import React, { useState, useEffect, useRef, useCallback } from 'react';
import { state, subscribe, addModule, emit, addConnection, updateModulePosition, deserialize } from './engine/state.js';
import { startAudio, stopAudio, connectWire, rebuildGraph } from './engine/audioEngine.js';
import { getModuleDef } from './engine/moduleRegistry.js';
import { autoSave, autoLoad, exportPatch, importPatch } from './engine/presets.js';
import { playEngineStart, playEngineStop } from './engine/uiSounds.js';
import ModuleNode from './components/ModuleNode.jsx';
import WireLayer from './components/WireLayer.jsx';
import ModulePalette from './components/ModulePalette.jsx';
import PresetModal from './components/PresetModal.jsx';
import BottomSheet from './components/BottomSheet.jsx';
import { CHIPTUNE_PRESET } from './presets/chiptune.js';
import { useIsMobile } from './hooks/useIsMobile.js';
import { usePinchZoom } from './hooks/usePinchZoom.js';
import { getModulesByCategory } from './engine/moduleRegistry.js';

export default function App({ onSwitchToGame }) {
  const [, forceUpdate] = useState(0);
  const containerRef = useRef(null);
  const portPositions = useRef({});
  const [tempWire, setTempWire] = useState(null);
  const connectingRef = useRef(null);
  const [presetModal, setPresetModal] = useState(null);
  const importRef = useRef(null);
  const isMobile = useIsMobile();
  const [menuOpen, setMenuOpen] = useState(false);

  // Pinch-to-zoom on mobile
  const getZoom = useCallback(() => state.zoom, []);
  const setZoom = useCallback((z) => { state.zoom = z; emit(); }, []);
  usePinchZoom(containerRef, getZoom, setZoom);

  // Subscribe to state changes
  useEffect(() => {
    const unsub = subscribe(() => forceUpdate(n => n + 1));
    return unsub;
  }, []);

  // Auto-load on mount, or load chiptune demo if empty
  useEffect(() => {
    const loaded = autoLoad();
    if (!loaded || state.modules.length === 0) {
      // Load chiptune demo preset
      deserialize(CHIPTUNE_PRESET);
    }
  }, []);

  // Auto-save interval
  useEffect(() => {
    const interval = setInterval(autoSave, 3000);
    return () => clearInterval(interval);
  }, []);

  // Port position reporting
  const handlePortPosition = useCallback((moduleId, portName, direction, el) => {
    const key = `${moduleId}-${portName}-${direction}`;
    portPositions.current[key] = el;
  }, []);

  // Start connecting a wire
  const handleStartConnect = useCallback((info) => {
    connectingRef.current = info;
    const containerRect = containerRef.current.getBoundingClientRect();
    setTempWire({
      portType: info.portType,
      startX: info.startX - containerRect.left,
      startY: info.startY - containerRect.top,
      endX: info.startX - containerRect.left,
      endY: info.startY - containerRect.top,
    });
  }, []);

  // Find port-dot element at pointer position (including nearby)
  // Robust port detection — searches all port-dots by bounding rect distance
  // instead of elementFromPoint (which gets blocked by SVG wire overlay)
  const findPortAtPoint = (clientX, clientY) => {
    const portDots = document.querySelectorAll('.port-dot[data-module-id]');
    let closest = null;
    let closestDist = 18;
    for (const dot of portDots) {
      const rect = dot.getBoundingClientRect();
      const cx = rect.left + rect.width / 2;
      const cy = rect.top + rect.height / 2;
      const dist = Math.sqrt((clientX - cx) ** 2 + (clientY - cy) ** 2);
      if (dist < closestDist) {
        closestDist = dist;
        closest = dot;
      }
    }
    return closest;
  };

