import { content } from "@deadhead/content";
import { useMutation, useQueryClient } from "@tanstack/react-query";
import { useEffect, useRef, useState, type KeyboardEvent } from "react";
import { createPortal } from "react-dom";
import { useNavigate } from "react-router";
import { useApi } from "../api/context";
import { useLoadedPlayer } from "../state/actions";
import { PLAYER_STATE_KEY } from "../state/player";
import { reducedMotionOn, usePreferences } from "../state/preferences";
import { Button } from "../ui";

const FOCUSABLE = 'button:not([disabled]), [href], [tabindex]:not([tabindex="-1"])';

/** A card's body with the tutorial employer's name filled in. */
export function welcomeBody(body: string): string {
  return body.split("{company}").join(content.tutorialCompanyName);
}

/**
 * The three welcome cards (decisions 0.5.131, 0.5.132): Next through them,
 * Skip on every card, and a last button that starts the game ("Let's fly") or,
 * reopened from Settings → Help, just closes ("Close"). Cards slide in, or
 * change at once with reduced motion; focus stays inside until it closes.
 */
export function WelcomeCards({
  final,
  onClose,
}: {
  final: "start" | "close";
  onClose: () => void;
}) {
  const { cards, next, skip, start, close } = content.welcome;
  const [index, setIndex] = useState(0);
  const reduced = usePreferences(reducedMotionOn);
  const dialog = useRef<HTMLDivElement>(null);
  const touchX = useRef<number | null>(null);
  const card = cards[index]!;
  const last = index === cards.length - 1;

  // Focus moves into the pop-up, onto the main button of each card.
  useEffect(() => {
    dialog.current?.querySelector<HTMLElement>("[data-primary]")?.focus();
  }, [index]);

  const advance = () => (last ? onClose() : setIndex(index + 1));

  // Tab and Shift+Tab stay inside; Escape is Skip.
  const onKeyDown = (e: KeyboardEvent<HTMLDivElement>) => {
    if (e.key === "Escape") {
      e.preventDefault();
      onClose();
      return;
    }
    if (e.key !== "Tab" || !dialog.current) return;
    const focusable = [...dialog.current.querySelectorAll<HTMLElement>(FOCUSABLE)];
    if (focusable.length === 0) return;
    const first = focusable[0]!;
    const end = focusable.at(-1)!;
    if (e.shiftKey && document.activeElement === first) {
      e.preventDefault();
      end.focus();
    } else if (!e.shiftKey && document.activeElement === end) {
      e.preventDefault();
      first.focus();
    }
  };

  return createPortal(
    <div className="fixed inset-0 z-40 flex items-end justify-center bg-black/25 backdrop-blur-sm sm:items-center sm:p-4">
      <div
        ref={dialog}
        role="dialog"
        aria-modal="true"
        aria-labelledby="welcome-title"
        onKeyDown={onKeyDown}
        onTouchStart={(e) => {
          touchX.current = e.touches[0]?.clientX ?? null;
        }}
        onTouchEnd={(e) => {
          const from = touchX.current;
          const to = e.changedTouches[0]?.clientX;
          touchX.current = null;
          if (from === null || to === undefined) return;
          // Swipe left for the next card, right for the previous one.
          if (from - to > 50) advance();
          else if (to - from > 50 && index > 0) setIndex(index - 1);
        }}
        className="w-full max-w-md overflow-hidden rounded-t-2xl border border-glass-line bg-space-850 p-6 pb-[max(1.5rem,env(safe-area-inset-bottom))] shadow-panel sm:rounded-2xl"
      >
        <p aria-live="polite" className="font-display text-xs font-semibold text-ink-300">
          {index + 1} of {cards.length}
        </p>
        <div key={index} data-testid="welcome-card" className={reduced ? "" : "animate-slide"}>
          <h2 id="welcome-title" className="mt-2 font-title text-lg leading-snug">
            {card.title}
          </h2>
          <p className="mt-3 text-ink-200">{welcomeBody(card.body)}</p>
        </div>
        <div aria-hidden="true" className="mt-5 flex justify-center gap-1.5">
          {cards.map((_, i) => (
            <span
              key={i}
              className={`h-1.5 rounded-full ${i === index ? "w-5 bg-action" : "w-1.5 bg-white/25"}`}
            />
          ))}
        </div>
        <div className="mt-5 flex gap-3">
          <Button variant="secondary" onClick={onClose} className="flex-1">
            {skip}
          </Button>
          <Button data-primary onClick={advance} className="flex-1">
            {last ? (final === "start" ? start : close) : next}
          </Button>
        </div>
      </div>
    </div>,
    document.body,
  );
}

/**
 * A new company's welcome (decision 0.5.131): shown until this company has
 * seen it; closing it records that and goes to Contracts, where the tutorial
 * intro card follows.
 */
export function WelcomeGate() {
  const state = useLoadedPlayer();
  const api = useApi();
  const queryClient = useQueryClient();
  const navigate = useNavigate();
  // Closed for this company: a new company (Settings) gets its own welcome.
  const [closedFor, setClosedFor] = useState<string | null>(null);
  const seen = useMutation({
    mutationFn: () => api.call("markWelcomeSeen", {}),
    onSuccess: (next) => queryClient.setQueryData(PLAYER_STATE_KEY, next),
  });
  if (state.welcomeSeen || closedFor === state.company.id) return null;
  return (
    <WelcomeCards
      final="start"
      onClose={() => {
        setClosedFor(state.company.id);
        seen.mutate();
        void navigate("/contracts");
      }}
    />
  );
}