feat: pull request backporting

feat: backport still open pull requests

src/bin/cli.ts

@@ -0,0 +1,12 @@
+#!/usr/bin/env node
+
+import CLIArgsParser from "@bp/service/args/cli/cli-args-parser";
+import Runner from "@bp/service/runner/runner";
+
+// create CLI arguments parser
+const parser = new CLIArgsParser();
+
+// create runner
+const runner = new Runner(parser);
+
+runner.run();

src/bin/gha.ts

@@ -0,0 +1,12 @@
+#!/usr/bin/env node
+
+import GHAArgsParser from "@bp/service/args/gha/gha-args-parser";
+import Runner from "@bp/service/runner/runner";
+
+// create CLI arguments parser
+const parser = new GHAArgsParser();
+
+// create runner
+const runner = new Runner(parser);
+
+runner.run();

src/service/args/args-parser.ts

@@ -0,0 +1,10 @@
+import { Args } from "@bp/service/args/args.types";
+
+/**
+ * Abstract arguments parser interface in charge to parse inputs and 
+ * produce a common Args object
+ */
+export default interface ArgsParser {
+
+  parse(): Args;
+}

src/service/args/args.types.ts

@@ -0,0 +1,11 @@
+/**
+ * Input arguments
+ */
+export interface Args {
+  dryRun: boolean, // if enabled do not push anything remotely
+  auth: string, // git service auth, like github token
+  targetBranch: string,  // branch on the target repo where the change should be backported to
+  pullRequest: string, // url of the pull request to backport
+  folder?: string, // local folder where the repositories should be cloned
+  author?: string, // backport pr author, default taken from pr
+}

src/service/args/cli/cli-args-parser.ts

@@ -0,0 +1,34 @@
+import ArgsParser from "@bp/service/args/args-parser";
+import { Args } from "@bp/service/args/args.types";
+import { Command } from "commander";
+import { name, version, description } from "@bp/../package.json";
+
+
+export default class CLIArgsParser implements ArgsParser {
+
+  private getCommand(): Command {
+    return new Command(name)
+      .version(version)
+      .description(description)
+      .requiredOption("-tb, --target-branch <branch>", "branch where changes must be backported to.")
+      .requiredOption("-pr, --pull-request <pr url>", "pull request url, e.g., https://github.com/lampajr/backporting/pull/1.")
+      .option("-d, --dry-run", "if enabled the tool does not create any pull request nor push anything remotely", false)
+      .option("-a, --auth <auth>", "git service authentication string, e.g., github token.", "")
+      .option("-f, --folder <folder>", "local folder where the repo will be checked out, e.g., /tmp/folder.", undefined);
+  }
+
+  parse(): Args {
+    const opts = this.getCommand()
+      .parse()
+      .opts();
+    
+    return {
+      dryRun: opts.dryRun,
+      auth: opts.auth,
+      pullRequest: opts.pullRequest,
+      targetBranch: opts.targetBranch,
+      folder: opts.folder
+    };
+  }
+
+}

src/service/args/gha/gha-args-parser.ts

@@ -0,0 +1,17 @@
+import ArgsParser from "@bp/service/args/args-parser";
+import { Args } from "@bp/service/args/args.types";
+import { getInput } from "@actions/core";
+
+export default class GHAArgsParser implements ArgsParser {
+
+  parse(): Args {
+    return {
+      dryRun: getInput("dry-run") === "true",
+      auth: getInput("auth") ? getInput("auth") : "",
+      pullRequest: getInput("pull-request"),
+      targetBranch: getInput("target-branch"),
+      folder: getInput("folder") !== "" ? getInput("folder") : undefined
+    };
+  }
+
+}

