Resolve "Add zsh, fish, and bash shell completion helper function generation as well as the related command"

Closes #4 (closed)

NodeApp/src/commander/completion/subcommands/CompletionBashCommand.ts

-import { existsSync, writeFileSync }       from 'fs';
-import inquirer                            from 'inquirer';
-import CommanderCommand                    from '../../CommanderCommand';
+import { existsSync, renameSync, writeFileSync } from 'fs';
+import inquirer from 'inquirer';
+import CommanderCommand from '../../CommanderCommand';
 import { generateBashCompletion, getRoot } from '../../../helpers/AutoCompletionHelper';
-import ora                                 from 'ora';
-import TextStyle                           from '../../../types/TextStyle';
+import ora from 'ora';
+import TextStyle from '../../../types/TextStyle';
+import { homedir } from 'os';
+import { join } from 'path';
 
+async function askConfirmation(msg: string): Promise<boolean> {
+    return (await inquirer.prompt({
+        name: 'confirm',
+        message: msg,
+        type: 'confirm',
+        default: false
+    })).confirm
+}
 
 class CompletionBashCommand extends CommanderCommand {
     protected commandName: string = 'bash';
 
-    private defaultFilename: string = './dojo_bash_completion.sh';
+    private installPath = join(homedir(), '.bash_completion')
 
     protected defineCommand() {
         this.command
-        .description('generate bash completion')
-        .option('-f, --file <filename>', `complete path of the filename where the bash completion will be stored (default to ${ this.defaultFilename }).`, this.defaultFilename)
-        .option('-y, --force', 'don\'t ask for file overwrite confirmation')
-        .action(this.commandAction.bind(this));
+            .description('generate bash completion')
+            .option('-f, --file <filename>')
+            .option('-y, --force', 'don\'t ask for file overwrite confirmation')
+            .action(this.commandAction.bind(this));
     }
 
-    private writeFile(filename: string) {
-        const spinner: ora.Ora = ora('Writing Bash completion...').start();
+    private writeFile(filename: string, showInstructions: boolean) {
+        const spinner: ora.Ora = ora(`Writing Bash completion in ${TextStyle.CODE(filename)} ...`).start();
 
         try {
             writeFileSync(filename, generateBashCompletion(getRoot(this.command)));
 
-            spinner.succeed(`Bash completion successfully written.`);
-            console.log(`
-The easiest way to install the completion is to append the content of the generated file to the end of the ${ TextStyle.CODE('~/.bash_completion') } file or to overwrite it, if it only contains the 'dojo' completion.
+            spinner.succeed(`Bash completion successfully written in ${TextStyle.CODE(filename)}`);
+            if (showInstructions) {
+                console.log(`
+The easiest way to install the completion is to append the content of the generated file to the end of the ${TextStyle.CODE('~/.bash_completion')} file or to overwrite it, if it only contains the 'dojo' completion.
 
 This can be performed by either
-${ TextStyle.CODE(`
-cat ${ filename } > ~/.bash_completion  # overwrites .bash_completion
-cat ${ filename } >> ~/.bash_completion # appends to .bash_completion
-`) }
-For more details: ${ TextStyle.URL('https://github.com/scop/bash-completion/blob/master/README.md') }
-`);
-        } catch ( error ) {
-            spinner.fail(`Bash completion error: ${ error }.`);
+${TextStyle.CODE(`
+cat ${filename} > ~/.bash_completion  # overwrites .bash_completion
+cat ${filename} >> ~/.bash_completion # appends to .bash_completion
+`)}
+For more details: ${TextStyle.URL('https://github.com/scop/bash-completion/blob/master/README.md')}
+`
+                );
+            }
+        } catch (error) {
+            spinner.fail(`Bash completion error: ${error}`);
         }
     }
 
-    protected async commandAction(options: { file: string, force: boolean }): Promise<void> {
-        if ( !options.force && existsSync(options.file) ) {
-            // File exists in path
-            const confirm: boolean = (await inquirer.prompt({
-                                                                name   : 'confirm',
-                                                                message: `${ options.file } is going to be overwritten. Are you sure?`,
-                                                                type   : 'confirm',
-                                                                default: false
-                                                            })).confirm;
+    private renameFile(filename: string, showWarning: boolean) {
+        const old_filename = `${filename}.old`
+        const spinner: ora.Ora = ora(`Renaming ${TextStyle.CODE(filename)} in ${TextStyle.CODE(old_filename)} ...`).start();
+        try {
+            renameSync(filename, old_filename);
+            spinner.succeed(`Renaming success: ${TextStyle.CODE(filename)} in ${TextStyle.CODE(old_filename)}`);
 
-            if ( confirm ) {
-                this.writeFile(options.file);
+            if (showWarning) {
+                console.log(`${TextStyle.WARNING('Warning:')} Your ${TextStyle.CODE(filename)} was renamed ${TextStyle.CODE(old_filename)}. If this was not intended please revert this change.`);
             }
+        } catch (error) {
+            spinner.fail(`Renaming failed: ${error}.`);
+        }
+    }
+
+    /* The completion command must do the following:
+       - if a file is provided: 
+            - if force is not enabled:
+                - check if the file exists:
+                    - if it exists, prompt the user that it will be erased
+                        - if ok is given write the file and prompt that a backup has been created
+            - else create the file containing the completion
+        - else
+            - if force is not enabled:
+                - check if the default file exists:
+                    - if it exists, prompt the user that it will be erased:
+                        - if ok is given write the file and prompt that a backup has been created
+            - else
+                - create the file containing the completion
+    */
+    protected async commandAction(options: { file: string, force: boolean }): Promise<void> {
+        const path = options.file ?? this.installPath
+        const showInstructions = !!options.file
+        console.log(path)
+        const fileExists = existsSync(path)
+        if (options.force) {
+            this.renameFile(path, !options.force)
         } else {
-            this.writeFile(options.file);
+            if (fileExists) {
+                const confirm = await askConfirmation(`${TextStyle.CODE(path)} in ${TextStyle.CODE(path + '.old')}. Are you sure?`);
+                if (confirm) {
+                    this.renameFile(path, true)
+                } else {
+                    console.log(`${TextStyle.BLOCK('Completion generation interrupted.')}`)
+                    return
+                }
+            }
+
         }
+        this.writeFile(path, showInstructions);
     }
+
 }