package glog

import (
  "fmt"
  "io"
  "os"
  "path"
  "runtime"
  "sync"
  "time"
)

const (
  MaskUNKNOWN = 1 << iota
  MaskDEBUG
  MaskTRACE
  MaskINFO
  MaskWARNING
  MaskERROR
  MaskFATAL
  MaskStdMask = MaskINFO | MaskWARNING | MaskERROR | MaskFATAL
  MaskStdAll  = MaskUNKNOWN | MaskDEBUG | MaskTRACE | MaskINFO | MaskWARNING | MaskERROR | MaskFATAL
)

const (
  FlagDate = 1 << iota
  FlagTime
  FlagLongFile
  FlagShortFile
  FlagPrefix
  FlagStdFlag = FlagDate | FlagTime | FlagPrefix
)

var (
  prefixUNKNOWN = "[UNKNOWN] "
  prefixDEBUG   = "[DEBUG  ] "
  prefixTRACE   = "[TRACE  ] "
  prefixINFO    = "[INFO   ] "
  prefixWARNING = "[WARNING] "
  prefixERROR   = "[ERROR  ] "
  prefixFATAL   = "[FATAL  ] "
)

var mask = MaskStdAll
var flag = FlagStdFlag

var consoleStdout *File
var consoleStderr *File
var file *File
var lock sync.RWMutex

func init() {
  consoleStdout = new(File)
  consoleStdout.file = os.Stdout
  consoleStderr = new(File)
  consoleStderr.file = os.Stderr
  file = nil
  lock = sync.RWMutex{}
}

func SetMask(m int) {
  lock.Lock()
  defer lock.Unlock()
  mask = m
}

func SetFlag(f int) {
  lock.Lock()
  defer lock.Unlock()
  flag = f
}

func SetLogFile(path string) error {
  f, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
  if err != nil {
    return err
  }
  lock.Lock()
  defer lock.Unlock()
  file = new(File)
  file.file = f
  return nil
}

func CloseFile() {
  lock.Lock()
  defer lock.Unlock()
  if file == nil {
    return
  }
  err := file.file.Close()
  if err != nil {
    write(os.Stderr, prefixERROR, "failed to close log file")
  }
  file = nil
}

func write(w io.Writer, prefix string, format string, values ...any) {
  now := ""
  if (flag&FlagDate) != 0 && (flag&FlagTime) != 0 {
    now = time.Now().Format("2006-01-02 15:04:05 ")
  } else if (flag & FlagDate) != 0 {
    now = time.Now().Format("2006-01-02 ")
  } else if (flag & FlagTime) != 0 {
    now = time.Now().Format("15:04:05 ")
  }
  if (flag & FlagPrefix) != 0 {
    _, _ = w.Write([]byte(now))
    _, _ = w.Write([]byte(prefix))
  } else {
    _, _ = w.Write([]byte(prefix))
    _, _ = w.Write([]byte(now))
  }

  if (flag & FlagLongFile) != 0 {
    _, p, l, ok := runtime.Caller(2)
    if ok {
      _, _ = fmt.Fprintf(w, "%s:%d ", p, l)
    } else {
      _, _ = w.Write([]byte("?:? "))
    }
  } else if (flag & FlagShortFile) != 0 {
    _, p, l, ok := runtime.Caller(2)
    if ok {
      _, _ = fmt.Fprintf(w, "%s:%d ", path.Base(p), l)
    } else {
      _, _ = w.Write([]byte("?:? "))
    }
  }
  _, _ = w.Write([]byte("| "))
  _, _ = fmt.Fprintf(w, format, values...)
  _, _ = w.Write([]byte("\n"))
}

func Unknown(format string, values ...any) {
  if (mask & MaskUNKNOWN) != 0 {
    lock.Lock()
    defer lock.Unlock()
    if file != nil {
      write(file, prefixUNKNOWN, format, values...)
    }
    write(consoleStdout, prefixUNKNOWN, format, values...)
  }
}

func Debug(format string, values ...any) {
  if (mask & MaskDEBUG) != 0 {
    lock.Lock()
    defer lock.Unlock()
    if file != nil {
      write(file, prefixDEBUG, format, values...)
    }
    write(consoleStdout, prefixDEBUG, format, values...)
  }
}

func Trace(format string, values ...any) {
  if (mask & MaskTRACE) != 0 {
    lock.Lock()
    defer lock.Unlock()
    if file != nil {
      write(file, prefixTRACE, format, values...)
    }
    write(consoleStdout, prefixTRACE, format, values...)
  }
}

func Info(format string, values ...any) {
  if (mask & MaskINFO) != 0 {
    lock.Lock()
    defer lock.Unlock()
    if file != nil {
      write(file, prefixINFO, format, values...)
    }
    write(consoleStdout, prefixINFO, format, values...)
  }
}

func Warning(format string, values ...any) {
  if (mask & MaskWARNING) != 0 {
    lock.Lock()
    defer lock.Unlock()
    if file != nil {
      write(file, prefixWARNING, format, values...)
    }
    write(consoleStdout, prefixWARNING, format, values...)
  }
}

func Error(format string, values ...any) {
  if (mask & MaskERROR) != 0 {
    lock.Lock()
    defer lock.Unlock()
    if file != nil {
      write(file, prefixERROR, format, values...)
    }
    write(consoleStderr, prefixERROR, format, values...)
  }
}

func Fatal(format string, values ...any) {
  if (mask & MaskFATAL) != 0 {
    lock.Lock()
    defer lock.Unlock()
    if file != nil {
      write(file, prefixFATAL, format, values...)
    }
    write(consoleStderr, prefixFATAL, format, values...)
    os.Exit(0)
  }
}