package flagx

import (
	"encoding"
	"flag"
	"fmt"
	"os"
	"strings"
	"time"
)

var commandLine = []*flag.FlagSet{
	flag.NewFlagSet(os.Args[0], flag.ContinueOnError),
}

func init() {
	Parse()
}

func findProperFlagSet(name string) *flag.FlagSet {
	for _, cl := range commandLine {
		if cl.Lookup(name) == nil {
			return cl
		}
	}
	next := flag.NewFlagSet(fmt.Sprintf("%s-%d", os.Args[0], len(commandLine)), flag.ContinueOnError)
	commandLine = append(commandLine, next)
	return next
}

func VisitAll(fn func(*flag.Flag)) {
	for _, cl := range commandLine {
		cl.VisitAll(fn)
	}
}

// Visit visits the command-line flags in lexicographical order, calling fn
// for each. It visits only those flags that have been set.
func Visit(fn func(*flag.Flag)) {
	for _, cl := range commandLine {
		cl.Visit(fn)
	}
}

func Lookup(name string) *flag.Flag {
	for _, cl := range commandLine {
		f := cl.Lookup(name)
		if f != nil {
			return f
		}
	}
	return nil
}

func Set(name, value string) error {
	for _, cl := range commandLine {
		if cl.Lookup(name) != nil {
			return cl.Set(name, value)
		}
	}
	return fmt.Errorf("no such flag -%v", name)
}

func PrintDefaults() {
	for _, cl := range commandLine {
		cl.PrintDefaults()
	}
}

func BoolVar(p *bool, name string, value bool, usage string) {
	findProperFlagSet(name).BoolVar(p, name, value, usage)
}

func Bool(name string, value bool, usage string) *bool {
	return findProperFlagSet(name).Bool(name, value, usage)
}

func IntVar(p *int, name string, value int, usage string) {
	findProperFlagSet(name).IntVar(p, name, value, usage)
}
func Int(name string, value int, usage string) *int {
	return findProperFlagSet(name).Int(name, value, usage)
}
func Int64Var(p *int64, name string, value int64, usage string) {
	findProperFlagSet(name).Int64Var(p, name, value, usage)
}

func Int64(name string, value int64, usage string) *int64 {
	return findProperFlagSet(name).Int64(name, value, usage)
}

func UintVar(p *uint, name string, value uint, usage string) {
	findProperFlagSet(name).UintVar(p, name, value, usage)
}

func Uint(name string, value uint, usage string) *uint {
	return findProperFlagSet(name).Uint(name, value, usage)
}

func Uint64Var(p *uint64, name string, value uint64, usage string) {
	findProperFlagSet(name).Uint64Var(p, name, value, usage)
}

func Uint64(name string, value uint64, usage string) *uint64 {
	return findProperFlagSet(name).Uint64(name, value, usage)
}

func StringVar(p *string, name string, value string, usage string) {
	findProperFlagSet(name).StringVar(p, name, value, usage)
}

func String(name string, value string, usage string) *string {
	return findProperFlagSet(name).String(name, value, usage)
}

func Float64Var(p *float64, name string, value float64, usage string) {
	findProperFlagSet(name).Float64Var(p, name, value, usage)
}

func Float64(name string, value float64, usage string) *float64 {
	return findProperFlagSet(name).Float64(name, value, usage)
}

func DurationVar(p *time.Duration, name string, value time.Duration, usage string) {
	findProperFlagSet(name).DurationVar(p, name, value, usage)
}

func Duration(name string, value time.Duration, usage string) *time.Duration {
	return findProperFlagSet(name).Duration(name, value, usage)
}

func TextVar(p encoding.TextUnmarshaler, name string, value encoding.TextMarshaler, usage string) {
	findProperFlagSet(name).TextVar(p, name, value, usage)
}
func Func(name, usage string, fn func(string) error) {
	findProperFlagSet(name).Func(name, usage, fn)
}

func Var(value flag.Value, name string, usage string) {
	findProperFlagSet(name).Var(value, name, usage)
}

func Parse() {
	args := os.Args[1:]
	for _, cl := range commandLine {
		if cl.Parsed() {
			continue
		}

		var filtered []string
		cl.VisitAll(func(f *flag.Flag) {
			for _, arg := range args {
				test := strings.TrimLeft(arg, "-")
				if test == f.Name || strings.HasPrefix(test, f.Name+"=") {
					filtered = append(filtered, arg)
					break
				}
			}
		})
		cl.Parse(filtered)
	}
}

func Parsed() bool {
	for _, cl := range commandLine {
		if !cl.Parsed() {
			return false
		}
	}
	return true
}

func NewFlagSet(name string, errorHandling flag.ErrorHandling) *flag.FlagSet {
	return flag.NewFlagSet(name, errorHandling)
}