lib/src/cli/directive/UsageDirective.ts

import {Directive} from '../Directive'
import {Injectable, Inject} from '../../di'
import {padRight} from '../../util'
import {CommandLine} from '../service'

/**
 * Directive that prints the help message and usage information about
 * directives registered with the command line utility.
 */
@Injectable()
export class UsageDirective extends Directive {
    @Inject()
    protected readonly cli!: CommandLine

    public getKeywords(): string | string[] {
        return 'help'
    }

    public getDescription(): string {
        return 'print information about available commands'
    }

    public handle(): void | Promise<void> {
        const directiveStrings = this.cli.getDirectives()
            .map(cls => this.make<Directive>(cls))
            .map<[string, string]>(dir => {
                return [dir.getMainKeyword(), dir.getDescription()]
            })

        const maxLen = directiveStrings.max<number>(x => x[0].length)

        const printStrings = directiveStrings.map(grp => {
            return [padRight(grp[0], maxLen + 1), grp[1]]
        })
            .map(grp => {
                return `    ${grp[0]}: ${grp[1]}`
            })
            .toArray()

        this.nativeOutput(this.cli.getASCIILogo())
        this.nativeOutput([
            '',
            'Welcome to Extollo! Specify a command to get started.',
            '',
            `USAGE: ex <directive> [..options]`,
            '',
            ...printStrings,
            '',
            'For usage information about a particular command, pass the --help flag.',
            '-------------------------------------------',
            `powered by Extollo, © ${(new Date()).getFullYear()} Garrett Mills`,
        ].join('\n'))
    }
}