  // Canvas pointer events
  const handlePointerDown = useCallback((e) => {
    if (e.button === 1 || (e.button === 0 && e.altKey) || e.button === 2) {
      state.panning = true;
      state.panStart = { x: e.clientX - state.camX, y: e.clientY - state.camY };
      e.preventDefault();
    } else if (e.button === 0 && !connectingRef.current) {
      // On mobile (touch), single finger on empty canvas = pan
      if (isMobile && e.pointerType === 'touch') {
        state.panning = true;
        state.panStart = { x: e.clientX - state.camX, y: e.clientY - state.camY };
        e.preventDefault();
        return;
      }
      state.selectedModuleId = null;
      emit();
    }
  }, [isMobile]);

  const handlePointerMove = useCallback((e) => {
    if (state.panning && state.panStart) {
      state.camX = e.clientX - state.panStart.x;
      state.camY = e.clientY - state.panStart.y;
      emit();
      return;
    }
    if (state.dragging) {
      const newX = e.clientX / state.zoom - state.dragging.offsetX;
      const newY = e.clientY / state.zoom - state.dragging.offsetY;
      updateModulePosition(state.dragging.moduleId, newX, newY);
      return;
    }
    if (connectingRef.current && containerRef.current) {
      const containerRect = containerRef.current.getBoundingClientRect();
      setTempWire(prev => prev ? {
        ...prev,
        endX: e.clientX - containerRect.left,
        endY: e.clientY - containerRect.top,
      } : null);
    }
  }, []);

  const handlePointerUp = useCallback((e) => {
    if (state.panning) {
      state.panning = false;
      state.panStart = null;
    }
    if (state.dragging) {
      state.dragging = null;
      emit();
    }

    // End connecting
    if (connectingRef.current) {
      const portEl = findPortAtPoint(e.clientX, e.clientY);
      if (portEl) {
        finishConnection(portEl);
      }
      connectingRef.current = null;
      setTempWire(null);
    }
  }, []);

  const finishConnection = (portEl) => {
    const from = connectingRef.current;
    if (!from) return;

    // Read data attributes directly — clean and reliable
    const targetModuleId = parseInt(portEl.dataset.moduleId);
    const targetPort = portEl.dataset.portName;
    const targetDirection = portEl.dataset.portDirection;

    if (!targetModuleId || !targetPort || !targetDirection) return;
    if (targetModuleId === from.moduleId && targetPort === from.port) return;

    // Determine from/to
    let fromMod, fromPort, toMod, toPort;
    if (from.direction === 'output' && targetDirection === 'input') {
      fromMod = from.moduleId; fromPort = from.port;
      toMod = targetModuleId; toPort = targetPort;
    } else if (from.direction === 'input' && targetDirection === 'output') {
      fromMod = targetModuleId; fromPort = targetPort;
      toMod = from.moduleId; toPort = from.port;
    } else {
      return; // same direction — invalid
    }

    const connId = addConnection(fromMod, fromPort, toMod, toPort);
    if (connId && state.isRunning) {
      const conn = state.connections.find(c => c.id === connId);
      if (conn) connectWire(conn);
    }
  };

  const handleWheel = useCallback((e) => {
    e.preventDefault();
    const delta = -e.deltaY * 0.001;
    state.zoom = Math.max(0.3, Math.min(3, state.zoom + delta));
    emit();
  }, []);

  const handleContextMenu = useCallback((e) => e.preventDefault(), []);

  // Zoom controls (Google Maps style)
  const handleZoomIn = useCallback(() => {
    state.zoom = Math.min(3, state.zoom * 1.25);
    emit();
  }, []);
  const handleZoomOut = useCallback(() => {
    state.zoom = Math.max(0.3, state.zoom / 1.25);
    emit();
  }, []);
  const handleZoomReset = useCallback(() => {
    state.zoom = 1;
    state.camX = 0;
    state.camY = 0;
    emit();
  }, []);

  // Center view on all modules
  const handleCenterView = useCallback(() => {
    if (state.modules.length === 0) { state.camX = 0; state.camY = 0; emit(); return; }
    const container = containerRef.current;
    const cw = container?.clientWidth || 800;
    const ch = container?.clientHeight || 600;
    let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
    for (const m of state.modules) {
      minX = Math.min(minX, m.x);
      minY = Math.min(minY, m.y);
      maxX = Math.max(maxX, m.x + 200);
      maxY = Math.max(maxY, m.y + 150);
    }
    const cx = (minX + maxX) / 2 * state.zoom;
    const cy = (minY + maxY) / 2 * state.zoom;
    state.camX = cw / 2 - cx;
    state.camY = ch / 2 - cy;
    emit();
  }, []);

  const handleToggleAudio = async () => {
    if (state.isRunning) {
      stopAudio();
      playEngineStop();
    } else {
      await startAudio();
      playEngineStart();
    }
    emit();
  };

