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api.js
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const gjv = require('geojson-validation')
const extent = require('@mapbox/extent')
const yaml = require('js-yaml')
const fs = require('fs')
const logger = console
const path = require('path')
const httpMethods = require('../utils/http-methods')
// max number of collections to retrieve
const COLLECTION_LIMIT = process.env.STAC_SERVER_COLLECTION_LIMIT || 100
const extractIntersects = function (params) {
let intersectsGeometry
const geojsonError = new Error('Invalid GeoJSON geometry')
const geojsonFeatureError =
new Error('Expected GeoJSON geometry, not Feature or FeatureCollection')
const { intersects } = params
if (intersects) {
let geojson
// if we receive a string, try to parse as GeoJSON, otherwise assume it is GeoJSON
if (typeof intersects === 'string') {
try {
geojson = JSON.parse(intersects)
} catch (e) {
throw geojsonError
}
} else {
geojson = Object.assign({}, intersects)
}
if (gjv.valid(geojson)) {
if (geojson.type === 'FeatureCollection') {
throw geojsonFeatureError
} else if (geojson.type === 'Feature') {
throw geojsonFeatureError
}
intersectsGeometry = geojson
} else {
throw geojsonError
}
}
return intersectsGeometry
}
const extractBbox = function (params) {
let intersectsGeometry
const { bbox } = params
if (bbox) {
let bboxArray
if (typeof bbox === 'string') {
bboxArray = JSON.parse(bbox)
} else {
bboxArray = bbox
}
const boundingBox = extent(bboxArray)
intersectsGeometry = boundingBox.polygon()
}
return intersectsGeometry
}
const extractStacQuery = function (params) {
let stacQuery
const { query } = params
if (query) {
if (typeof query === 'string') {
const parsed = JSON.parse(query)
stacQuery = parsed
} else {
stacQuery = Object.assign({}, query)
}
}
return stacQuery
}
const extractSortby = function (params) {
let sortbyRules
const { sortby } = params
if (sortby) {
if (typeof sortby === 'string') {
// GET request - different syntax
sortbyRules = []
const sortbys = sortby.split(',')
sortbys.forEach((sortbyRule) => {
if (sortbyRule[0] === '-') {
sortbyRules.push({ 'field': sortbyRule.slice(1), 'direction': 'desc' })
} else if (sortbyRule[0] === '+') {
sortbyRules.push({ 'field': sortbyRule.slice(1), 'direction': 'asc' })
} else {
sortbyRules.push({ 'field': sortbyRule, 'direction': 'asc' })
}
})
} else {
// POST request
sortbyRules = sortby.slice()
}
}
return sortbyRules
}
const extractFields = function (params) {
let fieldRules
const { fields } = params
if (fields) {
if (typeof fields === 'string') {
// GET request - different syntax
const _fields = fields.split(',')
const include = []
_fields.forEach((fieldRule) => {
if (fieldRule[0] !== '-') {
include.push(fieldRule)
}
})
const exclude = []
_fields.forEach((fieldRule) => {
if (fieldRule[0] === '-') {
exclude.push(fieldRule.slice(1))
}
})
fieldRules = { include, exclude }
} else {
// POST request - JSON
fieldRules = fields
}
} else if (params.hasOwnProperty('fields')) {
// fields was provided as an empty object
fieldRules = {}
}
return fieldRules
}
const extractIds = function (params) {
let idsRules
const { ids } = params
if (ids) {
if (typeof ids === 'string') {
idsRules = JSON.parse(ids)
} else {
idsRules = ids.slice()
}
}
return idsRules
}
const extractCollectionIds = function (params) {
let idsRules
const { collections } = params
if (collections) {
if (typeof collections === 'string') {
idsRules = JSON.parse(collections)
} else {
idsRules = collections.slice()
}
}
return idsRules
}
const parsePath = function (inpath) {
const searchFilters = {
root: false,
api: false,
conformance: false,
stac: false,
collections: false,
search: false,
collectionId: false,
items: false,
itemId: false,
edit: false
}
const api = 'api'
const conformance = 'conformance'
const collections = 'collections'
const search = 'search'
const items = 'items'
const edit = 'edit'
const stac = 'stac'
const pathComponents = inpath.split('/').filter((x) => x)
const { length } = pathComponents
searchFilters.root = length === 0
searchFilters.api = pathComponents[0] === api
searchFilters.conformance = pathComponents[0] === conformance
searchFilters.collections = pathComponents[0] === collections
searchFilters.stac = pathComponents[0] === stac
// searchFilters.stac = pathComponents[0] === stac.length > 3
searchFilters.collectionId =
pathComponents[0] === collections && length >= 2 ? pathComponents[1] : false
searchFilters.search = pathComponents[0] === search
searchFilters.items = pathComponents[2] === items
searchFilters.itemId =
pathComponents[2] === items && length >= 4 ? pathComponents[3] : false
searchFilters.edit = pathComponents[4] === edit
return searchFilters
