feat: config file as option (#42)

Fix https://github.com/lampajr/backporting/issues/37

This enhancement required a huge refactoring where all arguments
defaults have been centralized in one single place ArgsParser#parse

src/service/args/args-parser.ts

@@ -4,7 +4,38 @@ 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 {
+export default abstract class ArgsParser {
 
-  parse(): Args;
+  abstract readArgs(): Args;
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  private getOrDefault(parsedValue: any, defaultValue?: any) {
+    return parsedValue === undefined ? defaultValue : parsedValue;
+  }
+
+  public parse(): Args {
+    const args = this.readArgs();
+
+    // validate and fill with defaults
+    if (!args.pullRequest || !args.targetBranch) {
+      throw new Error("Missing option: pull request and target branch must be provided");
+    }
+    
+    return {
+      pullRequest: args.pullRequest,
+      targetBranch: args.targetBranch,
+      dryRun: this.getOrDefault(args.dryRun, false),
+      auth: this.getOrDefault(args.auth),
+      folder: this.getOrDefault(args.folder),
+      gitUser: this.getOrDefault(args.gitUser),
+      gitEmail: this.getOrDefault(args.gitEmail),
+      title: this.getOrDefault(args.title),
+      body: this.getOrDefault(args.body),
+      bodyPrefix: this.getOrDefault(args.bodyPrefix),
+      bpBranchName: this.getOrDefault(args.bpBranchName),
+      reviewers: this.getOrDefault(args.reviewers, []),
+      assignees: this.getOrDefault(args.assignees, []),
+      inheritReviewers: this.getOrDefault(args.inheritReviewers, true),
+    };
+  }
 }

src/service/args/args-utils.ts

@@ -0,0 +1,22 @@
+import { Args } from "@bp/service/args/args.types";
+import * as fs from "fs";
+
+/**
+ * Parse the input configuation string as json object and 
+ * return it as Args
+ * @param configFileContent 
+ * @returns {Args}
+ */
+export function parseArgs(configFileContent: string): Args {
+  return JSON.parse(configFileContent) as Args;
+}
+
+/**
+ * Read a configuration file in json format anf parse it as {Args}
+ * @param pathToFile Full path name of the config file, e.g., /tmp/dir/config-file.json
+ * @returns {Args}
+ */
+export function readConfigFile(pathToFile: string): Args {
+  const asString: string = fs.readFileSync(pathToFile, "utf-8");
+  return parseArgs(asString);
+}

src/service/args/args.types.ts

@@ -2,18 +2,18 @@
  * 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
+  dryRun?: boolean, // if enabled do not push anything remotely
+  auth?: string, // git service auth, like github token
   folder?: string, // local folder where the repositories should be cloned
-  gitUser: string, // local git user, default 'GitHub'
-  gitEmail: string, // local git email, default 'noreply@github.com'
+  gitUser?: string, // local git user, default 'GitHub'
+  gitEmail?: string, // local git email, default 'noreply@github.com'
   title?: string, // backport pr title, default original pr title prefixed by target branch
   body?: string, // backport pr title, default original pr body prefixed by bodyPrefix
   bodyPrefix?: string, // backport pr body prefix, default `backport <original-pr-link>`
   bpBranchName?: string, // backport pr branch name, default computed from commit
   reviewers?: string[], // backport pr reviewers
   assignees?: string[], // backport pr assignees
-  inheritReviewers: boolean, // if true and reviewers == [] then inherit reviewers from original pr
+  inheritReviewers?: boolean, // if true and reviewers == [] then inherit reviewers from original pr
 }

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

@@ -2,6 +2,7 @@ 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";
+import { readConfigFile } from "@bp/service/args/args-utils";
 
 function commaSeparatedList(value: string, _prev: unknown): string[] {
   // remove all whitespaces
@@ -9,49 +10,58 @@ function commaSeparatedList(value: string, _prev: unknown): string[] {
   return cleanedValue !== "" ? cleanedValue.replace(/\s/g, "").split(",") : [];
 }
 
