"use client";

import {
  createContext,
  type ReactNode,
  useCallback,
  useContext,
  useEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { useReducedMotion } from "@/app/hooks/useReducedMotion";
import type { PortfolioProjectView } from "@/lib/portfolio-data";
import { SHOWCASE, type ShowcaseConfig } from "@/lib/project-showcase";
import { ProjectLightbox } from "./ProjectLightbox";
import { pickActiveCard } from "./showcase-math";
import "./showcase.css";

export interface ShowcaseItem {
  config: ShowcaseConfig;
  project: PortfolioProjectView;
}

interface ShowcaseApi {
  register(id: string, element: HTMLElement): () => void;
  setHover(id: string, hovered: boolean): void;
  open(id: string): void;
  /** Pausa (ou retoma) os vídeos que tocam sozinhos nos cards: quem não quer movimento na página tem como desligar. */
  toggleAutoplay(): void;
  items: ShowcaseItem[];
}

interface ActiveState {
  activeId: string | null;
  userPaused: boolean;
}

const ApiContext = createContext<ShowcaseApi | null>(null);
const ActiveContext = createContext<ActiveState>({
  activeId: null,
  userPaused: false,
});

/** Só aparece como card com vídeo o projeto que existe na lista e tem vídeo gravado. */
export function buildShowcaseItems(
  projects: PortfolioProjectView[],
): ShowcaseItem[] {
  const items: ShowcaseItem[] = [];
  for (const config of SHOWCASE) {
    const project = projects.find((candidate) => candidate.id === config.id);
    if (project) items.push({ config, project });
  }
  return items;
}

/** Itens da vitrine para quem está dentro do provedor (a vitrine animada usa a mesma lista dos cards). */
export function useShowcaseItems() {
  return useContext(ApiContext)?.items ?? [];
}

/** Abre a janela ampliada de um projeto (nada acontece fora do provedor). */
export function useShowcaseOpen() {
  const api = useContext(ApiContext);
  return useCallback((id: string) => api?.open(id), [api]);
}

/**
 * Um vídeo por vez nos cards: toca o card sob o mouse (ou com foco); sem mouse sobre nenhum, o mais perto do
 * centro da tela. Também guarda qual card está ampliado e mostra a janela ampliada.
 */
export function ShowcaseProvider({
  projects,
  children,
}: {
  projects: PortfolioProjectView[];
  children: ReactNode;
}) {
  const reducedMotion = useReducedMotion();
  const items = useMemo(() => buildShowcaseItems(projects), [projects]);
  const [activeId, setActiveId] = useState<string | null>(null);
  const [openId, setOpenId] = useState<string | null>(null);
  const [userPaused, setUserPaused] = useState(false);

  const cards = useRef(
    new Map<string, { el: HTMLElement; visible: boolean }>(),
  );
  const hovered = useRef<string | null>(null);
  const paused = useRef(false);
  const queued = useRef(false);
  const frame = useRef(0);
  const observer = useRef<IntersectionObserver | null>(null);

  const evaluate = useCallback(() => {
    queued.current = false;
    if (paused.current || document.hidden) {
      setActiveId(null);
      return;
    }
    const middle = window.innerHeight / 2;
    const candidates = [...cards.current].map(([id, { el, visible }]) => {
      // só quem está à vista entra na disputa: os outros nem têm o layout lido a cada quadro de rolagem
      if (!visible) return { id, visible, distance: Number.POSITIVE_INFINITY };
      const rect = el.getBoundingClientRect();
      return {
        id,
        visible,
        distance: Math.abs(rect.top + rect.height / 2 - middle),
      };
    });
    setActiveId(pickActiveCard(candidates, hovered.current));
  }, []);

  // sem cards registrados (a home mostra só a vitrine animada) não há o que decidir a cada quadro de rolagem;
  // `force` vale para o que acabou de mudar a lista (um card saiu), que ainda precisa ser reavaliado
  const schedule = useCallback(
    (force = false) => {
      if (queued.current || (!force && cards.current.size === 0)) return;
      queued.current = true;
      frame.current = requestAnimationFrame(evaluate);
    },
    [evaluate],
  );

