feat: implement upload support with verification

fix #2

src/upload.ts

@@ -0,0 +1,142 @@
+import { HTTPRequest } from './types';
+import { buildPointerInfo, PointerInfo } from './pointers';
+import { bodyToBuffer, getAuthHeader } from './util';
+
+
+interface LFSInfoResponse {
+  objects: {
+    actions?: {
+      upload: {
+        href: string;
+        header?: Record<string, string>;
+      };
+      verify?: {
+        href: string;
+        header?: Record<string, string>;
+      };
+    };
+  }[];
+}
+
+function isValidLFSInfoResponseData(val: Record<string, any>): val is LFSInfoResponse {
+  const obj = val.objects?.[0];
+  return obj && (
+    !obj.actions ||
+    obj.actions.upload.href.trim !== undefined
+  );
+}
+
+
+/**
+ * Given a blob, uploads the blob to LFS server and returns a PointerInfo,
+ * which the caller can then combine with object path into a Pointer
+ * and commit in place of the original Git blob.
+ */
+export default async function uploadBlob(
+  { http: { request }, headers = {}, url, auth }: HTTPRequest,
+  content: Buffer,
+): Promise<PointerInfo> {
+
+  const info = await buildPointerInfo(content);
+
+  const authHeaders: Record<string, string> = auth
+    ? getAuthHeader(auth)
+    : {};
+
+  // Request LFS transfer
+
+  const lfsInfoRequestData = {
+    operation: 'upload',
+    transfers: ['basic'],
+    objects: [info],
+  };
+
+  const { body: lfsInfoBody } = await request({
+    url: `${url}/info/lfs/objects/batch`,
+    method: 'POST',
+    headers: {
+      // Github LFS doesn’t seem to accept this UA
+      // 'User-Agent': `git/isomorphic-git@${git.version()}`,
+      ...headers,
+      ...authHeaders,
+      'Accept': 'application/vnd.git-lfs+json',
+      'Content-Type': 'application/vnd.git-lfs+json',
+    },
+    body: [Buffer.from(JSON.stringify(lfsInfoRequestData))],
+  });
+
+  const lfsInfoResponseRaw = (await bodyToBuffer(lfsInfoBody)).toString();
+  let lfsInfoResponseData: any;
+  try {
+    lfsInfoResponseData = JSON.parse(lfsInfoResponseRaw);
+  } catch (e) {
+    throw new Error(`Unexpected structure received from LFS server: unable to parse JSON ${lfsInfoResponseRaw}`);
+  }
+
+  if (isValidLFSInfoResponseData(lfsInfoResponseData)) {
+
+    // Upload the actual blob
+
+    const actions = lfsInfoResponseData.objects[0].actions;
+
+    if (!actions) {
+      // Presume LFS already has the blob. Don’t fail loudly.
+      return info;
+    } else {
+
+      const uploadAction = actions.upload;
+      const lfsObjectUploadURL = uploadAction.href;
+      const lfsObjectUploadHeaders = uploadAction.header ?? {};
+
+      const dlHeaders = {
+        ...headers,
+        ...authHeaders,
+        ...lfsObjectUploadHeaders,
+      };
+
+      const resp = await request({
+        url: lfsObjectUploadURL,
+        method: 'PUT',
+        headers: dlHeaders,
+        body: [content],
+      });
+
+      if (resp.statusCode === 200) {
+        const verifyAction = actions.verify;
+
+        // Upload verification was requested. Do that
+
+        if (verifyAction) {
+          const verificationResp = await request({
+            url: verifyAction.href,
+            method: 'POST',
+            headers: {
+              // Isomorphic Git’s UA header is considered invalid
+              // and missing UA header causes an error in this case;
+              // cURL is considered valid, so…
+              'User-Agent': `curl/7.54`,
+              // TODO: Generalize UA header handling
+              // - Leave UA header twiddling to callers?
+              // - Figure out which LFS implementation wants which UA header?
+              ...(verifyAction.header ?? {}),
+            },
+            body: [info],
+          });
+
+          if (verificationResp.statusCode === 200) {
+            return info;
+          } else {
+            throw new Error(`Upload might have been unsuccessful, verification action yielded HTTP ${verificationResp.statusCode}`);
+          }
+        } else {
+          return info;
+        }
+      } else {
+        throw new Error(`Upload might have been unsuccessful, upload action yielded HTTP ${resp.statusCode}`);
+      }
+    }
+
+  } else {
+    throw new Error("Unexpected JSON structure received for LFS upload request");
+  }
+}