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// this work for additional information regarding copyright
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// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

// Package status reads Apache HTTPD server status from the mod_status module.
package status

import (
	"github.com/elastic/beats/libbeat/common"
	"github.com/elastic/beats/libbeat/logp"
	"github.com/elastic/beats/metricbeat/helper"
	"github.com/elastic/beats/metricbeat/mb"
	"github.com/elastic/beats/metricbeat/mb/parse"
)

const (
	// defaultScheme is the default scheme to use when it is not specified in
	// the host config.
	defaultScheme = "http"

	// defaultPath is the default path to the mod_status endpoint on the
	// Apache HTTPD server.
	defaultPath = "/server-status"

	// autoQueryParam is a query parameter added to the request so that
	// mod_status returns machine-readable output.
	autoQueryParam = "auto"
)

var (
	debugf = logp.MakeDebug("apache-status")

	hostParser = parse.URLHostParserBuilder{
		DefaultScheme: defaultScheme,
		PathConfigKey: "server_status_path",
		DefaultPath:   defaultPath,
		QueryParams:   autoQueryParam,
	}.Build()
)

func init() {
	mb.Registry.MustAddMetricSet("apache", "status", New,
		mb.WithHostParser(hostParser),
		mb.DefaultMetricSet(),
	)
}

// MetricSet for fetching Apache HTTPD server status.
type MetricSet struct {
	mb.BaseMetricSet
	http *helper.HTTP
}

// New creates new instance of MetricSet.
func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
	http, err := helper.NewHTTP(base)
	if err != nil {
		return nil, err
	}
	return &MetricSet{
		base,
		http,
	}, nil
}

// Fetch makes an HTTP request to fetch status metrics from the mod_status endpoint.
func (m *MetricSet) Fetch() (common.MapStr, error) {
	scanner, err := m.http.FetchScanner()
	if err != nil {
		return nil, err
	}

	data, _ := eventMapping(scanner, m.Host())
	return data, nil
}