Feat: editorial workflow bitbucket gitlab (#3014)

* refactor: typescript the backends

* feat: support multiple files upload for GitLab and BitBucket

* fix: load entry media files from media folder or UI state

* chore: cleanup log message

* chore: code cleanup

* refactor: typescript the test backend

* refactor: cleanup getEntry unsued variables

* refactor: moved shared backend code to lib util

* chore: rename files to preserve history

* fix: bind readFile method to API classes

* test(e2e): switch to chrome in cypress tests

* refactor: extract common api methods

* refactor: remove most of immutable js usage from backends

* feat(backend-gitlab): initial editorial workflow support

* feat(backend-gitlab): implement missing workflow methods

* chore: fix lint error

* feat(backend-gitlab): support files deletion

* test(e2e): add gitlab cypress tests

* feat(backend-bitbucket): implement missing editorial workflow methods

* test(e2e): add BitBucket backend e2e tests

* build: update node version to 12 on netlify builds

* fix(backend-bitbucket): extract BitBucket avatar url

* test: fix git-gateway AuthenticationPage test

* test(e2e): fix some backend tests

* test(e2e): fix tests

* test(e2e): add git-gateway editorial workflow test

* chore: code cleanup

* test(e2e): revert back to electron

* test(e2e): add non editorial workflow tests

* fix(git-gateway-gitlab): don't call unpublishedEntry in simple workflow

gitlab git-gateway doesn't support editorial workflow APIs yet. This change makes sure not to call them in simple workflow

* refactor(backend-bitbucket): switch to diffstat API instead of raw diff

* chore: fix test

* test(e2e): add more git-gateway tests

* fix: post rebase typescript fixes

* test(e2e): fix tests

* fix: fix parsing of content key and add tests

* refactor: rename test file

* test(unit): add getStatues unit tests

* chore: update cypress

* docs: update beta docs

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

@@ -0,0 +1,78 @@
+export const CMS_BRANCH_PREFIX = 'cms';
+export const DEFAULT_PR_BODY = 'Automatically generated by Netlify CMS';
+export const MERGE_COMMIT_MESSAGE = 'Automatically generated. Merged on Netlify CMS.';
+
+const NETLIFY_CMS_LABEL_PREFIX = 'netlify-cms/';
+export const isCMSLabel = (label: string) => label.startsWith(NETLIFY_CMS_LABEL_PREFIX);
+export const labelToStatus = (label: string) => label.substr(NETLIFY_CMS_LABEL_PREFIX.length);
+export const statusToLabel = (status: string) => `${NETLIFY_CMS_LABEL_PREFIX}${status}`;
+
+export const generateContentKey = (collectionName: string, slug: string) =>
+  `${collectionName}/${slug}`;
+
+export const parseContentKey = (contentKey: string) => {
+  const index = contentKey.indexOf('/');
+  return { collection: contentKey.substr(0, index), slug: contentKey.substr(index + 1) };
+};
+
+export interface FetchError extends Error {
+  status: number;
+}
+
+export const readFile = async (
+  id: string | null | undefined,
+  fetchContent: () => Promise<string | Blob>,
+  localForage: LocalForage,
+  isText: boolean,
+) => {
+  const key = id ? (isText ? `gh.${id}` : `gh.${id}.blob`) : null;
+  const cached = key ? await localForage.getItem<string | Blob>(key) : null;
+  if (cached) {
+    return cached;
+  }
+
+  const content = await fetchContent();
+  if (key) {
+    localForage.setItem(key, content);
+  }
+  return content;
+};
+
+/**
+ * Keywords for inferring a status that will provide a deploy preview URL.
+ */
+const PREVIEW_CONTEXT_KEYWORDS = ['deploy'];
+
+/**
+ * Check a given status context string to determine if it provides a link to a
+ * deploy preview. Checks for an exact match against `previewContext` if given,
+ * otherwise checks for inclusion of a value from `PREVIEW_CONTEXT_KEYWORDS`.
+ */
+export const isPreviewContext = (context: string, previewContext: string) => {
+  if (previewContext) {
+    return context === previewContext;
+  }
+  return PREVIEW_CONTEXT_KEYWORDS.some(keyword => context.includes(keyword));
+};
+
+export enum PreviewState {
+  Other = 'other',
+  Success = 'success',
+}
+
+/**
+ * Retrieve a deploy preview URL from an array of statuses. By default, a
+ * matching status is inferred via `isPreviewContext`.
+ */
+export const getPreviewStatus = (
+  statuses: {
+    context: string;
+    target_url: string;
+    state: PreviewState;
+  }[],
+  previewContext: string,
+) => {
+  return statuses.find(({ context }) => {
+    return isPreviewContext(context, previewContext);
+  });
+};