package logger

import (
	"bytes"
	"context"
	"io"
	"time"
)

// Entity interface defines the entity of the log.
type Entity interface {
	// Name returns the logger name.
	Name() string

	// Time returns the log time.
	Time() time.Time

	// TimeString returns the log time string formatted with the default time format.
	TimeString() string

	// Level returns the log level.
	Level() Level

	// Message returns the log message.
	Message() string

	// Fields returns the log fields.
	Fields() map[string]interface{}

	// Context returns the log context.
	Context() context.Context

	// Caller returns the log caller.
	// If it is not enabled, an empty string is always returned.
	Caller() string
}

// Summary interface defines the summary of the log.
// The log summary is the final state of a log, and the content of the log will no longer change.
type Summary interface {
	Entity
	io.Reader

	// Bytes returns the log content bytes.
	// This method returns the content processed by the formatter.
	Bytes() []byte

	// String returns the log content string.
	// This method returns the content processed by the formatter.
	String() string

	// Size returns the log content size.
	Size() int
}

// The logEntity type is a built-in implementation of the Entity interface.
type logEntity struct {
	name       string
	time       time.Time
	timeFormat string
	level      Level
	message    string
	fields     map[string]interface{}
	ctx        context.Context
	buffer     bytes.Buffer
	caller     string
}

// Name returns the logger name.
func (o *logEntity) Name() string {
	return o.name
}

// Time returns the log time.
func (o *logEntity) Time() time.Time {
	return o.time
}

// TimeString returns the log time string formatted with the default time format.
func (o *logEntity) TimeString() string {
	return o.time.Format(o.timeFormat)
}

// Level returns the log level.
func (o *logEntity) Level() Level {
	return o.level
}

// Message returns the log message.
func (o *logEntity) Message() string {
	return o.message
}

// Fields returns the log fields.
func (o *logEntity) Fields() map[string]interface{} {
	return o.fields
}

// Context returns the log context.
func (o *logEntity) Context() context.Context {
	if o.ctx == nil {
		return context.Background()
	}
	return o.ctx
}

// Caller returns the log caller.
// If it is not enabled, an empty string is always returned.
func (o *logEntity) Caller() string {
	return o.caller
}

// Bytes returns the log content bytes.
// This method returns the content processed by the formatter.
func (o *logEntity) Bytes() []byte {
	return o.buffer.Bytes()
}

// String returns the log content string.
// This method returns the content processed by the formatter.
func (o *logEntity) String() string {
	return o.buffer.String()
}

// Size returns the log content size.
func (o *logEntity) Size() int {
	return o.buffer.Len()
}

// Read is the implementation of io.Reader interface.
func (o *logEntity) Read(p []byte) (int, error) {
	return o.buffer.Read(p)
}