import React, { useState, useEffect, useRef } from 'react';
import { Canvas, useFrame } from '@react-three/fiber';
import { MOUSE } from 'three';
import { OrbitControls, Grid, GizmoHelper, GizmoViewcube } from '@react-three/drei';
import { Sidebar } from './components/Sidebar';
import { IOPanel } from './components/IOPanel';
import { LadderEditor } from './components/LadderEditor';
import {
  SimObject, ObjectType, AxisObject, CylinderObject, SwitchObject, LedObject,
  IOLogicRule, LogicCondition, LogicAction, ProjectData
} from './types';
import { EditableObject } from './components/SceneObjects';
import { Layout as LayoutIcon, Cpu, Play, Pause, Square, Download, Upload, Magnet } from 'lucide-react';

// --- Simulation Manager (PLC Scan Cycle) ---
const SimulationLoop = ({
  isPlaying,
  objects,
  setObjects,
  logicRules,
  manualInputs,
  manualOutputs,
  setInputs,
  setOutputs
}: {
  isPlaying: boolean,
  objects: SimObject[],
  setObjects: React.Dispatch<React.SetStateAction<SimObject[]>>,
  logicRules: IOLogicRule[],
  manualInputs: boolean[],
  manualOutputs: boolean[],
  setInputs: (inputs: boolean[]) => void,
  setOutputs: (outputs: boolean[]) => void
}) => {

  useFrame((state, delta) => {
    if (!isPlaying) return;

    // --- 1. PLC Input Scan (Physical + Manual Force) ---
    const sensorInputs = new Array(16).fill(false);
    objects.forEach(obj => {
      if (obj.type === ObjectType.SWITCH && (obj as SwitchObject).isOn) {
        const port = (obj as SwitchObject).inputPort;
        if (port >= 0 && port < 16) sensorInputs[port] = true;
      }
      if ((obj.type === ObjectType.AXIS_LINEAR || obj.type === ObjectType.AXIS_ROTARY) && (obj as AxisObject).triggers) {
        const axis = obj as AxisObject;
        axis.triggers.forEach(trig => {
          const met = trig.condition === '>' ? axis.currentValue > trig.position : axis.currentValue < trig.position;
          if (met && trig.targetInputPort >= 0 && trig.targetInputPort < 16) sensorInputs[trig.targetInputPort] = true;
        });
      }
    });

    const effectiveInputs = sensorInputs.map((bit, i) => bit || manualInputs[i]);
    setInputs(effectiveInputs);

    // --- 2. PLC Logic Execution ---
    const logicOutputs = new Array(16).fill(false);
    logicRules.forEach(rule => {
      if (!rule.enabled) return;
      const inputState = effectiveInputs[rule.inputPort];
      const conditionMet = rule.condition === LogicCondition.IS_ON ? inputState : !inputState;
      if (conditionMet && rule.action === LogicAction.SET_ON) {
        logicOutputs[rule.outputPort] = true;
      }
    });

    // Effective Outputs = Logic OR Manual Force
    const effectiveOutputs = logicOutputs.map((bit, i) => bit || manualOutputs[i]);
    setOutputs(effectiveOutputs);

    // --- 3. Physical Update Scan ---
    setObjects(prevObjects => {
      let hasChanges = false;
      const newObjects = prevObjects.map(obj => {
        let newObj = { ...obj };
        let changed = false;

        if (obj.type === ObjectType.LED) {
          const led = obj as LedObject;
          const shouldBeOn = effectiveOutputs[led.outputPort];
          if (led.isOn !== shouldBeOn) {
            newObj = { ...led, isOn: shouldBeOn };
            changed = true;
          }
        }
        else if (obj.type === ObjectType.CYLINDER) {
          const cyl = obj as CylinderObject;
          const shouldExtend = effectiveOutputs[cyl.outputPort];
          const targetPos = shouldExtend ? cyl.stroke : 0;
          if (Math.abs(cyl.currentPosition - targetPos) > 0.01) {
            const step = cyl.speed * delta * 5;
            if (cyl.currentPosition < targetPos) {
              newObj = { ...cyl, extended: shouldExtend, currentPosition: Math.min(targetPos, cyl.currentPosition + step) };
            } else {
              newObj = { ...cyl, extended: shouldExtend, currentPosition: Math.max(targetPos, cyl.currentPosition - step) };
            }
            changed = true;
          }
        }
        else if (obj.type === ObjectType.AXIS_LINEAR || obj.type === ObjectType.AXIS_ROTARY) {
          const axis = obj as AxisObject;
          if (axis.currentValue !== axis.targetValue) {
            const diff = axis.targetValue - axis.currentValue;
            const step = axis.speed * delta * 10;
            if (Math.abs(diff) < step) {
              newObj = { ...axis, currentValue: axis.targetValue };
            } else {
              newObj = { ...axis, currentValue: axis.currentValue + Math.sign(diff) * step };
            }
            changed = true;
          }
        }

