package command

import (
	"errors"
	"fmt"
	"strings"
)

var (
	ErrWrongCommand = errors.New("wrong command")
	ErrInvalidArg   = errors.New("invalid argument")
)

type ArgSet struct {
	Main  string
	Flags map[string]string
}

func (as *ArgSet) HasFlag(name string) bool {
	_, ok := as.Flags[name]
	return ok
}

func (as *ArgSet) Flag(name string) string {
	return as.Flags[name]
}

func (as *ArgSet) SetFlag(name, value string) {
	as.Flags[name] = value
}

type Command interface {
	Parse(args []string) (*ArgSet, error)
	Do(args *ArgSet) error
}

type CLI struct {
	Commands []Command
}

func (cli *CLI) Run(args []string) error {
	for _, c := range cli.Commands {
		as, err := c.Parse(args)
		switch {
		case errors.Is(err, ErrWrongCommand):
			continue
		case err != nil:
			return err
		default:
			return c.Do(as)
		}
	}

	return fmt.Errorf("could not find matching command")
}

func ParseArgs(args []string) (*ArgSet, error) {
	flags := make(map[string]string)
	main := make([]string, 0)
	var inMain bool
	for i := 0; i < len(args); i++ {
		if strings.HasPrefix(args[i], "-") {
			inMain = false
			if i+1 >= len(args) {
				return &ArgSet{}, fmt.Errorf("flag wihout value")
			}
			flags[strings.TrimPrefix(args[i], "-")] = args[i+1]
			i++
			continue
		}

		if !inMain && len(main) > 0 {
			return &ArgSet{}, fmt.Errorf("two mains")
		}
		inMain = true
		main = append(main, args[i])
	}

	return &ArgSet{
		Main:  strings.Join(main, " "),
		Flags: flags,
	}, nil
}