/**
 * ControlMode.jsx — RC / Autonomous control mode display.
 *
 * Topics:
 *   /saltybot/control_mode  (std_msgs/String JSON)
 *     {
 *       mode: "RC" | "RAMP_TO_AUTO" | "AUTO" | "RAMP_TO_RC",
 *       blend_alpha: 0.0..1.0,
 *       slam_ok: bool,
 *       rc_link_ok: bool,
 *       override_active: bool
 *     }
 *   /saltybot/balance_state (std_msgs/String JSON) — robot state, mode label
 */

import { useEffect, useState } from 'react';

const MODE_CONFIG = {
  RC: {
    label: 'RC MANUAL',
    color: 'text-blue-300',
    bg: 'bg-blue-950',
    border: 'border-blue-600',
    description: 'Pilot has full control via CRSF/ELRS RC link',
  },
  RAMP_TO_AUTO: {
    label: 'RAMP → AUTO',
    color: 'text-amber-300',
    bg: 'bg-amber-950',
    border: 'border-amber-600',
    description: 'Transitioning from RC to autonomous (500 ms blend)',
  },
  AUTO: {
    label: 'AUTONOMOUS',
    color: 'text-green-300',
    bg: 'bg-green-950',
    border: 'border-green-600',
    description: 'Jetson AI/Nav2 in full control',
  },
  RAMP_TO_RC: {
    label: 'RAMP → RC',
    color: 'text-orange-300',
    bg: 'bg-orange-950',
    border: 'border-orange-600',
    description: 'Returning control to pilot (500 ms blend)',
  },
};

function SafetyFlag({ label, ok, invert }) {
  const isOk = invert ? !ok : ok;
  return (
    <div className={`flex items-center gap-2 rounded px-3 py-2 border ${
      isOk ? 'bg-green-950 border-green-800' : 'bg-red-950 border-red-800'
    }`}>
      <div className={`w-2 h-2 rounded-full ${isOk ? 'bg-green-400' : 'bg-red-400 animate-pulse'}`} />
      <span className="text-xs">
        <span className={isOk ? 'text-green-300' : 'text-red-300'}>{label}</span>
      </span>
      <span className={`ml-auto text-xs font-bold ${isOk ? 'text-green-400' : 'text-red-400'}`}>
        {isOk ? 'OK' : 'FAULT'}
      </span>
    </div>
  );
}

export function ControlMode({ subscribe }) {
  const [ctrlMode, setCtrlMode] = useState(null);
  const [balState, setBalState] = useState(null);
  const [lastTs, setLastTs]     = useState(null);

  useEffect(() => {
    const unsub = subscribe('/saltybot/control_mode', 'std_msgs/String', (msg) => {
      try {
        setCtrlMode(JSON.parse(msg.data));
        setLastTs(Date.now());
      } catch { /* ignore */ }
    });
    return unsub;
  }, [subscribe]);

  useEffect(() => {
    const unsub = subscribe('/saltybot/balance_state', 'std_msgs/String', (msg) => {
      try { setBalState(JSON.parse(msg.data)); }
      catch { /* ignore */ }
    });
    return unsub;
  }, [subscribe]);

  const mode     = ctrlMode?.mode ?? 'RC';
  const cfg      = MODE_CONFIG[mode] ?? MODE_CONFIG.RC;
  const alpha    = ctrlMode?.blend_alpha ?? 0;
  const stale    = lastTs && Date.now() - lastTs > 5000;

  return (
    <div className="space-y-4">
      {/* Main mode badge */}
      <div className={`${cfg.bg} border ${cfg.border} rounded-xl p-5`}>
        <div className="flex items-start justify-between gap-4">
          <div>
            <div className="text-gray-500 text-xs font-bold tracking-widest mb-1">CONTROL MODE</div>
            <div className={`text-3xl font-bold tracking-widest ${cfg.color}`}>{cfg.label}</div>
            <div className="text-gray-500 text-xs mt-1">{cfg.description}</div>
          </div>
          <div className="shrink-0 text-right">
            <div className="text-gray-600 text-xs">Blend α</div>
            <div className={`text-2xl font-bold ${alpha > 0.5 ? 'text-green-400' : 'text-blue-400'}`}>
              {alpha.toFixed(2)}
            </div>
            {stale && <div className="text-red-500 text-xs mt-1">STALE</div>}
          </div>
        </div>

