package gologger
  
  import (
  	"fmt"

  	"net/http"

  	"net/http/httputil"

  	"os"

  	"path/filepath"

  	"runtime"

  	"strings"

  	"sync"

  	"time"

  )

  const (
  	MaxLogSize5MB   int64 = 5 * 1024 * 1024
  	MaxLogSize1MB   int64 = 1 * 1024 * 1024
  	MaxLogSize500KB int64 = 500 * 1024
  	MaxLogSize100KB int64 = 100 * 1024
  	MaxLogSize512B  int64 = 512

  	logDirName            = "log"

  )

  type Logger struct {

  	mu         *sync.Mutex
  	outputFile *os.File

  	outputFileName string
  	maxFileSize    int64

  
  	splitCount int

  }

  func New(name string, maxFileSize int64) (logger *Logger, err error) {

  	logger = &Logger{}

  	logger.outputFileName = name + "-log"
  	logger.mu = &sync.Mutex{}
  	logger.maxFileSize = maxFileSize

  	err = os.Mkdir(logDirName, os.ModePerm)
  	if err != nil {
  		if !os.IsExist(err) {
  			fmt.Printf("logger: mkdir: couldn't create event log directory
  ")

  			return nil, err

  		}
  	}

  	date := strings.Replace(time.Now().Format(time.RFC3339), ":", ".", -1)
  	logger.outputFileName += "_" + date + ".txt"
  	path := filepath.Join(logDirName, logger.outputFileName)

  	logger.outputFile, err = os.Create(path)
  	if err != nil {
  		fmt.Printf("logger: new: couldn't create event log file
  ")
  		return nil, err

  	}

  	return logger, nil

  }

  func (l *Logger) Print(format string, v ...interface{}) {

  	msg := fmt.Sprintf(format, v...)
  	fmt.Printf(time.Now().Format(time.RFC3339) + ": " + msg + "
  ")

  }

  func (l *Logger) Log(format string, v ...interface{}) {
  	if l.outputFile != nil {
  		l.mu.Lock()
  		defer l.mu.Unlock()

  		msg := fmt.Sprintf(format, v...)
  		s := time.Now().Format(time.RFC3339) + ": " + msg + "
  "

  		if l.shouldSplit(len(s)) {
  			l.split()

  		}

  		l.outputFile.WriteString(s)

  	}

  }

  func (l *Logger) LogRequest(req *http.Request, userid string) {
  	if l.outputFile != nil {
  		if userid == "" {
  			userid = "-"
  		}

  		var b strings.Builder

  		b.WriteString("Request:
  ")

  		// CLF-like header
  		ts := time.Now().Format(time.RFC3339)

  		fmt.Fprintf(&b, "%s %s
  ", req.RemoteAddr, ts)

  		body, err := httputil.DumpRequest(req, true)
  		if err != nil {

  			fmt.Fprintf(os.Stderr, "%v
  ", err)

  		} else {
  			b.WriteString(string(body))

  		}

  		b.WriteString("
  ")

  
  		msg := b.String()

  
  		l.mu.Lock()
  		defer l.mu.Unlock()
  
  		if l.shouldSplit(len(msg)) {
  			l.split()
  		}
  		l.outputFile.WriteString(msg)
  	}
  }

  func (l *Logger) LogResponse(w http.ResponseWriter, req *http.Request, duration time.Duration) {

  	if l.outputFile != nil {
  		var b strings.Builder
  		b.WriteString("Response:
  ")

  		fmt.Fprintf(&b, "%s %s
  ", req.Method, req.RequestURI)

  		for k, v := range w.Header() {

  			fmt.Fprintf(&b, "%s: %s
  ", k, v)

  		}

  		fmt.Fprintf(&b, "
  Completed in: %v
  ", duration)
  		b.WriteString("==============================================================
  
  ")

  		msg := b.String()

  
  		l.mu.Lock()
  		defer l.mu.Unlock()
  
  		if l.shouldSplit(len(msg)) {
  			l.split()

  		}

  		l.outputFile.WriteString(msg)

  	}

  }

  func (l *Logger) Trace(format string, v ...interface{}) {
  	if l.outputFile != nil {
  		l.mu.Lock()
  		defer l.mu.Unlock()

  		_, file, line, ok := runtime.Caller(1)

  
  		s := ""
  		msg := fmt.Sprintf(format, v...)

  		if ok {

  			s = fmt.Sprintf("%s: %s %d: %s
  ", time.Now().Format(time.RFC3339), file, line, msg)

  		} else {

  			s = fmt.Sprintf(time.Now().Format(time.RFC3339) + ": [can't retreive stack details]:" + msg + "
  ")
  		}

  		if l.shouldSplit(len(s)) {
  			l.split()

  		}

  		l.outputFile.WriteString(s)

  	}

  }

  func (l *Logger) Close() {
  	if l.outputFile != nil {
  		err := l.outputFile.Close()

  		if err != nil {
  			fmt.Printf("logger: on exit: couldn't close event log file
  ")
  		}

  	}

  }

  func (l *Logger) split() {

  	// close old file
  	err := l.outputFile.Close()
  	if err != nil {
  		fmt.Printf("logger: split: couldn't close event file
  ")
  		return
  	}

  
  	l.splitCount++

  	// open new file
  	var errnew error

  	path := filepath.Join(logDirName, l.outputFileName+fmt.Sprintf("(%d)", l.splitCount))

  	l.outputFile, errnew = os.Create(path)

  	if errnew != nil {
  		fmt.Printf("logger: split: couldn't create event log file
  ")

  	}
  }

  func (l *Logger) shouldSplit(nextEntrySize int) bool {
  	stats, _ := l.outputFile.Stat()
  	return int64(nextEntrySize) >= (l.maxFileSize - stats.Size())

  }