import { useEffect, useRef, useState } from "react";
import { Link } from "react-router";
import { ChevronDown } from "lucide-react";
import { Button } from "~/components/ui/button";
import { Card, CardContent } from "~/components/ui/card";
import { SectionCardHeader } from "~/components/ui/SectionCardHeader";
import { BRACKT_GRADIENT } from "~/lib/brand";
import { BracketDecor } from "./BracketDecor";
import { SPORTS, HOW_IT_WORKS_STEPS, FEATURES } from "~/lib/landing-data";

// ─── Slot Machine ────────────────────────────────────────────────────────────

function shuffle<T>(arr: T[]): T[] {
  const a = [...arr];
  for (let i = a.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [a[i], a[j]] = [a[j], a[i]];
  }
  return a;
}

const TOTAL_TICKS = 12;

// WCAG 2.3.1: no more than 3 flashes/second → minimum interval 334 ms.
// Curve runs 800 ms → 340 ms over 12 ticks (ramps to full speed at tick 8).
function getInterval(tick: number): number {
  const pct = Math.min((tick / TOTAL_TICKS) * 1.5, 1);
  return Math.round(800 - (800 - 340) * (pct * pct));
}

function SlotMachineHeadline() {
  const [text, setText] = useState(SPORTS[0]);
  const [landed, setLanded] = useState(false);
  const [animKey, setAnimKey] = useState(0);
  const tickRef = useRef(0);
  const timerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  const sportsSeq = useRef<string[]>([]);

  useEffect(() => {
    if (typeof window !== "undefined" && window.matchMedia("(prefers-reduced-motion: reduce)").matches) {
      setLanded(true);
      return;
    }

    sportsSeq.current = shuffle(SPORTS);
    let idx = 0;

    function tick() {
      tickRef.current++;
      const sport = sportsSeq.current[idx % sportsSeq.current.length];
      idx++;
      setText(sport);
      setAnimKey((k) => k + 1);

      if (tickRef.current >= TOTAL_TICKS) {
        setLanded(true);
        return;
      }
      timerRef.current = setTimeout(tick, getInterval(tickRef.current));
    }

    timerRef.current = setTimeout(tick, 800);
    return () => {
      if (timerRef.current) clearTimeout(timerRef.current);
    };
  }, []);

  if (landed) {
    return (
      <span
        className="animate-sport-land block bg-clip-text text-transparent pb-[0.12em]"
        style={{ backgroundImage: BRACKT_GRADIENT }}
      >
        Every Sport.
      </span>
    );
  }

  return (
    <span key={animKey} className="animate-spin-in block text-white">
      {text}
    </span>
  );
}

// ─── Scroll Hint ─────────────────────────────────────────────────────────────

function ScrollHint() {
  const [visible, setVisible] = useState(true);
  useEffect(() => {
    const onScroll = () => { if (window.scrollY > 50) setVisible(false); };
    window.addEventListener("scroll", onScroll, { passive: true });
    return () => window.removeEventListener("scroll", onScroll);
  }, []);
  return (
    <div
      className="pointer-events-none absolute bottom-8 left-1/2 -translate-x-1/2 animate-bounce transition-opacity duration-500"
      style={{ opacity: visible ? 0.35 : 0 }}
    >
      <ChevronDown className="h-6 w-6 text-white" />
    </div>
  );
}

// ─── Sport Ticker ─────────────────────────────────────────────────────────────

const TICKER_ITEMS = [
  ...SPORTS.map((s) => ({ sport: s.toUpperCase(), key: `${s}-a` })),
  ...SPORTS.map((s) => ({ sport: s.toUpperCase(), key: `${s}-b` })),
];

function SportTicker() {
  const [paused, setPaused] = useState(false);

  return (
    <div className="relative overflow-hidden pb-px" style={{ marginTop: "52px" }}>
      <button
        type="button"
        onClick={() => setPaused((p) => !p)}
        aria-label={paused ? "Resume sport ticker" : "Pause sport ticker"}
        className="sr-only focus:not-sr-only focus:absolute focus:top-0 focus:right-0 focus:z-20 focus:px-2 focus:py-1 focus:text-xs focus:bg-background focus:border focus:rounded-md"
      >
        {paused ? "Resume" : "Pause"}
      </button>
      <div
        aria-hidden="true"
        className="pointer-events-none absolute inset-y-0 left-0 z-10 w-[60px]"
        style={{ background: "linear-gradient(to right, #14171e, transparent)" }}
      />
      <div
        aria-hidden="true"
        className="pointer-events-none absolute inset-y-0 right-0 z-10 w-[60px]"
        style={{ background: "linear-gradient(to left, #14171e, transparent)" }}
      />
      <div
        aria-hidden="true"
        className={paused ? "flex" : "flex animate-ticker"}
        style={{ width: "max-content" }}
      >
        {TICKER_ITEMS.map(({ sport, key }) => (
          <span
            key={key}
            className="mx-1.5 shrink-0 rounded-[3px] px-3 py-1 text-[11px] font-bold uppercase tracking-[0.05em] border bg-card text-muted-foreground"
          >
            {sport}
          </span>
        ))}
      </div>
    </div>
  );
}

