"use client";

import { useState, useEffect, useRef, useCallback } from "react";
import Link from "next/link";

const FIELD_W = 600;
const FIELD_H = 400;
const BALL_R = 12;
const PADDLE_W = 12;
const PADDLE_H = 70;
const CPU_SPEED = 3.2;
const INITIAL_SPEED = 4.5;

type Vec = { x: number; y: number };
type GameState = "idle" | "playing" | "paused" | "over";

function clamp(v: number, lo: number, hi: number) {
  return Math.max(lo, Math.min(hi, v));
}

const HIGH_SCORE_KEY = "cyberlux-pong-hs";

function getHighScore() {
  if (typeof window === "undefined") return 0;
  return parseInt(localStorage.getItem(HIGH_SCORE_KEY) ?? "0", 10);
}
function setHighScore(n: number) {
  if (typeof window !== "undefined") localStorage.setItem(HIGH_SCORE_KEY, String(n));
}

export default function PongPage() {
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const stateRef = useRef<GameState>("idle");
  const ballRef = useRef<Vec>({ x: FIELD_W / 2, y: FIELD_H / 2 });
  const velRef = useRef<Vec>({ x: INITIAL_SPEED, y: INITIAL_SPEED });
  const playerYRef = useRef((FIELD_H - PADDLE_H) / 2);
  const cpuYRef = useRef((FIELD_H - PADDLE_H) / 2);
  const scoreRef = useRef({ player: 0, cpu: 0 });
  const rafRef = useRef<number>(0);
  const mouseYRef = useRef(FIELD_H / 2);

  const [displayScore, setDisplayScore] = useState({ player: 0, cpu: 0 });
  const [gameState, setGameState] = useState<GameState>("idle");
  const [highScore, setHighScoreState] = useState(0);
  const [rally, setRally] = useState(0);
  const rallyRef = useRef(0);

  useEffect(() => {
    setHighScoreState(getHighScore());
  }, []);

  const reset = useCallback(() => {
    ballRef.current = { x: FIELD_W / 2, y: FIELD_H / 2 };
    const angle = (Math.random() * Math.PI) / 3 - Math.PI / 6;
    const dir = Math.random() > 0.5 ? 1 : -1;
    velRef.current = {
      x: INITIAL_SPEED * dir * Math.cos(angle),
      y: INITIAL_SPEED * Math.sin(angle),
    };
    rallyRef.current = 0;
    setRally(0);
  }, []);

  const draw = useCallback(() => {
    const canvas = canvasRef.current;
    if (!canvas) return;
    const ctx = canvas.getContext("2d");
    if (!ctx) return;

    // Background
    ctx.fillStyle = "#050510";
    ctx.fillRect(0, 0, FIELD_W, FIELD_H);

    // Center line
    ctx.setLineDash([8, 8]);
    ctx.strokeStyle = "rgba(0,255,200,0.1)";
    ctx.lineWidth = 2;
    ctx.beginPath();
    ctx.moveTo(FIELD_W / 2, 0);
    ctx.lineTo(FIELD_W / 2, FIELD_H);
    ctx.stroke();
    ctx.setLineDash([]);

    // Paddles
    const drawPaddle = (x: number, y: number, color: string) => {
      ctx.shadowColor = color;
      ctx.shadowBlur = 12;
      ctx.fillStyle = color;
      ctx.fillRect(x, y, PADDLE_W, PADDLE_H);
      ctx.shadowBlur = 0;
    };
    drawPaddle(8, playerYRef.current, "#00ffcc");
    drawPaddle(FIELD_W - 8 - PADDLE_W, cpuYRef.current, "#ff00ff");

    // Ball
    ctx.shadowColor = "#00ffcc";
    ctx.shadowBlur = 20;
    ctx.fillStyle = "#fff";
    ctx.beginPath();
    ctx.arc(ballRef.current.x, ballRef.current.y, BALL_R, 0, Math.PI * 2);
    ctx.fill();
    ctx.shadowBlur = 0;

