package common

import(
	"fmt"
	"log"
	"log/syslog"
	"io"
)

type Logger struct {
	useSyslog bool
	verbosity int
	
	syslog *syslog.Writer
	stdlog *log.Logger
}


func NewLogger(prefix string, useSyslog bool, syslogFailOutput io.Writer, verbosity int) (*Logger, error) {
	out := Logger{
		verbosity: verbosity,
		useSyslog: useSyslog}

	var err error
	out.stdlog = log.New(syslogFailOutput, prefix+" ", log.LstdFlags)

	if useSyslog {
		out.syslog, err = syslog.New(syslog.LOG_INFO, prefix)
	}


	return &out, err
}


func (l *Logger) Debug(m string, v ...interface{}) {
	var err error
	
	if l.verbosity < 2 { // -vv
		return
	}

	if l.useSyslog {
		err = l.syslog.Debug(l.buildString("", m, v...))
	}

	if err != nil || !l.useSyslog {
		l.stdlog.Println(l.buildString("DEBUG", m, v...))
	}
}

func (l *Logger) Info(m string, v ...interface{}) {
	var err error

	if l.verbosity < 1 { // -v
		return
	}

	if l.useSyslog {
		err = l.syslog.Info(l.buildString("", m, v...))
	}

	if err != nil || !l.useSyslog {
		l.stdlog.Println(l.buildString(" INFO", m, v...))
	}
}

func (l *Logger) Warn(m string, v ...interface{}) {
	var err error
	
	// Warnings are always shown

	if l.useSyslog {
		err = l.syslog.Warning(l.buildString("", m, v...))
	}

	if err != nil || !l.useSyslog {
		l.stdlog.Println(l.buildString(" WARN", m, v...))
	}
}

func (l *Logger) Error(m string, v ...interface{}) {
	var err error
	
	// Errors are always shown

	if l.useSyslog {
		err = l.syslog.Err(l.buildString("", m, v...))
	}

	if err != nil || !l.useSyslog {
		l.stdlog.Println(l.buildString("ERROR", m, v...))
	}
}

func (l *Logger) buildString(level, m string, v ...interface{}) string {
	out := m

	if level != "" {
		out = level + ":" + m
	}

	if len(v) > 0 {
		out = fmt.Sprintf(out, v...)
	}

	return out
}