        if (changed) hasChanges = true;
        return newObj;
      });
      return hasChanges ? newObjects : prevObjects;
    });
  });

  return null;
};

export default function App() {
  const [activeView, setActiveView] = useState<'layout' | 'logic'>('layout');
  const [objects, setObjects] = useState<SimObject[]>([]);
  const [logicRules, setLogicRules] = useState<IOLogicRule[]>([]);

  const [inputs, setInputs] = useState<boolean[]>(new Array(16).fill(false));
  const [outputs, setOutputs] = useState<boolean[]>(new Array(16).fill(false));
  const [manualInputs, setManualInputs] = useState<boolean[]>(new Array(16).fill(false));
  const [manualOutputs, setManualOutputs] = useState<boolean[]>(new Array(16).fill(false));

  const [inputNames, setInputNames] = useState<string[]>(new Array(16).fill(''));
  const [outputNames, setOutputNames] = useState<string[]>(new Array(16).fill(''));
  const [selectedId, setSelectedId] = useState<string | null>(null);
  const [isPlaying, setIsPlaying] = useState(false);
  const [isSnapEnabled, setIsSnapEnabled] = useState(false);
  const controlsRef = useRef<any>(null);

  const handleSetView = (view: 'TOP' | 'BOTTOM' | 'FRONT' | 'BACK' | 'LEFT' | 'RIGHT') => {
    const ctrl = controlsRef.current;
    if (!ctrl) return;
    const dist = 15;
    ctrl.target.set(0, 0, 0);
    switch (view) {
      case 'TOP': ctrl.object.position.set(0, dist, 0); break;
      case 'BOTTOM': ctrl.object.position.set(0, -dist, 0); break;
      case 'FRONT': ctrl.object.position.set(0, 0, dist); break;
      case 'BACK': ctrl.object.position.set(0, 0, -dist); break;
      case 'RIGHT': ctrl.object.position.set(dist, 0, 0); break;
      case 'LEFT': ctrl.object.position.set(-dist, 0, 0); break;
    }
    ctrl.update();
  };

  useEffect(() => {
    if (!isPlaying) {
      setObjects(prev => prev.map(obj => {
        if (obj.type === ObjectType.LED) {
          const led = obj as LedObject;
          return { ...led, isOn: manualOutputs[led.outputPort] };
        }
        if (obj.type === ObjectType.CYLINDER) {
          const cyl = obj as CylinderObject;
          const extended = manualOutputs[cyl.outputPort];
          return { ...cyl, extended, currentPosition: extended ? cyl.stroke : 0 };
        }
        return obj;
      }));
      setInputs([...manualInputs]);
      setOutputs([...manualOutputs]);
    }
  }, [manualInputs, manualOutputs, isPlaying]);

  const handleUpdatePortName = (type: 'input' | 'output', index: number, name: string) => {
    if (type === 'input') {
      const next = [...inputNames]; next[index] = name; setInputNames(next);
    } else {
      const next = [...outputNames]; next[index] = name; setOutputNames(next);
    }
  };

  const handleToggleManualInput = (index: number) => {
    const next = [...manualInputs]; next[index] = !next[index]; setManualInputs(next);
  };

  const handleToggleManualOutput = (index: number) => {
    const next = [...manualOutputs]; next[index] = !next[index]; setManualOutputs(next);
  };

