package commands

import "strings"

const (
	ArgumentTypeBasic = iota
	ArgumentTypeUserMention
	ArgumentTypeChannelMention
)

func parseCommandUsage(prefix string) *CommandHolder {
	holder := &CommandHolder{}

	holder.Name = prefix
	holder.Usage = prefix

	if idx := strings.Index(prefix, " "); idx != -1 {
		holder.Name = prefix[0:idx]

		prefix = prefix[idx+1:]

		// Parse out command arguments, example:
		// test <arg1> [optional arg2]
		// Walk through string, match < and >, [ and ]
		holder.Arguments = make(map[string]*CommandArgument)

		str := prefix

		var name string

		var index int

		for {
			if len(str) == 0 {
				break
			}

			ch := str[0]

			if ch == '<' || ch == '[' {
				// Scan until closing arrow or end of string
				for i := 1; i < len(str); i++ {
					if (str[i] == '>' || str[i] == ']') && str[i-1] != '\\' {
						name = str[1:i]
						if i+2 < len(str) {
							str = str[i+2:]
						} else {
							str = ""
						}

						required := false

						if ch == '<' {
							required = true

							holder.RequiredArgumentCount++
						}

						t := ArgumentTypeBasic

						if name[0] == '@' {
							t = ArgumentTypeUserMention
							name = name[1:]
						} else if name[0] == '#' {
							t = ArgumentTypeChannelMention
							name = name[1:]
						}

						holder.Arguments[name] = &CommandArgument{
							Index:    index,
							Name:     name,
							Required: required,
							Type:     t,
						}

						index++

						break
					}
				}
			}
		}

		holder.ArgumentCount = len(holder.Arguments)
	}

	return holder
}