implement offline fallback map fastify plugin

package.json

@@ -88,6 +88,7 @@
     "husky": "^8.0.0",
     "light-my-request": "^5.10.0",
     "lint-staged": "^14.0.1",
+    "mapeo-offline-map": "^2.0.0",
     "math-random-seed": "^2.0.0",
     "nanobench": "^3.0.0",
     "npm-run-all": "^4.1.5",

src/fastify-plugins/maps/index.js

@@ -1,15 +1,20 @@
 import fp from 'fastify-plugin'
 
+import {
+  NotFoundError,
+  createStyleJsonResponseHeaders,
+  getFastifyServerAddress,
+} from '../utils.js'
 import { PLUGIN_NAME as MAPEO_STATIC_MAPS } from './static-maps.js'
-import { NotFoundError, getFastifyServerAddress } from '../utils.js'
+import { PLUGIN_NAME as MAPEO_OFFLINE_FALLBACK } from './offline-fallback-map.js'
 
 export const PLUGIN_NAME = 'mapeo-maps'
 
 export const plugin = fp(mapsPlugin, {
   fastify: '4.x',
   name: PLUGIN_NAME,
-  decorators: { fastify: ['mapeoStaticMaps'] },
-  dependencies: [MAPEO_STATIC_MAPS],
+  decorators: { fastify: ['mapeoStaticMaps', 'mapeoFallbackMap'] },
+  dependencies: [MAPEO_STATIC_MAPS, MAPEO_OFFLINE_FALLBACK],
 })
 
 /**
@@ -33,32 +38,39 @@ async function routes(fastify) {
     {
       const styleId = 'default'
 
-      let stats, styleJson
+      const results = await Promise.all([
+        fastify.mapeoStaticMaps.getStyleJsonStats(styleId),
+        fastify.mapeoStaticMaps.getResolvedStyleJson(styleId, serverAddress),
+      ]).catch(() => {
+        fastify.log.warn('Cannot read default static map')
+        return null
+      })
+
+      if (results) {
+        const [stats, styleJson] = results
+        rep.headers(createStyleJsonResponseHeaders(stats.mtime))
+        return styleJson
+      }
+    }
+
+    // TODO: 2. Attempt to get map's style.json from online source
+
+    // 3. Provide offline fallback map's style.json
+    {
+      let results = null
+
       try {
-        const results = await Promise.all([
-          fastify.mapeoStaticMaps.getStyleJsonStats(styleId),
-          fastify.mapeoStaticMaps.getResolvedStyleJson(styleId, serverAddress),
+        results = await Promise.all([
+          fastify.mapeoFallbackMap.getStyleJsonStats(),
+          fastify.mapeoFallbackMap.getResolvedStyleJson(serverAddress),
         ])
-
-        stats = results[0]
-        styleJson = results[1]
       } catch (err) {
-        throw new NotFoundError(`id = ${styleId}, style.json`)
+        throw new NotFoundError(`id = fallback, style.json`)
       }
 
-      rep.headers({
-        'Cache-Control': 'max-age=' + 5 * 60, // 5 minutes
-        'Access-Control-Allow-Headers':
-          'Authorization, Content-Type, If-Match, If-Modified-Since, If-None-Match, If-Unmodified-Since',
-        'Access-Control-Allow-Origin': '*',
-        'Last-Modified': new Date(stats.mtime).toUTCString(),
-      })
-
+      const [stats, styleJson] = results
+      rep.headers(createStyleJsonResponseHeaders(stats.mtime))
       return styleJson
     }
-
-    // TODO: 2. Attempt to get map's style.json from online source
-
-    // TODO: 3. Provide offline fallback map's style.json
   })
 }

