package skate

import (
	"regexp"
	"strings"
)

var (
	PatDOI          = regexp.MustCompile(`10[.][0-9]{1,8}/[^ ]*[\w]`)
	PatDOINoHyphen  = regexp.MustCompile(`10[.][0-9]{1,8}/[^ -]*[\w]`)
	PatArxivPDF     = regexp.MustCompile(`https?://arxiv.org/pdf/([0-9]{4,4}[.][0-9]{1,8})(v[0-9]{1,2})?(.pdf)?`)
	PatArxivAbs     = regexp.MustCompile(`https?://arxiv.org/abs/([0-9]{4,4}[.][0-9]{1,8})(v[0-9]{1,2})?(.pdf)?`)
	DOILinkPrefixes = []string{
		"http://doi.org/",
		"http://dx.doi.org/",
		"https://doi.org/",
		"https://dx.doi.org/",
	}
)

// ParseUnstructured will in-place augment missing DOI, arxiv id and so on.
func ParseUnstructured(ref *Ref) error {
	var (
		uns = ref.Biblio.Unstructured
		v   string
		vs  []string
	)
	// Handle things like: 10.1111/j.1550-7408.1968.tb02138.x-BIB5|cit5,
	// 10.1111/j.1558-5646.1997.tb02431.x-BIB0008|evo02431-cit-0008, ...
	if strings.Contains(strings.ToLower(ref.Key), "-bib") && ref.Biblio.DOI == "" {
		parts := strings.Split(strings.ToLower(ref.Key), "-bib")
		ref.Biblio.DOI = parts[0]
	}
	// DOI
	v = PatDOI.FindString(uns)
	if v != "" && ref.Biblio.DOI == "" {
		ref.Biblio.DOI = v
	}
	// DOI in Key
	v = PatDOINoHyphen.FindString(ref.Key)
	if v != "" && ref.Biblio.DOI == "" {
		ref.Biblio.DOI = v
	}
	// DOI in URL
	for _, prefix := range DOILinkPrefixes {
		if ref.Biblio.DOI != "" && strings.HasPrefix(ref.Biblio.Url, prefix) {
			ref.Biblio.DOI = strings.Replace(ref.Biblio.Url, prefix, "", -1)
		}
	}
	v = PatDOINoHyphen.FindString(ref.Key)
	if v != "" && ref.Biblio.DOI == "" {
		ref.Biblio.DOI = v
	}
	// Arxiv
	vs = PatArxivPDF.FindStringSubmatch(uns)
	if len(vs) != 0 && ref.Biblio.ArxivId == "" {
		ref.Biblio.ArxivId = vs[1]
	} else {
		vs = PatArxivAbs.FindStringSubmatch(uns)
		if len(vs) != 0 && ref.Biblio.ArxivId == "" {
			ref.Biblio.ArxivId = vs[1]
		}
	}
	return nil
}