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 { generateBashCompletion, getRoot } from '../../../helpers/AutoCompletionHelper';
+
+class CompletionBashCommand extends CommanderCommand {
+    protected commandName: string = 'bash';
+
+    protected default_filename: string = './dojo_bash_completion.sh'
+
+    writeFile(filename: string) {
+        const installInstructions: string = `
+The easiest way to install the completion is to append the content of the
+generated file to the end of the '~/.bash_completion' file or to
+overwrite it, if it only contains the 'dojo' completion.
+
+This can be performed by either
+
+cat ${filename} > ~/.bash_completion  # overwrites .bash_completion
+cat ${filename} >> ~/.bash_completion # appends to .bash_completion
+
+For more details: <https://github.com/scop/bash-completion/blob/master/README.md>
+`
+        try {
+            writeFileSync(filename, generateBashCompletion(getRoot(this.command)))
+            console.log(`Bash completion successfully written.`)
+            console.log(`${installInstructions}`)
+        } catch (error) {
+            console.log(`Error: ${error}, failed to write ${filename}`)
+        }
+    }
+
+    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 ${this.default_filename}).`)
+            .action(this.commandAction.bind(this));
+    }
+
+    protected async commandAction(options: { file?: string }): Promise<void> {
+        const filename = options.file ?? this.default_filename
+        if (existsSync(filename)) {
+            // File exists in path
+            const confirm: boolean = (await inquirer.prompt({
+                name: 'confirm',
+                message: `${options.file} is going to be overwritten. Are you sure?`,
+                type: 'confirm',
+                default: false
+            })).confirm;
+
+            if (confirm) {
+                this.writeFile(filename)
+            }
+        } else {
+            this.writeFile(filename)
+        }
+    }
+}
+
+
+export default new CompletionBashCommand();
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