import { useEffect, useRef, useState } from "react";
import { Link } from "react-router";
import { Users, Shuffle, Trophy, ChevronDown } from "lucide-react";
import { Button } from "~/components/ui/button";
import { Card, CardContent } from "~/components/ui/card";
import { SectionCardHeader } from "~/components/ui/SectionCardHeader";

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

const SPORTS = [
  "Football", "Baseball", "Hockey", "Basketball", "Soccer", "Tennis", "Golf",
  "eSports", "Formula 1", "Aussie Rules", "Lacrosse", "Darts", "College Football", "Snooker", "March Madness",
];

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(() => {
    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: "linear-gradient(to bottom, #adf661, #2ce1c1)" }}
      >
        Every Sport.
      </span>
    );
  }

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

// ─── Bracket Decoration ──────────────────────────────────────────────────────

function BracketDecor({ flip = false, mobileTall = false }: { flip?: boolean; mobileTall?: boolean }) {
  const base = flip ? "r" : "l";
  const id = mobileTall ? `${base}-m` : base;
  const W = 399;
  const H = mobileTall ? 2000 : 560;

  const pad = 36;
  const spacing = (H - 2 * pad) / 7;
  const r1Ys = Array.from({ length: 8 }, (_, i) => pad + i * spacing);
  const r2Ys = [0, 1, 2, 3].map((i) => (r1Ys[i * 2] + r1Ys[i * 2 + 1]) / 2);
  const r3Ys = [0, 1].map((i) => (r2Ys[i * 2] + r2Ys[i * 2 + 1]) / 2);
  const champY = (r3Ys[0] + r3Ys[1]) / 2;

  const x0 = 4;
  const x1 = 77;
  const x2 = 161;
  const x3 = 252;

  const gradId = `grad-${id}`;
  const glowId = `glow-${id}`;
  const dotsGlowId = `dots-glow-${id}`;
  const finalsGlowId = `finals-glow-${id}`;
  const finalsHaloId = `finals-halo-${id}`;
  const finalsFadeMaskGradId = `finals-fade-mask-grad-${id}`;
  const finalsFadeMaskId = `finals-fade-mask-${id}`;
  const finalsLineGlowId = `finals-line-glow-${id}`;


  return (
    <svg
      viewBox={`0 0 ${W} ${H}`}
      style={{
        position: "absolute",
        top: "50%",
        transform: `translateY(-52%)${flip ? " scaleX(-1)" : ""}`,
        [flip ? "right" : "left"]: 0,
        pointerEvents: "none",
        height: mobileTall ? "auto" : "75vh",
        width: mobileTall ? "32vw" : "auto",
      }}
    >
      <defs>
        <linearGradient id={gradId} x1="0" y1="0" x2="0" y2={H} gradientUnits="userSpaceOnUse">
          <stop offset="0%" stopColor="#adf661" />
          <stop offset="100%" stopColor="#2ce1c1" />
        </linearGradient>
        <filter id={glowId} x="-50%" y="-50%" width="200%" height="200%">
          <feGaussianBlur stdDeviation="3" result="blur" />
          <feMerge>
            <feMergeNode in="blur" />
            <feMergeNode in="SourceGraphic" />
          </feMerge>
        </filter>
        <filter id={finalsGlowId} filterUnits="userSpaceOnUse"
          x={x2 - 15} y={r3Ys[0] - 15} width={x3 - x2 + 30} height={r3Ys[1] - r3Ys[0] + 30}>
          <feGaussianBlur stdDeviation="7" result="blur" />
          <feMerge>
            <feMergeNode in="blur" />
            <feMergeNode in="SourceGraphic" />
          </feMerge>
        </filter>
        <filter id={finalsHaloId} filterUnits="userSpaceOnUse"
          x={x2 - 40} y={r3Ys[0] - 40} width={x3 - x2 + 80} height={r3Ys[1] - r3Ys[0] + 80}>
          <feGaussianBlur stdDeviation="16" />
        </filter>
        <linearGradient id={finalsFadeMaskGradId} x1={x3} y1="0" x2={W} y2="0" gradientUnits="userSpaceOnUse">
          <stop offset="0%" stopColor="white" />
          <stop offset="50%" stopColor="white" />
          <stop offset="100%" stopColor="white" stopOpacity="0" />
        </linearGradient>
        <mask id={finalsFadeMaskId} maskUnits="userSpaceOnUse" x={x3} y={champY - 20} width={W - x3} height={40}>
          <rect x="0" y="0" width={W} height={H} fill={`url(#${finalsFadeMaskGradId})`} />
        </mask>
        <filter id={finalsLineGlowId} filterUnits="userSpaceOnUse" x={x3 - 10} y={champY - 15} width={W - x3 + 20} height={30}>
          <feGaussianBlur stdDeviation="3" result="blur" />
          <feMerge>
            <feMergeNode in="blur" />
            <feMergeNode in="SourceGraphic" />
          </feMerge>
        </filter>
        <filter id={dotsGlowId} x="-200%" y="-200%" width="500%" height="500%">
          <feGaussianBlur stdDeviation="5" result="blur" />
          <feMerge>
            <feMergeNode in="blur" />
            <feMergeNode in="blur" />
            <feMergeNode in="SourceGraphic" />
          </feMerge>
        </filter>
      </defs>
      <g filter={`url(#${finalsHaloId})`} stroke={`url(#${gradId})`} strokeWidth={2} fill="none" opacity={0.75}>
        {r3Ys.map((midY) => (
          <line key={midY} x1={x2} y1={midY} x2={x3} y2={midY} />
        ))}
        <line x1={x3} y1={r3Ys[0]} x2={x3} y2={r3Ys[1]} />
      </g>
      <g filter={`url(#${finalsGlowId})`} stroke={`url(#${gradId})`} strokeWidth={1.5} fill="none">
        {r3Ys.map((midY) => (
          <line key={midY} x1={x2} y1={midY} x2={x3} y2={midY} />
        ))}
        <line x1={x3} y1={r3Ys[0]} x2={x3} y2={r3Ys[1]} />
      </g>
      <g filter={`url(#${glowId})`} stroke={`url(#${gradId})`} strokeWidth={1.5} fill="none">
        {r1Ys.map((y) => (
          <g key={y}>
            <circle cx={x0} cy={y} r={3} fill={`url(#${gradId})`} stroke="none" filter={`url(#${dotsGlowId})`} />
            <line x1={x0} y1={y} x2={x1} y2={y} />
          </g>
        ))}
        {r2Ys.map((midY, i) => (
          <g key={midY}>
            <line x1={x1} y1={r1Ys[i * 2]} x2={x1} y2={r1Ys[i * 2 + 1]} />
            <circle cx={x1} cy={midY} r={3} fill={`url(#${gradId})`} stroke="none" filter={`url(#${dotsGlowId})`} />
            <line x1={x1} y1={midY} x2={x2} y2={midY} />
          </g>
        ))}
        {r3Ys.map((midY, i) => (
          <g key={midY}>
            <line x1={x2} y1={r2Ys[i * 2]} x2={x2} y2={r2Ys[i * 2 + 1]} />
            <circle cx={x2} cy={midY} r={3} fill={`url(#${gradId})`} stroke="none" filter={`url(#${dotsGlowId})`} />
            <line x1={x2} y1={midY} x2={x3} y2={midY} />
          </g>
        ))}
        <line x1={x3} y1={r3Ys[0]} x2={x3} y2={r3Ys[1]} />
        <circle cx={x3} cy={champY} r={3} fill={`url(#${gradId})`} stroke="none" filter={`url(#${dotsGlowId})`} />
      </g>
      <line
        x1={x3} y1={champY} x2={W} y2={champY}
        stroke={`url(#${gradId})`}
        strokeWidth={1.5}
        fill="none"
        filter={`url(#${finalsLineGlowId})`}
        mask={`url(#${finalsFadeMaskId})`}
      />
    </svg>
  );
}

