Fix: handle branch names conflicts (#3879)

packages/netlify-cms-backend-bitbucket/src/API.ts

@@ -26,6 +26,7 @@ import {
   branchFromContentKey,
   requestWithBackoff,
   readFileMetadata,
+  throwOnConflictingBranches,
 } from 'netlify-cms-lib-util';
 import { oneLine } from 'common-tags';
 import { parse } from 'what-the-diff';
@@ -250,10 +251,18 @@ export default class API {
     return response.ok;
   };
 
+  getBranch = async (branchName: string) => {
+    const branch: BitBucketBranch = await this.requestJSON(
+      `${this.repoURL}/refs/branches/${branchName}`,
+    );
+
+    return branch;
+  };
+
   branchCommitSha = async (branch: string) => {
     const {
       target: { hash: branchSha },
-    }: BitBucketBranch = await this.requestJSON(`${this.repoURL}/refs/branches/${branch}`);
+    }: BitBucketBranch = await this.getBranch(branch);
 
     return branchSha;
   };
@@ -442,11 +451,20 @@ export default class API {
       formData.append('parents', parentSha);
     }
 
-    await this.request({
-      url: `${this.repoURL}/src`,
-      method: 'POST',
-      body: formData,
-    });
+    try {
+      await this.requestText({
+        url: `${this.repoURL}/src`,
+        method: 'POST',
+        body: formData,
+      });
+    } catch (error) {
+      const message = error.message || '';
+      // very descriptive message from Bitbucket
+      if (parentSha && message.includes('Something went wrong')) {
+        await throwOnConflictingBranches(branch, name => this.getBranch(name), API_NAME);
+      }
+      throw error;
+    }
 
     return files;
   }

packages/netlify-cms-backend-github/src/API.ts

@@ -27,6 +27,7 @@ import {
   requestWithBackoff,
   unsentRequest,
   ApiRequest,
+  throwOnConflictingBranches,
 } from 'netlify-cms-lib-util';
 import { Octokit } from '@octokit/rest';
 
@@ -1253,8 +1254,45 @@ export default class API {
     return result;
   }
 
-  createBranch(branchName: string, sha: string) {
-    return this.createRef('heads', branchName, sha);
+  async backupBranch(branchName: string) {
+    try {
+      const existingBranch = await this.getBranch(branchName);
+      await this.createBranch(
+        existingBranch.name.replace(
+          new RegExp(`${CMS_BRANCH_PREFIX}/`),
+          `${CMS_BRANCH_PREFIX}_${Date.now()}/`,
+        ),
+        existingBranch.commit.sha,
+      );
+    } catch (e) {
+      console.warn(e);
+    }
+  }
+
+  async createBranch(branchName: string, sha: string) {
+    try {
+      const result = await this.createRef('heads', branchName, sha);
+      return result;
+    } catch (e) {
+      const message = String(e.message || '');
+      if (message === 'Reference update failed') {
+        await throwOnConflictingBranches(branchName, name => this.getBranch(name), API_NAME);
+      } else if (
+        message === 'Reference already exists' &&
+        branchName.startsWith(`${CMS_BRANCH_PREFIX}/`)
+      ) {
+        try {
+          // this can happen if the branch wasn't deleted when the PR was merged
+          // we backup the existing branch just in case and patch it with the new sha
+          await this.backupBranch(branchName);
+          const result = await this.patchBranch(branchName, sha, { force: true });
+          return result;
+        } catch (e) {
+          console.log(e);
+        }
+      }
+      throw e;
+    }
   }
 
   assertCmsBranch(branchName: string) {

packages/netlify-cms-backend-github/src/GraphQLAPI.ts

@@ -14,8 +14,9 @@ import {
   DEFAULT_PR_BODY,
   branchFromContentKey,
   CMS_BRANCH_PREFIX,
+  throwOnConflictingBranches,
 } from 'netlify-cms-lib-util';
-import { trim } from 'lodash';
+import { trim, trimStart } from 'lodash';
 import introspectionQueryResultData from './fragmentTypes';
 import API, { Config, BlobArgs, API_NAME, PullRequestState, MOCK_PULL_REQUEST } from './API';
 import * as queries from './queries';
@@ -134,10 +135,44 @@ export default class GraphQLAPI extends API {
     });
   }
 
-  mutate(options: MutationOptions<OperationVariables>) {
-    return this.client.mutate(options).catch(error => {
+  async mutate(options: MutationOptions<OperationVariables>) {
+    try {
+      const result = await this.client.mutate(options);
+      return result;
+    } catch (error) {
+      const errors = error.graphQLErrors;
+      if (Array.isArray(errors) && errors.some(e => e.message === 'Ref cannot be created.')) {
+        const refName = options?.variables?.createRefInput?.name || '';
+        const branchName = trimStart(refName, 'refs/heads/');
+        if (branchName) {
+          await throwOnConflictingBranches(branchName, name => this.getBranch(name), API_NAME);
+        }
+      } else if (
+        Array.isArray(errors) &&
+        errors.some(e =>
+          new RegExp(
+            `A ref named "refs/heads/${CMS_BRANCH_PREFIX}/.+?" already exists in the repository.`,
+          ).test(e.message),
+        )
+      ) {
+        const refName = options?.variables?.createRefInput?.name || '';
+        const sha = options?.variables?.createRefInput?.oid || '';
+        const branchName = trimStart(refName, 'refs/heads/');
+        if (branchName && branchName.startsWith(`${CMS_BRANCH_PREFIX}/`) && sha) {
+          try {
+            // this can happen if the branch wasn't deleted when the PR was merged
+            // we backup the existing branch just in case an re-run the mutation
+            await this.backupBranch(branchName);
+            await this.deleteBranch(branchName);
+            const result = await this.client.mutate(options);
+            return result;
+          } catch (e) {
+            console.log(e);
+          }
+        }
+      }
       throw new APIError(error.message, 500, 'GitHub');
-    });
+    }
   }
 
