package main

import (
	"bufio"
	"log"
	"os"
	"regexp"
	"strings"
	"time"

	"git.scraperwall.com/scw/data/v2"
	"github.com/hpcloud/tail"
	"github.com/kr/pretty"
	"github.com/satyrius/gonx"
)

func nginxLogCapture(logfile, format, serverHost string) {
	if _, err := os.Stat(logfile); err != nil {
		log.Fatalf("%s: %s", logfile, err)
	}

	t, err := tail.TailFile(logfile, tail.Config{
		Follow:   true,                                 // follow the file
		ReOpen:   true,                                 // reopen log file when it gets closed/rotated
		Poll:     config.TailPoll,                      // use file polling to detect a file rollover
		Logger:   tail.DiscardingLogger,                // don't log anything
		Location: &tail.SeekInfo{Offset: 0, Whence: 2}, // start at the end of the file
	})
	if err != nil {
		log.Fatalf("%s: %s", logfile, err)
	}

	// `$remote_addr - $remote_user [$time_local] "$request" $status $body_bytes_sent "$http_referer" "$http_user_agent"`
	p := gonx.NewParser(format)
	reqRegexp := regexp.MustCompile(`^([A-Z]+)\s+(.+?)\s+(HTTP/\d+\.\d+)$`)

	for line := range t.Lines {
		var remote string
		var err error

		l := line.Text

		logEntry, err := p.ParseString(l)
		if err != nil {
			log.Println(err)
			continue
		}

		remote, err = logEntry.Field("remote_addr")
		if err != nil {
			log.Println(err)
			continue
		}

		xff, err := logEntry.Field("http_x_forwarded_for")
		if err != nil && xff != "" {
			if config.Trace {
				log.Printf("Using XFF: %s\n", xff)
			}

			remote = xff
		}

		if remote == "" {
			log.Println("remote is empty: ignoring request.")
			continue
		}

		// only use the first host in case there are multiple hosts in the log
		if cidx := strings.Index(remote, ","); cidx >= 0 {
			remote = remote[0:cidx]
		}

		timestampStr, err := logEntry.Field("time_local")
		if err != nil {
			log.Println(err)
			continue
		}
		timeStamp, err := time.Parse("02/Jan/2006:15:04:05 -0700", timestampStr)
		if err != nil {
			log.Println(err)
			continue
		}

		httpRequest, err := logEntry.Field("request")
		if err != nil {
			log.Println(err)
			continue
		}

		reqData := reqRegexp.FindStringSubmatch(httpRequest)
		if len(reqData) < 4 {
			log.Printf("reqData is too short: %d instead of 4\n", len(reqData))
			continue
		}

		host, err := logEntry.Field("host")
		if err != nil {
			host = serverHost
			if host == "" {
				host = "[not available]"
			}
		}

		customer, err := logEntry.Field("sc_customer")
		if err != nil {
			customer = "[not set]"
		}

		request := data.Request{
			IpSrc:     remote,
			Origin:    remote,
			Source:    remote,
			IpDst:     "127.0.0.1",
			PortSrc:   0,
			PortDst:   0,
			TcpSeq:    0,
			CreatedAt: timeStamp.Unix(),
			Url:       reqData[2],
			Method:    reqData[1],
			Host:      host,
			Protocol:  reqData[3],
			Customer:  customer,
		}

		request.Referer, _ = logEntry.Field("http_referer")
		request.UserAgent, _ = logEntry.Field("http_user_agent")

		if config.Trace {
			log.Printf("[%s] %s\n", request.Source, request.Url)
		}

		count++
		publishRequest(config.NatsQueue, &request)
	}
}

func nginxLogReplay(logfile, format string) {
	file, err := os.Open(logfile)
	if err != nil {
		log.Fatalf("%s: %s", logfile, err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	var tOffset time.Duration

	// `$remote_addr - $remote_user [$time_local] "$request" $status $body_bytes_sent "$http_referer" "$http_user_agent"`
	p := gonx.NewParser(format)
	reqRegexp := regexp.MustCompile(`^([A-Z]+)\s+(.+?)\s+(HTTP/\d+\.\d+)$`)

	for scanner.Scan() {
		l := scanner.Text()

		if err := scanner.Err(); err != nil {
			log.Fatal(err)
		}

		var remote string
		var err error

		logEntry, err := p.ParseString(l)
		if err != nil {
			log.Println(err)
			continue
		}

		if config.Trace {
			pretty.Println(logEntry)
		}

		remote, err = logEntry.Field("remote_addr")
		if err != nil {
			log.Println(err)
			continue
		}

		xff, err := logEntry.Field("http_x_forwarded_for")
		if err != nil && xff != "" {
			if config.Trace {
				log.Printf("Using XFF: %s\n", xff)
			}

			remote = xff
		}

		if remote == "" {
			log.Println("remote is empty: ignoring request.")
			continue
		}

		// only use the first host in case there are multiple hosts in the log
		if cidx := strings.Index(remote, ","); cidx >= 0 {
			remote = remote[0:cidx]
		}

		timestampStr, err := logEntry.Field("time_local")
		if err != nil {
			log.Println(err)
			continue
		}
		timeStamp, err := time.Parse("02/Jan/2006:15:04:05 -0700", timestampStr)
		if err != nil {
			log.Println(err)
			continue
		}

		if tOffset == 0 {
			tOffset = time.Now().Sub(timeStamp)
		}

		if timeStamp.Add(tOffset).After(time.Now()) {
			time.Sleep(timeStamp.Add(tOffset).Sub(time.Now()))
		}

		httpRequest, err := logEntry.Field("request")
		if err != nil {
			log.Println(err)
			continue
		}

		reqData := reqRegexp.FindStringSubmatch(httpRequest)
		if len(reqData) < 4 {
			log.Printf("reqData is too short: %d instead of 4\n", len(reqData))
			continue
		}

		host := config.HostName
		if host == "" {
			host = "[not available]"
		}

		request := data.Request{
			IpSrc:     remote,
			Origin:    remote,
			Source:    remote,
			IpDst:     "127.0.0.1",
			PortSrc:   0,
			PortDst:   0,
			TcpSeq:    0,
			CreatedAt: timeStamp.Add(tOffset).UnixNano(),
			Url:       reqData[2],
			Method:    reqData[1],
			Host:      host,
			Protocol:  reqData[3],
		}

		request.Referer, _ = logEntry.Field("http_referer")
		request.UserAgent, _ = logEntry.Field("http_user_agent")

		if config.Trace {
			log.Printf("[%s] %s\n", request.Source, request.Url)
		}

		count++
		publishRequest(config.NatsQueue, &request)

	}
}