-export default class CLIArgsParser implements ArgsParser {
+export default class CLIArgsParser extends 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("-gu, --git-user <git-user>", "local git user name, default is 'GitHub'.", "GitHub")
-      .option("-ge, --git-email <git-email>", "local git user email, default is 'noreply@github.com'.", "noreply@github.com")
-      .option("-f, --folder <folder>", "local folder where the repo will be checked out, e.g., /tmp/folder.", undefined)
-      .option("--title <bp-title>", "backport pr title, default original pr title prefixed by target branch.", undefined)
-      .option("--body <bp-body>", "backport pr title, default original pr body prefixed by bodyPrefix.", undefined)
-      .option("--body-prefix <bp-body-prefix>", "backport pr body prefix, default `backport <original-pr-link>`.", undefined)
-      .option("--bp-branch-name <bp-branch-name>", "backport pr branch name, default auto-generated by the commit.", undefined)
-      .option("--reviewers <reviewers>", "comma separated list of reviewers for the backporting pull request.", commaSeparatedList, [])
-      .option("--assignees <assignees>", "comma separated list of assignees for the backporting pull request.", commaSeparatedList, [])
-      .option("--no-inherit-reviewers", "if provided and reviewers option is empty then inherit them from original pull request", true);
+      .option("-tb, --target-branch <branch>", "branch where changes must be backported to.")
+      .option("-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")
+      .option("-a, --auth <auth>", "git service authentication string, e.g., github token.")
+      .option("-gu, --git-user <git-user>", "local git user name, default is 'GitHub'.")
+      .option("-ge, --git-email <git-email>", "local git user email, default is 'noreply@github.com'.")
+      .option("-f, --folder <folder>", "local folder where the repo will be checked out, e.g., /tmp/folder.")
+      .option("--title <bp-title>", "backport pr title, default original pr title prefixed by target branch.")
+      .option("--body <bp-body>", "backport pr title, default original pr body prefixed by bodyPrefix.")
+      .option("--body-prefix <bp-body-prefix>", "backport pr body prefix, default `backport <original-pr-link>`.")
+      .option("--bp-branch-name <bp-branch-name>", "backport pr branch name, default auto-generated by the commit.")
+      .option("--reviewers <reviewers>", "comma separated list of reviewers for the backporting pull request.", commaSeparatedList)
+      .option("--assignees <assignees>", "comma separated list of assignees for the backporting pull request.", commaSeparatedList)
+      .option("--no-inherit-reviewers", "if provided and reviewers option is empty then inherit them from original pull request")
+      .option("-cf, --config-file <config-file>", "configuration file containing all valid options, the json must match Args interface.");
   }
 
-  parse(): Args {
+  readArgs(): Args {
     const opts = this.getCommand()
       .parse()
       .opts();
     
-    return {
-      dryRun: opts.dryRun,
-      auth: opts.auth,
-      pullRequest: opts.pullRequest,
-      targetBranch: opts.targetBranch,
-      folder: opts.folder,
-      gitUser: opts.gitUser,
-      gitEmail: opts.gitEmail,
-      title: opts.title,
-      body: opts.body,
-      bodyPrefix: opts.bodyPrefix,
-      bpBranchName: opts.bpBranchName,
-      reviewers: opts.reviewers,
-      assignees: opts.assignees,
-      inheritReviewers: opts.inheritReviewers,
-    };
+    let args: Args; 
+    if (opts.configFile) {
+      // if config file is set ignore all other options
+      args = readConfigFile(opts.configFile);
+    } else {
+      args = {
+        dryRun: opts.dryRun,
+        auth: opts.auth,
+        pullRequest: opts.pullRequest,
+        targetBranch: opts.targetBranch,
+        folder: opts.folder,
+        gitUser: opts.gitUser,
+        gitEmail: opts.gitEmail,
+        title: opts.title,
+        body: opts.body,
+        bodyPrefix: opts.bodyPrefix,
+        bpBranchName: opts.bpBranchName,
+        reviewers: opts.reviewers,
+        assignees: opts.assignees,
+        inheritReviewers: opts.inheritReviewers,
+      };
+    }
+
+    return args;
   }
 
