export type Dictionary<K, V> = {
	entries: Array<[K, V]>;
	indices: Map<K, number>;
	isIterating: boolean;
	deleteQueue: Array<K>;
	setQueue: Array<[K, V]>;
};

export function createDictionary<K, V>(
	iterable?: Iterable<[K, V]>,
): Dictionary<K, V> {
	const entries = iterable ? [...iterable] : [];
	const indices = new Map(entries.map(([k], i) => [k, i]));

	return {
		entries,
		indices,
		isIterating: false,
		deleteQueue: [],
		setQueue: [],
	};
}

export function deleteEntry<K, V>(dict: Dictionary<K, V>, key: K): void {
	const index = dict.indices.get(key);
	if (index === undefined) {
		return;
	}

	const last = dict.entries.length - 1;
	if (index !== last) {
		dict.entries[index] = dict.entries[last];
		dict.indices.set(dict.entries[index][0], index);
	}

	dict.entries.pop();
	dict.indices.delete(key);
}

export function deleteEntrySave<K, V>(dict: Dictionary<K, V>, key: K): void {
	if (dict.isIterating) {
		dict.deleteQueue.push();
	} else {
		deleteEntry(dict, key);
	}
}

export function setEntry<K, V>(
	dict: Dictionary<K, V>,
	[key, value]: [K, V],
): void {
	const index = dict.indices.get(key);
	if (index === undefined) {
		dict.indices.set(key, dict.entries.length);
		dict.entries.push([key, value]);
	} else {
		dict.entries[index][1] = value;
	}
}

export function setEntrySave<K, V>(
	dict: Dictionary<K, V>,
	key: K,
	value: V,
): void {
	if (dict.isIterating) {
		dict.setQueue.push([key, value]);
	} else {
		setEntry(dict, [key, value]);
	}
}

export function getEntry<K, V>(dict: Dictionary<K, V>, key: K): V | undefined {
	const index = dict.indices.get(key);
	return index === undefined ? undefined : dict.entries[index][1];
}

export function forEntry<K, V>(
	dict: Dictionary<K, V>,
	callback: (value: V, key: K, index: number) => void,
): void {
	dict.isIterating = true;
	for (let i = 0; i < dict.entries.length; i++) {
		callback(dict.entries[i][1], dict.entries[i][0], i);
	}
	dict.isIterating = false;

	while (dict.deleteQueue.length > 0) {
		deleteEntry(dict, dict.deleteQueue.pop()!);
	}

	while (dict.setQueue.length > 0) {
		setEntry(dict, dict.setQueue.pop()!);
	}
}