import { field, option, variant } from "@dao-xyz/borsh";
import { BORSH_ENCODING, type Change, Log } from "@peerbit/log";
import { Entry } from "@peerbit/log";
import { Program } from "@peerbit/program";
import { Range } from "./range.js";

@variant(0)
export class StringOperation {
	@field({ type: Range })
	index: Range;

	@field({ type: option("string") })
	value?: string;

	constructor(props?: { index: Range; value?: string }) {
		if (props) {
			this.index = props.index;
			this.value = props.value;
		}
	}
}
export const encoding = BORSH_ENCODING(StringOperation);

@variant("string_index")
export class StringIndex extends Program {
	_string: string;
	_log: Log<StringOperation>;
	constructor() {
		super();
		this._string = "";
	}

	get string(): string {
		return this._string;
	}
	async open(store: Log<StringOperation>) {
		this._log = store;
	}

	async close(parent: any): Promise<boolean> {
		const closed = await super.close(parent);
		if (closed) {
			this._string = "";
			this._log = undefined!;
		}
		return closed;
	}

	async updateIndex(_change: Change<StringOperation>) {
		this._string = await applyOperations("", await this._log.toArray()); // TODO improve performance
	}
}

export const applyOperations = async (
	string: string,
	operations: Entry<StringOperation>[],
): Promise<string> => {
	await Promise.all(operations.map((operation) => operation.getPayloadValue()));

	operations.reduce((handled: string[], item: Entry<StringOperation>, _) => {
		if (!handled.includes(item.hash)) {
			handled.push(item.hash);
			string = applyOperation(string, item.payload.getValue(encoding));
		}

		return handled;
	}, []);
	return string;
};
export const applyOperation = (
	s: string,
	operation: StringOperation,
): string => {
	// TODO check bounds number
	const to = Number(operation.index.offset) + Number(operation.index.length);
	if (operation.value !== undefined) {
		s = s.padEnd(to);
		s =
			s.slice(0, Number(operation.index.offset)) +
			operation.value +
			s.slice(to);
		return s;
	} else {
		s = s.slice(0, Number(operation.index.offset)) + s.slice(to);
	}
	return s;
};