package main

// get https://www.expressvpn.com/vpn-server
// remove everyting starting with >
// remove until "Not supported" and after What the green checks mean

import (
	"bufio"
	"errors"
	"fmt"
	"net"
	"net/http"
	"strings"
	"sync"
	"time"
)

func (s *OpenVpnMgt) getServerList() error {
	var mux sync.Mutex
	requestCount := 0
	VPNNames := map[string]bool{}

	// Create HTTP client with timeout
	client := &http.Client{
		Timeout: 30 * time.Second,
	}

	// Make request
	resp, err := client.Get("https://www.expressvpn.com/vpn-server")
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return errors.New(fmt.Sprintf("Server List URL is not valid (%d)\n", resp.StatusCode))
	}

	buf := bufio.NewReader(bufio.NewReader(resp.Body))
	start := false
	for {
		line, err := buf.ReadString('\n')
		if err != nil {
			break
		}
		line = strings.Trim(line, "\n\r ")
		if strings.HasPrefix(line, "<") {
			continue
		}
		if line == "Not supported" {
			start = true
			continue
		}
		if line == "What the green checks mean" {
			start = false
		}
		if !start {
			continue
		}

		if line == "" {
			continue
		}

		requestCount++
		go func(line string) {
			line = strings.ToLower(line)
			line = strings.Replace(line, " &amp; ", "", -1)
			line = strings.Replace(line, " ", "", -1)

			name := fmt.Sprintf("%s-ca-version-2.expressnetw.com", line)
			if _, err := net.ResolveIPAddr("ip4", name); err == nil {
				mux.Lock()
				VPNNames[name] = true
				mux.Unlock()
			}
			requestCount--
		}(line)
	}

	// wait for all resolutions
	for requestCount > 0 {
		time.Sleep(100 * time.Millisecond)
	}

	if len(VPNNames) == 0 {
		return errors.New("Can't get a list of VPN endpoints")
	}

	// add the right values
	keys := make([]string, 0, len(VPNNames))
	for k := range VPNNames {
		keys = append(keys, k)
	}

	s.Lock()
	s.VpnRemotes = keys
	s.Unlock()
	return nil
}