import { decodeHTML, decodeHTMLAttribute, decodeXML, escapeText } from 'entities';

/**
 * Pre-compiled RegExp patterns for encoding/decoding.
 * Using pre-compiled patterns avoids RegExp compilation on each call.
 */

// Encoding patterns
const ENCODE_XML_ATTR_REGEXP = /[&"<>\t\n\r]/g;
const ENCODE_HTML_ATTR_REGEXP = /[&"]/g;

// Decoding patterns
const DECODE_TEXT_CONTENT_REGEXP = /&(?:nbsp|lt|gt|amp);/g;

// Encoding lookup tables
const ENCODE_XML_ATTR_MAP: { [key: string]: string } = {
	'&': '&amp;',
	'"': '&quot;',
	'<': '&lt;',
	'>': '&gt;',
	'\t': '&#x9;',
	'\n': '&#xA;',
	'\r': '&#xD;'
};

const ENCODE_HTML_ATTR_MAP: { [key: string]: string } = {
	'&': '&amp;',
	'"': '&quot;'
};

// Decoding lookup tables
const DECODE_TEXT_CONTENT_MAP: { [key: string]: string } = {
	'&nbsp;': String.fromCharCode(160),
	'&lt;': '<',
	'&gt;': '>',
	'&amp;': '&'
};

/**
 * Utility for encoding.
 */
export default class XMLEncodeUtility {
	/**
	 * Encodes attribute value.
	 *
	 * @param value Value.
	 * @returns Escaped value.
	 */
	public static encodeXMLAttributeValue(value: string | null): string {
		if (value === null) {
			return '';
		}
		return value.replace(ENCODE_XML_ATTR_REGEXP, (char) => ENCODE_XML_ATTR_MAP[char]);
	}

	/**
	 * Decodes attribute value.
	 *
	 * Uses the 'entities' library for comprehensive XML character reference support.
	 *
	 * @param value Value.
	 * @returns Decoded value.
	 */
	public static decodeXMLAttributeValue(value: string | null): string {
		if (value === null) {
			return '';
		}
		return decodeXML(value);
	}

	/**
	 * Encodes attribute value.
	 *
	 * @param value Value.
	 * @returns Escaped value.
	 */
	public static encodeHTMLAttributeValue(value: string | null): string {
		if (value === null) {
			return '';
		}
		return value.replace(ENCODE_HTML_ATTR_REGEXP, (char) => ENCODE_HTML_ATTR_MAP[char]);
	}

	/**
	 * Decodes attribute value.
	 *
	 * Uses the 'entities' library for comprehensive HTML5 character reference support,
	 * including named entities, decimal numeric references (&#34;), and
	 * hexadecimal numeric references (&#x22;).
	 *
	 * @param value Value.
	 * @returns Decoded value.
	 */
	public static decodeHTMLAttributeValue(value: string | null): string {
		if (value === null) {
			return '';
		}
		return decodeHTMLAttribute(value);
	}

	/**
	 * Encodes text content.
	 *
	 * Uses the 'entities' library which follows the WHATWG HTML serialization spec.
	 * Encodes &, <, >, and non-breaking space.
	 *
	 * @param text Value.
	 * @returns Escaped value.
	 */
	public static encodeTextContent(text: string | null): string {
		if (text === null) {
			return '';
		}
		return escapeText(text);
	}

	/**
	 * Decodes text content.
	 *
	 * @param text Value.
	 * @returns Decoded value.
	 */
	public static decodeTextContent(text: string | null): string {
		if (text === null) {
			return '';
		}
		return text.replace(DECODE_TEXT_CONTENT_REGEXP, (entity) => DECODE_TEXT_CONTENT_MAP[entity]);
	}

	/**
	 * Decodes HTML entities.
	 *
	 * Uses the 'entities' library for comprehensive HTML5 named character reference support.
	 *
	 * @param value Value.
	 * @returns Decoded value.
	 */
	public static decodeHTMLEntities(value: string): string {
		if (value === null) {
			return '';
		}

		return decodeHTML(value);
	}

	/**
	 * Decodes XML entities.
	 *
	 * Uses the 'entities' library for comprehensive XML character reference support,
	 * including named entities and numeric references.
	 *
	 * @param value Value.
	 * @returns Decoded value.
	 */
	public static decodeXMLEntities(value: string): string {
		if (value === null) {
			return '';
		}
		return decodeXML(value);
	}
}