(function () {

if (typeof self === 'undefined' || !self.Prism || !self.document) {
        return;
}

/**
 * Class name for <pre> which is activating the plugin
 * @type {String}
 */
var PLUGIN_CLASS = 'line-numbers';

/**
 * Resizes line numbers spans according to height of line of code
 * @param  {Element} element <pre> element
 */
var _resizeElement = function (element) {
        var codeStyles = getStyles(element);
        var whiteSpace = codeStyles['white-space'];

        if (whiteSpace === 'pre-wrap' || whiteSpace === 'pre-line') {
                var codeElement = element.querySelector('code');
                var lineNumbersWrapper = element.querySelector('.line-numbers-rows');
                var lineNumberSizer = element.querySelector('.line-numbers-sizer');
                var codeLines = element.textContent.split('\n');

                if (!lineNumberSizer) {
                        lineNumberSizer = document.createElement('span');
                        lineNumberSizer.className = 'line-numbers-sizer';

                        codeElement.appendChild(lineNumberSizer);
                }

                lineNumberSizer.style.display = 'block';

                codeLines.forEach(function (line, lineNumber) {
                        lineNumberSizer.textContent = line || '\n';
                        var lineSize = lineNumberSizer.getBoundingClientRect().height;
                        lineNumbersWrapper.children[lineNumber].style.height = lineSize + 'px';
                });

                lineNumberSizer.textContent = '';
                lineNumberSizer.style.display = 'none';
        }
};

/**
 * Returns style declarations for the element
 * @param {Element} element
 */
var getStyles = function (element) {
        if (!element) {
                return null;
        }

        return window.getComputedStyle ? getComputedStyle(element) : (element.currentStyle || null);
};

window.addEventListener('resize', function () {
        Array.prototype.forEach.call(document.querySelectorAll('pre.' + PLUGIN_CLASS), _resizeElement);
});

Prism.hooks.add('complete', function (env) {
        if (!env.code) {
                return;
        }

        // works only for <code> wrapped inside <pre> (not inline)
        var pre = env.element.parentNode;
        // Original regex check for class, leaving it here
        // for its redundancy check
        var clsReg = /\s*\bline-numbers\b\s*/;
        // New regex check for opt-out class
        var clsRegB = /\s*\bno-line-numbers\b\s*/;

        if (env.element.querySelector(".line-numbers-rows")) {
                // Abort if line numbers already exists
                return;
        }

        // Added to facilitate opting out
        if (clsRegB.test(pre.className)) {
                // Respect the opt-out
                return;
        }

        if (clsReg.test(env.element.className)) {
                // Remove the class "line-numbers" from the <code>
                env.element.className = env.element.className.replace(clsReg, ' ');
        }
        if (!clsReg.test(pre.className)) {
                // Add the class "line-numbers" to the <pre>
                pre.className += ' line-numbers';
        }

        var match = env.code.match(/\n(?!$)/g);
        var linesNum = match ? match.length + 1 : 1;
        var lineNumbersWrapper;

        var lines = new Array(linesNum + 1);
        lines = lines.join('<span></span>');

        lineNumbersWrapper = document.createElement('span');
        lineNumbersWrapper.setAttribute('aria-hidden', 'true');
        lineNumbersWrapper.className = 'line-numbers-rows';
        lineNumbersWrapper.innerHTML = lines;

        if (pre.hasAttribute('data-start')) {
                pre.style.counterReset = 'linenumber ' + (parseInt(pre.getAttribute('data-start'), 10) - 1);
        }

        env.element.appendChild(lineNumbersWrapper);

        _resizeElement(pre);
});

}());