feat: auto-detect the value of the no-squash option (#118)

The auto-no-squash option is added to:

* backport all the commits when the pull/merge request has been merged
* backport the squashed commit otherwise

It is equivalent to dynamically adjust the value of the no-squash
option, depending on the context.

The no-squash option is kept for backward compatibility for a single
use case: backporting the merged commit instead of backporting the
commits of the pull/merge request request.

Detecting if a pull/merge request was squashed or not depends on the
underlying forge:

* Forgejo / GitHub: use the API to count the number of parents
* GitLab: if the squash_commit_sha is set, the merge request was
  squashed

If the pull/merge request is open, always backport all the commits it
contains.

Fixes: https://github.com/kiegroup/git-backporting/issues/113

Co-authored-by: Andrea Lamparelli <a.lamparelli95@gmail.com>

src/service/args/args-parser.ts

@@ -44,6 +44,7 @@ export default abstract class ArgsParser {
       labels: this.getOrDefault(args.labels, []),
       inheritLabels: this.getOrDefault(args.inheritLabels, false),
       squash: this.getOrDefault(args.squash, true),
+      autoNoSquash: this.getOrDefault(args.autoNoSquash, false),
       strategy: this.getOrDefault(args.strategy),
       strategyOption: this.getOrDefault(args.strategyOption),
       cherryPickOptions: this.getOrDefault(args.cherryPickOptions),

src/service/args/args.types.ts

@@ -22,7 +22,8 @@ export interface Args {
   inheritReviewers?: boolean, // if true and reviewers == [] then inherit reviewers from original pr
   labels?: string[], // backport pr labels
   inheritLabels?: boolean, // if true inherit labels from original pr
-  squash?: boolean, // if false use squashed/merged commit otherwise backport all commits as part of the pr
+  squash?: boolean,
+  autoNoSquash?: boolean,
   strategy?: string, // cherry-pick merge strategy
   strategyOption?: string, // cherry-pick merge strategy option
   cherryPickOptions?: string, // additional cherry-pick options

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

@@ -28,7 +28,8 @@ export default class CLIArgsParser extends ArgsParser {
       .option("--no-inherit-reviewers", "if provided and reviewers option is empty then inherit them from original pull request")
       .option("--labels <labels>", "comma separated list of labels to be assigned to the backported pull request", getAsCommaSeparatedList)
       .option("--inherit-labels", "if true the backported pull request will inherit labels from the original one")
-      .option("--no-squash", "if provided the tool will backport all commits as part of the pull request")
+      .option("--no-squash", "Backport all commits found in the pull request. The default behavior is to only backport the first commit that was merged in the base branch")
+      .option("--auto-no-squash", "If the pull request was merged or is open, backport all commits. If the pull request commits were squashed, backport the squashed commit.")
       .option("--strategy <strategy>", "cherry-pick merge strategy, default to 'recursive'", undefined)
       .option("--strategy-option <strategy-option>", "cherry-pick merge strategy option, default to 'theirs'")
       .option("--cherry-pick-options <options>", "additional cherry-pick options")
@@ -66,6 +67,7 @@ export default class CLIArgsParser extends ArgsParser {
         labels: opts.labels,
         inheritLabels: opts.inheritLabels,
         squash: opts.squash,
+        autoNoSquash: opts.autoNoSquash,
         strategy: opts.strategy,
         strategyOption: opts.strategyOption,
         cherryPickOptions: opts.cherryPickOptions,

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

@@ -32,6 +32,7 @@ export default class GHAArgsParser extends ArgsParser {
         labels: getAsCommaSeparatedList(getInput("labels")),
         inheritLabels: getAsBooleanOrDefault(getInput("inherit-labels")),
         squash: !getAsBooleanOrDefault(getInput("no-squash")),
+        autoNoSquash: getAsBooleanOrDefault(getInput("auto-no-squash")),
         strategy: getOrUndefined(getInput("strategy")),
         strategyOption: getOrUndefined(getInput("strategy-option")),
         cherryPickOptions: getOrUndefined(getInput("cherry-pick-options")),

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

@@ -16,9 +16,12 @@ export default class PullRequestConfigsParser extends ConfigsParser {
   }
   
   public async parse(args: Args): Promise<Configs> {
-    let pr: GitPullRequest; 
+    let pr: GitPullRequest;
+    if (args.autoNoSquash) {
+      args.squash = undefined;
+    }
     try {
-      pr = await this.gitClient.getPullRequestFromUrl(args.pullRequest, args.squash!);
+      pr = await this.gitClient.getPullRequestFromUrl(args.pullRequest, args.squash);
     } catch(error) {
       this.logger.error("Something went wrong retrieving pull request");
       throw error;

src/service/git/git-client.ts

@@ -25,7 +25,7 @@ import { BackportPullRequest, GitClientType, GitPullRequest } from "@bp/service/
    * @param squash if true keep just one single commit, otherwise get the full list
    * @returns {Promise<PullRequest>}
    */
-  getPullRequest(owner: string, repo: string, prNumber: number, squash: boolean): Promise<GitPullRequest>;
+  getPullRequest(owner: string, repo: string, prNumber: number, squash: boolean | undefined): Promise<GitPullRequest>;
 
   /**
    * Get a pull request object from the underneath git service
@@ -33,7 +33,7 @@ import { BackportPullRequest, GitClientType, GitPullRequest } from "@bp/service/
    * @param squash if true keep just one single commit, otherwise get the full list
    * @returns {Promise<PullRequest>}
    */
-   getPullRequestFromUrl(prUrl: string, squash: boolean): Promise<GitPullRequest>;
+   getPullRequestFromUrl(prUrl: string, squash: boolean | undefined): Promise<GitPullRequest>;
 