src/service/configs/configs-parser.ts

@@ -0,0 +1,37 @@
+import { Args } from "@bp/service/args/args.types";
+import { Configs } from "@bp/service/configs/configs.types";
+import LoggerService from "../logger/logger-service";
+import LoggerServiceFactory from "../logger/logger-service-factory";
+
+/**
+ * Abstract configuration parser class in charge to parse 
+ * Args and produces a common Configs object
+ */
+ export default abstract class ConfigsParser {
+  
+  private readonly logger: LoggerService;
+
+  constructor() {
+    this.logger = LoggerServiceFactory.getLogger();
+  }
+
+  abstract parse(args: Args): Promise<Configs>;
+
+  async parseAndValidate(args: Args): Promise<Configs> {
+    const configs: Configs = await this.parse(args);
+
+    // apply validation, throw errors if something is wrong
+    
+    // if pr is opened check if the there exists one single commit
+    if (configs.originalPullRequest.state == "open") {
+      this.logger.warn("Trying to backport an open pull request!");
+    }
+
+    // if PR is closed and not merged log a warning
+    if (configs.originalPullRequest.state == "closed" && !configs.originalPullRequest.merged) {
+      throw new Error("Provided pull request is closed and not merged!");
+    }
+
+    return Promise.resolve(configs);
+  }
+}

src/service/configs/configs.types.ts

@@ -0,0 +1,17 @@
+
+
+import { GitPullRequest } from "@bp/service/git/git.types";
+
+/**
+ * Internal configuration object
+ */
+export interface Configs {
+  dryRun: boolean,
+  auth: string,
+  author: string, // author of the backport pr
+  folder: string,
+  targetBranch: string,
+  originalPullRequest: GitPullRequest,
+  backportPullRequest: GitPullRequest
+ }
+

src/service/configs/pullrequest/pr-configs-parser.ts

@@ -0,0 +1,61 @@
+import { Args } from "@bp/service/args/args.types";
+import ConfigsParser from "@bp/service/configs/configs-parser";
+import { Configs } from "@bp/service/configs/configs.types";
+import GitService from "@bp/service/git/git-service";
+import GitServiceFactory from "@bp/service/git/git-service-factory";
+import { GitPullRequest } from "@bp/service/git/git.types";
+
+export default class PullRequestConfigsParser extends ConfigsParser {
+
+  private gitService: GitService;
+
+  constructor() {
+    super();
+    this.gitService = GitServiceFactory.getService();
+  }
+  
+  public async parse(args: Args): Promise<Configs> {
+    const pr: GitPullRequest = await this.gitService.getPullRequestFromUrl(args.pullRequest);
+    const folder: string = args.folder ?? this.getDefaultFolder();
+
+    return {
+      dryRun: args.dryRun,
+      auth: args.auth,
+      author: args.author ?? pr.author,
+      folder: `${folder.startsWith("/") ? "" : process.cwd() + "/"}${args.folder ?? this.getDefaultFolder()}`,
+      targetBranch: args.targetBranch,
+      originalPullRequest: pr,
+      backportPullRequest: this.getDefaultBackportPullRequest(pr, args.targetBranch)
+    };
+  }
+  
+  private getDefaultFolder() {
+    return "bp";
+  }
+
+  /**
+   * Create a default backport pull request starting from the target branch and 
+   * the original pr to be backported
+   * @param originalPullRequest original pull request
+   * @param targetBranch target branch where the backport should be applied
+   * @returns {GitPullRequest}
+   */
+  private getDefaultBackportPullRequest(originalPullRequest: GitPullRequest, targetBranch: string): GitPullRequest {
+    const reviewers = [];
+    reviewers.push(originalPullRequest.author);
+    if (originalPullRequest.mergedBy) {
+      reviewers.push(originalPullRequest.mergedBy);  
+    }
+
+    return {
+      author: originalPullRequest.author,
+      title: `[${targetBranch}] ${originalPullRequest.title}`, 
+      body: `**Backport:** ${originalPullRequest.htmlUrl}\r\n\r\n${originalPullRequest.body}\r\n\r\nPowered by [BPer](https://github.com/lampajr/backporting).`,
+      reviewers: [...new Set(reviewers)],
+      targetRepo: originalPullRequest.targetRepo,
+      sourceRepo: originalPullRequest.targetRepo,
+      nCommits: 0, // TODO: needed?
+      commits: [] // TODO needed?
+    };
+  }
+}