src/fastify-plugins/maps/offline-fallback-map.js

@@ -0,0 +1,117 @@
+import path from 'path'
+import fs from 'fs/promises'
+import FastifyStatic from '@fastify/static'
+import fp from 'fastify-plugin'
+
+import {
+  NotFoundError,
+  createStyleJsonResponseHeaders,
+  getFastifyServerAddress,
+} from '../utils.js'
+
+export const PLUGIN_NAME = 'mapeo-static-maps'
+
+export const plugin = fp(offlineFallbackMapPlugin, {
+  fastify: '4.x',
+  name: PLUGIN_NAME,
+})
+
+/**
+ * @typedef {object} OfflineFallbackMapPluginOpts
+ * @property {string} [prefix]
+ * @property {string} styleJsonPath
+ * @property {string} sourcesDir
+ */
+
+/**
+ * @typedef {object} FallbackMapPluginDecorator
+ * @property {(serverAddress: string) => Promise<any>} getResolvedStyleJson
+ * @property {() => Promise<import('node:fs').Stats>} getStyleJsonStats
+ */
+
+/** @type {import('fastify').FastifyPluginAsync<OfflineFallbackMapPluginOpts>} */
+async function offlineFallbackMapPlugin(fastify, opts) {
+  const { styleJsonPath, sourcesDir } = opts
+
+  fastify.decorate(
+    'mapeoFallbackMap',
+    /** @type {FallbackMapPluginDecorator} */
+    ({
+      async getResolvedStyleJson(serverAddress) {
+        const rawStyleJson = await fs.readFile(styleJsonPath, 'utf-8')
+        const styleJson = JSON.parse(rawStyleJson)
+
+        const sources = styleJson.sources || {}
+
+        const sourcesDirFiles = await fs.readdir(sourcesDir, {
+          withFileTypes: true,
+        })
+
+        for (const file of sourcesDirFiles) {
+          // Only work with files
+          if (file.isDirectory()) continue
+
+          // Ignore the style.json file if it exists
+          if (file.name === 'style.json') continue
+
+          // Only work with json or geojson files
+          const extension = path.extname(file.name)
+          if (!(extension === '.json' || extension === '.geojson')) continue
+
+          const sourceName = path.basename(file.name, extension) + '-source'
+
+          sources[sourceName] = {
+            type: 'geojson',
+            data: new URL(`${opts.prefix || ''}/${file.name}`, serverAddress)
+              .href,
+          }
+        }
+
+        styleJson.sources = sources
+
+        return styleJson
+      },
+      async getStyleJsonStats() {
+        return fs.stat(styleJsonPath)
+      },
+    })
+  )
+
+  fastify.register(routes, {
+    prefix: opts.prefix,
+    styleJsonPath: opts.styleJsonPath,
+    sourcesDir: opts.sourcesDir,
+  })
+}
+
+/** @type {import('fastify').FastifyPluginAsync<OfflineFallbackMapPluginOpts, import('fastify').RawServerDefault, import('@fastify/type-provider-typebox').TypeBoxTypeProvider>} */
+async function routes(fastify, opts) {
+  const { sourcesDir } = opts
+
+  fastify.register(FastifyStatic, {
+    root: sourcesDir,
+    decorateReply: false,
+  })
+
+  fastify.get('/style.json', async (req, rep) => {
+    const serverAddress = await getFastifyServerAddress(req.server.server)
+
+    let stats, styleJson
+
+    try {
+      const results = await Promise.all([
+        fastify.mapeoFallbackMap.getStyleJsonStats(),
+        fastify.mapeoFallbackMap.getResolvedStyleJson(serverAddress),
+      ])
+
+      stats = results[0]
+      styleJson = results[1]
+    } catch (err) {
+      throw new NotFoundError(`id = fallback, style.json`)
+    }
+
+    rep.headers(createStyleJsonResponseHeaders(stats.mtime))
+
+    return styleJson
+  })
+}

src/fastify-plugins/maps/static-maps.js

@@ -7,7 +7,11 @@ import asar from '@electron/asar'
 import { Mime } from 'mime/lite'
 import standardTypes from 'mime/types/standard.js'
 
-import { NotFoundError, getFastifyServerAddress } from '../utils.js'
+import {
+  NotFoundError,
+  createStyleJsonResponseHeaders,
+  getFastifyServerAddress,
+} from '../utils.js'
 
 export const PLUGIN_NAME = 'mapeo-static-maps'
 
@@ -192,15 +196,7 @@ async function routes(fastify, opts) {
         throw new NotFoundError(`id = ${styleId}, style.json`)
       }
 
