8 files changed, 121 insertions, 21 deletions
diff --git a/client/jest.config.js b/client/jest.config.js
index 758fa13..6f79391 100644
--- a/client/jest.config.js
+++ b/client/jest.config.js
@@ -1,4 +1,5 @@
 module.exports = {
   preset: 'ts-jest',
-  testEnvironment: 'node'
+  testEnvironment: 'node',
+  modulePathIgnorePatterns: ['dist']
 }
diff --git a/client/package.json b/client/package.json
index b7489f0..66ea261 100644
--- a/client/package.json
+++ b/client/package.json
@@ -13,6 +13,7 @@
   "devDependencies": {
     "@types/jest": "^23.3.13",
     "@types/node": "^10.12.18",
+    "@types/ws": "^6.0.1",
     "jest": "^23.6.0",
     "ts-jest": "^23.10.5",
     "ts-node": "^7.0.1",
diff --git a/client/src/config.model.ts b/client/src/config.model.ts
index 278f7f7..09925bf 100644
--- a/client/src/config.model.ts
+++ b/client/src/config.model.ts
@@ -1,4 +1,4 @@
 export interface Config {
-  wsPort: number
+  wsUrl: string
   httpUrl: string
 }
diff --git a/client/src/database-connection.model.ts b/client/src/database-connection.model.ts
index 0523e22..86999be 100644
--- a/client/src/database-connection.model.ts
+++ b/client/src/database-connection.model.ts
@@ -1,7 +1,8 @@
 export interface DatabaseConnection {
   init(): Promise<any>
-  close(): Promise<any>
+  close(): any
   subscribe(path: string, callback: (e: any) => any): Promise<() => any>
   write(path: string, toWrite: Object): Promise<any>
+  read(path: string): Promise<any>
   remove(path: string): Promise<any>
 }
diff --git a/client/src/database-connection.ts b/client/src/database-connection.ts
index 3cf733c..f37b298 100644
--- a/client/src/database-connection.ts
+++ b/client/src/database-connection.ts
@@ -1,7 +1,28 @@
 import { Config } from './config.model'
+import { getKey } from '../../lib/util'
+import { encodePath } from '../../lib/path'
 import { DatabaseConnection } from './database-connection.model'
+import { DatabaseChange } from '../../lib/database-change.model'
+import { Body } from 'node-fetch'
 
-const IS_NODE = true
+import WebSocket from 'ws'
+
+const objectToQuery = (query: Object): string =>
+  Object.values(query).reduce(
+    (acc: string, [key, val]: [string, string]) => acc + `${key}=${val}&`,
+    '?'
+  )
+
+// each path has one or more callbacks
+// that must be fired with each change
+interface CallbackTable {
+  [path: string]: CallbackRef[]
+}
+
+interface CallbackRef {
+  id: string
+  callback: (e: Object) => void
+}
 
