feat(draft-pr): add new option to not process PRs which are in draft (#539)

* chore(assignees): add logs

* feat(draft-pr): add new option to not process PRs which are in draft

* refactor(draft-pr): create a dedicated class to handle the logic

* chore(index): update index file

src/classes/issues-processor.ts

@@ -17,6 +17,7 @@ import {IIssuesProcessorOptions} from '../interfaces/issues-processor-options';
 import {IPullRequest} from '../interfaces/pull-request';
 import {Assignees} from './assignees';
 import {IgnoreUpdates} from './ignore-updates';
+import {ExemptDraftPullRequest} from './exempt-draft-pull-request';
 import {Issue} from './issue';
 import {IssueLogger} from './loggers/issue-logger';
 import {Logger} from './loggers/logger';
@@ -207,6 +208,19 @@ export class IssuesProcessor {
     const daysBeforeStale: number = issue.isPullRequest
       ? this._getDaysBeforePrStale()
       : this._getDaysBeforeIssueStale();
+
+    if (issue.state === 'closed') {
+      issueLogger.info(`Skipping this $$type because it is closed`);
+      IssuesProcessor._endIssueProcessing(issue);
+      return; // Don't process closed issues
+    }
+
+    if (issue.locked) {
+      issueLogger.info(`Skipping this $$type because it is locked`);
+      IssuesProcessor._endIssueProcessing(issue);
+      return; // Don't process locked issues
+    }
+
     const onlyLabels: string[] = wordsToList(this._getOnlyLabels(issue));
 
     if (onlyLabels.length > 0) {
@@ -260,18 +274,6 @@ export class IssuesProcessor {
 
     const shouldMarkAsStale: boolean = shouldMarkWhenStale(daysBeforeStale);
 
-    if (issue.state === 'closed') {
-      issueLogger.info(`Skipping this $$type because it is closed`);
-      IssuesProcessor._endIssueProcessing(issue);
-      return; // Don't process closed issues
-    }
-
-    if (issue.locked) {
-      issueLogger.info(`Skipping this $$type because it is locked`);
-      IssuesProcessor._endIssueProcessing(issue);
-      return; // Don't process locked issues
-    }
-
     // Try to remove the close label when not close/locked issue or PR
     await this._removeCloseLabel(issue, closeLabel);
 
@@ -397,6 +399,23 @@ export class IssuesProcessor {
       return; // Don't process exempt assignees
     }
 
+    // Ignore draft PR
+    // Note that this check is so far below because it cost one read operation
+    // So it's simply better to do all the stale checks which don't cost more operation before this one
+    const exemptDraftPullRequest: ExemptDraftPullRequest =
+      new ExemptDraftPullRequest(this.options, issue);
+
+    if (
+      await exemptDraftPullRequest.shouldExemptDraftPullRequest(
+        async (): Promise<IPullRequest | undefined | void> => {
+          return this.getPullRequest(issue);
+        }
+      )
+    ) {
+      IssuesProcessor._endIssueProcessing(issue);
+      return; // Don't process draft PR
+    }
+
     // Determine if this issue needs to be marked stale first
     if (!issue.isStale) {
       issueLogger.info(`This $$type is not stale`);
@@ -574,6 +593,25 @@ export class IssuesProcessor {
     return staleLabeledEvent.created_at;
   }
 
+  async getPullRequest(issue: Issue): Promise<IPullRequest | undefined | void> {
+    const issueLogger: IssueLogger = new IssueLogger(issue);
+
+    try {
+      this._consumeIssueOperation(issue);
+      this._statistics?.incrementFetchedPullRequestsCount();
+
+      const pullRequest = await this.client.pulls.get({
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        pull_number: issue.number
+      });
+
+      return pullRequest.data;
+    } catch (error) {
+      issueLogger.error(`Error when getting this $$type: ${error.message}`);
+    }
+  }
+
   // handle all of the stale issue logic when we find a stale issue
   private async _processStaleIssue(
     issue: Issue,
@@ -666,7 +704,7 @@ export class IssuesProcessor {
         issueLogger.info(
           `Deleting the branch since the option ${issueLogger.createOptionLink(
             Option.DeleteBranch
-          )} was specified`
+          )} is enabled`
         );
         await this._deleteBranch(issue);
         this.deletedBranchIssues.push(issue);
@@ -830,34 +868,14 @@ export class IssuesProcessor {
     }
   }
 
-  private async _getPullRequest(
-    issue: Issue
-  ): Promise<IPullRequest | undefined | void> {
-    const issueLogger: IssueLogger = new IssueLogger(issue);
-
-    try {
-      this._consumeIssueOperation(issue);
-      this._statistics?.incrementFetchedPullRequestsCount();
-
-      const pullRequest = await this.client.pulls.get({
-        owner: context.repo.owner,
-        repo: context.repo.repo,
-        pull_number: issue.number
-      });
-
-      return pullRequest.data;
-    } catch (error) {
-      issueLogger.error(`Error when getting this $$type: ${error.message}`);
-    }
-  }
-
   // Delete the branch on closed pull request
   private async _deleteBranch(issue: Issue): Promise<void> {
     const issueLogger: IssueLogger = new IssueLogger(issue);
 
     issueLogger.info(`Delete branch from closed $$type - ${issue.title}`);
 
-    const pullRequest = await this._getPullRequest(issue);
+    const pullRequest: IPullRequest | undefined | void =
+      await this.getPullRequest(issue);
 
     if (!pullRequest) {
       issueLogger.info(