import React, { useEffect, useRef, useMemo } from 'react';
import { Network } from 'vis-network/standalone';
import { LAYOUT_MODES } from '../../utils/settings';

/** Known node positions for explicit-coordinate mode (vis-network canvas coords). */
const EXPLICIT_POSITIONS = {
  temperature: { x: 0, y: -140 },
  D1: { x: -120, y: 20 },
  D2: { x: 120, y: 20 },
  'actuator-1': { x: 0, y: 140 },
  D3: { x: 220, y: 20 },
};

function fallbackPosition(nodeId, index) {
  const angle = (index * 2 * Math.PI) / 8;
  return { x: Math.cos(angle) * 180, y: Math.sin(angle) * 120 };
}

function applyLayout(data, layoutMode) {
  const base = data || { nodes: [], edges: [] };
  const nodes = (base.nodes || []).map((node, index) => {
    if (layoutMode !== LAYOUT_MODES.EXPLICIT) return { ...node };
    const pos = EXPLICIT_POSITIONS[node.id] ?? fallbackPosition(node.id, index);
    return { ...node, x: pos.x, y: pos.y, fixed: true };
  });
  return { nodes, edges: base.edges || [] };
}

function buildOptions(layoutMode) {
  const options = {
    autoResize: true,
    nodes: {
      borderWidth: 2,
      font: { color: '#ffffff', size: 14 },
    },
    edges: {
      arrows: 'to',
      color: { color: '#9aa3b2', highlight: '#6366F1' },
      font: { size: 10, color: '#9aa3b2', strokeWidth: 0, align: 'middle' },
      smooth: { type: 'cubicBezier', roundness: 0.4 },
    },
    groups: {
      sensor: { shape: 'box', color: { background: '#3b82f6', border: '#1d4ed8' } },
      decidron: { shape: 'hexagon', color: { background: '#8b5cf6', border: '#6d28d9' } },
      actuator: { shape: 'triangle', color: { background: '#10b981', border: '#047857' } },
    },
    interaction: { hover: true, tooltipDelay: 120 },
  };

  if (layoutMode === LAYOUT_MODES.EXPLICIT) {
    options.physics = { enabled: false };
  } else {
    options.physics = {
      stabilization: { iterations: 150 },
      barnesHut: { springLength: 150, gravitationalConstant: -6000 },
    };
    if (layoutMode === LAYOUT_MODES.FIXED_SEED) {
      options.layout = { randomSeed: 42 };
    }
    // RANDOM: no randomSeed — vis-network picks a new seed each build (default).
  }

  return options;
}

export default function NetworkDiagram({ data, layoutMode = LAYOUT_MODES.RANDOM, height = 380 }) {
  const containerRef = useRef(null);
  const networkRef = useRef(null);

  const graphData = useMemo(
    () => applyLayout(data, layoutMode),
    [data, layoutMode],
  );

  useEffect(() => {
    if (!containerRef.current) return undefined;
    networkRef.current = new Network(
      containerRef.current,
      graphData,
      buildOptions(layoutMode),
    );
    return () => {
      if (networkRef.current) {
        networkRef.current.destroy();
        networkRef.current = null;
      }
    };
  }, [graphData, layoutMode]);

  return (
    <div
      ref={containerRef}
      className="decidron-diagram"
      style={{ height, width: '100%' }}
    />
  );
}