package log

import (
	"fmt"
	"io"
	"os"
	"text/template"
	"time"

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

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

type tout int

const (
	terror tout = iota
	tdebug
	tinfo
	twarn
)

var PROD = true
var LEVEL = Lerror | Linfo

const (
	DEFAULT_ERR = `{{Time}} [{{red}}ERROR{{reset}}]` +
		`{{if .System}}({{cyan}}{{.System}}{{reset}}){{end}} ` +
		`{{.Caller}} {{.Message}}{{"\n"}}` +
		`{{if .Fields}}{{printf "%v\n" .Fields}}{{end}}` +
		`{{if .Stack}}{{redl}}{{.Stack}}{{reset}}{{end}}`
	DEFAULT_DEBUG = `{{Time}} [{{magenta}}DEBUG{{reset}}]` +
		`{{if .System}}({{cyan}}{{.System}}{{reset}}){{end}} ` +
		`{{.Caller}} {{.Message}}{{"\n"}}` +
		`{{if .Fields}}{{green}}{{printf "%v\n" .Fields}}{{reset}}{{end}}` +
		`{{if .Stack}}{{redl}}{{.Stack}}{{reset}}{{end}}`
	DEFAULT_WARN = `{{Time}} [{{yellow}}WARN {{reset}}]` +
		`{{if .System}}({{cyan}}{{.System}}{{reset}}){{end}} ` +
		`{{.Message}}{{"\n"}}` +
		`{{if .Fields}}{{green}}{{printf "%v\n" .Fields}}{{reset}}{{end}}`
	DEFAULT_INFO = `{{Time}} [{{blue}}INFO {{reset}}]` +
		`{{if .System}}({{cyan}}{{.System}}{{reset}}){{end}} ` +
		`{{.Message}}{{"\n"}}` +
		`{{if .Fields}}{{green}}{{printf "%v\n" .Fields}}{{reset}}{{end}}`
)

type LogFormater struct {
	ErrTmplStr   string
	WarnTmplStr  string
	InfoTmplStr  string
	DebugTmplStr string
}

type H map[string]interface{}

type Ldata struct {
	Message string
	System  string

	// 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

	err io.Writer
	out io.Writer

	formatter  *LogFormater
	err_tmpl   *template.Template
	debug_tmpl *template.Template
	warn_tmpl  *template.Template
	info_tmpl  *template.Template
}

func Default() *logger {
	l := &logger{
		err:       os.Stderr,
		out:       os.Stdout,
		color:     true,
		formatter: NewLogFormater(),
	}
	l.guessColor()
	l.ParseTmpl()
	return l
}

func (l *logger) Sub(sys string) *logger {
	ret := &logger{
		system:    sys,
		err:       l.err,
		out:       l.out,
		color:     l.color,
		formatter: l.formatter,

		err_tmpl:   l.err_tmpl,
		debug_tmpl: l.debug_tmpl,
		warn_tmpl:  l.warn_tmpl,
		info_tmpl:  l.info_tmpl,
	}
	return ret
}

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

func NewLogFormater() *LogFormater {
	return &LogFormater{
		ErrTmplStr:   DEFAULT_ERR,
		WarnTmplStr:  DEFAULT_WARN,
		InfoTmplStr:  DEFAULT_INFO,
		DebugTmplStr: DEFAULT_DEBUG,
	}
}

func (l *logger) FuncMap() template.FuncMap {
	funcMap := template.FuncMap{
		"Time": func() string { return time.Now().Format("2006/01/02 15:04:05") },
	}
	setColorMap(funcMap, l.color)
	return funcMap
}

func (l *logger) ParseTmpl() error {
	funcMap := l.FuncMap()
	err_tmpl, err := template.New("err_tmpl").Funcs(funcMap).Parse(l.formatter.ErrTmplStr)
	if err != nil {
		return err
	}
	l.err_tmpl = err_tmpl
	warn_tmpl, err := template.New("warn_tmpl").Funcs(funcMap).Parse(l.formatter.WarnTmplStr)
	if err != nil {
		return err
	}
	l.warn_tmpl = warn_tmpl
	info_tmpl, err := template.New("info_tmpl").Funcs(funcMap).Parse(l.formatter.InfoTmplStr)
	if err != nil {
		return err
	}
	l.info_tmpl = info_tmpl
	debug_tmpl, err := template.New("debug_tmpl").Funcs(funcMap).Parse(l.formatter.DebugTmplStr)
	if err != nil {
		return err
	}
	l.debug_tmpl = debug_tmpl
	return nil
}

func (l *logger) SetTmpl(formatter *LogFormater) error {
	l.formatter = formatter
	return l.ParseTmpl()
}

func (l *logger) output(t tout, depth int, stack string, fields H, v ...interface{}) {
	msg := fmt.Sprint(v...)
	data := Ldata{
		Fields:  fields,
		Message: msg,
		System:  l.system,
		Caller:  caller(depth),
		Color:   l.color,
		Stack:   stack,
	}
	var err error
	switch t {
	case terror:
		err = l.err_tmpl.Execute(l.err, data)
	case tdebug:
		err = l.debug_tmpl.Execute(l.err, data)
	case twarn:
		err = l.warn_tmpl.Execute(l.out, data)
	case tinfo:
		err = l.info_tmpl.Execute(l.out, data)
	}
	if err != nil {
		fmt.Fprintln(l.err, "[FATAL] logger error:", err)
		panic(err)
	}
}

func (l *logger) ErrorF(fields H, v ...interface{}) {
	if PROD {
		l.output(terror, 3, "", fields, v...)
	} else {
		l.output(terror, 3, stack(), fields, v...)
	}
}

func (l *logger) Error(v ...interface{}) {
	if PROD {
		l.output(terror, 3, "", H{}, v...)
	} else {
		l.output(terror, 3, stack(), H{}, v...)
	}
}

func (l *logger) DebugF(fields H, v ...interface{}) {
	if PROD {
		l.output(tdebug, 3, "", fields, v...)
	} else {
		l.output(tdebug, 3, stack(), fields, v...)
	}
}

func (l *logger) Debug(v ...interface{}) {
	if PROD {
		l.output(tdebug, 3, "", H{}, v...)
	} else {
		l.output(tdebug, 3, stack(), H{}, v...)
	}
}

func (l *logger) WarnF(fields H, v ...interface{}) {
	l.output(twarn, 3, "", fields, v...)
}

func (l *logger) Warn(v ...interface{}) {
	l.output(twarn, 3, "", H{}, v...)
}

func (l *logger) InfoF(fields H, v ...interface{}) {
	l.output(tinfo, 3, "", fields, v...)
}

func (l *logger) Info(v ...interface{}) {
	l.output(tinfo, 3, "", H{}, v...)
}