package core

import (
	"errors"
	"regexp"
	"strings"
)

var ErrNotFound = errors.New("not found")

type Page[T any] struct {
	Items  []T
	Cursor string
}

type PageReq struct {
	Limit  int
	Cursor string
}

type Path string

var pathSegment = regexp.MustCompile(`^[a-z0-9_]+$`)

func (p Path) Valid() error {
	s := string(p)
	if s == "" {
		return errors.New("path is empty")
	}
	segments := strings.Split(s, ".")
	for _, seg := range segments {
		if seg == "" {
			return errors.New("path contains empty segment")
		}
		if !pathSegment.MatchString(seg) {
			return errors.New("path segment must match [a-z0-9_]+: " + seg)
		}
	}
	return nil
}

func (p Path) Parent() Path {
	s := string(p)
	i := strings.LastIndex(s, ".")
	if i < 0 {
		return ""
	}
	return Path(s[:i])
}