package domain

import (
	"fmt"
	"strings"
)

type Tag struct {
	name string
}

func NewTag(name string) (*Tag, error) {
	if name == "" {
		return nil, fmt.Errorf("tag name cannot be empty")
	}

	if !strings.HasPrefix(name, "#") {
		name = "#" + name
	}

	if !isValidTagName(name) {
		return nil, ErrInvalidTag
	}

	return &Tag{name: name}, nil
}

func (t *Tag) Name() string {
	return t.name
}

func (t *Tag) Parent() *Tag {
	if !t.IsNested() {
		return nil
	}

	lastSlash := strings.LastIndex(t.name, "/")
	if lastSlash == -1 {
		return nil
	}

	parentName := t.name[:lastSlash]
	parent, _ := NewTag(parentName)
	return parent
}

func (t *Tag) IsNested() bool {
	return strings.Contains(t.name, "/")
}

func (t *Tag) String() string {
	return t.name
}

func isValidTagName(name string) bool {
	if !strings.HasPrefix(name, "#") {
		return false
	}

	if len(name) <= 1 {
		return false
	}

	tagContent := name[1:]

	if strings.Contains(tagContent, " ") {
		return false
	}

	if strings.HasPrefix(tagContent, "/") || strings.HasSuffix(tagContent, "/") {
		return false
	}

	if strings.Contains(tagContent, "//") {
		return false
	}

	return true
}