(function (Prism) {

	// https://freemarker.apache.org/docs/dgui_template_exp.html

	// FTL expression with 4 levels of nesting supported
	var FTL_EXPR = /[^<()"']|\((?:<expr>)*\)|<(?!#--)|<#--(?:[^-]|-(?!->))*-->|"(?:[^\\"]|\\.)*"|'(?:[^\\']|\\.)*'/.source;
	for (var i = 0; i < 2; i++) {
		FTL_EXPR = FTL_EXPR.replace(/<expr>/g, function () { return FTL_EXPR; });
	}
	FTL_EXPR = FTL_EXPR.replace(/<expr>/g, /[^\s\S]/.source);

	var ftl = {
		'comment': /<#--[\s\S]*?-->/,
		'string': [
			{
				// raw string
				pattern: /\br("|')(?:(?!\1)[^\\]|\\.)*\1/,
				greedy: true
			},
			{
				pattern: RegExp(/("|')(?:(?!\1|\$\{)[^\\]|\\.|\$\{(?:(?!\})(?:<expr>))*\})*\1/.source.replace(/<expr>/g, function () { return FTL_EXPR; })),
				greedy: true,
				inside: {
					'interpolation': {
						pattern: RegExp(/((?:^|[^\\])(?:\\\\)*)\$\{(?:(?!\})(?:<expr>))*\}/.source.replace(/<expr>/g, function () { return FTL_EXPR; })),
						lookbehind: true,
						inside: {
							'interpolation-punctuation': {
								pattern: /^\$\{|\}$/,
								alias: 'punctuation'
							},
							rest: null
						}
					}
				}
			}
		],
		'keyword': /\b(?:as)\b/,
		'boolean': /\b(?:true|false)\b/,
		'builtin-function': {
			pattern: /((?:^|[^?])\?\s*)\w+/,
			lookbehind: true,
			alias: 'function'
		},
		'function': /\w+(?=\s*\()/,
		'number': /\d+(?:\.\d+)?/,
		'operator': /\.\.[<*!]?|->|--|\+\+|&&|\|\||\?{1,2}|[-+*/%!=<>]=?|\b(?:gt|gte|lt|lte)\b/,
		'punctuation': /[,;.:()[\]{}]/
	};

	ftl.string[1].inside.interpolation.inside.rest = ftl;

	Prism.languages.ftl = {
		'ftl-comment': {
			// the pattern is shortened to be more efficient
			pattern: /^<#--[\s\S]*/,
			alias: 'comment'
		},
		'ftl-directive': {
			pattern: /^<[\s\S]+>$/,
			inside: {
				'directive': {
					pattern: /(^<\/?)[#@][a-z]\w*/i,
					lookbehind: true,
					alias: 'keyword'
				},
				'punctuation': /^<\/?|\/?>$/,
				'content': {
					pattern: /\s*\S[\s\S]*/,
					alias: 'ftl',
					inside: ftl
				}
			}
		},
		'ftl-interpolation': {
			pattern: /^\$\{[\s\S]*\}$/,
			inside: {
				'punctuation': /^\$\{|\}$/,
				'content': {
					pattern: /\s*\S[\s\S]*/,
					alias: 'ftl',
					inside: ftl
				}
			}
		}
	};

	Prism.hooks.add('before-tokenize', function (env) {
		var pattern = RegExp(/<#--[\s\S]*?-->|<\/?[#@][a-zA-Z](?:<expr>)*?>|\$\{(?:<expr>)*?\}/.source.replace(/<expr>/g, function () { return FTL_EXPR; }), 'gi');
		Prism.languages['markup-templating'].buildPlaceholders(env, 'ftl', pattern);
	});

	Prism.hooks.add('after-tokenize', function (env) {
		Prism.languages['markup-templating'].tokenizePlaceholders(env, 'ftl');
	});

}(Prism));