src/service/git/git-cli.ts

@@ -0,0 +1,128 @@
+import LoggerService from "@bp/service/logger/logger-service";
+import LoggerServiceFactory from "@bp/service/logger/logger-service-factory";
+import simpleGit, { SimpleGit } from "simple-git";
+import fs from "fs";
+
+/**
+ * Command line git commands executor service
+ */
+export default class GitCLIService {
+
+  private readonly logger: LoggerService;
+  private readonly auth: string;
+  private readonly author: string;
+
+  constructor(auth: string, author: string) {
+    this.logger = LoggerServiceFactory.getLogger();
+    this.auth  = auth;
+    this.author = author;
+  }
+
+  /**
+   * Return a pre-configured SimpleGit instance able to execute commands from current
+   * directory or the provided one
+   * @param cwd [optional] current working directory
+   * @returns {SimpleGit} 
+   */
+  private git(cwd?: string): SimpleGit {
+    const gitConfig = { ...(cwd ? { baseDir: cwd } : {})};
+    return simpleGit(gitConfig).addConfig("user.name", this.author).addConfig("user.email", "noreply@github.com");
+  }
+
+  /**
+   * Update the provided remote URL by adding the auth token if not empty
+   * @param remoteURL remote link, e.g., https://github.com/lampajr/backporting-example.git
+   */
+  private remoteWithAuth(remoteURL: string): string {
+    if (this.auth && this.author) {
+      return remoteURL.replace("://", `://${this.author}:${this.auth}@`);
+    }
+
+    // return remote as it is
+    return remoteURL;
+  }
+
+  /**
+   * Return the git version
+   * @returns {Promise<string | undefined>}
+   */
+  async version(cwd: string): Promise<string | undefined> {
+    const rawOutput = await this.git(cwd).raw("version");
+    const match = rawOutput.match(/(\d+\.\d+(\.\d+)?)/);
+    return match ? match[1] : undefined;
+  }
+
+  /**
+   * Clone a git repository
+   * @param from url or path from which the repository should be cloned from
+   * @param to location at which the repository should be cloned at
+   * @param branch branch which should be cloned
+   */
+  async clone(from: string, to: string, branch: string): Promise<void> {
+    this.logger.info(`Cloning repository ${from} to ${to}.`);
+    if (!fs.existsSync(to)) {
+      await simpleGit().clone(this.remoteWithAuth(from), to, ["--quiet", "--shallow-submodules", "--no-tags", "--branch", branch]);
+    } else {
+      this.logger.warn(`Folder ${to} already exist. Won't clone`);
+    }
+  }
+
+  /**
+   * Create a new branch starting from the current one and checkout in it
+   * @param cwd repository in which createBranch should be performed
+   * @param newBranch new branch name
+   */
+  async createLocalBranch(cwd: string, newBranch: string): Promise<void> {
+    this.logger.info(`Creating branch ${newBranch}.`);
+    await this.git(cwd).checkoutLocalBranch(newBranch);
+  }
+
+  /**
+   * Add a new remote to the current repository
+   * @param cwd repository in which addRemote should be performed
+   * @param remote remote git link
+   * @param remoteName [optional] name of the remote, by default 'fork' is used 
+   */
+  async addRemote(cwd: string, remote: string, remoteName = "fork"): Promise<void> {
+    this.logger.info(`Adding new remote ${remote}.`);
+    await this.git(cwd).addRemote(remoteName, this.remoteWithAuth(remote));
+  }
+
+  /**
+   * Git fetch from a particular branch
+   * @param cwd repository in which fetch should be performed
+   * @param branch fetch from the given branch
+   * @param remote [optional] the remote to fetch, by default origin
+   */
+  async fetch(cwd: string, branch: string, remote = "origin"): Promise<void> {
+    this.logger.info(`Fetching ${remote} ${branch}.`);
+    await this.git(cwd).fetch(remote, branch, ["--quiet"]);
+  }
+
+  /**
+   * Get cherry-pick a specific sha
+   * @param cwd repository in which the sha should be cherry picked to
+   * @param sha commit sha
+   */
+  async cherryPick(cwd: string, sha: string): Promise<void> {
+    this.logger.info(`Cherry picking ${sha}.`);
+    await this.git(cwd).raw(["cherry-pick", "-m", "1", "--strategy=recursive", "--strategy-option=theirs", sha]);
+  }
+
+  /**
+   * Push a branch to a remote
+   * @param cwd repository in which the push should be performed
+   * @param branch branch to be pushed
+   * @param remote [optional] remote to which the branch should be pushed to, by default 'origin'
+   */
+  async push(cwd: string, branch: string, remote = "origin", force = false): Promise<void> {
+    this.logger.info(`Pushing ${branch} to ${remote}.`);
+    
+    const options = ["--quiet"];
+    if (force) {
+      options.push("--force-with-lease");
+    }
+    await this.git(cwd).push(remote, branch, options);
+  }
+
+}