}
// Impure - mutates results
const addCollectionLinks = function (results, endpoint) {
results.forEach((result) => {
const { id, links } = result
// self link
links.splice(0, 0, {
rel: 'self',
href: `${endpoint}/collections/${id}`
})
// parent catalog
links.push({
rel: 'parent',
href: `${endpoint}/`
})
// root catalog
links.push({
rel: 'root',
href: `${endpoint}/`
})
// child items
links.push({
rel: 'items',
href: `${endpoint}/collections/${id}/items`
})
})
return results
}
// Impure - mutates results
const addItemLinks = function (results, endpoint) {
results.forEach((result) => {
let { links } = result
const { id, collection } = result
links = (links === undefined) ? [] : links
// self link
links.splice(0, 0, {
rel: 'self',
href: `${endpoint}/collections/${collection}/items/${id}`
})
// parent catalogs
links.push({
rel: 'parent',
href: `${endpoint}/collections/${collection}`
})
links.push({
rel: 'collection',
href: `${endpoint}/collections/${collection}`
})
// root catalog
links.push({
rel: 'root',
href: `${endpoint}/`
})
result.type = 'Feature'
return result
})
return results
}
const collectionsToCatalogLinks = function (results, endpoint) {
const stac_version = process.env.STAC_VERSION
const stac_api_version = process.env.STAC_API_VERSION
const stac_id = process.env.STAC_ID || 'stac-server'
const stac_title = process.env.STAC_TITLE || 'A STAC API'
const stac_description = process.env.STAC_DESCRIPTION || 'A STAC API running on stac-server'
const catalog = {
stac_version,
stac_api_version,
id: stac_id,
title: stac_title,
description: stac_description
}
console.log(`Results: ${results}`)
catalog.links = results.map((result) => {
const { id } = result
return {
rel: 'child',
href: `${endpoint}/collections/${id}`
}
})
return catalog
}
const wrapResponseInFeatureCollection = function (
meta, features = [], links = []
) {
return {
type: 'FeatureCollection',
'stac_version': process.env.STAC_VERSION,
'stac_extensions': [],
'context': meta,
'numberMatched': meta.matched,
'numberReturned': meta.returned,
features,
links
}
}
const buildPageLinks = function (meta, parameters, endpoint, httpMethod) {
const pageLinks = []
const dictToURI = (dict) => (
Object.keys(dict).map(
(p) => {
if (p === "collections") {
return `${encodeURIComponent(p)}[]=${encodeURIComponent(dict[p])}`
} else {
return `${encodeURIComponent(p)}=${encodeURIComponent(dict[p])}`
}
}).join('&')
)
const { matched, page, limit } = meta
let newParams, link
if ((page * limit) < matched) {
newParams = Object.assign({}, parameters, { page: page + 1, limit })
link = {
rel: 'next',
title: 'Next page of results',
method: httpMethod
}
if (httpMethod === 'GET') {
const nextQueryParameters = dictToURI(newParams)
links.href = `${endpoint}?${nextQueryParameters}`
} else if (httpMethod === 'POST') {
links.href = endpoint,
links.merge = false,
links.body = newParams
}
pageLinks.push(link)
}
if (page > 1) {
newParams = Object.assign({}, parameters, { page: page - 1, limit })
link = {
rel: 'prev',
title: 'Previous page of results',
method: httpMethod
}
if (httpMethod === 'GET') {
const prevQueryParameters = dictToURI(newParams)
links.href = `${endpoint}?${nextQueryParameters}`
} else if (httpMethod === 'POST') {
links.href = endpoint
links.merge = false,
links.body = newParams
}
pageLinks.push(link)
}
return pageLinks
}
const searchItems = async function (collectionId, queryParameters, backend, endpoint, httpMethod) {
logger.debug(`Query parameters: ${JSON.stringify(queryParameters)}`)
const {
limit,
page,
datetime
} = queryParameters
const bbox = extractBbox(queryParameters)
const hasIntersects = extractIntersects(queryParameters)
if (bbox && hasIntersects) {
throw new Error('Expected bbox OR intersects, not both')
}
const sortby = extractSortby(queryParameters)
// Prefer intersects
const intersects = hasIntersects || bbox
const query = extractStacQuery(queryParameters)
const fields = extractFields(queryParameters)
const ids = extractIds(queryParameters)
const collections = extractCollectionIds(queryParameters)
const parameters = {
datetime,
intersects,
query,
sortby,
fields,
ids,
collections
}
// Keep only existing parameters
const searchParameters = Object.keys(parameters)
.filter((key) => parameters[key])
.reduce((obj, key) => ({
...obj,
[key]: parameters[key]
}), {})
let new_endpoint = `${endpoint}/search`
if (collectionId) {
searchParameters.collections = [collectionId]
new_endpoint = `${endpoint}/collections/${collectionId}/items`
}
logger.debug(`Search parameters: ${JSON.stringify(searchParameters)}`)
const { 'results': itemsResults, 'context': itemsMeta } =
await backend.search(searchParameters, page, limit)
