import {
	combatantId,
	createEncounter,
	isDomainError,
} from "@initiative/domain";
import { beforeEach, describe, expect, it } from "vitest";
import { loadEncounter, saveEncounter } from "../encounter-storage.js";

const STORAGE_KEY = "initiative:encounter";

function makeEncounter() {
	const result = createEncounter(
		[
			{ id: combatantId("1"), name: "Aria", initiative: 18 },
			{ id: combatantId("c-2"), name: "Brak", initiative: 12 },
			{ id: combatantId("3"), name: "Cael" },
		],
		1,
		3,
	);
	if (isDomainError(result)) throw new Error("Failed to create test encounter");
	return result;
}

function createMockLocalStorage() {
	const store = new Map<string, string>();
	return {
		getItem: (key: string) => store.get(key) ?? null,
		setItem: (key: string, value: string) => store.set(key, value),
		removeItem: (key: string) => store.delete(key),
		clear: () => store.clear(),
		get length() {
			return store.size;
		},
		key: (_index: number) => null,
	} as Storage;
}

beforeEach(() => {
	Object.defineProperty(globalThis, "localStorage", {
		value: createMockLocalStorage(),
		writable: true,
		configurable: true,
	});
});

describe("saveEncounter", () => {
	it("writes encounter to localStorage", () => {
		const encounter = makeEncounter();
		saveEncounter(encounter);
		expect(localStorage.getItem(STORAGE_KEY)).not.toBeNull();
	});
});

describe("loadEncounter", () => {
	it("returns null when localStorage is empty", () => {
		expect(loadEncounter()).toBeNull();
	});

	it("round-trip save/load preserves encounter state", () => {
		const encounter = makeEncounter();
		saveEncounter(encounter);
		const loaded = loadEncounter();

		expect(loaded).not.toBeNull();
		expect(loaded?.combatants).toHaveLength(3);
		expect(loaded?.activeIndex).toBe(1);
		expect(loaded?.roundNumber).toBe(3);
	});

	it("round-trip preserves combatant IDs, names, and initiative values", () => {
		const encounter = makeEncounter();
		saveEncounter(encounter);
		const loaded = loadEncounter();
		expect(loaded).not.toBeNull();

		expect(loaded?.combatants[0].id).toBe("1");
		expect(loaded?.combatants[0].name).toBe("Aria");
		expect(loaded?.combatants[0].initiative).toBe(18);

		expect(loaded?.combatants[1].id).toBe("c-2");
		expect(loaded?.combatants[1].name).toBe("Brak");
		expect(loaded?.combatants[1].initiative).toBe(12);

		expect(loaded?.combatants[2].id).toBe("3");
		expect(loaded?.combatants[2].name).toBe("Cael");
		expect(loaded?.combatants[2].initiative).toBeUndefined();
	});

	it("returns null for non-JSON strings", () => {
		localStorage.setItem(STORAGE_KEY, "not json at all");
		expect(loadEncounter()).toBeNull();
	});

	it("returns null for JSON missing required fields", () => {
		localStorage.setItem(STORAGE_KEY, JSON.stringify({ foo: "bar" }));
		expect(loadEncounter()).toBeNull();
	});

	it("returns empty encounter for cleared state (empty combatants)", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({ combatants: [], activeIndex: 0, roundNumber: 1 }),
		);
		const result = loadEncounter();
		expect(result).toEqual({
			combatants: [],
			activeIndex: 0,
			roundNumber: 1,
		});
	});

	it("returns null for out-of-bounds activeIndex", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({
				combatants: [{ id: "1", name: "Aria" }],
				activeIndex: 5,
				roundNumber: 1,
			}),
		);
		expect(loadEncounter()).toBeNull();
	});

