/*
Copyright 2016 The Kubernetes Authors.

Licensed under 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 main

import (
	"fmt"
	"io/ioutil"
	"net/http"
	"regexp"
	"strconv"
)

var (
	ac      = regexp.MustCompile(`Active connections: (\d+)`)
	sahr    = regexp.MustCompile(`(\d+)\s(\d+)\s(\d+)`)
	reading = regexp.MustCompile(`Reading: (\d+)`)
	writing = regexp.MustCompile(`Writing: (\d+)`)
	waiting = regexp.MustCompile(`Waiting: (\d+)`)
)

type nginxStatus struct {
	// Active total number of active connections
	Active int
	// Accepted total number of accepted client connections
	Accepted int
	// Handled total number of handled connections. Generally, the parameter value is the same as accepts unless some resource limits have been reached (for example, the worker_connections limit).
	Handled int
	// Requests total number of client requests.
	Requests int
	// Reading current number of connections where nginx is reading the request header.
	Reading int
	// Writing current number of connections where nginx is writing the response back to the client.
	Writing int
	// Waiting current number of idle client connections waiting for a request.
	Waiting int
}

func getNginxStatus() (*nginxStatus, error) {
	resp, err := http.DefaultClient.Get(fmt.Sprintf("http://localhost:%v%v", ngxHealthPort, ngxStatusPath))
	if err != nil {
		return nil, fmt.Errorf("unexpected error scraping nginx status page: %v", err)
	}

	data, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("unexpected error scraping nginx status page (%v)", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
		return nil, fmt.Errorf("unexpected error scraping nginx status page (status %v)", resp.StatusCode)
	}

	return parse(string(data)), nil
}

func parse(data string) *nginxStatus {
	acr := ac.FindStringSubmatch(data)
	sahrr := sahr.FindStringSubmatch(data)
	readingr := reading.FindStringSubmatch(data)
	writingr := writing.FindStringSubmatch(data)
	waitingr := waiting.FindStringSubmatch(data)

	return &nginxStatus{
		toInt(acr, 1),
		toInt(sahrr, 1),
		toInt(sahrr, 2),
		toInt(sahrr, 3),
		toInt(readingr, 1),
		toInt(writingr, 1),
		toInt(waitingr, 1),
	}
}

func toInt(data []string, pos int) int {
	if len(data) == 0 {
		return 0
	}
	if pos > len(data) {
		return 0
	}
	if v, err := strconv.Atoi(data[pos]); err == nil {
		return v
	}
	return 0
}