  const handleAddModule = (type) => {
    const x = (-state.camX + 300) / state.zoom + Math.random() * 50;
    const y = (-state.camY + 200) / state.zoom + Math.random() * 50;
    addModule(type, x, y);
    if (state.isRunning) rebuildGraph();
  };

  const handleImport = async (e) => {
    const file = e.target.files[0];
    if (!file) return;
    await importPatch(file);
    emit();
    e.target.value = '';
  };

  const handleLoadDemo = () => {
    deserialize(CHIPTUNE_PRESET);
    if (state.isRunning) rebuildGraph();
    emit();
  };

  const handleClearCanvas = () => {
    if (state.isRunning) stopAudio();
    deserialize({ modules: [], connections: [] });
    emit();
  };

  // Flatten all modules for mobile grid
  const allModuleDefs = Object.values(getModulesByCategory()).flat();

  return (
    <div className="app">
      {/* Toolbar */}
      <div className="toolbar">
        {onSwitchToGame && !isMobile && (
          <button className="toolbar-btn" onClick={onSwitchToGame} style={{ color: 'var(--yellow)' }}>
            🎮 Game
          </button>
        )}
        <span className="toolbar-title">Reaktor</span>
        {!isMobile && <div className="toolbar-sep" />}
        {!isMobile && (
          <button className={`toolbar-btn start-btn ${state.isRunning ? 'active' : ''}`} onClick={handleToggleAudio}>
            {state.isRunning ? '⏹ Stop' : '▶ Start'}
          </button>
        )}
        {!isMobile && <div className="toolbar-sep" />}
        {!isMobile && (
          <div className="toolbar-group">
            <button className="toolbar-btn save-btn" onClick={() => setPresetModal('save')}>💾 Save</button>
            <button className="toolbar-btn load-btn" onClick={() => setPresetModal('load')}>📂 Load</button>
            <button className="toolbar-btn export-btn" onClick={exportPatch}>📤 Export</button>
            <button className="toolbar-btn import-btn" onClick={() => importRef.current?.click()}>📥 Import</button>
            <input ref={importRef} type="file" accept=".json" style={{ display: 'none' }} onChange={handleImport} />
          </div>
        )}
        {!isMobile && <div className="toolbar-sep" />}
        {!isMobile && (
          <>
            <button className="toolbar-btn demo-btn" onClick={handleLoadDemo} style={{ color: 'var(--yellow)' }}>
              🎮 Chiptune Demo
            </button>
            <button className="toolbar-btn clear-btn" onClick={handleClearCanvas}>
              🗑 Limpiar
            </button>
            <div className="toolbar-sep" />
          </>
        )}
        <span className="toolbar-label" style={{ color: state.isRunning ? 'var(--green)' : 'var(--text2)', marginLeft: isMobile ? 'auto' : undefined }}>
          {state.isRunning ? '● LIVE' : '○ OFF'}
        </span>
        {!isMobile && (
          <span className="toolbar-label" style={{ marginLeft: 'auto' }}>
            {state.modules.length} modules · {state.connections.length} wires
          </span>
        )}
        {isMobile && (
          <button className="mobile-menu-btn" onClick={() => setMenuOpen(true)}>≡</button>
        )}
      </div>

      {/* Mobile menu overlay */}
      {isMobile && menuOpen && (
        <div className="mobile-menu-overlay" onClick={() => setMenuOpen(false)}>
          <div className="mobile-menu-panel" onClick={e => e.stopPropagation()}>
            {onSwitchToGame && (
              <button className="toolbar-btn" onClick={() => { setMenuOpen(false); onSwitchToGame(); }} style={{ color: 'var(--yellow)' }}>
                🎮 Game
              </button>
            )}
            <button className="toolbar-btn" onClick={() => { setPresetModal('save'); setMenuOpen(false); }}>💾 Save</button>
            <button className="toolbar-btn" onClick={() => { setPresetModal('load'); setMenuOpen(false); }}>📂 Load</button>
            <button className="toolbar-btn" onClick={() => { exportPatch(); setMenuOpen(false); }}>📤 Export</button>
            <button className="toolbar-btn" onClick={() => { importRef.current?.click(); setMenuOpen(false); }}>📥 Import</button>
            <input ref={importRef} type="file" accept=".json" style={{ display: 'none' }} onChange={handleImport} />
            <button className="toolbar-btn" onClick={() => { handleLoadDemo(); setMenuOpen(false); }} style={{ color: 'var(--yellow)' }}>
              🎮 Chiptune Demo
            </button>
            <button className="toolbar-btn" onClick={() => { handleClearCanvas(); setMenuOpen(false); }}>🗑 Limpiar</button>
          </div>
        </div>
      )}

