// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @constructor
 * @param {string} metric
 * @param {number} value
 * @param {string} description
 */
WebInspector.ServerTiming = function(metric, value, description)
{
    this.metric = metric;
    this.value = value;
    this.description = description;
}

/**
 * @param {!Array<!WebInspector.NetworkRequest.NameValue>} headers
 * @return {?Array<!WebInspector.ServerTiming>}
 */
WebInspector.ServerTiming.parseHeaders = function(headers)
{
    var rawServerTimingHeaders = headers.filter(item => item.name.toLowerCase() === "server-timing");
    if (!rawServerTimingHeaders.length)
        return null;

    /**
     * @param {?string} valueString
     * @return {?Array<!WebInspector.ServerTiming>}
     */
    function createFromHeaderValue(valueString)
    {
        // https://www.w3.org/TR/server-timing/
        var serverTimingMetricRegExp = /[ \t]*([\!\#\$\%\&\'\*\+\-\.\^\_\`\|\~0-9A-Za-z]+)[ \t]*(?:=[ \t]*(\d+(?:\.\d+)?))?[ \t]*(?:;[ \t]*(?:"([^"]+)"|([\!\#\$\%\&\'\*\+\-\.\^\_\`\|\~0-9A-Za-z]+)))?[ \t]*(?:,(.*))?/;
        var metricMatch;
        var result = [];
        while (valueString && (metricMatch = serverTimingMetricRegExp.exec(valueString))) {
            var metric = metricMatch[1];
            var value = metricMatch[2];
            var description = metricMatch[3] || metricMatch[4];
            if (value !== null)
                value = Math.abs(parseFloat(metricMatch[2]));
            valueString = metricMatch[5]; // comma delimited headers
            result.push(new WebInspector.ServerTiming(metric, value, description));
        }
        return result;
    }

    var serverTimings = rawServerTimingHeaders.reduce((memo, header) => {
        var timing = createFromHeaderValue(header.value);
        Array.prototype.push.apply(memo, timing);
        return memo;
    }, []);
    serverTimings.sort((a, b) => a.metric.toLowerCase().compareTo(b.metric.toLowerCase()));
    return serverTimings;
}