  // com a janela ampliada aberta, ou com preferência por menos movimento, nenhum card toca
  useEffect(() => {
    paused.current = reducedMotion || openId !== null || userPaused;
    schedule(true);
  }, [schedule, openId, reducedMotion, userPaused]);

  useEffect(() => {
    const onChange = () => schedule();
    window.addEventListener("scroll", onChange, { passive: true });
    window.addEventListener("resize", onChange);
    document.addEventListener("visibilitychange", onChange);
    return () => {
      window.removeEventListener("scroll", onChange);
      window.removeEventListener("resize", onChange);
      document.removeEventListener("visibilitychange", onChange);
      cancelAnimationFrame(frame.current);
      queued.current = false;
      observer.current?.disconnect();
      observer.current = null;
    };
  }, [schedule]);

  const api = useMemo<ShowcaseApi>(
    () => ({
      items,
      register(id, element) {
        if (!observer.current && typeof IntersectionObserver !== "undefined") {
          observer.current = new IntersectionObserver(
            (entries) => {
              for (const entry of entries) {
                for (const card of cards.current.values()) {
                  // um card só vale como "à vista" com pelo menos um terço dele na tela
                  if (card.el === entry.target)
                    card.visible = entry.intersectionRatio >= 0.33;
                }
              }
              schedule();
            },
            { threshold: [0, 0.33, 0.66, 1] },
          );
        }
        cards.current.set(id, { el: element, visible: false });
        observer.current?.observe(element);
        return () => {
          observer.current?.unobserve(element);
          cards.current.delete(id);
          if (hovered.current === id) hovered.current = null;
          schedule(true);
        };
      },
      setHover(id, isHovered) {
        if (isHovered) hovered.current = id;
        else if (hovered.current === id) hovered.current = null;
        schedule();
      },
      open(id) {
        setOpenId(id);
      },
      toggleAutoplay() {
        setUserPaused((paused) => !paused);
      },
    }),
    [items, schedule],
  );

  const activeState = useMemo(
    () => ({ activeId, userPaused }),
    [activeId, userPaused],
  );

  const openIndex = openId
    ? items.findIndex((item) => item.config.id === openId)
    : -1;

  return (
    <ApiContext.Provider value={api}>
      <ActiveContext.Provider value={activeState}>
        {children}
        {openIndex >= 0 && (
          <ProjectLightbox
            items={items}
            index={openIndex}
            onClose={() => setOpenId(null)}
            onNavigate={(index) => setOpenId(items[index]?.config.id ?? null)}
          />
        )}
      </ActiveContext.Provider>
    </ApiContext.Provider>
  );
}

/** Liga um card à vitrine: devolve a ref da moldura, se ele é o card que toca agora e como ampliá-lo. */
export function useShowcaseCard(id: string) {
  const api = useContext(ApiContext);
  const { activeId, userPaused } = useContext(ActiveContext);
  const frameRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    const element = frameRef.current;
    if (!api || !element) return;
    const unregister = api.register(id, element);
    const card = element.closest<HTMLElement>(".ds-card") ?? element;
    const enter = (event: PointerEvent) => {
      // no toque não existe "passar o mouse": só o mouse e a caneta mandam na vitrine
      if (event.pointerType !== "touch") api.setHover(id, true);
    };
    const leave = () => api.setHover(id, false);
    const focusIn = () => api.setHover(id, true);
    const focusOut = (event: FocusEvent) => {
      if (!card.contains(event.relatedTarget as Node | null))
        api.setHover(id, false);
    };
    card.addEventListener("pointerenter", enter);
    card.addEventListener("pointerleave", leave);
    card.addEventListener("focusin", focusIn);
    card.addEventListener("focusout", focusOut);
    return () => {
      unregister();
      card.removeEventListener("pointerenter", enter);
      card.removeEventListener("pointerleave", leave);
      card.removeEventListener("focusin", focusIn);
      card.removeEventListener("focusout", focusOut);
    };
  }, [api, id]);

  return {
    frameRef,
    active: activeId === id,
    userPaused,
    toggleAutoplay: useCallback(() => api?.toggleAutoplay(), [api]),
    open: useCallback(() => api?.open(id), [api, id]),
  };
}