initiative/packages/domain/src/create-player-character.ts

import type { DomainEvent } from "./events.js";
import type {
	PlayerCharacter,
	PlayerCharacterId,
} from "./player-character-types.js";
import {
	VALID_PLAYER_COLORS,
	VALID_PLAYER_ICONS,
} from "./player-character-types.js";
import type { DomainError } from "./types.js";

export interface CreatePlayerCharacterSuccess {
	readonly characters: readonly PlayerCharacter[];
	readonly events: DomainEvent[];
}

export function createPlayerCharacter(
	characters: readonly PlayerCharacter[],
	id: PlayerCharacterId,
	name: string,
	ac: number,
	maxHp: number,
	color: string | undefined,
	icon: string | undefined,
): CreatePlayerCharacterSuccess | DomainError {
	const trimmed = name.trim();

	if (trimmed === "") {
		return {
			kind: "domain-error",
			code: "invalid-name",
			message: "Player character name must not be empty",
		};
	}

	if (!Number.isInteger(ac) || ac < 0) {
		return {
			kind: "domain-error",
			code: "invalid-ac",
			message: "AC must be a non-negative integer",
		};
	}

	if (!Number.isInteger(maxHp) || maxHp < 1) {
		return {
			kind: "domain-error",
			code: "invalid-max-hp",
			message: "Max HP must be a positive integer",
		};
	}

	if (color !== undefined && !VALID_PLAYER_COLORS.has(color)) {
		return {
			kind: "domain-error",
			code: "invalid-color",
			message: `Invalid color: ${color}`,
		};
	}

	if (icon !== undefined && !VALID_PLAYER_ICONS.has(icon)) {
		return {
			kind: "domain-error",
			code: "invalid-icon",
			message: `Invalid icon: ${icon}`,
		};
	}

	const newCharacter: PlayerCharacter = {
		id,
		name: trimmed,
		ac,
		maxHp,
		color: color as PlayerCharacter["color"],
		icon: icon as PlayerCharacter["icon"],
	};

	return {
		characters: [...characters, newCharacter],
		events: [
			{
				type: "PlayerCharacterCreated",
				playerCharacterId: id,
				name: trimmed,
			},
		],
	};
}