package ytid

import (
	"fmt"
	"regexp"

	"github.com/flosch/pongo2"
	p2v3 "gopkg.in/flosch/pongo2.v3"
)

var (
	regexpYoutubeDomain = regexp.MustCompile(`youtu\.?be`)
	regexpURLPatterns   = []*regexp.Regexp{
		regexp.MustCompile(`youtu\.be\/([^#\&\?]{11})`),
		regexp.MustCompile(`\?v=([^#\&\?]{11})`),
		regexp.MustCompile(`\&v=([^#\&\?]{11})`),
		regexp.MustCompile(`embed\/([^#\&\?]{11})`),
		regexp.MustCompile(`\/v\/([^#\&\?]{11})`),
	}
)

func RegisterPongo2V3() {
	p2v3.RegisterFilter("ytid", filterYtid2v3)
}
func filterYtid2v3(in *p2v3.Value, param *p2v3.Value) (*p2v3.Value, *p2v3.Error) {
	return p2v3.AsValue(GetID(in.String())), nil
}

func RegisterPongo() {
	pongo2.RegisterFilter("ytid", filterYtid)

}
func filterYtid(in *pongo2.Value, param *pongo2.Value) (*pongo2.Value, *pongo2.Error) {
	return pongo2.AsValue(GetID(in.String())), nil
}

func GetID(url string) string {
	if !regexpYoutubeDomain.MatchString(url) {
		return ""
	}
	for _, pattern := range regexpURLPatterns {
		if pattern.MatchString(url) {
			return pattern.FindStringSubmatch(url)[1]
		}
	}
	return ""
}

func GetIDWithError(url string) (string, error) {
	if !regexpYoutubeDomain.MatchString(url) {
		return "", fmt.Errorf("ytid: not a youtube domain")
	}
	for _, pattern := range regexpURLPatterns {
		if pattern.MatchString(url) {
			return pattern.FindStringSubmatch(url)[1], nil
		}
	}
	return "", fmt.Errorf("ytid: no match found")

}