import { ValidationError } from "../ValidationError.js";

export class DnsTool {
	static allowWhitespaceAroundSeparator;
	static fields = [];

	constructor(text) {
		this.text = text;
	}

	tokenize() {
		throw new Error("Unimplemented");
	}

	getKeyValues() {
		const result = [];

		for (const token of this.tokenize()) {
			const key = token.match(/^\w*/)[0];

			const field = this.constructor.fields.find(f => f.key === key);
			if (!field) {
				throw new ValidationError(`Unknown field: ${key}`);
			}

			const wsp = this.constructor.allowWhitespaceAroundSeparator ? "\\s*" : "";
			const separator = new RegExp(wsp + field.separator + wsp);

			const value = token.split(separator)[1];

			if (!value) {
				throw new ValidationError(`Field "${key}" is missing a value`);
			}

			result.push({ key, value });
		}

		return result;
	}

	validate() {
		const values = this.getKeyValues();

		for (const field of this.constructor.fields) {
			if (field.isRequired && !values.some(v => v.key === field.key)) {
				throw new ValidationError(`Field "${field.key}" is required`);
			}
		}

		let lastPos = 0;
		for (let i = 0; i < values.length; i++) {
			const input = values[i];
			const field = this.constructor.fields.find(f => f.key === input.key);

			if (!field) {
				throw new ValidationError(`Unknown field: ${input.key}`);
			}

			if (field.position < lastPos) {
				const lastField = this.constructor.fields.find(f => f.key === values[i-1].key);

				throw new ValidationError(`Field "${lastField.key}" must come after "${field.key}"`);
			}

			field.validate(input.value);

			lastPos = field.position;
		}

		return true;
	}
}