package logger

import (
	"bytes"
)

// Formatter interface defines a standard log formatter.
// The log formatter is not necessary for built-in loggers. We serialize logs to
// JSON format by default. This interface only provides a simple way to change
// this default behavior.
type Formatter interface {
	// Format formats the given log entity into character data and writes it to
	// the given buffer. If the error returned is not empty, the log will be discarded
	// and the registered log hook will not be triggered. We will output the error
	// information to os.Stderr.
	Format(Entity, *bytes.Buffer) error
}

// FormatterFunc type defines a log formatter in the form of a function.
type FormatterFunc func(Entity, *bytes.Buffer) error

// Format formats the given log entity into character data and writes it to
// the given buffer.
func (f FormatterFunc) Format(e Entity, b *bytes.Buffer) error {
	return f(e, b)
}