    // Score overlay
    ctx.fillStyle = "rgba(0,255,200,0.15)";
    ctx.font = "bold 36px monospace";
    ctx.textAlign = "center";
    ctx.fillText(String(scoreRef.current.player), FIELD_W / 4, 50);
    ctx.fillStyle = "rgba(255,0,255,0.15)";
    ctx.fillText(String(scoreRef.current.cpu), (FIELD_W * 3) / 4, 50);
  }, []);

  const tick = useCallback(() => {
    if (stateRef.current !== "playing") return;

    // Move ball
    const b = ballRef.current;
    const v = velRef.current;
    b.x += v.x;
    b.y += v.y;

    // Wall bounce top/bottom
    if (b.y - BALL_R <= 0) { b.y = BALL_R; v.y = Math.abs(v.y); }
    if (b.y + BALL_R >= FIELD_H) { b.y = FIELD_H - BALL_R; v.y = -Math.abs(v.y); }

    // CPU paddle AI
    const cpuCenter = cpuYRef.current + PADDLE_H / 2;
    if (cpuCenter < b.y - 4) cpuYRef.current = clamp(cpuYRef.current + CPU_SPEED, 0, FIELD_H - PADDLE_H);
    if (cpuCenter > b.y + 4) cpuYRef.current = clamp(cpuYRef.current - CPU_SPEED, 0, FIELD_H - PADDLE_H);

    // Player paddle follow mouse
    playerYRef.current = clamp(mouseYRef.current - PADDLE_H / 2, 0, FIELD_H - PADDLE_H);

    // Player paddle hit
    if (b.x - BALL_R <= 8 + PADDLE_W && b.y >= playerYRef.current && b.y <= playerYRef.current + PADDLE_H && v.x < 0) {
      b.x = 8 + PADDLE_W + BALL_R;
      const hitPos = (b.y - playerYRef.current) / PADDLE_H - 0.5;
      const speed = Math.min(Math.sqrt(v.x ** 2 + v.y ** 2) + 0.15, 10);
      v.x = Math.abs(speed * Math.cos(hitPos * Math.PI * 0.6));
      v.y = speed * Math.sin(hitPos * Math.PI * 0.6);
      rallyRef.current++;
      setRally(rallyRef.current);
    }

    // CPU paddle hit
    if (b.x + BALL_R >= FIELD_W - 8 - PADDLE_W && b.y >= cpuYRef.current && b.y <= cpuYRef.current + PADDLE_H && v.x > 0) {
      b.x = FIELD_W - 8 - PADDLE_W - BALL_R;
      const hitPos = (b.y - cpuYRef.current) / PADDLE_H - 0.5;
      const speed = Math.sqrt(v.x ** 2 + v.y ** 2);
      v.x = -Math.abs(speed * Math.cos(hitPos * Math.PI * 0.6));
      v.y = speed * Math.sin(hitPos * Math.PI * 0.6);
      rallyRef.current++;
      setRally(rallyRef.current);
    }

    // Scoring
    if (b.x < 0) {
      scoreRef.current.cpu++;
      setDisplayScore({ ...scoreRef.current });
      if (scoreRef.current.cpu >= 7) {
        stateRef.current = "over";
        setGameState("over");
        const hs = getHighScore();
        if (rallyRef.current > hs) { setHighScore(rallyRef.current); setHighScoreState(rallyRef.current); }
      } else reset();
    }
    if (b.x > FIELD_W) {
      scoreRef.current.player++;
      setDisplayScore({ ...scoreRef.current });
      if (scoreRef.current.player >= 7) {
        stateRef.current = "over";
        setGameState("over");
        const hs = getHighScore();
        if (rallyRef.current > hs) { setHighScore(rallyRef.current); setHighScoreState(rallyRef.current); }
      } else reset();
    }

    draw();
    rafRef.current = requestAnimationFrame(tick);
  }, [draw, reset]);

  const startGame = useCallback(() => {
    scoreRef.current = { player: 0, cpu: 0 };
    setDisplayScore({ player: 0, cpu: 0 });
    stateRef.current = "playing";
    setGameState("playing");
    reset();
    if (rafRef.current) cancelAnimationFrame(rafRef.current);
    rafRef.current = requestAnimationFrame(tick);
  }, [tick, reset]);