const pageLinks = buildPageLinks(itemsMeta, searchParameters, new_endpoint, httpMethod)
const items = addItemLinks(itemsResults, endpoint)
const response = wrapResponseInFeatureCollection(itemsMeta, items, pageLinks)
return response
}
const getAPI = async function () {
const spec = yaml.safeLoad(fs.readFileSync(path.resolve(__dirname, './api.yaml'), 'utf8'))
return spec
}
const getConformance = async function () {
const conformance = {
conformsTo: [
'http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/core',
'http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/html',
'http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/geojson'
]
}
return conformance
}
const getCatalog = async function (backend, endpoint = '') {
const collections = await backend.getCollections(1, COLLECTION_LIMIT)
const catalog = collectionsToCatalogLinks(collections, endpoint)
catalog.links.push({
rel: 'service-desc',
type: 'application/vnd.oai.openapi+json;version=3.0',
href: `${endpoint}/api`
})
catalog.links.push({
rel: 'conformance',
type: 'application/json',
href: `${endpoint}/conformance`
})
catalog.links.push({
rel: 'children',
type: 'application/json',
href: `${endpoint}/collections`
})
catalog.links.push({
rel: 'self',
type: 'application/json',
href: `${endpoint}/`
})
catalog.links.push({
rel: 'search',
type: 'application/json',
href: `${endpoint}/search`
})
const docsUrl = process.env.STAC_DOCS_URL || 'https://stac-utils.github.io/stac-api'
if (docsUrl) {
catalog.links.push({
rel: 'docs',
href: process.env.STAC_DOCS_URL
})
}
return catalog
}
const getCollections = async function (backend, endpoint = '') {
const results = await backend.getCollections(1, COLLECTION_LIMIT)
const linkedCollections = addCollectionLinks(results, endpoint)
const resp = {
collections: results,
links: []
}
return resp
}
const getCollection = async function (collectionId, backend, endpoint = '') {
const result = await backend.getCollection(collectionId)
const col = addCollectionLinks([result], endpoint)
if (col.length > 0) {
return col[0]
}
return { code: 404, message: 'Collection not found' }
}
const getItem = async function (collectionId, itemId, backend, endpoint = '') {
const itemQuery = { collections: [collectionId], id: itemId }
const { results } = await backend.search(itemQuery)
const [it] = addItemLinks(results, endpoint)
if (it) {
return it
}
return { code: 404, message: 'Item not found' }
}
const editPartialItem = async function (itemId, queryParameters, backend, endpoint = '') {
const response = await backend.editPartialItem(itemId, queryParameters)
logger.debug(`Edit Item: ${response}`)
if (response) {
return addItemLinks([response.get._source], endpoint)[0]
}
return { code: 404, message: `Error editing item ${itemId}` }
}
const API = async function (
inpath = '', queryParameters = {}, backend, endpoint = '', httpMethod = 'GET'
) {
let apiResponse
try {
const pathElements = parsePath(inpath)
const {
root,
api,
conformance,
search: searchPath,
collections,
collectionId,
items,
itemId
} = pathElements
// API Root
if (root) {
apiResponse = await getCatalog(backend, endpoint)
}
// API Definition
if (api) {
apiResponse = await getAPI()
}
// Conformance
if (conformance) {
apiResponse = await getConformance()
}
// STAC Search
if (searchPath) {
apiResponse = await searchItems(
null, queryParameters, backend, endpoint, httpMethod
)
}
// Search
// All collections
if (collections && !collectionId) {
apiResponse = await getCollections(backend, endpoint)
}
// Specific collection
if (collections && collectionId && !items) {
apiResponse = await getCollection(collectionId, backend, endpoint)
}
// Items in a collection
if (collections && collectionId && items && !itemId) {
apiResponse = await searchItems(collectionId, queryParameters, backend, endpoint, httpMethod)
}
// Specific item
const pathIsToSpecificItem = (collections && collectionId && items && itemId)
if (pathIsToSpecificItem) {
if (httpMethod === httpMethods.GET) {
apiResponse = await getItem(collectionId, itemId, backend, endpoint)
} else if (httpMethod === httpMethods.PATCH && process.env.ENABLE_TRANSACTIONS_EXTENSION) {
// Right now this is the only Transaction extension we support.
// https://github.com/radiantearth/stac-api-spec/tree/master/extensions/transaction
// When we do more, let's make a more scalable check and not look
// for ENABLE_TRANSACTIONS_EXTENSION each time
apiResponse = await editPartialItem(itemId, queryParameters, backend, endpoint)
}
}
} catch (error) {
logger.error(error)
apiResponse = { code: 500, message: error.message }
}
return apiResponse
}
module.exports = {
getAPI,
getConformance,
getCatalog,
getCollections,
getCollection,
getItem,
searchItems,
API,
parsePath,
extractIntersects
}