package ethlog

import (
	"fmt"
	"io"
	"log"
	"os"
	"sync"
)

type LogSystem interface {
	GetLogLevel() LogLevel
	SetLogLevel(i LogLevel)
	Println(v ...interface{})
	Printf(format string, v ...interface{})
}

type logMessage struct {
	LogLevel LogLevel
	format   bool
	msg      string
}

func newPrintlnLogMessage(level LogLevel, tag string, v ...interface{}) *logMessage {
	return &logMessage{level, false, fmt.Sprintf("[%s] %s", tag, fmt.Sprint(v...))}
}

func newPrintfLogMessage(level LogLevel, tag string, format string, v ...interface{}) *logMessage {
	return &logMessage{level, true, fmt.Sprintf("[%s] %s", tag, fmt.Sprintf(format, v...))}
}

func (msg *logMessage) send(logger LogSystem) {
	if msg.format {
		logger.Printf(msg.msg)
	} else {
		logger.Println(msg.msg)
	}
}

var logMessages chan (*logMessage)
var logSystems []LogSystem
var quit chan chan error
var drained chan bool
var mutex = sync.Mutex{}

type LogLevel uint8

const (
	Silence LogLevel = iota
	ErrorLevel
	WarnLevel
	InfoLevel
	DebugLevel
	DebugDetailLevel
)

func dispatch(msg *logMessage) {
	for _, logSystem := range logSystems {
		if logSystem.GetLogLevel() >= msg.LogLevel {
			msg.send(logSystem)
		}
	}
}

// log messages are dispatched to log writers
func start() {
	for {
		select {
		case status := <-quit:
			status <- nil
			return
		case msg := <-logMessages:
			dispatch(msg)
		default:
			drained <- true // this blocks until a message is sent to the queue
		}
	}
}

func send(msg *logMessage) {
	logMessages <- msg
	select {
	case <-drained:
	default:
	}
}

func Reset() {
	mutex.Lock()
	defer mutex.Unlock()
	if logSystems != nil {
		status := make(chan error)
		quit <- status
		select {
		case <-drained:
		default:
		}
		<-status
	}
	logSystems = nil
}

// waits until log messages are drained (dispatched to log writers)
func Flush() {
	if logSystems != nil {
		<-drained
	}
}

type Logger struct {
	tag string
}

func NewLogger(tag string) *Logger {
	return &Logger{tag}
}

func AddLogSystem(logSystem LogSystem) {
	mutex.Lock()
	defer mutex.Unlock()
	if logSystems == nil {
		logMessages = make(chan *logMessage, 5)
		quit = make(chan chan error, 1)
		drained = make(chan bool, 1)
		go start()
	}
	logSystems = append(logSystems, logSystem)
}

func (logger *Logger) sendln(level LogLevel, v ...interface{}) {
	if logSystems != nil {
		send(newPrintlnLogMessage(level, logger.tag, v...))
	}
}

func (logger *Logger) sendf(level LogLevel, format string, v ...interface{}) {
	if logSystems != nil {
		send(newPrintfLogMessage(level, logger.tag, format, v...))
	}
}

func (logger *Logger) Errorln(v ...interface{}) {
	logger.sendln(ErrorLevel, v...)
}

func (logger *Logger) Warnln(v ...interface{}) {
	logger.sendln(WarnLevel, v...)
}

func (logger *Logger) Infoln(v ...interface{}) {
	logger.sendln(InfoLevel, v...)
}

func (logger *Logger) Debugln(v ...interface{}) {
	logger.sendln(DebugLevel, v...)
}

func (logger *Logger) DebugDetailln(v ...interface{}) {
	logger.sendln(DebugDetailLevel, v...)
}

func (logger *Logger) Errorf(format string, v ...interface{}) {
	logger.sendf(ErrorLevel, format, v...)
}

func (logger *Logger) Warnf(format string, v ...interface{}) {
	logger.sendf(WarnLevel, format, v...)
}

func (logger *Logger) Infof(format string, v ...interface{}) {
	logger.sendf(InfoLevel, format, v...)
}

func (logger *Logger) Debugf(format string, v ...interface{}) {
	logger.sendf(DebugLevel, format, v...)
}

func (logger *Logger) DebugDetailf(format string, v ...interface{}) {
	logger.sendf(DebugDetailLevel, format, v...)
}

func (logger *Logger) Fatalln(v ...interface{}) {
	logger.sendln(ErrorLevel, v...)
	Flush()
	os.Exit(0)
}

func (logger *Logger) Fatalf(format string, v ...interface{}) {
	logger.sendf(ErrorLevel, format, v...)
	Flush()
	os.Exit(0)
}

type StdLogSystem struct {
	logger *log.Logger
	level  LogLevel
}

func (t *StdLogSystem) Println(v ...interface{}) {
	t.logger.Println(v...)
}

func (t *StdLogSystem) Printf(format string, v ...interface{}) {
	t.logger.Printf(format, v...)
}

func (t *StdLogSystem) SetLogLevel(i LogLevel) {
	t.level = i
}

func (t *StdLogSystem) GetLogLevel() LogLevel {
	return t.level
}

func NewStdLogSystem(writer io.Writer, flags int, level LogLevel) *StdLogSystem {
	logger := log.New(writer, "", flags)
	return &StdLogSystem{logger, level}
}