import React, { useMemo } from 'react';
import './QRCode.css';

const N = 25;

function matrix(value, n) {
  let seed = 0; for (let i = 0; i < value.length; i++) seed = (seed * 31 + value.charCodeAt(i)) >>> 0;
  const rnd = () => { seed = (seed * 1103515245 + 12345) >>> 0; return seed / 4294967296; };
  const m = []; for (let r = 0; r < n; r++) m.push(new Array(n).fill(false));
  for (let r = 0; r < n; r++) for (let c = 0; c < n; c++) if (rnd() > 0.5) m[r][c] = true;
  const place = (r0, c0) => {
    for (let r = 0; r < 7; r++) for (let c = 0; c < 7; c++) {
      const edge = r === 0 || r === 6 || c === 0 || c === 6, inner = r >= 2 && r <= 4 && c >= 2 && c <= 4;
      m[r0 + r][c0 + c] = edge || inner;
    }
    for (let rr = -1; rr < 8; rr++) for (let cc = -1; cc < 8; cc++) {
      const y = r0 + rr, x = c0 + cc; if (y >= 0 && y < n && x >= 0 && x < n) { if (rr < 0 || rr === 7 || cc < 0 || cc === 7) m[y][x] = false; }
    }
  };
  place(0, 0); place(0, n - 7); place(n - 7, 0);
  return m;
}

export default function QRCode({ value = '', size = 200, color = '#1F2329', showText = true }) {
  const cell = size / N;
  const cells = useMemo(() => {
    const m = matrix(value, N), out = [];
    for (let r = 0; r < N; r++) for (let c = 0; c < N; c++) if (m[r][c]) out.push({ x: c * cell, y: r * cell });
    return out;
  }, [value, size]);

  return (
    <div className="aa-qrcode">
      <svg width={size} height={size} viewBox={`0 0 ${size} ${size}`} fill={color}>
        {cells.map((rc, i) => <rect key={i} x={rc.x} y={rc.y} width={cell} height={cell} />)}
      </svg>
      {showText ? <div className="aa-qrcode-text">{value}</div> : null}
    </div>
  );
}