import { useMemo } from 'react';
import { useDockIr } from '../hooks/useDockIr.js';

const SVG_W = 120;
const SVG_H = 110;
const CX = SVG_W / 2;
const DOCK_Y = 16;
const ROVER_Y = 86;

function lobePath(side = 'left') {
  if (side === 'left') {
    return `M ${CX} ${DOCK_Y} C ${CX - 12} ${DOCK_Y + 8} ${CX - 14} ${ROVER_Y - 16} ${CX - 4} ${ROVER_Y - 2} L ${CX} ${ROVER_Y - 4} Z`;
  }
  return `M ${CX} ${DOCK_Y} C ${CX + 12} ${DOCK_Y + 8} ${CX + 14} ${ROVER_Y - 16} ${CX + 4} ${ROVER_Y - 2} L ${CX} ${ROVER_Y - 4} Z`;
}

export default function DockAssistHUD({ sensors }) {
  const state = useDockIr(sensors);
  const palette = useMemo(
    () => ({
      green: ['rgba(16,185,129,0.6)', 'rgba(16,185,129,0.45)', 'rgba(16,185,129,0)'],
      red: ['rgba(239,68,68,0.6)', 'rgba(239,68,68,0.45)', 'rgba(239,68,68,0)'],
      forceOutline: 'rgba(191,219,254,0.85)',
      roverBody: '#0f172a',
      roverFill: '#e5e7eb',
    }),
    [],
  );

  if (!state.visible) return null;

  const nudge = state.balance * 6;
  const leftActive = state.left.red || state.left.green || state.left.force;
  const rightActive = state.right.red || state.right.green || state.right.force;
  const allAligned = state.left.red && state.left.green && state.right.red && state.right.green && state.forceDetected;

  return (
    <div className="pointer-events-none absolute inset-x-0 top-0 flex justify-center p-0.25">
      <svg width={SVG_W} height={SVG_H} viewBox={`0 0 ${SVG_W} ${SVG_H}`} role="img" aria-label="Docking assist">
        <defs>
          <linearGradient id="gradGreen" x1="0%" y1="0%" x2="0%" y2="100%">
            <stop offset="0%" stopColor={palette.green[0]} />
            <stop offset="60%" stopColor={palette.green[1]} />
            <stop offset="100%" stopColor={palette.green[2]} />
          </linearGradient>
          <linearGradient id="gradRed" x1="0%" y1="0%" x2="0%" y2="100%">
            <stop offset="0%" stopColor={palette.red[0]} />
            <stop offset="60%" stopColor={palette.red[1]} />
            <stop offset="100%" stopColor={palette.red[2]} />
          </linearGradient>
          <radialGradient id="halo" cx="50%" cy="20%" r="60%">
            <stop offset="0%" stopColor="rgba(59,130,246,0.45)" />
            <stop offset="100%" stopColor="rgba(59,130,246,0)" />
          </radialGradient>
        </defs>

        {/* Force field halo */}
        <circle
          cx={CX}
          cy={DOCK_Y - 4}
          r={18}
          fill={state.forceDetected ? 'url(#halo)' : 'rgba(59,130,246,0.12)'}
          stroke={state.forceDetected ? palette.forceOutline : 'none'}
          strokeWidth={state.forceDetected ? 1.2 : 0}
        />

        {/* Lobes */}
        <path d={lobePath('left')} fill={leftActive ? 'url(#gradGreen)' : 'rgba(16,185,129,0.12)'} />
        <path d={lobePath('right')} fill={rightActive ? 'url(#gradRed)' : 'rgba(239,68,68,0.12)'} />
        {leftActive && rightActive ? (
          <path
            d={`M ${CX - 6} ${ROVER_Y - 12} Q ${CX} ${ROVER_Y - 4} ${CX + 6} ${ROVER_Y - 12}`}
            fill="rgba(255,255,255,0.08)"
          />
        ) : null}

        {/* Dock icon: simple rounded square with symmetric top corners */}
        <path
          d={`
            M ${CX - 16} ${DOCK_Y - 10}
            Q ${CX - 12} ${DOCK_Y - 14} ${CX - 6} ${DOCK_Y - 14}
            H ${CX + 6}
            Q ${CX + 12} ${DOCK_Y - 14} ${CX + 16} ${DOCK_Y - 10}
            L ${CX + 16} ${DOCK_Y + 10}
            Q ${CX + 16} ${DOCK_Y + 22} ${CX} ${DOCK_Y + 24}
            Q ${CX - 16} ${DOCK_Y + 22} ${CX - 16} ${DOCK_Y + 10}
            Z
          `}
          fill="#0b1220"
          stroke="#94a3b8"
          strokeWidth="0.8"
        />
        {/* Force field emitter dot */}
        <circle cx={CX} cy={DOCK_Y - 6} r="2.1" fill="#60a5fa" />
        {/* Contacts */}
        <rect x={CX - 10} y={DOCK_Y + 8} width="3.2" height="8.5" rx="1" fill="#e2e8f0" />
        <rect x={CX + 6.5} y={DOCK_Y + 8} width="3.2" height="8.5" rx="1" fill="#e2e8f0" />

        {/* Rover cue */}
        <g transform={`translate(${CX + nudge}, ${ROVER_Y})`}>
          <circle r="6" fill={palette.roverBody} stroke="#6b7280" strokeWidth="1" />
          <path d="M 0 -5 L 4 4 L -4 4 Z" fill={palette.roverFill} />
        </g>

        {/* Nudge arrow */}
        {state.bias !== 'center' && (
          <path
            d={
              state.bias === 'left'
                ? `M ${CX - 12} ${ROVER_Y - 5} L ${CX - 18} ${ROVER_Y} L ${CX - 12} ${ROVER_Y + 5}`
                : `M ${CX + 12} ${ROVER_Y - 5} L ${CX + 18} ${ROVER_Y} L ${CX + 12} ${ROVER_Y + 5}`
            }
            fill="none"
            stroke="#e5e7eb"
            strokeWidth="1.3"
            strokeLinecap="round"
            strokeLinejoin="round"
          />
        )}

        {/* Thumbs up when fully aligned */}
        {allAligned ? (
          <text x={CX + 30} y={DOCK_Y + 8} fontSize="12" fill="#fbbf24" fontFamily="sans-serif">
            👍
          </text>
        ) : null}
      </svg>
    </div>
  );
}