-      rep.headers({
-        'Content-Type': 'application/json; charset=utf-8',
-        'Cache-Control': 'max-age=' + 5 * 60, // 5 minutes
-        'Access-Control-Allow-Headers':
-          'Authorization, Content-Type, If-Match, If-Modified-Since, If-None-Match, If-Unmodified-Since',
-        'Access-Control-Allow-Origin': '*',
-        'Last-Modified': new Date(stats.mtime).toUTCString(),
-        'Content-Length': Buffer.from(styleJson).length,
-      })
+      rep.headers(createStyleJsonResponseHeaders(stats.mtime))
 
       return styleJson
     }

src/fastify-plugins/utils.js

@@ -37,3 +37,16 @@ export async function getFastifyServerAddress(server, { timeout } = {}) {
 
   return 'http://' + addr
 }
+
+/**
+ * @param {Date} lastModified
+ */
+export function createStyleJsonResponseHeaders(lastModified) {
+  return {
+    'Cache-Control': 'max-age=' + 5 * 60, // 5 minutes
+    'Access-Control-Allow-Headers':
+      'Authorization, Content-Type, If-Match, If-Modified-Since, If-None-Match, If-Unmodified-Since',
+    'Access-Control-Allow-Origin': '*',
+    'Last-Modified': new Date(lastModified).toUTCString(),
+  }
+}

tests/fastify-plugins/maps.js

@@ -1,11 +1,18 @@
 import { test } from 'brittle'
+import path from 'node:path'
 import Fastify from 'fastify'
 
 import { plugin as MapServerPlugin } from '../../src/fastify-plugins/maps/index.js'
 import { plugin as StaticMapsPlugin } from '../../src/fastify-plugins/maps/static-maps.js'
+import { plugin as OfflineFallbackMapPlugin } from '../../src/fastify-plugins/maps/offline-fallback-map.js'
 
 const MAP_FIXTURES_PATH = new URL('../fixtures/maps', import.meta.url).pathname
 
+const MAPEO_FALLBACK_MAP_PATH = new URL(
+  '../../node_modules/mapeo-offline-map',
+  import.meta.url
+).pathname
+
 test('fails to register when dependent plugins are not registered', async (t) => {
   const server = setup(t)
 
@@ -21,6 +28,11 @@ test('prefix opt is handled correctly', async (t) => {
     prefix: 'static',
     staticRootDir: MAP_FIXTURES_PATH,
   })
+  server.register(OfflineFallbackMapPlugin, {
+    prefix: 'fallback',
+    styleJsonPath: path.join(MAPEO_FALLBACK_MAP_PATH, 'style.json'),
+    sourcesDir: path.join(MAPEO_FALLBACK_MAP_PATH, 'dist'),
+  })
 
   server.register(MapServerPlugin, { prefix: 'maps' })
 
@@ -47,14 +59,43 @@ test('prefix opt is handled correctly', async (t) => {
   }
 })
 
-// TODO: Add similar tests/fixtures for proxied online style and offline fallback style
 test('/style.json resolves style.json of local "default" static map when available', async (t) => {
   const server = setup(t)
 
   server.register(StaticMapsPlugin, {
     prefix: 'static',
     staticRootDir: MAP_FIXTURES_PATH,
   })
+  server.register(OfflineFallbackMapPlugin, {
+    prefix: 'fallback',
+    styleJsonPath: path.join(MAPEO_FALLBACK_MAP_PATH, 'style.json'),
+    sourcesDir: path.join(MAPEO_FALLBACK_MAP_PATH, 'dist'),
+  })
+  server.register(MapServerPlugin)
+
+  await server.listen()
+
+  const response = await server.inject({
+    method: 'GET',
+    url: '/style.json',
+  })
+
+  t.is(response.statusCode, 200)
+})
+
+test('/style.json resolves style.json of offline fallback map when static and online are not available', async (t) => {
+  const server = setup(t)
+
+  server.register(StaticMapsPlugin, {
+    prefix: 'static',
+    // Need to choose a directory that doesn't have any map fixtures
+    staticRootDir: path.resolve(MAP_FIXTURES_PATH, '../does-not-exist'),
+  })
+  server.register(OfflineFallbackMapPlugin, {
+    prefix: 'fallback',
+    styleJsonPath: path.join(MAPEO_FALLBACK_MAP_PATH, 'style.json'),
+    sourcesDir: path.join(MAPEO_FALLBACK_MAP_PATH, 'dist'),
+  })
   server.register(MapServerPlugin)
 
   await server.listen()
@@ -64,9 +105,12 @@ test('/style.json resolves style.json of local "default" static map when availab
     url: '/style.json',
   })
 
+  t.is(response.json().id, 'blank', 'gets fallback style.json')
   t.is(response.statusCode, 200)
 })
 
+// TODO: add test for proxying online map style.json
+
 /**
  * @param {import('brittle').TestInstance} t
  */