import {
	type Combatant,
	createEncounter,
	type Encounter,
	isDomainError,
	rehydrateCombatant,
} from "@initiative/domain";

const STORAGE_KEY = "initiative:encounter";

export function saveEncounter(encounter: Encounter): void {
	try {
		localStorage.setItem(STORAGE_KEY, JSON.stringify(encounter));
	} catch {
		// Silently swallow errors (quota exceeded, storage unavailable)
	}
}

export function rehydrateEncounter(parsed: unknown): Encounter | null {
	if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed))
		return null;

	const obj = parsed as Record<string, unknown>;

	if (!Array.isArray(obj.combatants)) return null;
	if (typeof obj.activeIndex !== "number") return null;
	if (typeof obj.roundNumber !== "number") return null;

	const combatants = obj.combatants as unknown[];

	// Handle empty encounter (cleared state) directly — createEncounter rejects empty arrays
	if (combatants.length === 0) {
		return {
			combatants: [],
			activeIndex: 0,
			roundNumber: 1,
		};
	}

	const rehydrated: Combatant[] = [];
	for (const c of combatants) {
		const result = rehydrateCombatant(c);
		if (result === null) return null;
		rehydrated.push(result);
	}

	const encounter = createEncounter(
		rehydrated,
		obj.activeIndex,
		obj.roundNumber,
	);
	if (isDomainError(encounter)) return null;

	return encounter;
}

export function loadEncounter(): Encounter | null {
	try {
		const raw = localStorage.getItem(STORAGE_KEY);
		if (raw === null) return null;

		const parsed: unknown = JSON.parse(raw);
		return rehydrateEncounter(parsed);
	} catch {
		return null;
	}
}