import shajs from 'sha.js';

/**
 * Converts string into camelCase.
 *
 * @see http://stackoverflow.com/questions/2970525/converting-any-string-into-camel-case
 */
export function camelCase(str: string, firstCapital: boolean = false): string {
	if (firstCapital) str = ' ' + str;
	return str.replace(/^([A-Z])|[\s-_](\w)/g, function (match, p1, p2) {
		if (p2) return p2.toUpperCase();
		return p1.toLowerCase();
	});
}

/**
 * Converts string into snake_case.
 *
 */
export function snakeCase(str: string): string {
	return (
		str
			// ABc -> a_bc
			.replace(/([A-Z])([A-Z])([a-z])/g, '$1_$2$3')
			// aC -> a_c
			.replace(/([a-z0-9])([A-Z])/g, '$1_$2')
			.toLowerCase()
	);
}

/**
 * Converts string into Title Case.
 *
 * @see http://stackoverflow.com/questions/196972/convert-string-to-title-case-with-javascript
 */
export function titleCase(str: string): string {
	return str.replace(/\w\S*/g, (txt) => txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase());
}

/**
 * Builds abbreviated string from given string;
 */
export function abbreviate(str: string, abbrLettersCount: number = 1): string {
	const words = str.replace(/([a-z\xE0-\xFF])([A-Z\xC0\xDF])/g, '$1 $2').split(' ');
	return words.reduce((res, word) => {
		res += word.substr(0, abbrLettersCount);
		return res;
	}, '');
}

export interface IShortenOptions {
	/** String used to split "segments" of the alias/column name */
	separator?: string;
	/** Maximum length of any "segment" */
	segmentLength?: number;
	/** Length of any "term" in a "segment"; "OrderItem" is a segment, "Order" and "Items" are terms */
	termLength?: number;
}

/**
 * Shorten a given `input`. Useful for RDBMS imposing a limit on the
 * maximum length of aliases and column names in SQL queries.
 *
 * @param input String to be shortened.
 * @param options Default to `4` for segments length, `2` for terms length, `'__'` as a separator.
 *
 * @return Shortened `input`.
 *
 * @example
 * // returns: "UsShCa__orde__mark__dire"
 * shorten('UserShoppingCart__order__market__director')
 *
 * // returns: "cat_wit_ver_lon_nam_pos_wit_ver_lon_nam_pos_wit_ver_lon_nam"
 * shorten(
 *   'category_with_very_long_name_posts_with_very_long_name_post_with_very_long_name',
 *   { separator: '_', segmentLength: 3 }
 * )
 *
 * // equals: UsShCa__orde__mark_market_id
 * `${shorten('UserShoppingCart__order__market')}_market_id`
 */
export function shorten(input: string, options: IShortenOptions = {}): string {
	const { segmentLength = 4, separator = '__', termLength = 2 } = options;

	const segments = input.split(separator);
	const shortSegments = segments.reduce((acc: string[], val: string) => {
		// split the given segment into many terms based on an eventual camel cased name
		const segmentTerms = val.replace(/([a-z\xE0-\xFF])([A-Z\xC0-\xDF])/g, '$1 $2').split(' ');
		// "OrderItemList" becomes "OrItLi", while "company" becomes "comp"
		const length = segmentTerms.length > 1 ? termLength : segmentLength;
		const shortSegment = segmentTerms.map((term) => term.substr(0, length)).join('');

		acc.push(shortSegment);
		return acc;
	}, []);

	return shortSegments.join(separator);
}

interface IHashOptions {
	length?: number;
}

/**
 * Returns a hashed input.
 *
 * @param input String to be hashed.
 * @param options.length Optionally, shorten the output to desired length.
 */
export function hash(input: string, options: IHashOptions = {}): string {
	const hashFunction = shajs('sha1');
	hashFunction.update(input, 'utf8');
	const hashedInput = hashFunction.digest('hex');
	if (options.length) {
		return hashedInput.slice(0, options.length);
	}
	return hashedInput;
}