;
              return (
                <button
                  key={preset.labelKey}
                  type="button"
                  disabled={pending}
                  aria-pressed={selected}
                  aria-label={t(preset.labelKey)}
                  title={t(preset.labelKey)}
                  data-testid={`appearance-accent-${preset.value}`}
                  onClick={() => accent.mutate(preset.value)}
                  className={`h-8 w-8 rounded-full border transition-transform duration-[var(--duration-fast)] active:scale-95 ${
                    selected ? 'border-fg ring-2 ring-accent' : 'border-border/60'
                  }`}
                  style={
                    preset.value === 0
                      ? { background: 'var(--color-accent)' }
                      : { background: `#${preset.value.toString(16).padStart(6, '0')}` }
                  }
                />
              );
            })}
          </div>
        </div>

        {error === null || error === undefined ? null : (
          <p className="text-sm text-danger" role="alert" data-testid="appearance-error">
            {error instanceof Error ? error.message : describeError(error)}
          </p>
        )}
      </div>
    </SettingsSection>
  );
}

interface AppearanceRowProps {
  testId: string;
  label: string;
  hint: string;
  fileId: string | undefined;
  preview: string | undefined;
  name: string;
  seed: string;
  shape: 'square' | 'wide';
  disabled: boolean;
  onPick: () => void;
  onRemove: () => void;
}

/** AppearanceRow — превью, выбор файла и удаление для одного вида оформления. */
function AppearanceRow({
  testId,
  label,
  hint,
  fileId,
  preview,
  name,
  seed,
  shape,
  disabled,
  onPick,
  onRemove,
}: AppearanceRowProps) {
  const { t } = useTranslation();
  const url = avatarUrl(fileId);
  const src = preview ?? (url === null ? undefined : url);

  return (
    <div className="flex flex-wrap items-center gap-3" data-testid={testId}>
      {shape === 'wide' ? (
        <span
          className="flex h-16 w-40 items-center justify-center overflow-hidden rounded-[var(--radius-md)] border border-border/60 bg-surface-2 text-xs text-fg-muted"
          data-testid={`${testId}-preview`}
        >
          {src === undefined ? (
            t('settings.servers.appearance.empty')
          ) : (
            <img src={src} alt="" className="h-full w-full object-cover" />
          )}
        </span>
      ) : (
        <span data-testid={`${testId}-preview`}>
          <Avatar
            name={name}
            seed={seed}
            fileId={fileId}
            preview={preview}
            size="lg"
            shape="square"
          />
        </span>
      )}
      <span className="min-w-0 flex-1">
        <span className="block text-sm font-medium">{label}</span>
        <span className="block text-xs text-fg-muted">{hint}</span>
      </span>
      <Button variant="ghost" disabled={disabled} onClick={onPick} data-testid={`${testId}-upload`}>
        {t('settings.servers.appearance.upload')}
      </Button>
      <Button
        variant="ghost"
        disabled={disabled || src === undefined}
        onClick={onRemove}
        data-testid={`${testId}-remove`}
      >
        {t('settings.servers.appearance.remove')}
      </Button>
    </div>
  );
}