Willem van den Ende
fc2cf73b34
- Allium spec: damage-and-health.allium - 5 fast-check properties: damage reduces health, health non-negative, death at zero, self-damage forbidden, dead cannot take damage - Character.createWithHealth factory for testing with arbitrary health - Character.dealDamage(target, damage) method
82 lines
2.2 KiB
TypeScript
82 lines
2.2 KiB
TypeScript
/**
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* Character entity — value-object-driven.
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*
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* "I can't believe it's not Haskell": invariants at boundaries.
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* State is encapsulated in a CharacterState record type.
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*/
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import { Health } from './Health.ts';
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import type { Level } from './Level.ts';
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import type { Status } from './Status.ts';
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import { StatusAlive, StatusDead } from './Status.ts';
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import { CharacterState } from './CharacterState.ts';
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import type { Faction } from './Faction.ts';
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export interface CharacterCtor {
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name: string;
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level: Level;
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}
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export interface CharacterCtorWithHealth {
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name: string;
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level: Level;
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health: number;
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}
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export class Character {
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#state: CharacterState;
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private constructor(state: CharacterState) {
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this.#state = state;
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}
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/** Create a new character with default health (1000) and alive status. */
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static create({ name, level }: CharacterCtor): Character {
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const state = new CharacterState(name, Health.create(1000), StatusAlive, level, new Set());
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return new Character(state);
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}
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/** Create a character with a specific health value (for testing). */
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static createWithHealth({ name, level, health }: CharacterCtorWithHealth): Character {
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const state = new CharacterState(name, Health.create(health), StatusAlive, level, new Set());
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return new Character(state);
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}
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get name(): string {
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return this.#state.name;
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}
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get health(): Health {
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return this.#state.health;
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}
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get status(): Status {
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return this.#state.status;
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}
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get level(): Level {
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return this.#state.level;
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}
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get factions(): ReadonlySet<Faction> {
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return this.#state.factions;
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}
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/** Deal damage to another character. Mutates target in place. */
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dealDamage(target: Character, damage: number): void {
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// Self-damage is forbidden
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if (this.name === target.name) return;
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// Dead characters cannot take damage
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if (target.status.kind === 'dead') return;
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// Reduce health
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const newHealth = target.health.sub(damage);
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const newStatus = newHealth.value === 0 ? StatusDead : StatusAlive;
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target.#state = new CharacterState(
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target.name,
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newHealth,
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newStatus,
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target.level,
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target.factions,
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);
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}
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}
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