112 lines
3 KiB
JavaScript
112 lines
3 KiB
JavaScript
'use strict'
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const computeEtag = require('etag')
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const serveBuffer = require('serve-buffer')
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const autocomplete = require('db-stations-autocomplete')
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const parse = require('cli-native').to
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const createFilter = require('db-stations/create-filter')
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let pAllStations = require('../lib/db-stations')
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const JSON_MIME = 'application/json'
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const NDJSON_MIME = 'application/x-ndjson'
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const toNdjsonBuf = (data) => {
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const chunks = []
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let i = 0, bytes = 0
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for (const id in data) {
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const sep = i++ === 0 ? '' : '\n'
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const buf = Buffer.from(sep + JSON.stringify(data[id]), 'utf8')
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chunks.push(buf)
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bytes += buf.length
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}
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return Buffer.concat(chunks, bytes)
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}
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pAllStations = pAllStations.then(({data, timeModified}) => {
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const asJson = Buffer.from(JSON.stringify(data), 'utf8')
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const asNdjson = toNdjsonBuf(data)
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return {
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stations: data,
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timeModified,
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asJson: {data: asJson, etag: computeEtag(asJson)},
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asNdjson: {data: asNdjson, etag: computeEtag(asNdjson)},
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}
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})
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.catch((err) => {
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console.error(err)
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process.exit(1)
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})
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const err = (msg, statusCode = 500) => {
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const err = new Error(msg)
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err.statusCode = statusCode
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return err
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}
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const complete = (req, res, next, q, allStations, onStation, onEnd) => {
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const limit = q.results && parseInt(q.results) || 3
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const fuzzy = parse(q.fuzzy) === true
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const completion = parse(q.completion) !== false
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const results = autocomplete(q.query, limit, fuzzy, completion)
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const data = []
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for (const result of results) {
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const station = allStations[result.id]
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if (!station) continue
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Object.assign(result, station)
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onStation(result)
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}
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onEnd()
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}
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const filter = (req, res, next, q, allStations, onStation, onEnd) => {
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const selector = Object.create(null)
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for (const prop in q) selector[prop] = parse(q[prop])
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const filter = createFilter(selector)
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for (const id in allStations) {
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const station = allStations[id]
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if (filter(station)) onStation(station)
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}
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onEnd()
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}
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const stationsRoute = (req, res, next) => {
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const t = req.accepts([JSON_MIME, NDJSON_MIME])
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if (t !== JSON_MIME && t !== NDJSON_MIME) {
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return next(err(JSON + ' or ' + NDJSON_MIME, 406))
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}
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const head = t === JSON_MIME ? '{\n' : ''
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const sep = t === JSON_MIME ? ',\n' : '\n'
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const tail = t === JSON_MIME ? '\n}\n' : '\n'
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let i = 0
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const onStation = (s) => {
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const j = JSON.stringify(s)
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const field = t === JSON_MIME ? `"${s.id}":` : ''
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res.write(`${i++ === 0 ? head : sep}${field}${j}`)
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}
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const onEnd = () => {
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if (i > 0) res.end(tail)
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else res.end(head + tail)
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}
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const q = req.query
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pAllStations
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.then(({stations, timeModified, asJson, asNdjson}) => {
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res.setHeader('Last-Modified', timeModified.toUTCString())
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if (Object.keys(req.query).length === 0) {
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const data = t === JSON_MIME ? asJson.data : asNdjson.data
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const etag = t === JSON_MIME ? asJson.etag : asNdjson.etag
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serveBuffer(req, res, data, {timeModified, etag})
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} else if (q.query) {
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complete(req, res, next, q, stations, onStation, onEnd)
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} else {
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filter(req, res, next, q, stations, onStation, onEnd)
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}
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})
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.catch(next)
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}
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module.exports = stationsRoute
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