import { createContext, useContext, useEffect, useMemo, useState, type ReactNode } from "react";
import { useTranslation } from "react-i18next";
import { useQuery, useQueryClient } from "@tanstack/react-query";
import { qk } from "../lib/queryKeys";
import {
  api,
  coercePlexFilters,
  coerceTagModes,
  getActiveAccount,
  plexFiltersSignature,
  type FeedFilters,
  type PlexFilters,
  type SavedView,
} from "../lib/api";
import { filtersToParams } from "../lib/urlState";
import { preferSticky } from "../lib/savedViews";
import { notifyActionError } from "../lib/actionErrors";
import { accountKey, LS, writeJSON } from "../lib/storage";
import { useConfirm } from "./ConfirmProvider";
import { useNavigation } from "./NavigationProvider";
import { useFeedFilters, useFeedFiltersActions } from "./FeedFiltersProvider";
import { usePlex, usePlexActions } from "./PlexProvider";

// Saved "smart views" now serve TWO modules — the feed and Plex — keyed by `source`. This one provider
// switches which module it operates on by the active page (both filter providers are global, so it can
// read either), so the shared UI (popover / modal / chip) works on the feed page against feed views and
// on the plex page against plex views without a second provider or an App-layout change.

// A saved view's `filters` is an opaque JSON blob from the DB; coerce it to the module's shape before it
// reaches app state or a serializer (an older build's dropped field just falls away — NOT a migration).
export const asFilters = (raw: FeedFilters): FeedFilters => ({
  ...raw,
  tags: raw.tags ?? [],
  channelIds: raw.channelIds ?? [],
  tagModes: coerceTagModes(raw),
});

type ViewSource = "feed" | "plex";

// The per-source wiring the generic logic runs on: the live filters, how to apply a view's, a stable
// signature for matching, coercion, and what to strip before saving (the feed's transient shuffle seed).
interface ViewConfig {
  source: ViewSource;
  filters: Record<string, unknown>;
  setFilters: (f: Record<string, unknown>) => void;
  keyOf: (f: Record<string, unknown>) => string;
  asFilters: (raw: Record<string, unknown>) => Record<string, unknown>;
  stripForSave: (f: Record<string, unknown>) => Record<string, unknown>;
  /** Feed only: mirror the default view's filters to localStorage so it seeds before the network returns. */
  syncDefaultMirror?: (views: SavedView[]) => void;
}

const feedKeyOf = (f: Record<string, unknown>) =>
  filtersToParams(asFilters(f as unknown as FeedFilters)).toString();
const plexKeyOf = (f: Record<string, unknown>) => plexFiltersSignature(coercePlexFilters(f));

// Mirror the feed default view's filters to localStorage (read by FeedFiltersProvider on load).
function syncFeedDefaultMirror(views: SavedView[]): void {
  const key = accountKey(LS.defaultViewFilters, getActiveAccount());
  if (!key) return;
  const def = views.find((v) => v.is_default);
  writeJSON(key, def ? def.filters : null);
}

export interface SavedViewsContext {
  /** Which module these views belong to — the shared UI branches its filter-describer on it. */
  source: ViewSource;
  views: SavedView[];
  loading: boolean;
  activeViewId: number | null;
  displayView: SavedView | null;
  isDirty: boolean;
  modalOpen: boolean;
  openModal: () => void;
  closeModal: () => void;
  apply: (v: SavedView) => void;
  clearActive: () => void;
  create: (name: string) => Promise<boolean>;
  rename: (id: number, name: string) => Promise<boolean>;
  toggleDefault: (v: SavedView) => Promise<void>;
  remove: (v: SavedView) => Promise<boolean>;
  reorder: (nextIds: number[]) => Promise<void>;
}

const Ctx = createContext<SavedViewsContext | null>(null);

export function SavedViewsProvider({ children }: { children: ReactNode }) {
  const { t } = useTranslation();
  const qc = useQueryClient();
  const confirm = useConfirm();
  const { page } = useNavigation();

  // Both filter providers are global — read both, then use the one the active page owns.
  const feedFilters = useFeedFilters();
  const { setFilters: setFeedFilters } = useFeedFiltersActions();
  const { filters: plexFilters } = usePlex();
  const { setFilters: setPlexFilters } = usePlexActions();

