import { describe, expect, it } from "vitest";
import { toggleConcentration } from "../toggle-concentration.js";
import type { Combatant, Encounter } from "../types.js";
import { combatantId, isDomainError } from "../types.js";

function makeCombatant(name: string, isConcentrating?: boolean): Combatant {
	return isConcentrating
		? { id: combatantId(name), name, isConcentrating }
		: { id: combatantId(name), name };
}

function enc(combatants: Combatant[]): Encounter {
	return { combatants, activeIndex: 0, roundNumber: 1 };
}

function success(encounter: Encounter, id: string) {
	const result = toggleConcentration(encounter, combatantId(id));
	if (isDomainError(result)) {
		throw new Error(`Expected success, got error: ${result.message}`);
	}
	return result;
}

describe("toggleConcentration", () => {
	it("toggles concentration on when falsy", () => {
		const e = enc([makeCombatant("A")]);
		const { encounter, events } = success(e, "A");

		expect(encounter.combatants[0].isConcentrating).toBe(true);
		expect(events).toEqual([
			{ type: "ConcentrationStarted", combatantId: combatantId("A") },
		]);
	});

	it("toggles concentration off when true", () => {
		const e = enc([makeCombatant("A", true)]);
		const { encounter, events } = success(e, "A");

		expect(encounter.combatants[0].isConcentrating).toBeUndefined();
		expect(events).toEqual([
			{ type: "ConcentrationEnded", combatantId: combatantId("A") },
		]);
	});

	it("returns error for nonexistent combatant", () => {
		const e = enc([makeCombatant("A")]);
		const result = toggleConcentration(e, combatantId("missing"));

		expect(isDomainError(result)).toBe(true);
		if (isDomainError(result)) {
			expect(result.code).toBe("combatant-not-found");
		}
	});

	it("does not mutate input encounter", () => {
		const e = enc([makeCombatant("A")]);
		const original = JSON.parse(JSON.stringify(e));
		toggleConcentration(e, combatantId("A"));
		expect(e).toEqual(original);
	});

	it("does not affect other combatants", () => {
		const e = enc([makeCombatant("A"), makeCombatant("B", true)]);
		const { encounter } = success(e, "A");

		expect(encounter.combatants[0].isConcentrating).toBe(true);
		expect(encounter.combatants[1].isConcentrating).toBe(true);
	});
});