efritz/ij

package logging

import (
    "io"
)

type (
    Logger interface {
        Debug(prefix *Prefix, format string, args ...interface{})
        Info(prefix *Prefix, format string, args ...interface{})
        Warn(prefix *Prefix, format string, args ...interface{})
        Error(prefix *Prefix, format string, args ...interface{})
    }

    LogFunc func(prefix *Prefix, format string, args ...interface{})

    logger struct {
        processor   *processor
        outStream   io.Writer
        outFile     io.Writer
        errStream   io.Writer
        errFile     io.Writer
        writePrefix bool
    }

    nilLogger struct{}
)

var NilLogger = &nilLogger{}

func newLogger(
    processor *processor,
    outStream io.Writer,
    outFile io.Writer,
    errStream io.Writer,
    errFile io.Writer,
    writePrefix bool,
) Logger {
    return &logger{
        processor:   processor,
        outStream:   outStream,
        outFile:     outFile,
        errStream:   errStream,
        errFile:     errFile,
        writePrefix: writePrefix,
    }
}

func (l *logger) Debug(prefix *Prefix, format string, args ...interface{}) {
    if !l.processor.verbose {
        return
    }

    l.enqueue(LevelDebug, prefix, format, args)
}

func (l *logger) Info(prefix *Prefix, format string, args ...interface{}) {
    l.enqueue(LevelInfo, prefix, format, args)
}

func (l *logger) Warn(prefix *Prefix, format string, args ...interface{}) {
    l.enqueue(LevelWarn, prefix, format, args)
}

func (l *logger) Error(prefix *Prefix, format string, args ...interface{}) {
    l.enqueue(LevelError, prefix, format, args)
}

func (l *logger) enqueue(level LogLevel, prefix *Prefix, format string, args []interface{}) {
    stream, file := l.getTargets(level)

    l.processor.enqueue(&message{
        level:       level,
        format:      format,
        args:        args,
        timestamp:   l.processor.clock.Now(),
        prefix:      prefix,
        writePrefix: l.writePrefix,
        stream:      stream,
        file:        file,
    })
}

func (l *logger) getTargets(level LogLevel) (io.Writer, io.Writer) {
    if level == LevelError {
        return l.errStream, l.errFile
    }

    return l.outStream, l.outFile
}

func (l *nilLogger) Debug(*Prefix, string, ...interface{}) {}
func (l *nilLogger) Info(*Prefix, string, ...interface{})  {}
func (l *nilLogger) Warn(*Prefix, string, ...interface{})  {}
func (l *nilLogger) Error(*Prefix, string, ...interface{}) {}