feat: pull request backporting

feat: backport still open pull requests

src/service/git/github/github-service.ts

@@ -0,0 +1,83 @@
+import GitService from "@bp/service/git/git-service";
+import { BackportPullRequest, GitPullRequest } from "@bp/service/git/git.types";
+import GitHubMapper from "@bp/service/git/github/github-mapper";
+import OctokitFactory from "@bp/service/git/github/octokit-factory";
+import LoggerService from "@bp/service/logger/logger-service";
+import LoggerServiceFactory from "@bp/service/logger/logger-service-factory";
+import { Octokit } from "@octokit/rest";
+import { PullRequest } from "@octokit/webhooks-types";
+
+export default class GitHubService implements GitService {
+  
+  private logger: LoggerService;
+  private octokit: Octokit;
+  private mapper: GitHubMapper;
+
+  constructor(token: string) {
+    this.logger = LoggerServiceFactory.getLogger();
+    this.octokit = OctokitFactory.getOctokit(token);
+    this.mapper = new GitHubMapper();
+  }
+
+  // READ
+
+  async getPullRequest(owner: string, repo: string, prNumber: number): Promise<GitPullRequest> {
+    this.logger.info(`Getting pull request ${owner}/${repo}/${prNumber}.`);
+    const { data } = await this.octokit.rest.pulls.get({
+      owner: owner,
+      repo: repo,
+      pull_number: prNumber
+    });
+
+    return this.mapper.mapPullRequest(data as PullRequest);
+  }
+
+  async getPullRequestFromUrl(prUrl: string): Promise<GitPullRequest> {
+    const {owner, project} = this.getRepositoryFromPrUrl(prUrl);
+    return this.getPullRequest(owner, project, parseInt(prUrl.substring(prUrl.lastIndexOf("/") + 1, prUrl.length)));
+  }
+
+  // WRITE
+  
+  async createPullRequest(backport: BackportPullRequest): Promise<void> {
+    this.logger.info(`Creating pull request ${backport.head} -> ${backport.base}.`);
+    this.logger.info(`${JSON.stringify(backport, null, 2)}`);
+
+    const { data } = await this.octokit.pulls.create({
+      owner: backport.owner,
+      repo: backport.repo,
+      head: backport.head,
+      base: backport.base,
+      title: backport.title,
+      body: backport.body
+    });
+
+    if (backport.reviewers.length > 0) {
+      try {
+        await this.octokit.pulls.requestReviewers({
+          owner: backport.owner,
+          repo: backport.repo,
+          pull_number: (data as PullRequest).number,
+          reviewers: backport.reviewers
+        });
+      } catch (error) {
+        this.logger.error(`Error requesting reviewers: ${error}`);
+      }
+    }
+  }
+
+  // UTILS
+
+  /**
+   * Extract repository owner and project from the pull request url
+   * @param prUrl pull request url
+   * @returns {{owner: string, project: string}}
+   */
+  private getRepositoryFromPrUrl(prUrl: string): {owner: string, project: string} {
+    const elems: string[] = prUrl.split("/");
+    return {
+      owner: elems[elems.length - 4],
+      project: elems[elems.length - 3]
+    };
+  } 
+}