	// US3: Corrupt data scenarios
	it("returns null for non-object JSON (string)", () => {
		localStorage.setItem(STORAGE_KEY, JSON.stringify("hello"));
		expect(loadEncounter()).toBeNull();
	});

	it("returns null for non-object JSON (number)", () => {
		localStorage.setItem(STORAGE_KEY, JSON.stringify(42));
		expect(loadEncounter()).toBeNull();
	});

	it("returns null for non-object JSON (array)", () => {
		localStorage.setItem(STORAGE_KEY, JSON.stringify([1, 2, 3]));
		expect(loadEncounter()).toBeNull();
	});

	it("returns null for non-object JSON (null)", () => {
		localStorage.setItem(STORAGE_KEY, "null");
		expect(loadEncounter()).toBeNull();
	});

	it("returns null when combatants is a string instead of array", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({
				combatants: "not-array",
				activeIndex: 0,
				roundNumber: 1,
			}),
		);
		expect(loadEncounter()).toBeNull();
	});

	it("returns null when activeIndex is a string instead of number", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({
				combatants: [{ id: "1", name: "Aria" }],
				activeIndex: "zero",
				roundNumber: 1,
			}),
		);
		expect(loadEncounter()).toBeNull();
	});

	it("returns null when combatant entry is missing id", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({
				combatants: [{ name: "Aria" }],
				activeIndex: 0,
				roundNumber: 1,
			}),
		);
		expect(loadEncounter()).toBeNull();
	});

	it("returns null when combatant entry is missing name", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({
				combatants: [{ id: "1" }],
				activeIndex: 0,
				roundNumber: 1,
			}),
		);
		expect(loadEncounter()).toBeNull();
	});

	it("returns null for negative roundNumber", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({
				combatants: [{ id: "1", name: "Aria" }],
				activeIndex: 0,
				roundNumber: -1,
			}),
		);
		expect(loadEncounter()).toBeNull();
	});

	it("returns empty encounter for zero combatants (cleared state)", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({ combatants: [], activeIndex: 0, roundNumber: 1 }),
		);
		const result = loadEncounter();
		expect(result).toEqual({
			combatants: [],
			activeIndex: 0,
			roundNumber: 1,
		});
	});

	it("round-trip preserves combatant AC value", () => {
		const result = createEncounter(
			[{ id: combatantId("1"), name: "Aria", ac: 18 }],
			0,
			1,
		);
		if (isDomainError(result)) throw new Error("unreachable");
		saveEncounter(result);
		const loaded = loadEncounter();
		expect(loaded?.combatants[0].ac).toBe(18);
	});

	it("round-trip preserves combatant without AC", () => {
		const result = createEncounter(
			[{ id: combatantId("1"), name: "Aria" }],
			0,
			1,
		);
		if (isDomainError(result)) throw new Error("unreachable");
		saveEncounter(result);
		const loaded = loadEncounter();
		expect(loaded?.combatants[0].ac).toBeUndefined();
	});

	it("discards invalid AC values during rehydration", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({
				combatants: [
					{ id: "1", name: "Neg", ac: -1 },
					{ id: "2", name: "Float", ac: 3.5 },
					{ id: "3", name: "Str", ac: "high" },
				],
				activeIndex: 0,
				roundNumber: 1,
			}),
		);
		const loaded = loadEncounter();
		expect(loaded).not.toBeNull();
		expect(loaded?.combatants[0].ac).toBeUndefined();
		expect(loaded?.combatants[1].ac).toBeUndefined();
		expect(loaded?.combatants[2].ac).toBeUndefined();
	});

	it("preserves AC of 0 during rehydration", () => {
		localStorage.setItem(
			STORAGE_KEY,
			JSON.stringify({
				combatants: [{ id: "1", name: "Aria", ac: 0 }],
				activeIndex: 0,
				roundNumber: 1,
			}),
		);
		const loaded = loadEncounter();
		expect(loaded?.combatants[0].ac).toBe(0);
	});

	it("saving after modifications persists the latest state", () => {
		const encounter = makeEncounter();
		saveEncounter(encounter);

		const modified = createEncounter(
			[
				{ id: combatantId("1"), name: "Aria", initiative: 18 },
				{ id: combatantId("c-2"), name: "Brak", initiative: 12 },
			],
			0,
			5,
		);
		if (isDomainError(modified)) throw new Error("unreachable");

		saveEncounter(modified);
		const loaded = loadEncounter();

		expect(loaded?.combatants).toHaveLength(2);
		expect(loaded?.roundNumber).toBe(5);
	});
});