// npm install martinez-polygon-clipping polygon-clipping
// node index.js

const fs = require('fs')

const martinez = require('martinez-polygon-clipping')
const polygonClipping = require('polygon-clipping')

const input = require('./input.json')
const clip = require('./clip.json')

function apply (intersection) {
  const result = intersection(
    input.features[0].geometry.coordinates,
    clip.features[0].geometry.coordinates)

  const features = result.map((coordinates) => ({
    "type": "Feature",
    "properties": {},
    "geometry": {
      "type": "Polygon",
      "coordinates": coordinates
    }
  }))

  return JSON.stringify({
    "type": "FeatureCollection",
    "features": features
  })
}

fs.writeFileSync('./expected.json', apply(polygonClipping.intersection))
fs.writeFileSync('./actual.json', apply(martinez.intersection))