 /**
  * Client side implementation is implemented using
@@ -10,31 +31,100 @@ const IS_NODE = true
  */
 export const dbFactory = (config: Config): DatabaseConnection => {
   // TODO figure out how to patch
-  // in native fetch instead
+  // in native fetch/websocke instead
   // when this is running in the browser
-  const send = require('node-fetch')
+  const nodeFetch = require('node-fetch')
+  const WebSocket = require('ws')
+
+  let ws: WebSocket | null
+  let subCallbacks: CallbackTable = {}
+
+  const send = (method: string) => (
+    route: string,
+    body: Object | void
+  ): Promise<Body> => {
+    const isGet = method === 'GET'
+    if (isGet && body) {
+      route += objectToQuery(body)
+    }
+    return nodeFetch(route, {
+      method,
+      ...(isGet ? undefined : { body: JSON.stringify(body) }),
+      headers: {
+        Accept: 'application/json',
+        'Content-Type': 'application/json'
+      }
+    })
+  }
+
+  const hget = (route: string, body: Object | void) =>
+    send('GET')(route, body).then((r: any) => r.json())
+  const hpost = send('POST')
+
   const write = (path: string, toWrite: Object | null) => {
     const { httpUrl } = config
-    const body = JSON.stringify({
+    return hpost(`${httpUrl}/write`, {
       path,
       toWrite
     })
-    return send(`${httpUrl}/write`, {
-      method: 'POST',
-      body,
-      headers: {
-        Accept: 'application/json',
-        'Content-Type': 'application/json'
+  }
+
+  const read = (path: string): Promise<any> => {
+    const { httpUrl } = config
+    return hget(`${httpUrl}/read/${encodePath(path)}`)
+  }
+
+  const socketMessageHandler = (event: {
+    data: any
+    type: string
+    target: WebSocket
+  }) => {
+    const dbChange: DatabaseChange = JSON.parse(event.data)
+    const callbackRefs = subCallbacks[dbChange.path]
+    if (callbackRefs && callbackRefs.length) {
+      for (let ref of callbackRefs) {
+        ref.callback(dbChange.change)
       }
-    })
+    }
   }
+
   return {
-    async init() {},
-    async close() {},
-    async subscribe(path: string, callback: (e: any) => Promise<any>) {
-      return () => {}
+    init() {
+      return new Promise(resolve => {
+        ws = new WebSocket(config.wsUrl)
+        // @ts-ignore
+        ws.addEventListener('message', socketMessageHandler)
+        // @ts-ignore
+        ws.addEventListener('open', () => resolve())
+      })
+    },
+    close() {
+      if (ws) {
+        ws.removeEventListener('message', socketMessageHandler)
+        ws.close()
+        ws = null
+      }
+    },
+    async subscribe(path: string, callback: (e: Object) => void) {
+      const id = getKey('callbackref')
+      const ref: CallbackRef = {
+        id,
+        callback
+      }
+      if (!subCallbacks[path]) {
+        const { httpUrl } = config
+        subCallbacks[path] = [ref]
+        await hpost(`${httpUrl}/subscribe`, { path })
+      } else subCallbacks[path].push(ref)
+      // return a fucntion
+      // to remove our new sub from
+      // the table
+      return () => {
+        subCallbacks[path] = subCallbacks[path].filter(k => k.id !== id)
+      }
     },
     write,
+    read,
     async remove(path: string) {
       write(path, null)
     }
diff --git a/client/src/index.ts b/client/src/index.ts
index f11e59c..d2a9d21 100644
--- a/client/src/index.ts
+++ b/client/src/index.ts
@@ -1,4 +1,3 @@
 export { dbFactory } from './database-connection'
 export { DatabaseConnection } from './database-connection.model'
 export { Config } from './config.model'
-declare var fetch: any
diff --git a/client/tsconfig.json b/client/tsconfig.json
index 1b31a6d..abe6846 100644
--- a/client/tsconfig.json
+++ b/client/tsconfig.json
@@ -34,8 +34,8 @@
     // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
 
     /* Additional Checks */
-    // "noUnusedLocals": true,                /* Report errors on unused locals. */
-    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
+    "noUnusedLocals": true /* Report errors on unused locals. */,
+    "noUnusedParameters": true /* Report errors on unused parameters. */,
     // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
     // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
 
diff --git a/client/yarn.lock b/client/yarn.lock
index 97a7de5..b29c5e1 100644
--- a/client/yarn.lock
+++ b/client/yarn.lock
@@ -89,6 +89,14 @@
     "@types/glob" "*"
     "@types/node" "*"
 
+"@types/ws@^6.0.1":
+  version "6.0.1"
+  resolved "https://registry.yarnpkg.com/@types/ws/-/ws-6.0.1.tgz#ca7a3f3756aa12f62a0a62145ed14c6db25d5a28"
+  integrity sha512-EzH8k1gyZ4xih/MaZTXwT2xOkPiIMSrhQ9b8wrlX88L0T02eYsddatQlwVFlEPyEqV0ChpdpNnE51QPH6NVT4Q==
+  dependencies:
+    "@types/events" "*"
+    "@types/node" "*"
+
 abab@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/abab/-/abab-2.0.0.tgz#aba0ab4c5eee2d4c79d3487d85450fb2376ebb0f"