src/service/git/git-service-factory.ts

@@ -0,0 +1,43 @@
+import GitService from "@bp/service/git/git-service";
+import { GitServiceType } from "@bp/service/git/git.types";
+import GitHubService from "@bp/service/git/github/github-service";
+import LoggerService from "@bp/service/logger/logger-service";
+import LoggerServiceFactory from "@bp/service/logger/logger-service-factory";
+
+/**
+ * Singleton git service factory class
+ */
+export default class GitServiceFactory {
+  
+  private static logger: LoggerService = LoggerServiceFactory.getLogger();
+  private static instance?: GitService;
+
+  public static getService(): GitService {
+    if (!GitServiceFactory.instance) {
+      throw new Error("You must call `init` method first!");
+    }
+
+    return GitServiceFactory.instance;
+  }
+
+  /**
+   * Initialize the singleton git management service
+   * @param type git management service type
+   * @param auth authentication, like github token
+   */
+  public static init(type: GitServiceType, auth: string): void {
+
+    if (GitServiceFactory.instance) {
+      GitServiceFactory.logger.warn("Git service already initialized!");
+      return;
+    }
+
+    switch(type) {
+      case GitServiceType.GITHUB:
+        GitServiceFactory.instance = new GitHubService(auth);   
+        break;
+      default:
+        throw new Error(`Invalid git service type received: ${type}`);
+    }
+  }
+}

src/service/git/git-service.ts

@@ -0,0 +1,34 @@
+import { BackportPullRequest, GitPullRequest } from "@bp/service/git/git.types";
+
+/**
+ * Git management service interface, which provides a common API for interacting 
+ * with several git management services like GitHub, Gitlab or Bitbucket.
+ */
+ export default interface GitService {
+
+  // READ
+
+  /**
+   * Get a pull request object from the underneath git service
+   * @param owner repository's owner
+   * @param repo repository's name
+   * @param prNumber pull request number
+   * @returns {Promise<PullRequest>}
+   */
+  getPullRequest(owner: string, repo: string, prNumber: number): Promise<GitPullRequest>;
+
+  /**
+   * Get a pull request object from the underneath git service
+   * @param prUrl pull request html url
+   * @returns {Promise<PullRequest>}
+   */
+   getPullRequestFromUrl(prUrl: string): Promise<GitPullRequest>;
+
+  // WRITE
+
+  /**
+   * Create a new pull request on the underneath git service
+   * @param backport backport pull request data
+   */
+  createPullRequest(backport: BackportPullRequest): Promise<void>;
+}

src/service/git/git.types.ts

@@ -0,0 +1,36 @@
+export interface GitPullRequest {
+  number?: number,
+  author: string,
+  url?: string,
+  htmlUrl?: string,
+  state?: "open" | "closed",
+  merged?: boolean,
+  mergedBy?: string,
+  title: string,
+  body: string,
+  reviewers: string[],
+  targetRepo: GitRepository,
+  sourceRepo: GitRepository,
+  nCommits: number, // number of commits in the pr
+  commits: string[] // merge commit or last one
+}
+
+export interface GitRepository {
+  owner: string,
+  project: string,
+  cloneUrl: string
+}
+
+export interface BackportPullRequest {
+  owner: string, // repository's owner
+  repo: string, // repository's name
+  head: string, // name of the source branch
+  base: string, // name of the target branch
+  title: string, // pr title
+  body: string, // pr body
+  reviewers: string[] // pr list of reviewers
+}
+
+export enum GitServiceType {
+  GITHUB = "github"
+}