  useEffect(() => {
    draw();
    return () => { if (rafRef.current) cancelAnimationFrame(rafRef.current); };
  }, [draw]);

  const handleMouseMove = useCallback((e: React.MouseEvent<HTMLCanvasElement>) => {
    const rect = canvasRef.current?.getBoundingClientRect();
    if (!rect) return;
    const scaleY = FIELD_H / rect.height;
    mouseYRef.current = (e.clientY - rect.top) * scaleY;
  }, []);

  const handleTouchMove = useCallback((e: React.TouchEvent<HTMLCanvasElement>) => {
    e.preventDefault();
    const rect = canvasRef.current?.getBoundingClientRect();
    if (!rect || !e.touches[0]) return;
    const scaleY = FIELD_H / rect.height;
    mouseYRef.current = (e.touches[0].clientY - rect.top) * scaleY;
  }, []);

  return (
    <div className="flex min-h-screen flex-col items-center justify-center bg-[#050510] p-6 font-mono text-white">
      <div className="w-full max-w-[620px]">
        <div className="mb-4 flex items-center justify-between">
          <div>
            <h1 className="text-xl font-black uppercase tracking-widest text-neon-cyan">VOID PONG</h1>
            <p className="text-[10px] text-white/30">Move mouse over field to control paddle. First to 7.</p>
          </div>
          <div className="text-right text-xs text-white/40">
            <div>Rally record: <span className="text-neon-cyan">{highScore}</span></div>
            {rally > 0 && gameState === "playing" && (
              <div>Current rally: <span className="text-neon-purple">{rally}</span></div>
            )}
          </div>
        </div>

        {gameState !== "idle" && (
          <div className="mb-3 flex items-center justify-between text-sm">
            <span className="text-neon-cyan font-bold">YOU — {displayScore.player}</span>
            <span className="text-xs text-white/30">vs</span>
            <span className="text-neon-purple font-bold">{displayScore.cpu} — CPU</span>
          </div>
        )}

        <canvas
          ref={canvasRef}
          width={FIELD_W}
          height={FIELD_H}
          onMouseMove={handleMouseMove}
          onTouchMove={handleTouchMove}
          className="w-full rounded-lg border border-neon-cyan/20 cursor-none"
          style={{ touchAction: "none" }}
        />

        {gameState === "idle" && (
          <div className="mt-6 text-center">
            <button
              type="button"
              onClick={startGame}
              className="rounded-full border-2 border-neon-cyan px-8 py-3 font-black uppercase text-neon-cyan hover:bg-neon-cyan/10 transition-all"
            >
              Start Game
            </button>
            <p className="mt-3 text-xs text-white/30">Move your mouse over the field to control the left paddle.</p>
          </div>
        )}

        {gameState === "playing" && (
          <div className="mt-4 text-center text-xs text-white/20">
            Rally: {rally} hits
          </div>
        )}

        {gameState === "over" && (
          <div className="mt-6 text-center">
            <div className="mb-3 text-2xl font-black uppercase">
              {displayScore.player >= 7 ? (
                <span className="text-neon-cyan">You Win</span>
              ) : (
                <span className="text-neon-purple">CPU Wins</span>
              )}
            </div>
            <div className="mb-4 text-sm text-white/50">
              Score: {displayScore.player} — {displayScore.cpu} · Rally: {rallyRef.current}
              {rallyRef.current > 0 && rallyRef.current >= highScore && (
                <span className="ml-2 text-neon-cyan">New record!</span>
              )}
            </div>
            <button
              type="button"
              onClick={startGame}
              className="rounded-full border-2 border-neon-cyan px-8 py-3 font-black uppercase text-neon-cyan hover:bg-neon-cyan/10 transition-all"
            >
              Play Again
            </button>
          </div>
        )}

        <div className="mt-6 flex justify-center gap-6 text-[10px] text-white/20">
          <Link href="/" className="hover:text-white/50">Hub</Link>
          <Link href="/arcade" className="hover:text-white/50">Arcade</Link>
          <Link href="/drops" className="hover:text-white/50">Shadow Lotto</Link>
        </div>
      </div>
    </div>
  );
}