Write initial github backend

package.json

@@ -71,6 +71,7 @@
     "json-stable-stringify": "^1.0.1",
     "module-alias": "^2.1.0",
     "original-require": "^1.0.1",
+    "request-promise": "^4.2.4",
     "source-map-support": "^0.5.9",
     "web3": "^1.0.0-beta.36"
   },

src/storage/github/index.ts

@@ -4,22 +4,40 @@
 
 import * as config from "ethpm/config";
 import * as storage from "ethpm/storage";
+import * as t from "io-ts";
+import { Maybe } from "ethpm/types";
+import { URL } from "url";
+import { isValidGithubUri } from "./validation";
+
+import request = require("request-promise");
+export { isValidGithubUri } from "./validation";
+
+async function makeGithubRequest(blobUri: URL): Promise<string> {
+  let response: any = {};
+  const options = {
+    uri: blobUri,
+    json: true,
+    headers: { "user-agent": "node.js" }
+  };
+
+  await request
+    .get(options)
+    .then(body => {
+      const decoded = new Buffer(body.content, "base64");
+      response = decoded.toString("ascii");
+    })
+    .catch(err => {
+      response = err.toString();
+    });
+  return response;
+}
 
 export class GithubService implements storage.Service {
   async read(uri: URL): Promise<Maybe<string>> {
-
-	// validate uri
-    // fetch contents 
-    // validate fetched contents
+    if (!isValidGithubUri(uri)) {
+      throw new TypeError(uri + "is not a valid content addressed Github uri.");
+    }
+    let base64Contents = await makeGithubRequest(uri);
+    return base64Contents;
   }
 }
-
-export default class GithubConnector extends config.Connector<storage.Service> {
-  /**
-   * Construct GithubService and load with specified contents
-   */
-	async init(): Promise<GithubService> {
-	  const service = new GithubService();
-	  return service;
-	}
-}

src/storage/github/test/integration.ts

@@ -0,0 +1,14 @@
+import { GithubService } from "ethpm/storage/github";
+import { URL } from "url";
+import examples from "test/examples/manifests";
+
+describe("Github service returns URI contents", () => {
+  it("with valid blob URI", async () => {
+    const ownedBlobUri = new URL(
+      "https://api.github.com/repos/ethpm/ethpm-spec/git/blobs/8f9dc767d4c8b31fec4a08d9c0858d4f37b83180"
+    );
+    const service = new GithubService();
+    const actualContents = await service.read(ownedBlobUri);
+    expect(actualContents).toBe(examples.owned);
+  });
+});

src/storage/github/test/validation.ts

@@ -0,0 +1,36 @@
+import { isValidGithubUri } from "ethpm/storage/github";
+import { URL } from "url";
+
+const invalidUris = [
+  // http is not valid protocol
+  "http://api.github.com/repos/ethpm/ethpm-spec/git/blobs/123",
+  // www.github.com is not valid hostname
+  "https://www.github.com/repos/ethpm/ethpm-spec/git/blobs/123",
+  // path doesn't contain 'repos' & 'git' & 'blobs'
+  "https://api.github.com/ethpm/ethpm-spec/git/blobs/123",
+  "https://api.github.com/repos/ethpm/ethpm-spec/blobs/123",
+  "https://api.github.com/repos/ethpm/ethpm-spec/git/123"
+];
+
+const validUris = [
+  "https://api.github.com/repos/ethpm/ethpm-spec/git/blobs/123",
+  "https://api.github.com/repos/other/repository/git/blobs/123"
+];
+
+invalidUris.forEach(uri => {
+  describe("Github uri validator invalidates", () => {
+    it(uri, () => {
+      const result = isValidGithubUri(new URL(uri));
+      expect(result).toBe(false);
+    });
+  });
+});
+
+validUris.forEach(uri => {
+  describe("Github uri validator validates", () => {
+    it(uri, () => {
+      const result = isValidGithubUri(new URL(uri));
+      expect(result).toBe(true);
+    });
+  });
+});

src/storage/github/validation.ts

@@ -1,7 +1,26 @@
 /**
- * @module "ethpm/storage/github"
+ * @module "ethpm/storage/github/validation"
  */
 
-export default function isValidGithubUri(uri: URL): boolean {
+import { URL } from "url";
 
+/**
+ * Returns a bool indicating whether the given uri conforms to this scheme.
+ * https://api.github.com/repos/:owner/:repo/git/blobs/:file_sha
+ */
+export function isValidGithubUri(uri: URL): boolean {
+  if (uri.hostname != "api.github.com") {
+    return false;
+  }
+  if (uri.protocol != "https:") {
+    return false;
+  }
+  if (
+    !uri.pathname.includes("/repos/") ||
+    !uri.pathname.includes("/git/") ||
+    !uri.pathname.includes("/blobs/")
+  ) {
+    return false;
+  }
+  return true;
 }