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

@@ -0,0 +1,33 @@
+import { GitPullRequest } from "@bp/service/git/git.types";
+import { PullRequest, User } from "@octokit/webhooks-types";
+
+export default class GitHubMapper {
+
+  mapPullRequest(pr: PullRequest): GitPullRequest {
+    return {
+      number: pr.number,
+      author: pr.user.login,
+      url: pr.url,
+      htmlUrl: pr.html_url,
+      title: pr.title,
+      body: pr.body ?? "",
+      state: pr.state,
+      merged: pr.merged ?? false,
+      mergedBy: pr.merged_by?.login,
+      reviewers: pr.requested_reviewers.filter(r => "login" in r).map((r => (r as User)?.login)),
+      sourceRepo: {
+        owner: pr.head.repo.full_name.split("/")[0],
+        project: pr.head.repo.full_name.split("/")[1],
+        cloneUrl: pr.head.repo.clone_url
+      },
+      targetRepo: {
+        owner: pr.base.repo.full_name.split("/")[0],
+        project: pr.base.repo.full_name.split("/")[1],
+        cloneUrl: pr.base.repo.clone_url
+      },
+      nCommits: pr.commits,
+      // if pr is open use latest commit sha otherwise use merge_commit_sha
+      commits: pr.state === "open" ? [pr.head.sha] : [pr.merge_commit_sha as string]
+    };
+  }
+}

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]
+    };
+  } 
+}

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

@@ -0,0 +1,24 @@
+import LoggerService from "@bp/service/logger/logger-service";
+import LoggerServiceFactory from "@bp/service/logger/logger-service-factory";
+import { Octokit } from "@octokit/rest";
+
+/**
+ * Singleton factory class for {Octokit} instance
+ */
+export default class OctokitFactory {
+  
+  private static logger: LoggerService = LoggerServiceFactory.getLogger();
+  private static octokit?: Octokit;
+
+  public static getOctokit(token: string): Octokit {
+    if (!OctokitFactory.octokit) {
+      OctokitFactory.logger.info("Creating octokit instance.");
+      OctokitFactory.octokit = new Octokit({
+        auth: token,
+        userAgent: "lampajr/backporting"
+      });
+    }
+
+    return OctokitFactory.octokit;
+  }
+}

src/service/logger/console-logger-service.ts

@@ -0,0 +1,32 @@
+import Logger from "@bp/service/logger/logger";
+import LoggerService from "@bp/service/logger/logger-service";
+
+export default class ConsoleLoggerService implements LoggerService {
+
+  private readonly logger;
+
+  constructor() {
+    this.logger = new Logger();
+  }
+  
+  trace(message: string): void {
+    this.logger.log("[TRACE]", message);
+  }
+  
+  debug(message: string): void {
+    this.logger.log("[DEBUG]", message);
+  }
+  
+  info(message: string): void {
+    this.logger.log("[INFO]", message);
+  }
+  
+  warn(message: string): void {
+    this.logger.log("[WARN]", message);
+  }
+  
+  error(message: string): void {
+    this.logger.log("[ERROR]", message);
+  }
+
+}

src/service/logger/logger-service-factory.ts

@@ -0,0 +1,18 @@
+import ConsoleLoggerService from "@bp/service/logger/console-logger-service";
+import LoggerService from "@bp/service/logger/logger-service";
+
+/**
+ * Singleton factory class
+ */
+export default class LoggerServiceFactory {
+
+  private static instance?: LoggerService;
+
+  public static getLogger(): LoggerService {
+    if (!LoggerServiceFactory.instance) {
+      LoggerServiceFactory.instance = new ConsoleLoggerService();
+    }
+
+    return LoggerServiceFactory.instance;
+  }
+}

src/service/logger/logger-service.ts

@@ -0,0 +1,15 @@
+/**
+ * Logger service interface providing the most commong logging functionalities
+ */
+export default interface LoggerService {
+
+  trace(message: string): void;
+
+  debug(message: string): void;
+
+  info(message: string): void;
+
+  warn(message: string): void;
+
+  error(message: string): void;
+}

src/service/logger/logger.ts

@@ -0,0 +1,15 @@
+
+/**
+ * Common logger class based on the console.log functionality
+ */
+ export default class Logger {
+
+  log(prefix: string, ...str: string[]) {
+    // eslint-disable-next-line no-console
+    console.log.apply(console, [prefix, ...str]);
+  }
+
+  emptyLine() {
+    this.log("", "");
+  }
+}