        {/* Blend alpha bar */}
        {(mode === 'RAMP_TO_AUTO' || mode === 'RAMP_TO_RC' || alpha > 0) && (
          <div className="mt-3">
            <div className="flex justify-between text-xs text-gray-500 mb-1">
              <span>RC</span>
              <span>AUTO</span>
            </div>
            <div className="w-full h-3 bg-gray-950 rounded overflow-hidden border border-gray-800">
              <div
                className="h-full transition-all duration-200 rounded"
                style={{
                  width: `${alpha * 100}%`,
                  background: `linear-gradient(to right, #2563eb, #16a34a)`,
                }}
              />
            </div>
          </div>
        )}
      </div>

      {/* Safety flags */}
      <div className="bg-gray-950 rounded-lg border border-cyan-950 p-4">
        <div className="text-cyan-700 text-xs font-bold tracking-widest mb-3">SAFETY INTERLOCKS</div>
        <div className="space-y-2">
          <SafetyFlag label="SLAM Fix"      ok={ctrlMode?.slam_ok ?? false} />
          <SafetyFlag label="RC Link"       ok={ctrlMode?.rc_link_ok ?? false} />
          <SafetyFlag label="Stick Override" ok={ctrlMode?.override_active ?? false} invert />
        </div>
        {!ctrlMode && (
          <div className="text-gray-600 text-xs mt-2">
            Waiting for /saltybot/control_mode…
          </div>
        )}
      </div>

      {/* Balance state detail */}
      {balState && (
        <div className="bg-gray-950 rounded-lg border border-cyan-950 p-4">
          <div className="text-cyan-700 text-xs font-bold tracking-widest mb-3">BALANCE STATE</div>
          <div className="grid grid-cols-2 gap-2 text-xs">
            <div>
              <span className="text-gray-600">ESP32 State: </span>
              <span className={`font-bold ${
                balState.state === 'ARMED' ? 'text-green-400' :
                balState.state === 'TILT FAULT' ? 'text-red-400' : 'text-gray-400'
              }`}>{balState.state}</span>
            </div>
            <div>
              <span className="text-gray-600">ESP32 Mode: </span>
              <span className="text-cyan-400">{balState.mode}</span>
            </div>
            <div>
              <span className="text-gray-600">Pitch: </span>
              <span className="text-amber-400">{balState.pitch_deg}°</span>
            </div>
            <div>
              <span className="text-gray-600">Motor CMD: </span>
              <span className="text-orange-400">{balState.motor_cmd}</span>
            </div>
          </div>
        </div>
      )}

      {/* Mode transition guide */}
      <div className="bg-gray-950 rounded-lg border border-cyan-950 p-4">
        <div className="text-cyan-700 text-xs font-bold tracking-widest mb-2">STATE MACHINE</div>
        <div className="flex items-center gap-1 text-xs flex-wrap">
          {['RC', 'RAMP_TO_AUTO', 'AUTO', 'RAMP_TO_RC'].map((m, i) => (
            <div key={m} className="flex items-center gap-1">
              <span className={`px-2 py-0.5 rounded border ${
                mode === m
                  ? `${MODE_CONFIG[m].bg} ${MODE_CONFIG[m].border} ${MODE_CONFIG[m].color} font-bold`
                  : 'border-gray-800 text-gray-600'
              }`}>{m}</span>
              {i < 3 && <span className="text-gray-700">→</span>}
            </div>
          ))}
        </div>
        <div className="mt-2 text-gray-700 text-xs space-y-0.5">
          <div>AUX2 switch → RC⇄AUTO | Stick &gt; 10% while AUTO → instant RC</div>
          <div>SLAM fix lost while AUTO → RAMP_TO_RC | RC link lost → instant RC</div>
        </div>
      </div>
    </div>
  );
}