  const handleReset = () => {
    setIsPlaying(false);
    setManualInputs(new Array(16).fill(false));
    setManualOutputs(new Array(16).fill(false));
    setObjects(prev => prev.map(o => {
      if (o.type === ObjectType.AXIS_LINEAR || o.type === ObjectType.AXIS_ROTARY) return { ...o, currentValue: (o as AxisObject).min, targetValue: (o as AxisObject).min };
      if (o.type === ObjectType.CYLINDER) return { ...o, currentPosition: 0, extended: false };
      if (o.type === ObjectType.LED) return { ...o, isOn: false };
      if (o.type === ObjectType.SWITCH) return { ...o, isOn: false };
      return o;
    }));
  };

  const handleExport = () => {
    const project: ProjectData = { version: "1.0", objects, logicRules, inputNames, outputNames };
    const blob = new Blob([JSON.stringify(project, null, 2)], { type: 'application/json' });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url; a.download = `motion-sim-project.json`; a.click();
    URL.revokeObjectURL(url);
  };

  const handleImport = (e: React.ChangeEvent<HTMLInputElement>) => {
    const file = e.target.files?.[0];
    if (!file) return;
    const reader = new FileReader();
    reader.onload = (event) => {
      try {
        const data = JSON.parse(event.target?.result as string) as ProjectData;
        if (data.objects) setObjects(data.objects);
        if (data.logicRules) setLogicRules(data.logicRules);
        if (data.inputNames) setInputNames(data.inputNames);
        if (data.outputNames) setOutputNames(data.outputNames);
      } catch (err) { alert("Invalid JSON"); }
    };
    reader.readAsText(file);
    e.target.value = '';
  };

  const handleAddObject = (type: ObjectType) => {
    const id = crypto.randomUUID();
    const position = { x: 0, y: 0.1, z: 0 };
    let newObj: SimObject;
    switch (type) {
      case ObjectType.AXIS_LINEAR:
        newObj = { id, type, name: 'Linear Axis', position, rotation: { x: 0, y: 0, z: 0 }, min: 0, max: 100, currentValue: 0, targetValue: 0, speed: 1, isOscillating: false, triggers: [] } as AxisObject;
        break;
      case ObjectType.AXIS_ROTARY:
        newObj = { id, type, name: 'Rotary Axis', position, rotation: { x: 0, y: 0, z: 0 }, min: 0, max: 360, currentValue: 0, targetValue: 0, speed: 1, isOscillating: false, triggers: [] } as AxisObject;
        break;
      case ObjectType.CYLINDER:
        newObj = { id, type, name: 'Cylinder', position, rotation: { x: 0, y: 0, z: 0 }, stroke: 2, extended: false, currentPosition: 0, speed: 2, outputPort: 0 } as CylinderObject;
        break;
      case ObjectType.SWITCH:
        newObj = { id, type, name: 'Switch', position, rotation: { x: 0, y: 0, z: 0 }, isOn: false, isMomentary: true, inputPort: 0 } as SwitchObject;
        break;
      case ObjectType.LED:
        newObj = { id, type, name: 'LED', position, rotation: { x: 0, y: 0, z: 0 }, isOn: false, color: '#00ff00', outputPort: 0 } as LedObject;
        break;
      default: return;
    }
    setObjects(prev => [...prev, newObj]);
    setSelectedId(id);
    setActiveView('layout');
  };

  return (
    <div className="flex flex-col w-screen h-screen bg-black text-white overflow-hidden font-sans">

      {/* Top Navigation */}
      <div className="h-16 bg-gray-900 border-b border-gray-800 flex items-center px-6 justify-between shrink-0 z-20 shadow-lg">
        <div className="flex items-center gap-8">
          <div className="flex items-center gap-2">
            <div className="w-8 h-8 bg-blue-600 rounded flex items-center justify-center font-bold text-lg shadow-[0_0_15px_rgba(37,99,235,0.4)]">M</div>
            <span className="font-bold tracking-tight text-lg">MotionSim</span>
          </div>