   // WRITE
 

src/service/git/git-util.ts

@@ -1,3 +1,4 @@
+import LoggerServiceFactory from "@bp/service/logger/logger-service-factory";
 import { GitClientType } from "@bp/service/git/git.types";
 import { AuthTokenId } from "@bp/service/configs/configs.types";
 
@@ -41,6 +42,29 @@ export const inferGitApiUrl = (prUrl: string, apiVersion = "v4"): string => {
   return `${baseUrl}/api/${apiVersion}`;
 };
 
+/**
+ * Infer the value of the squash option
+ * @param open true if the pull/merge request is still open
+ * @param squash_commit undefined if the pull/merge request was merged, the sha of the squashed commit if it was squashed
+ * @returns true if a single commit must be cherry-picked, false if all merged commits must be cherry-picked
+ */
+export const inferSquash = (open: boolean, squash_commit: string | undefined): boolean => {
+  const logger = LoggerServiceFactory.getLogger();
+
+  if (open) {
+    logger.debug("cherry-pick all commits because they have not been merged (or squashed) in the base branch yet");
+    return false;
+  } else {
+    if (squash_commit !== undefined) {
+      logger.debug(`cherry-pick the squashed commit ${squash_commit}`);
+      return true;
+    } else {
+      logger.debug("cherry-pick the merged commit(s)");
+      return false;
+    }
+  }
+};
+
 /**
  * Retrieve the git token from env variable, the default is taken from GIT_TOKEN env.
  * All specific git env variable have precedence and override the default one.

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

@@ -1,4 +1,5 @@
 import GitClient from "@bp/service/git/git-client";
+import { inferSquash } from "@bp/service/git/git-util";
 import { BackportPullRequest, GitClientType, 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";
@@ -37,7 +38,7 @@ export default class GitHubClient implements GitClient {
     return "noreply@github.com";
   }
 
-  async getPullRequest(owner: string, repo: string, prNumber: number, squash = true): Promise<GitPullRequest> {
+  async getPullRequest(owner: string, repo: string, prNumber: number, squash: boolean | undefined): Promise<GitPullRequest> {
     this.logger.debug(`Fetching pull request ${owner}/${repo}/${prNumber}`);
     const { data } = await this.octokit.rest.pulls.get({
       owner: owner,
@@ -45,6 +46,22 @@ export default class GitHubClient implements GitClient {
       pull_number: prNumber,
     });
 
+    if (squash === undefined) {
+      let commit_sha: string | undefined = undefined;
+      const open: boolean = data.state == "open";
+      if (!open) {
+	const commit = await this.octokit.rest.git.getCommit({
+          owner: owner,
+          repo: repo,
+          commit_sha: (data.merge_commit_sha as string),
+	});
+        if (commit.data.parents.length === 1) {
+          commit_sha = (data.merge_commit_sha as string);
+        }
+      }
+      squash = inferSquash(open, commit_sha);
+    }
+
     const commits: string[] = [];
     if (!squash) {
       // fetch all commits
@@ -64,7 +81,7 @@ export default class GitHubClient implements GitClient {
     return this.mapper.mapPullRequest(data as PullRequest, commits);
   }
 
-  async getPullRequestFromUrl(prUrl: string, squash = true): Promise<GitPullRequest> {
+  async getPullRequestFromUrl(prUrl: string, squash: boolean | undefined): Promise<GitPullRequest> {
     const { owner, project, id } = this.extractPullRequestData(prUrl);
     return this.getPullRequest(owner, project, id, squash);
   }

src/service/git/gitlab/gitlab-client.ts

@@ -1,5 +1,6 @@
 import LoggerService from "@bp/service/logger/logger-service";
 import GitClient from "@bp/service/git/git-client";
+import { inferSquash } from "@bp/service/git/git-util";
 import { GitPullRequest, BackportPullRequest, GitClientType } from "@bp/service/git/git.types";
 import LoggerServiceFactory from "@bp/service/logger/logger-service-factory";
 import { CommitSchema, MergeRequestSchema, UserSchema } from "@gitbeaker/rest";
@@ -45,10 +46,14 @@ export default class GitLabClient implements GitClient {
   // READ
 
   // example: <host>/api/v4/projects/<namespace>%2Fbackporting-example/merge_requests/1
-  async getPullRequest(namespace: string, repo: string, mrNumber: number, squash = true): Promise<GitPullRequest> {
+  async getPullRequest(namespace: string, repo: string, mrNumber: number, squash: boolean | undefined): Promise<GitPullRequest> {
     const projectId = this.getProjectId(namespace, repo);
     const { data } = await this.client.get(`/projects/${projectId}/merge_requests/${mrNumber}`);
 
+    if (squash === undefined) {
+      squash = inferSquash(data.state === "opened", data.squash_commit_sha);
+    }
+
     const commits: string[] = [];
     if (!squash) {
       // fetch all commits
@@ -65,7 +70,7 @@ export default class GitLabClient implements GitClient {
     return this.mapper.mapPullRequest(data as MergeRequestSchema, commits);
   }
 
-  getPullRequestFromUrl(mrUrl: string, squash = true): Promise<GitPullRequest> {
+  getPullRequestFromUrl(mrUrl: string, squash: boolean | undefined): Promise<GitPullRequest> {
     const { namespace, project, id } = this.extractMergeRequestData(mrUrl);
     return this.getPullRequest(namespace, project, id, squash);
   }