package klog

import (
	"encoding/json"
	"fmt"
	"io"
	"os"
	"sync"
	"time"

	"github.com/mattn/go-isatty"
)

type Llevel int

const (
	Lerror Llevel = 1 << iota
	Ldebug
	Lwarn
	Linfo
)

var lock sync.Mutex

var PROD = true
var STACKSKIP = 0
var LEVEL = Lerror | Linfo

type H map[string]interface{}

type Ldata struct {
	Message string
	Time    time.Time
	Level   Llevel

	// Caller only evaluates in DEBUG, and ERROR calls
	Caller string

	// Stack only eval when !PROD and {DEBUG, ERROR}
	Stack  string
	Fields H

	Color bool
}

type Logger struct {
	System string
	color  bool

	explicit bool

	err io.Writer
	out io.Writer

	printer Printer

	subs []*Logger
}

type Printer func(io.Writer, *Ldata, *Logger)

func DefaultPrinter() Printer {
	return func(w io.Writer, d *Ldata, l *Logger) {
		var level string
		caller := ""
		sys := ""
		if l.System != "" {
			sys = fmt.Sprintf("(%s)", l.System)
		}
		fields := ""
		if d.Fields != nil {
			b, err := json.Marshal(d.Fields)
			if err != nil {
				fields = l.M(string(b), FgHiGreen)
			}
		}
		stack := ""
		if d.Stack != "" {
			stack = l.M(d.Stack, FgRed)
		}
		switch d.Level {
		case Lerror:
			level = l.M("ERROR", FgHiRed)
			caller = d.Caller
		case Ldebug:
			level = l.M("DEBUG", FgHiMagenta)
			caller = d.Caller
		case Lwarn:
			level = l.M("WARN ", FgHiYellow)
		case Linfo:
			level = l.M("INFO ", FgHiBlue)
		}
		_, err := fmt.Fprintf(w, "%s [%s]%s%s %s%s\n%s",
			d.Time.Format("2006/01/02 15:04:05"),
			level, l.M(sys, FgHiCyan),
			caller, d.Message, fields,
			stack,
		)
		if err != nil {
			fmt.Println(err)
		}
	}
}

func (l *Logger) output(lev Llevel, depth int, fields H, v ...interface{}) {
	if LEVEL&lev == 0 {
		return
	}
	msg := fmt.Sprint(v...)
	data := &Ldata{
		Fields:  fields,
		Message: msg,
		Level:   lev,
		Time:    time.Now(),
		Color:   l.color,
	}
	if !PROD {
		switch lev {
		case Lerror:
			if STACKSKIP == 0 {
				data.Stack = Stack()
			} else if STACKSKIP > 0 {
				data.Stack = StackSkip(STACKSKIP)
			}
			data.Caller = Caller(depth)
		case Ldebug:
			data.Caller = Caller(depth)

			// disable stack trace on debug
			// data.Stack = Stack()
		}
	}
	lock.Lock()
	defer lock.Unlock()
	if lev == Lerror || lev == Ldebug {
		l.printer(l.err, data, l)
	} else {
		l.printer(l.out, data, l)
	}
}

func New(name string) *Logger {
	l := &Logger{
		System:  name,
		err:     os.Stderr,
		out:     os.Stdout,
		color:   true,
		printer: DefaultPrinter(),
	}
	l.guessColor()
	return l
}

func (l *Logger) Sub(sys string) *Logger {
	ret := &Logger{
		System:  sys,
		err:     l.err,
		out:     l.out,
		color:   l.color,
		printer: l.printer,
	}
	if l.subs == nil {
		l.subs = make([]*Logger, 0)
	}
	l.subs = append(l.subs, ret)
	return ret
}

func (l *Logger) guessColor() {
	l.color = true
	if w, ok := l.out.(*os.File); !ok || os.Getenv("TERM") == "dumb" ||
		(!isatty.IsTerminal(w.Fd()) && !isatty.IsCygwinTerminal(w.Fd())) {
		l.color = false
	}
	if w, ok := l.err.(*os.File); !ok || os.Getenv("TERM") == "dumb" ||
		(!isatty.IsTerminal(w.Fd()) && !isatty.IsCygwinTerminal(w.Fd())) {
		l.color = false
	}
}
func (l *Logger) SetColor(c bool) {
	l.explicit = true
	l.color = c
}

func (l *Logger) SetColorAll(c bool) {
	for _, v := range getAllOffsprings(l) {
		v.SetColor(c)
	}
}

func (l *Logger) SetErrOutput(err io.Writer) {
	l.err = err
	l.guessColor()
}

func (l *Logger) SetErrOutputAll(err io.Writer) {
	for _, v := range getAllOffsprings(l) {
		v.SetErrOutput(err)
	}
}

func (l *Logger) SetOutput(out io.Writer) {
	l.out = out
	l.guessColor()
}

func (l *Logger) SetOutputAll(out io.Writer) {
	for _, v := range getAllOffsprings(l) {
		v.SetOutput(out)
	}
}

func (l *Logger) GetPrinter() Printer {
	return l.printer
}

func (l *Logger) SetPrinter(p Printer) {
	l.printer = p
}

func (l *Logger) SetPrinterAll(p Printer) {
	for _, v := range getAllOffsprings(l) {
		v.SetPrinter(p)
	}
}

// func (l *Logger) DefaultFuncMap() template.FuncMap {
// 	funcMap := template.FuncMap{
// 		"Time": func() string { return time.Now().Format("2006/01/02 15:04:05") },
// 		"json": func(i interface{}) (string, error) { r, err := json.Marshal(i); return string(r), err },
// 	}
// 	return funcMap
// }

func (l *Logger) ErrorF(fields H, v ...interface{}) {
	l.output(Lerror, 3, fields, v...)

}

func (l *Logger) Error(v ...interface{}) {
	l.output(Lerror, 3, H{}, v...)
}

func (l *Logger) DebugF(fields H, v ...interface{}) {
	l.output(Ldebug, 3, fields, v...)
}

func (l *Logger) Debug(v ...interface{}) {
	l.output(Ldebug, 3, H{}, v...)
}

func (l *Logger) WarnF(fields H, v ...interface{}) {
	l.output(Lwarn, 3, fields, v...)
}

func (l *Logger) Warn(v ...interface{}) {
	l.output(Lwarn, 3, H{}, v...)
}

func (l *Logger) InfoF(fields H, v ...interface{}) {
	l.output(Linfo, 3, fields, v...)
}

func (l *Logger) Info(v ...interface{}) {
	l.output(Linfo, 3, H{}, v...)
}