// ─── 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() {
  return (
    <div className="relative overflow-hidden pb-px" style={{ marginTop: "52px" }}>
      <div
        className="pointer-events-none absolute inset-y-0 left-0 z-10 w-[60px]"
        style={{ background: "linear-gradient(to right, #14171e, transparent)" }}
      />
      <div
        className="pointer-events-none absolute inset-y-0 right-0 z-10 w-[60px]"
        style={{ background: "linear-gradient(to left, #14171e, transparent)" }}
      />
      <div className="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>
  );
}

// ─── Static data ──────────────────────────────────────────────────────────────

const HOW_IT_WORKS_STEPS = [
  {
    icon: Users,
    title: "Create a League",
    body: "Start a league, pick your sports (we can help), and invite your friends. It takes 30 seconds to set the stage.",
  },
  {
    icon: Shuffle,
    title: "Draft Your Teams",
    body: "Pick teams from all the sports in order to build a superteam to win you bragging rights! Draft your way, slow or fast, with standard timers or high-pressure chess clocks.",
  },
  {
    icon: Trophy,
    title: "Watch & Win",
    body: "Your teams earn points for how well they perform in the playoffs. Follow your rooting interests along the way, and gloat over your leaguemates when they fall.",
  },
];

const FEATURES = [
  {
    title: "Every sport, one league",
    body: "NHL running at the same time as the NBA Finals? Draft from both. Brackt syncs across every major sports calendar.",
  },
  {
    title: "Live bracket view",
    body: "Watch your bracket update as games end. Heartbreak and glory, all on one screen.",
  },
  {
    title: "Snake draft",
    body: "Fair picks for everyone. No one ends up with dregs. The draft is the fun part — we let you enjoy it.",
  },
  {
    title: "Invite in one click",
    body: "Share a link. Friends join, pick a name, they're in. No downloads, no friction.",
  },
];

// ─── 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>

      {/* ── CTA Banner ── */}
      <section className="mx-auto w-full max-w-[1100px] px-10 pb-20">
        <div className="bg-card border flex flex-col gap-8 rounded-[6px] p-12 md:flex-row md:items-center md:justify-between">
          <div>
            <h2
              className="mb-3 font-black tracking-[-0.025em]"
              style={{ fontSize: "clamp(22px, 3vw, 34px)" }}
            >
              Your group chat is waiting for this.
            </h2>
            <p className="text-sm leading-[1.65] text-muted-foreground" style={{ maxWidth: "460px" }}>
              Free to play. Five minutes to set up. The real question is — who drafts the Colorado Avalanche?
            </p>
          </div>
          <Button asChild size="lg" className="shrink-0 text-sm font-extrabold">
            <Link to="/leagues/new">Create a League — It&apos;s Free</Link>
          </Button>
        </div>
      </section>
    </div>
  );
}