package main

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

var slugRE = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9-_]{0,63}$`)

// reserved words that would collide with routes
var reservedSlugs = map[string]bool{
	"api": true, "raw": true, "can": true, "cans": true, "public": true,
	"history": true, "static": true, "assets": true, "favicon.ico": true,
	"new": true, "login": true, "logout": true, "admin": true, "settings": true,
}

var errInvalidSlug = errors.New("custom slug must be 1-64 chars: letters, digits, dash, underscore; must start with letter or digit")
var errReservedSlug = errors.New("that slug is reserved")
var errSlugTaken = errors.New("that slug is already taken")

func ValidateCustomSlug(slug string) error {
	if !slugRE.MatchString(slug) {
		return errInvalidSlug
	}
	if reservedSlugs[strings.ToLower(slug)] {
		return errReservedSlug
	}
	return nil
}

func (s *Store) SlugTaken(slug string) (bool, error) {
	var n int
	err := s.db.QueryRow(`SELECT COUNT(*) FROM pastes WHERE custom_slug = ? OR id = ?`, slug, slug).Scan(&n)
	if err != nil {
		return false, err
	}
	if n > 0 {
		return true, nil
	}
	err = s.db.QueryRow(`SELECT COUNT(*) FROM paste_cans WHERE id = ?`, slug).Scan(&n)
	if err != nil {
		return false, err
	}
	return n > 0, nil
}

var _ = fmt.Sprintf // keep fmt if unused later