   async hasWriteAccess() {

packages/netlify-cms-backend-gitlab/src/API.ts

@@ -25,6 +25,7 @@ import {
   requestWithBackoff,
   readFileMetadata,
   FetchError,
+  throwOnConflictingBranches,
 } from 'netlify-cms-lib-util';
 import { Base64 } from 'js-base64';
 import { Map } from 'immutable';
@@ -407,7 +408,14 @@ export default class API {
   toBase64 = (str: string) => Promise.resolve(Base64.encode(str));
   fromBase64 = (str: string) => Base64.decode(str);
 
-  uploadAndCommit(
+  async getBranch(branchName: string) {
+    const branch: GitLabBranch = await this.requestJSON(
+      `${this.repoURL}/repository/branches/${encodeURIComponent(branchName)}`,
+    );
+    return branch;
+  }
+
+  async uploadAndCommit(
     items: CommitItem[],
     { commitMessage = '', branch = this.branch, newBranch = false },
   ) {
@@ -434,12 +442,21 @@ export default class API {
       commitParams.author_email = email;
     }
 
-    return this.requestJSON({
-      url: `${this.repoURL}/repository/commits`,
-      method: 'POST',
-      headers: { 'Content-Type': 'application/json; charset=utf-8' },
-      body: JSON.stringify(commitParams),
-    });
+    try {
+      const result = await this.requestJSON({
+        url: `${this.repoURL}/repository/commits`,
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json; charset=utf-8' },
+        body: JSON.stringify(commitParams),
+      });
+      return result;
+    } catch (error) {
+      const message = error.message || '';
+      if (newBranch && message.includes(`Could not update ${branch}`)) {
+        await throwOnConflictingBranches(branch, name => this.getBranch(name), API_NAME);
+      }
+      throw error;
+    }
   }
 
   async getCommitItems(files: (Entry | AssetProxy)[], branch: string) {
@@ -781,9 +798,7 @@ export default class API {
   }
 
   async getDefaultBranch() {
-    const branch: GitLabBranch = await this.requestJSON(
-      `${this.repoURL}/repository/branches/${encodeURIComponent(this.branch)}`,
-    );
+    const branch: GitLabBranch = await this.getBranch(this.branch);
     return branch;
   }
 

packages/netlify-cms-lib-util/src/API.ts

@@ -1,5 +1,6 @@
 import { asyncLock, AsyncLock } from './asyncLock';
 import unsentRequest from './unsentRequest';
+import APIError from './APIError';
 
 export interface FetchError extends Error {
   status: number;
@@ -174,3 +175,41 @@ export const getPreviewStatus = (
     return isPreviewContext(context, previewContext);
   });
 };
+
+const getConflictingBranches = (branchName: string) => {
+  // for cms/posts/post-1, conflicting branches are cms/posts, cms
+  const parts = branchName.split('/');
+  parts.pop();
+
+  const conflictingBranches = parts.reduce((acc, _, index) => {
+    acc = [...acc, parts.slice(0, index + 1).join('/')];
+    return acc;
+  }, [] as string[]);
+
+  return conflictingBranches;
+};
+
+export const throwOnConflictingBranches = async (
+  branchName: string,
+  getBranch: (name: string) => Promise<{ name: string }>,
+  apiName: string,
+) => {
+  const possibleConflictingBranches = getConflictingBranches(branchName);
+
+  const conflictingBranches = await Promise.all(
+    possibleConflictingBranches.map(b =>
+      getBranch(b)
+        .then(b => b.name)
+        .catch(() => ''),
+    ),
+  );
+
+  const conflictingBranch = conflictingBranches.filter(Boolean)[0];
+  if (conflictingBranch) {
+    throw new APIError(
+      `Failed creating branch '${branchName}' since there is already a branch named '${conflictingBranch}'. Please delete the '${conflictingBranch}' branch and try again`,
+      500,
+      apiName,
+    );
+  }
+};

packages/netlify-cms-lib-util/src/index.ts

@@ -49,6 +49,7 @@ import {
   FetchError as FE,
   ApiRequest as AR,
   requestWithBackoff,
+  throwOnConflictingBranches,
 } from './API';
 import {
   CMS_BRANCH_PREFIX,
@@ -140,6 +141,7 @@ export const NetlifyCmsLibUtil = {
   requestWithBackoff,
   allEntriesByFolder,
   AccessTokenError,
+  throwOnConflictingBranches,
 };
 export {
   APIError,
@@ -195,4 +197,5 @@ export {
   requestWithBackoff,
   allEntriesByFolder,
   AccessTokenError,
+  throwOnConflictingBranches,
 };