package pkg

import (
	"strings"
)

// 业务场景可能有些需要便利查找的部分可以替换为 Set

var Empty = struct{}{}

type Set map[string]struct{}

func NewSet(size int) Set {
	if size == 0 {
		return make(Set)
	}
	return make(Set, size)
}

func NewSetBySlice(keys []string) Set {
	s := NewSet(len(keys))
	s.SetSlice(keys)
	return s
}

func (s Set) Has(key string) (has bool) {
	_, has = s[key]
	return
}

func (s Set) Set(key string) Set {
	s[key] = Empty
	return s
}

func (s Set) SetSlice(keys []string) Set {
	for _, key := range keys {
		s[key] = Empty
	}
	return s
}

func (s Set) Del(key string) {
	delete(s, key)
}

func (s Set) String() string {
	var (
		str strings.Builder
		idx int
	)
	str.WriteByte('[')
	for key := range s {
		if idx > 0 {
			str.WriteByte(',')
		}
		str.WriteString(key)
		idx++
	}
	str.WriteByte(']')

	return str.String()
}