'use strict';

const _ = require('lodash');

const ignoredOptions = ['severity', 'message'];

/** @typedef {{possible: any, actual: any, optional: boolean}} Options */

/**
 * Validate a rule's options.
 *
 * See existing rules for examples.
 *
 * @param {import('stylelint').PostcssResult} result - postcss result
 * @param {string} ruleName
 * @param {...Options} optionDescriptions - Each optionDescription can
 *   have the following properties:
 *   	- `actual` (required): the actual passed option value or object.
 *   	- `possible` (required): a schema representation of what values are
 *      valid for those options. `possible` should be an object if the
 *      options are an object, with corresponding keys; if the options are not an
 *      object, `possible` isn't, either. All `possible` value representations
 *      should be **arrays of either values or functions**. Values are === checked
 *      against `actual`. Functions are fed `actual` as an argument and their
 *      return value is interpreted: truthy = valid, falsy = invalid.
 *    - `optional` (optional): If this is `true`, `actual` can be undefined.
 * @return {boolean} Whether or not the options are valid (true = valid)
 */

module.exports = function (result, ruleName, ...optionDescriptions) {
	let noErrors = true;

	optionDescriptions.forEach((optionDescription) => {
		validate(optionDescription, ruleName, complain);
	});

	/**
	 * @param {string} message
	 */
	function complain(message) {
		noErrors = false;
		result.warn(message, {
			stylelintType: 'invalidOption',
		});
		_.set(result, 'stylelint.stylelintError', true);
	}

	return noErrors;
};

/**
 * @param {Options} opts
 * @param {string} ruleName
 * @param {(s: string) => void} complain
 */
function validate(opts, ruleName, complain) {
	const possible = opts.possible;
	const actual = opts.actual;
	const optional = opts.optional;

	if (actual === null || _.isEqual(actual, [null])) {
		return;
	}

	const nothingPossible =
		possible === undefined || (Array.isArray(possible) && possible.length === 0);

	if (nothingPossible && actual === true) {
		return;
	}

	if (actual === undefined) {
		if (nothingPossible || optional) {
			return;
		}

		complain(`Expected option value for rule "${ruleName}"`);

		return;
	}

	if (nothingPossible) {
		if (optional) {
			complain(
				`Incorrect configuration for rule "${ruleName}". Rule should have "possible" values for options validation`,
			);

			return;
		}

		complain(`Unexpected option value "${String(actual)}" for rule "${ruleName}"`);

		return;
	}

	// If `possible` is a function ...
	if (_.isFunction(possible)) {
		if (!possible(actual)) {
			complain(`Invalid option "${JSON.stringify(actual)}" for rule ${ruleName}`);
		}

		return;
	}

	// If `possible` is an array instead of an object ...
	if (!_.isPlainObject(possible)) {
		[].concat(actual).forEach((a) => {
			if (isValid(possible, a)) {
				return;
			}

			complain(`Invalid option value "${String(a)}" for rule "${ruleName}"`);
		});

		return;
	}

	// If actual is NOT an object ...
	if (typeof actual !== 'object') {
		complain(
			`Invalid option value ${JSON.stringify(actual)} for rule "${ruleName}": should be an object`,
		);

		return;
	}

	Object.keys(actual).forEach((optionName) => {
		if (ignoredOptions.includes(optionName)) {
			return;
		}

		if (!possible[optionName]) {
			complain(`Invalid option name "${optionName}" for rule "${ruleName}"`);

			return;
		}

		const actualOptionValue = actual[optionName];

		[].concat(actualOptionValue).forEach((a) => {
			if (isValid(possible[optionName], a)) {
				return;
			}

			complain(`Invalid value "${a}" for option "${optionName}" of rule "${ruleName}"`);
		});
	});
}

/**
 * @param {any|Function} possible
 * @param {any} actual
 * @returns {boolean}
 */
function isValid(possible, actual) {
	const possibleList = /** @type {Array<any|Function>} */ ([]).concat(possible);

	for (let i = 0, l = possibleList.length; i < l; i++) {
		const possibility = possibleList[i];

		if (typeof possibility === 'function' && possibility(actual)) {
			return true;
		}

		if (actual === possibility) {
			return true;
		}
	}

	return false;
}
