facade-concept.ts

// The Facade pattern concept

class SubSystemClassA {
    // A hypothetically complicated class
    method(): string {
        return 'A'
    }
}

class SubSystemClassB {
    // A hypothetically complicated class
    method(value: string): string {
        return value
    }
}

class SubSystemClassC {
    // A hypothetically complicated class
    method(value: {C: number[]}): {C: number[]} {
        return value
    }
}

class Facade {
    // A simplified facade offering the services of subsystems
    subSystemClassA(): string {
        // Uses the subsystems method
        return new SubSystemClassA().method()
    }

    subSystemClassB(value: string): string {
        // Uses the subsystems method
        return new SubSystemClassB().method(value)
    }

    subSystemClassC(value: {C: number[]}): {C: number[]} {
        // Uses the subsystems method
        return new SubSystemClassC().method(value)
    }
}

// The Client
// Calling potentially complicated subsystems directly
console.log(new SubSystemClassA().method())
console.log(new SubSystemClassB().method('B'))
console.log(new SubSystemClassC().method({ C: [1, 2, 3] }))

// or using the simplified facade instead
const FACADE = new Facade()
console.log(FACADE.subSystemClassA())
console.log(FACADE.subSystemClassB('B'))
console.log(FACADE.subSystemClassC({ C: [1, 2, 3] }))