          <div className="flex bg-gray-950 p-1 rounded-xl border border-gray-800 shadow-inner">
            <button
              onClick={() => setActiveView('layout')}
              className={`flex items-center gap-2 px-6 py-2 rounded-lg text-sm font-bold transition-all ${activeView === 'layout' ? 'bg-blue-600 text-white shadow-md' : 'text-gray-500 hover:text-gray-300'}`}
            >
              <LayoutIcon size={16} /> Layout
            </button>
            <button
              onClick={() => setActiveView('logic')}
              className={`flex items-center gap-2 px-6 py-2 rounded-lg text-sm font-bold transition-all ${activeView === 'logic' ? 'bg-blue-600 text-white shadow-md' : 'text-gray-500 hover:text-gray-300'}`}
            >
              <Cpu size={16} /> Logic
            </button>
          </div>

          <div className="h-8 w-[1px] bg-gray-800 mx-2" />

          <button
            onClick={() => setIsSnapEnabled(!isSnapEnabled)}
            className={`p-2 rounded-lg transition-all ${isSnapEnabled ? 'bg-blue-600 text-white shadow shadow-blue-500/50' : 'bg-gray-950 text-gray-500 hover:text-gray-300 border border-gray-800'}`}
            title={isSnapEnabled ? "Snap: ON (1.0 Unit)" : "Snap: OFF"}
          >
            <Magnet size={18} />
          </button>

          <div className="h-8 w-[1px] bg-gray-800 mx-2" />

          <div className="flex bg-gray-950 p-1 rounded-xl border border-gray-800 shadow-inner">
            <button onClick={handleExport} className="px-3 py-2 rounded-lg text-gray-400 hover:text-blue-400 hover:bg-gray-800 transition-all" title="Export Project">
              <Download size={18} />
            </button>
            <label className="px-3 py-2 rounded-lg text-gray-400 hover:text-purple-400 hover:bg-gray-800 cursor-pointer transition-all flex items-center" title="Import Project">
              <Upload size={18} />
              <input type="file" className="hidden" accept=".json" onChange={handleImport} />
            </label>
          </div>

        </div>

        {/* Global Controls */}
        <div className="flex items-center gap-4">
          {isPlaying && (
            <div className="bg-green-900/20 border border-green-500/30 px-4 py-1.5 rounded-full flex items-center gap-2">
              <div className="w-2 h-2 bg-green-500 rounded-full animate-pulse shadow-[0_0_8px_#22c55e]" />
              <span className="text-[10px] font-black text-green-400 tracking-[0.2em] uppercase">PLC ACTIVE</span>
            </div>
          )}

          <div className="h-8 w-[1px] bg-gray-800 mx-2" />

          <div className="flex items-center gap-2 bg-gray-950 p-1 rounded-xl border border-gray-800">
            <button
              onClick={() => setIsPlaying(!isPlaying)}
              title={isPlaying ? "Stop PLC" : "Start PLC"}
              className={`flex items-center gap-2 px-4 py-1.5 rounded-lg text-xs font-black transition-all ${isPlaying ? 'bg-red-600/20 text-red-500 hover:bg-red-600/30' : 'bg-green-600 text-white hover:bg-green-500 shadow-lg shadow-green-900/20'}`}
            >
              {isPlaying ? <><Pause size={14} /> STOP</> : <><Play size={14} /> RUN</>}
            </button>
            <button
              onClick={handleReset}
              title="Reset System"
              className="p-1.5 rounded-lg text-gray-400 hover:text-white hover:bg-gray-800 transition-all"
            >
              <Square size={16} fill="currentColor" />
            </button>
          </div>
        </div>
      </div>

      {/* Main Content Area */}
      <div className="flex-1 flex overflow-hidden">

        {/* Left Side: Permanent IO Panel */}
        <IOPanel
          inputs={inputs}
          outputs={outputs}
          inputNames={inputNames}
          outputNames={outputNames}
          onToggleInput={handleToggleManualInput}
          onToggleOutput={handleToggleManualOutput}
        />

        {/* Center/Right: Dynamic Content based on tab */}
        {activeView === 'layout' ? (
          <div className="flex-1 flex overflow-hidden relative">