      {/* Main canvas area */}
      <div className="main-area">
        <div
          ref={containerRef}
          className={`node-canvas ${state.panning ? 'grabbing' : ''} ${connectingRef.current ? 'connecting' : ''}`}
          onPointerDown={handlePointerDown}
          onPointerMove={handlePointerMove}
          onPointerUp={handlePointerUp}
          onWheel={handleWheel}
          onContextMenu={handleContextMenu}
        >
          {/* Grid background */}
          <svg style={{ position: 'absolute', inset: 0, width: '100%', height: '100%', zIndex: 0 }}>
            <defs>
              <pattern id="grid" width={20 * state.zoom} height={20 * state.zoom}
                patternUnits="userSpaceOnUse"
                x={state.camX % (20 * state.zoom)} y={state.camY % (20 * state.zoom)}>
                <circle cx={1} cy={1} r={0.8} fill="#1a1a30" />
              </pattern>
            </defs>
            <rect width="100%" height="100%" fill="url(#grid)" />
          </svg>

          {/* Wire layer */}
          <WireLayer portPositions={portPositions} tempWire={tempWire} containerRef={containerRef} zoom={state.zoom} camX={state.camX} camY={state.camY} />

          {/* Modules container */}
          <div style={{ position: 'absolute', left: state.camX, top: state.camY, zIndex: 2 }}>
            {state.modules.map(mod => (
              <ModuleNode
                key={mod.id}
                mod={mod}
                zoom={state.zoom}
                onStartConnect={handleStartConnect}
                onPortPosition={handlePortPosition}
              />
            ))}
          </div>
        </div>

        {/* Zoom controls */}
        <div className="zoom-controls">
          <button className="zoom-btn" onClick={handleZoomIn} title="Zoom in">+</button>
          <button className="zoom-btn zoom-label" onClick={handleZoomReset} title="Reset zoom">
            {(state.zoom * 100).toFixed(0)}%
          </button>
          <button className="zoom-btn" onClick={handleZoomOut} title="Zoom out">−</button>
          <button className="zoom-btn" onClick={handleCenterView} title="Centrar vista">⌂</button>
        </div>

        {/* Desktop palette */}
        {!isMobile && <ModulePalette onAddModule={handleAddModule} />}
      </div>

      {/* Mobile action bar */}
      {isMobile && (
        <div className="mobile-action-bar">
          <button
            className={`start-btn-mobile ${state.isRunning ? 'active' : ''}`}
            onClick={handleToggleAudio}
          >
            {state.isRunning ? '⏹ STOP' : '▶ START'}
          </button>
          <button className="action-icon-btn" onClick={() => setPresetModal('save')}>💾</button>
          <button className="action-icon-btn" onClick={exportPatch}>📤</button>
          <button className="action-icon-btn" onClick={handleClearCanvas}>🗑</button>
        </div>
      )}

      {/* Mobile bottom sheet with modules */}
      {isMobile && (
        <BottomSheet>
          <div className="mobile-module-grid">
            {allModuleDefs.map(def => (
              <div key={def.type} className="mobile-module-tile" onClick={() => handleAddModule(def.type)}>
                <span className="tile-icon">{def.icon}</span>
                <span className="tile-name">{def.name}</span>
              </div>
            ))}
          </div>
        </BottomSheet>
      )}

      {/* Status bar (hidden on mobile via CSS) */}
      <div className="status-bar">
        <span className="status-accent">Reaktor — MontLab Modular Synth</span>
        <span>Zoom: {(state.zoom * 100).toFixed(0)}%</span>
        <span>RClick: pan · Wheel: zoom · Drag port: wire · Click wire: delete</span>
      </div>

      {presetModal && <PresetModal mode={presetModal} onClose={() => setPresetModal(null)} />}
    </div>
  );
}