src/service/runner/runner.ts

@@ -0,0 +1,126 @@
+import ArgsParser from "@bp/service/args/args-parser";
+import { Args } from "@bp/service/args/args.types";
+import { Configs } from "@bp/service/configs/configs.types";
+import PullRequestConfigsParser from "@bp/service/configs/pullrequest/pr-configs-parser";
+import GitCLIService from "@bp/service/git/git-cli";
+import GitService from "@bp/service/git/git-service";
+import GitServiceFactory from "@bp/service/git/git-service-factory";
+import { BackportPullRequest, GitPullRequest, GitServiceType } from "@bp/service/git/git.types";
+import LoggerService from "@bp/service/logger/logger-service";
+import LoggerServiceFactory from "@bp/service/logger/logger-service-factory";
+
+/**
+ * Main runner implementation, it implements the core logic flow
+ */
+export default class Runner {
+
+  private logger: LoggerService;
+  private argsParser: ArgsParser;
+
+  constructor(parser: ArgsParser) {
+    this.logger = LoggerServiceFactory.getLogger();
+    this.argsParser = parser;
+  }
+
+  /**
+   * Infer the remote GIT service to interact with based on the provided 
+   * pull request URL
+   * @param prUrl provided pull request URL
+   * @returns {GitServiceType}
+   */
+  private inferRemoteGitService(prUrl: string): GitServiceType {
+    const stdPrUrl = prUrl.toLowerCase().trim();
+
+    if (stdPrUrl.includes(GitServiceType.GITHUB.toString())) {
+      return GitServiceType.GITHUB;
+    }
+
+    throw new Error(`Remote GIT service not recognixed from PR url: ${prUrl}`);
+  }
+
+  /**
+   * Entry point invoked by the command line or gha
+   */
+  async run(): Promise<void> {
+    this.logger.info("Starting process.");
+
+    try {
+      await this.execute();
+
+      this.logger.info("Process succeeded!");
+      process.exit(0);
+
+    } catch (error) {
+      this.logger.error(`${error}`);
+      
+      this.logger.info("Process failed!");
+      process.exit(1);
+    }
+  }
+
+  /**
+   * Core logic
+   */
+  async execute(): Promise<void>{
+
+    // 1. parse args
+    const args: Args = this.argsParser.parse();
+
+    if (args.dryRun) {
+      this.logger.warn("Dry run enabled!");
+    }
+
+    // 2. init git service
+    GitServiceFactory.init(this.inferRemoteGitService(args.pullRequest), args.auth);
+    const gitApi: GitService = GitServiceFactory.getService();
+
+    // 3. parse configs
+    const configs: Configs = await new PullRequestConfigsParser().parseAndValidate(args);
+    const originalPR: GitPullRequest = configs.originalPullRequest;
+    const backportPR: GitPullRequest = configs.backportPullRequest;
+
+    // start local git operations
+    const git: GitCLIService = new GitCLIService(configs.auth, configs.author);
+    
+    // 4. clone the repository
+    await git.clone(configs.originalPullRequest.targetRepo.cloneUrl, configs.folder, configs.targetBranch);
+
+    // 5. create new branch from target one and checkout
+    const backportBranch = `bp-${configs.targetBranch}-${originalPR.commits.join("-")}`;
+    await git.createLocalBranch(configs.folder, backportBranch);
+
+    // 6. fetch pull request remote if source owner != target owner or pull request still open
+    if (configs.originalPullRequest.sourceRepo.owner !== configs.originalPullRequest.targetRepo.owner || 
+        configs.originalPullRequest.state === "open") {
+      await git.fetch(configs.folder, `pull/${configs.originalPullRequest.number}/head:pr/${configs.originalPullRequest.number}`);
+    }
+
+    // 7. apply all changes to the new branch
+    for (const sha of originalPR.commits) {
+      await git.cherryPick(configs.folder, sha);
+    }
+
+    const backport: BackportPullRequest = {
+      owner: originalPR.targetRepo.owner,
+      repo: originalPR.targetRepo.project,
+      head: backportBranch,
+      base: configs.targetBranch,
+      title: backportPR.title,
+      body: backportPR.body,
+      reviewers: backportPR.reviewers
+    };
+
+    if (!configs.dryRun) {
+      // 8. push the new branch to origin
+      await git.push(configs.folder, backportBranch);
+
+      // 9. create pull request new branch -> target branch (using octokit)
+      await gitApi.createPullRequest(backport);
+
+    } else {
+      this.logger.warn("Pull request creation and remote push skipped!");
+      this.logger.info(`${JSON.stringify(backport, null, 2)}`);
+    }
+  }
+
+}