// ─── Main Landing Page ────────────────────────────────────────────────────────

export function LandingPage() {
  // Interleave step cards with gradient triangle separators
  const howItWorksItems: React.ReactNode[] = [];
  HOW_IT_WORKS_STEPS.forEach((step, i) => {
    howItWorksItems.push(
      <Card key={step.title} className="flex-1 gap-2">
        <SectionCardHeader icon={step.icon} title={step.title} />
        <CardContent className="px-3 sm:px-6">
          <p className="text-sm text-muted-foreground">{step.body}</p>
        </CardContent>
      </Card>
    );
    if (i < HOW_IT_WORKS_STEPS.length - 1) {
      // Triangles reference #brackt-primary-gradient defined in <BracktGradients /> (mounted in root.tsx)
      howItWorksItems.push(
        <div key={`arrow-${step.title}`} className="flex shrink-0 items-center justify-center py-1 md:px-1 md:py-0">
          <svg width="20" height="20" viewBox="0 0 20 20" className="rotate-90 md:rotate-0">
            <polygon
              points="3,2 18,10 3,18"
              fill="url(#brackt-primary-gradient)"
              stroke="url(#brackt-primary-gradient)"
              strokeWidth={3}
              strokeLinejoin="round"
            />
          </svg>
        </div>
      );
    }
  });

  return (
    <div className="animate-page-fade-in">
      {/* ── Hero ── */}
      <section
        className="relative flex flex-col items-center justify-center overflow-hidden px-8"
        style={{ minHeight: "calc(100vh - var(--navbar-height))" }}
      >
        {/* Dot-grid texture */}
        <div
          aria-hidden
          className="pointer-events-none absolute inset-0"
          style={{
            backgroundImage: "radial-gradient(circle, rgba(255,255,255,0.07) 1px, transparent 1px)",
            backgroundSize: "32px 32px",
            maskImage: "radial-gradient(ellipse 85% 85% at 50% 50%, black 30%, transparent 100%)",
            WebkitMaskImage: "radial-gradient(ellipse 85% 85% at 50% 50%, black 30%, transparent 100%)",
          }}
        />

        {/* Bracket decorations */}
        <div className="lg:hidden">
          <BracketDecor mobileTall />
          <BracketDecor flip mobileTall />
        </div>
        <div className="hidden lg:block">
          <BracketDecor />
          <BracketDecor flip />
        </div>

        <ScrollHint />

        {/* Center content */}
        <div className="relative z-10 w-[80%] lg:w-full max-w-[680px] text-center px-6 py-4 lg:px-0 lg:py-0">
          <h1
            className="mb-0 leading-[0.95] tracking-[-0.04em]"
            style={{ fontSize: "clamp(38px, 8vw, 88px)", fontWeight: 900 }}
          >
            <span className="block text-white">Fantasy</span>
            <SlotMachineHeadline />
          </h1>

          <p
            className="mx-auto mt-8 text-muted-foreground"
            style={{ fontSize: "16px", fontWeight: 400, lineHeight: 1.65, maxWidth: "414px" }}
          >
            Draft teams across every league and sport, like the NFL, NHL, EPL, F1, and more.
            Compete against your friends in a season-long league.
          </p>

          <div className="mt-8 flex flex-col items-center justify-center gap-2.5 sm:flex-row">
            <Button asChild size="lg" className="text-sm font-extrabold">
              <Link to="/leagues/new">Create a League</Link>
            </Button>
            <Button asChild variant="outline" size="lg" className="text-sm font-semibold">
              <Link to="/how-to-play">How it works</Link>
            </Button>
          </div>

          <SportTicker />
        </div>
      </section>

      {/* ── How It Works ── */}
      <section className="mx-auto w-full max-w-[1100px] px-10 py-18">
        <div className="flex flex-col gap-4 md:flex-row md:items-stretch">
          {howItWorksItems}
        </div>
      </section>

      {/* ── Features Grid ── */}
      <section className="mx-auto w-full max-w-[1100px] px-10 pb-18">
        <div className="overflow-hidden rounded-[6px] border">
          <div className="grid grid-cols-1 md:grid-cols-2" style={{ gap: "1px", background: "rgb(255 255 255 / 10%)" }}>
            {FEATURES.map(({ title, body }) => (
              <div key={title} className="bg-card p-7 transition-colors hover:bg-[#22252e]">
                <h3 className="mb-2 text-base font-extrabold tracking-[-0.01em]">{title}</h3>
                <p className="text-sm leading-[1.65] text-muted-foreground">{body}</p>
              </div>
            ))}
          </div>
        </div>
      </section>

      {/* ── Footer CTA ── */}
      <section className="mx-auto w-full max-w-[1100px] px-10 pb-20">
        <div className="flex flex-col items-center gap-6 p-12 text-center">
          <h2
            className="font-black tracking-[-0.025em]"
            style={{ fontSize: "clamp(22px, 3vw, 34px)" }}
          >
            Stop managing your league and start watching it.
          </h2>
          <p className="text-sm leading-[1.65] text-muted-foreground" style={{ maxWidth: "600px" }}>
            Brackt is built for the sports fan who wants a stake in everything without the daily chore of a traditional fantasy roster. Setting up a league takes less than five minutes. Choose your sports, invite your friends, and let the draft decide the winner.
          </p>
          <Button asChild size="lg" className="text-sm font-extrabold">
            <Link to="/leagues/new">Create a League</Link>
          </Button>
        </div>
      </section>
    </div>
  );
}
