const express = require('express');
const authenticate = require('../middleware/auth');
const multer = require('multer');
const { parseString } = require('dxf-parser');
const router = express.Router();
const upload = multer({ storage: multer.memoryStorage(), limits: { fileSize: 10 * 1024 * 1024 } });

// Upload DXF file -> parse and return JSON representation (Fabric.js compatible)
router.post('/import', authenticate, upload.single('file'), async (req, res) => {
  try {
    if (!req.file) {
      return res.status(400).json({ error: 'No file uploaded' });
    }
    const dxfContent = req.file.buffer.toString('utf-8');
    console.log('DXF file size:', dxfContent.length);
    const parsed = parseString(dxfContent);
    // Convert parsed entities to Fabric.js objects (simplified)
    const fabricObjects = [];
    if (parsed && parsed.entities) {
      parsed.entities.forEach(entity => {
        const type = entity.type;
        if (type === 'LINE') {
          fabricObjects.push({
            type: 'line',
            x1: entity.start.x, y1: entity.start.y,
            x2: entity.end.x, y2: entity.end.y,
            stroke: '#000', strokeWidth: 1,
          });
        } else if (type === 'CIRCLE') {
          fabricObjects.push({
            type: 'circle',
            left: entity.center.x - entity.radius,
            top: entity.center.y - entity.radius,
            radius: entity.radius,
            fill: 'transparent', stroke: '#000',
          });
        } else if (type === 'ARC') {
          // simplified arc handling
          fabricObjects.push({
            type: 'path',
            path: `M ${entity.center.x} ${entity.center.y}`, // placeholder
            stroke: '#000', strokeWidth: 1,
          });
        } else if (type === 'POLYLINE' || type === 'LWPOLYLINE') {
          // convert vertices to polygon
          if (entity.vertices && entity.vertices.length >= 2) {
            const points = entity.vertices.map(v => ({ x: v.x, y: v.y }));
            fabricObjects.push({
              type: 'polygon',
              points,
              stroke: '#000', strokeWidth: 1, fill: 'transparent',
            });
          }
        }
      });
    }
    res.json({ objects: fabricObjects });
  } catch (err) {
    console.error('DXF import error:', err);
    res.status(500).json({ error: 'Failed to parse DXF file: ' + err.message });
  }
});

// Export canvas JSON to DXF string
router.post('/export', authenticate, (req, res) => {
  try {
    const { objects } = req.body;
    if (!objects || !Array.isArray(objects)) {
      return res.status(400).json({ error: 'Invalid objects array' });
    }
    // Build DXF content
    let dxf = '0\nSECTION\n2\nHEADER\n0\nENDSEC\n';
    dxf += '0\nSECTION\n2\nTABLES\n0\nENDSEC\n';
    dxf += '0\nSECTION\n2\nBLOCKS\n0\nENDSEC\n';
    dxf += '0\nSECTION\n2\nENTITIES\n';
    objects.forEach(obj => {
      if (obj.type === 'line') {
        dxf += `0\nLINE\n8\n0\n10\n${obj.x1}\n20\n${obj.y1}\n11\n${obj.x2}\n21\n${obj.y2}\n`;
      } else if (obj.type === 'circle') {
        const cx = obj.left + obj.radius;
        const cy = obj.top + obj.radius;
        dxf += `0\nCIRCLE\n8\n0\n10\n${cx}\n20\n${cy}\n40\n${obj.radius}\n`;
      } else if (obj.type === 'polygon') {
        // LWPOLYLINE
        dxf += `0\nLWPOLYLINE\n8\n0\n90\n${obj.points.length}\n`;
        obj.points.forEach((pt, i) => {
          dxf += `10\n${pt.x}\n20\n${pt.y}\n`;
        });
      }
    });
    dxf += '0\nENDSEC\n0\nEOF\n';
    res.setHeader('Content-Type', 'application/dxf');
    res.setHeader('Content-Disposition', 'attachment; filename=drawing.dxf');
    res.send(dxf);
  } catch (err) {
    console.error('DXF export error:', err);
    res.status(500).json({ error: 'Export failed' });
  }
});

module.exports = router;