  const cfg: ViewConfig = useMemo(() => {
    if (page === "plex") {
      return {
        source: "plex",
        filters: plexFilters as unknown as Record<string, unknown>,
        setFilters: (f) => setPlexFilters(f as unknown as PlexFilters),
        keyOf: plexKeyOf,
        asFilters: (raw) => coercePlexFilters(raw) as unknown as Record<string, unknown>,
        stripForSave: (f) => f, // Plex has no transient field to drop
      };
    }
    return {
      source: "feed",
      filters: feedFilters as unknown as Record<string, unknown>,
      setFilters: (f) => setFeedFilters(f as unknown as FeedFilters),
      keyOf: feedKeyOf,
      asFilters: (raw) =>
        asFilters(raw as unknown as FeedFilters) as unknown as Record<string, unknown>,
      // Strip the transient shuffle seed so a saved "shuffle" view re-rolls fresh on apply.
      stripForSave: (f) => {
        const { seed: _seed, ...rest } = f;
        return rest;
      },
      syncDefaultMirror: syncFeedDefaultMirror,
    };
  }, [page, feedFilters, plexFilters, setFeedFilters, setPlexFilters]);

  const source = cfg.source;
  const viewsQuery = useQuery({
    queryKey: qk.savedViews(source),
    queryFn: () => api.savedViews(source),
  });
  const views = useMemo(() => viewsQuery.data ?? [], [viewsQuery.data]);

  const [stickyId, setStickyId] = useState<number | null>(null);
  const [modalOpen, setModalOpen] = useState(false);

  // Switching modules (feed ⟷ plex) starts fresh: a feed view can't be the sticky/active one on plex,
  // and a feed modal shouldn't linger open on plex.
  useEffect(() => {
    setStickyId(null);
    setModalOpen(false);
  }, [source]);

  // Feed only: keep the default-view mirror (read on load) in sync with the server state. Depend on the
  // mirror fn (a module-stable ref, or undefined for plex) NOT the whole `cfg` object — cfg re-memoizes
  // on every live filter edit, which would fire this synchronous localStorage write far beyond its intent.
  const syncMirror = cfg.syncDefaultMirror;
  useEffect(() => {
    if (viewsQuery.data) syncMirror?.(viewsQuery.data);
  }, [viewsQuery.data, syncMirror]);

  const currentKey = cfg.keyOf(cfg.filters);
  const activeView = useMemo(
    () =>
      preferSticky(
        views.filter((v) => cfg.keyOf(v.filters) === currentKey),
        stickyId,
      ),
    [views, currentKey, stickyId, cfg],
  );
  useEffect(() => {
    if (activeView) setStickyId(activeView.id);
  }, [activeView]);

  const stickyView = useMemo(
    () => (stickyId == null ? null : (views.find((v) => v.id === stickyId) ?? null)),
    [views, stickyId],
  );
  const displayView = activeView ?? stickyView;
  const isDirty = displayView != null && activeView == null;

  const refresh = () => qc.invalidateQueries({ queryKey: qk.savedViews(source) });
  async function runViewMutation(fn: () => Promise<unknown>, failMsg: string): Promise<boolean> {
    try {
      await fn();
      return true;
    } catch (e) {
      notifyActionError(e, failMsg);
      return false;
    } finally {
      refresh();
    }
  }

  const value: SavedViewsContext = {
    source,
    views,
    loading: viewsQuery.isLoading,
    activeViewId: activeView?.id ?? null,
    displayView,
    isDirty,
    modalOpen,
    openModal: () => setModalOpen(true),
    closeModal: () => setModalOpen(false),
    apply: (v) => {
      cfg.setFilters(cfg.asFilters(v.filters));
      setStickyId(v.id);
    },
    clearActive: () => setStickyId(null),
    create: async (name) => {
      const clean = name.trim();
      if (!clean) return false;
      return runViewMutation(
        () => api.createView(clean, cfg.stripForSave(cfg.filters), source),
        t("views.actionFailed"),
      );
    },
    rename: async (id, name) => {
      const next = name.trim();
      if (!next) return false;
      return runViewMutation(() => api.updateView(id, { name: next }), t("views.actionFailed"));
    },
    toggleDefault: (v) =>
      runViewMutation(
        () => api.updateView(v.id, { is_default: !v.is_default }),
        t("views.actionFailed"),
      ).then(() => undefined),
    remove: async (v) => {
      const ok = await confirm({
        message: t("views.deleteConfirm", { name: v.name }),
        confirmLabel: t("views.delete"),
        danger: true,
      });
      if (!ok) return false;
      if (stickyId === v.id) setStickyId(null);
      return runViewMutation(() => api.deleteView(v.id), t("views.actionFailed"));
    },
    reorder: async (nextIds) => {
      qc.setQueryData<SavedView[]>(
        qk.savedViews(source),
        nextIds.map((id) => views.find((v) => v.id === id)!).filter(Boolean),
      );
      await runViewMutation(() => api.reorderViews(nextIds), t("views.reorderFailed"));
    },
  };

  return <Ctx.Provider value={value}>{children}</Ctx.Provider>;
}

export function useSavedViews(): SavedViewsContext {
  const ctx = useContext(Ctx);
  if (!ctx) throw new Error("useSavedViews must be used within a SavedViewsProvider");
  return ctx;
}