Classify Http & Ws providers (#120)

* Class-ify HttpProvider

* Class-ify WsProvider (tests still WIP)

* Rework tests

* rx-api usage

packages/api-provider/src/http/index.ts

@@ -2,29 +2,62 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
+import { Logger } from '@polkadot/util/types';
+import { RpcCoder } from '../coder/json/types';
 import { ProviderInterface, ProviderInterface$Callback, ProviderInterface$Emitted, ProviderInterface$EmitCb } from '../types';
 
 import './polyfill';
 
-import on from './on';
-import send from './send';
-import subscribe from './subscribe';
-import state from './state';
-import unsubscribe from './unsubscribe';
+import assert from '@polkadot/util/assert';
+import logger from '@polkadot/util/logger';
 
-export default function httpProvider (endpoint: string): ProviderInterface {
-  const self = state(endpoint);
+import coder from '../coder/json';
 
-  return {
-    isConnected: (): boolean =>
-      true,
-    on: (type: ProviderInterface$Emitted, sub: ProviderInterface$EmitCb): void =>
-      on(self, type, sub),
-    send: (method: string, params: Array<any>): Promise<any> =>
-      send(self, method, params),
-    subscribe: (method: string, params: Array<any>, cb: ProviderInterface$Callback): Promise<number> =>
-      subscribe(self, method, params, cb),
-    unsubscribe: (method: string, id: number): Promise<boolean> =>
-      unsubscribe(self, method, id)
-  };
+export default class HttpProvider implements ProviderInterface {
+  private coder: RpcCoder;
+  private endpoint: string;
+  private l: Logger;
+
+  constructor (endpoint: string) {
+    assert(/^(https|http):\/\//.test(endpoint), `Endpoint should start with 'http://', received '${endpoint}'`);
+
+    this.coder = coder();
+    this.endpoint = endpoint;
+    this.l = logger('api-http');
+  }
+
+  isConnected (): boolean {
+    return true;
+  }
+
+  on (type: ProviderInterface$Emitted, sub: ProviderInterface$EmitCb): void {
+    this.l.error(`Provider does not have 'on' emitters for type '${type}'`);
+  }
+
+  async send (method: string, params: Array<any>): Promise<any> {
+    const body = this.coder.encodeJson(method, params);
+    const response = await fetch(this.endpoint, {
+      body,
+      headers: {
+        'Accept': 'application/json',
+        'Content-Length': `${body.length}`,
+        'Content-Type': 'application/json'
+      },
+      method: 'POST'
+    });
+
+    assert(response.ok, `[${response.status}]: ${response.statusText}`);
+
+    const result = await response.json();
+
+    return this.coder.decodeResponse(result);
+  }
+
+  async subscribe (method: string, params: Array<any>, cb: ProviderInterface$Callback): Promise<number> {
+    throw new Error('Subscriptions has not been implemented');
+  }
+
+  async unsubscribe (method: string, id: number): Promise<boolean> {
+    throw new Error('Subscriptions has not been implemented');
+  }
 }