import {Unit} from '../../lifecycle/Unit'
import {Logging} from '../../service/Logging'
import {Singleton, Inject} from '../../di/decorator/injection'
import {CommandLine} from './CommandLine'
import {UsageDirective} from '../directive/UsageDirective'
import {Directive} from '../Directive'
import {ShellDirective} from '../directive/ShellDirective'
import {TemplateDirective} from '../directive/TemplateDirective'
import {RunDirective} from '../directive/RunDirective'

/**
 * Unit that takes the place of the final unit in the application that handles
 * invocations from the command line.
 */
@Singleton()
export class CommandLineApplication extends Unit {
    /** The unit that was replaced by the CLI app. */
    private static replacement?: typeof Unit

    /** Set the replaced unit. */
    public static setReplacement(unitClass?: typeof Unit): void {
        this.replacement = unitClass
    }

    /** Get the replaced unit. */
    public static getReplacement(): typeof Unit | undefined {
        return this.replacement
    }

    @Inject()
    protected readonly cli!: CommandLine

    @Inject()
    protected readonly logging!: Logging

    constructor() {
        super()
    }

    public async up(): Promise<void> {
        this.cli.registerDirective(UsageDirective)
        this.cli.registerDirective(ShellDirective)
        this.cli.registerDirective(TemplateDirective)
        this.cli.registerDirective(RunDirective)

        const argv = process.argv.slice(2)
        const match = this.cli.getDirectives()
            .map(dirCls => this.make<Directive>(dirCls))
            .firstWhere(dir => dir.matchesKeyword(argv[0]))

        if ( match ) {
            await match.invoke(argv.slice(1))
        } else {
            const usage = this.make<UsageDirective>(UsageDirective)
            await usage.handle()
        }
    }
}