            {/* View Controls Overlay */}
            <div className="absolute top-4 left-1/2 -translate-x-1/2 z-10 flex gap-2">
              <div className="bg-gray-900/90 p-1.5 rounded-xl border border-gray-700/50 backdrop-blur-sm shadow-xl flex items-center gap-1">
                <ViewBtn label="TOP" onClick={() => handleSetView('TOP')} color="text-blue-400" />
                <ViewBtn label="BTM" onClick={() => handleSetView('BOTTOM')} color="text-blue-400" />
                <div className="w-[1px] h-4 bg-gray-700 mx-1" />
                <ViewBtn label="FRT" onClick={() => handleSetView('FRONT')} color="text-red-400" />
                <ViewBtn label="BCK" onClick={() => handleSetView('BACK')} color="text-red-400" />
                <div className="w-[1px] h-4 bg-gray-700 mx-1" />
                <ViewBtn label="L" onClick={() => handleSetView('LEFT')} color="text-green-400" />
                <ViewBtn label="R" onClick={() => handleSetView('RIGHT')} color="text-green-400" />
              </div>
            </div>

            <div className="flex-1 relative cursor-crosshair">
              <Canvas shadows camera={{ position: [5, 5, 5], fov: 50 }}>
                <color attach="background" args={['#0f172a']} />
                <ambientLight intensity={0.5} />
                <directionalLight position={[10, 10, 5]} intensity={1} castShadow />
                <Grid position={[0, -0.01, 0]} args={[20, 20]} cellSize={1} cellThickness={0.5} cellColor="#1e293b" sectionSize={5} sectionThickness={1} sectionColor="#334155" fadeDistance={30} infiniteGrid />
                <OrbitControls
                  ref={controlsRef}
                  makeDefault
                  mouseButtons={{
                    LEFT: MOUSE.ROTATE,
                    MIDDLE: MOUSE.PAN,
                    RIGHT: MOUSE.PAN
                  }}
                />
                <GizmoHelper alignment="top-right" margin={[80, 80]}>
                  <GizmoViewcube />
                </GizmoHelper>

                {objects.map(obj => (
                  <EditableObject
                    key={obj.id}
                    data={obj}
                    isSelected={obj.id === selectedId}
                    isPlaying={isPlaying}
                    enableTransform={true}
                    snap={isSnapEnabled ? 0.5 : null}
                    onSelect={setSelectedId}
                    onUpdate={(id, updates) => setObjects(prev => prev.map(o => o.id === id ? { ...o, ...updates } as SimObject : o))}
                    onInteract={(id) => setObjects(prev => prev.map(o => (o.id === id && o.type === ObjectType.SWITCH) ? { ...o, isOn: !o.isOn } as SwitchObject : o))}
                  />
                ))}

                <SimulationLoop
                  isPlaying={isPlaying}
                  objects={objects}
                  setObjects={setObjects}
                  logicRules={logicRules}
                  manualInputs={manualInputs}
                  manualOutputs={manualOutputs}
                  setInputs={setInputs}
                  setOutputs={setOutputs}
                />
              </Canvas>
            </div>

            <Sidebar
              objects={objects}
              selectedId={selectedId}
              isPlaying={isPlaying}
              inputNames={inputNames}
              outputNames={outputNames}
              onAddObject={handleAddObject}
              onDeleteObject={(id) => { setObjects(prev => prev.filter(o => o.id !== id)); setSelectedId(null); }}
              onUpdateObject={(id, updates) => setObjects(prev => prev.map(o => o.id === id ? { ...o, ...updates } as SimObject : o))}
              onSelect={setSelectedId}
              onUpdatePortName={handleUpdatePortName}
            />
          </div>
        ) : (
          <LadderEditor
            logicRules={logicRules}
            inputNames={inputNames}
            outputNames={outputNames}
            currentInputs={inputs}
            currentOutputs={outputs}
            onAddRule={(r) => setLogicRules(prev => [...prev, r])}
            onDeleteRule={(id) => setLogicRules(prev => prev.filter(r => r.id !== id))}
            onUpdateRule={(id, updates) => setLogicRules(prev => prev.map(r => r.id === id ? { ...r, ...updates } : r))}
          />
        )}
      </div>
    </div>
  );
}

const ViewBtn: React.FC<{ label: string, onClick: () => void, color?: string }> = ({ label, onClick, color = "text-gray-400" }) => (
  <button
    onClick={onClick}
    className={`w-8 h-8 flex items-center justify-center rounded-lg bg-gray-950 border border-gray-800 ${color} hover:bg-gray-800 hover:text-white text-[10px] font-black transition-all hover:scale-105 active:scale-95`}
  >
    {label}
  </button>
);