 }

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

@@ -1,8 +1,9 @@
 import ArgsParser from "@bp/service/args/args-parser";
 import { Args } from "@bp/service/args/args.types";
 import { getInput } from "@actions/core";
+import { readConfigFile } from "@bp/service/args/args-utils";
 
-export default class GHAArgsParser implements ArgsParser {
+export default class GHAArgsParser extends ArgsParser {
 
   /**
    * Return the input only if it is not a blank or null string, otherwise returns undefined
@@ -14,39 +15,43 @@ export default class GHAArgsParser implements ArgsParser {
     return value !== "" ? value : undefined;
   }
 
-  public getOrDefault(key: string, defaultValue: string): string {
-    const value = getInput(key);
-    return value !== "" ? value : defaultValue;
-  }
-
-  public getAsCommaSeparatedList(key: string): string[] {
+  public getAsCommaSeparatedList(key: string): string[] | undefined {
     // trim the value
     const value: string = (getInput(key) ?? "").trim();
-    return value !== "" ? value.replace(/\s/g, "").split(",") : []; 
+    return value !== "" ? value.replace(/\s/g, "").split(",") : undefined; 
   }
 
-  public getAsBooleanOrDefault(key: string, defaultValue: boolean): boolean {
+  private getAsBooleanOrDefault(key: string): boolean | undefined {
     const value = getInput(key).trim();
-    return value !== "" ? value.toLowerCase() === "true" : defaultValue;
+    return value !== "" ? value.toLowerCase() === "true" : undefined;
   }
 
-  parse(): Args {
-    return {
-      dryRun: this.getAsBooleanOrDefault("dry-run", false),
-      auth: getInput("auth"),
-      pullRequest: getInput("pull-request"),
-      targetBranch: getInput("target-branch"),
-      folder: this.getOrUndefined("folder"),
-      gitUser: this.getOrDefault("git-user", "GitHub"),
-      gitEmail: this.getOrDefault("git-email", "noreply@github.com"),
-      title: this.getOrUndefined("title"),
-      body: this.getOrUndefined("body"),
-      bodyPrefix: this.getOrUndefined("body-prefix"),
-      bpBranchName: this.getOrUndefined("bp-branch-name"),
-      reviewers: this.getAsCommaSeparatedList("reviewers"),
-      assignees: this.getAsCommaSeparatedList("assignees"),
-      inheritReviewers: !this.getAsBooleanOrDefault("no-inherit-reviewers", false),
-    };
+  readArgs(): Args {
+    const configFile = this.getOrUndefined("config-file");
+
+    let args: Args; 
+    if (configFile) {
+      args = readConfigFile(configFile);
+    } else {
+      args = {
+        dryRun: this.getAsBooleanOrDefault("dry-run"),
+        auth: this.getOrUndefined("auth"),
+        pullRequest: getInput("pull-request"),
+        targetBranch: getInput("target-branch"),
+        folder: this.getOrUndefined("folder"),
+        gitUser: this.getOrUndefined("git-user"),
+        gitEmail: this.getOrUndefined("git-email"),
+        title: this.getOrUndefined("title"),
+        body: this.getOrUndefined("body"),
+        bodyPrefix: this.getOrUndefined("body-prefix"),
+        bpBranchName: this.getOrUndefined("bp-branch-name"),
+        reviewers: this.getAsCommaSeparatedList("reviewers"),
+        assignees: this.getAsCommaSeparatedList("assignees"),
+        inheritReviewers: !this.getAsBooleanOrDefault("no-inherit-reviewers"),
+      };
+    }
+
+    return args;
   }
 
 }