server.js

#!/usr/bin/env node --max-old-space-size=4096
const {features} = require('./dist/iris.json')
const express = require('express')
const {chain, min} = require('lodash')
const Flatbush = require('flatbush')
const {bbox: getBbox, booleanPointInPolygon, point, lineString, pointToLineDistance} = require('@turf/turf')
const morgan = require('morgan')
const cors = require('cors')

const app = express()

const geoIndex = new Flatbush(features.length)
features.forEach(f => geoIndex.add(...getBbox(f)))
geoIndex.finish()

if (process.env.NODE_ENV === 'production') {
  app.enable('trust proxy')
}

app.use(cors({origin: true}))

if (process.env.NODE_ENV !== 'production') {
  app.use(morgan('dev'))
}

app.get('/iris', (req, res) => {
  if (!req.query.lat || !req.query.lon || !req.query.codeCommune) {
    return res.sendStatus(400)
  }

  const lat = Number.parseFloat(req.query.lat)
  const lon = Number.parseFloat(req.query.lon)

  if (lat > 90 || lat < -90 || lon > 180 || lon < -180) {
    return res.sendStatus(400)
  }

  const candidates = geoIndex.neighbors(lon, lat, 10, 10, undefined)
    .filter(i => features[i].properties.codeCommune === req.query.codeCommune)
    .map(i => features[i])

  if (candidates.length === 0) {
    return res.sendStatus(404)
  }

  const exactResult = candidates.find(c => {
    return booleanPointInPolygon(
      point([lon, lat]),
      c
    )
  })

  if (exactResult) {
    return res.send(exactResult.properties)
  }

  const fuzzyResult = chain(candidates)
    .minBy(c => {
      const rings = []

      if (c.geometry.type === 'Polygon') {
        rings.push(...c.geometry.coordinates)
      }

      if (c.geometry.type === 'MultiPolygon') {
        c.geometry.coordinates.forEach(polygonRings => rings.push(...polygonRings))
      }

      return min(rings.map(ring => {
        return pointToLineDistance(point([lon, lat]), lineString(ring), {units: 'kilometers'})
      }))
    })
    .value()

  if (fuzzyResult) {
    return res.send(fuzzyResult.properties)
  }

  res.sendStatus(404)
})

const port = process.env.PORT || 5000

app.listen(port, () => {
  console.log(`Start listening on port ${port}`)
})