From 2f2ff3dd8f4f1f6413533af90fa0861fd0fc21a6 Mon Sep 17 00:00:00 2001
From: Las Zenow <zenow@riseup.net>
Date: Sun, 8 Feb 2015 00:16:29 -0500
Subject: [PATCH] Add isbn parser

---
 parser/isbn.go      | 81 +++++++++++++++++++++++++++++++++++++++++++++
 parser/isbn_test.go | 26 +++++++++++++++
 parser/parser.go    |  7 ++--
 3 files changed, 112 insertions(+), 2 deletions(-)
 create mode 100644 parser/isbn.go
 create mode 100644 parser/isbn_test.go

diff --git a/parser/isbn.go b/parser/isbn.go
new file mode 100644
index 0000000..de730fe
--- /dev/null
+++ b/parser/isbn.go
@@ -0,0 +1,81 @@
+package parser
+
+import (
+	"strings"
+	"unicode"
+)
+
+func ISBN(orig string) string {
+	isbn := getISBN(orig)
+
+	if len(isbn) != 13 && len(isbn) != 10 {
+		return ""
+	}
+	if !validChecksum(isbn) {
+		return ""
+	}
+
+	return toISBN13(isbn)
+}
+
+func getISBN(src string) string {
+	isbn := strings.ToUpper(src)
+	isNotNumber := func(r rune) bool {
+		return !unicode.IsNumber(r)
+	}
+	isNotNumberOrX := func(r rune) bool {
+		return !unicode.IsNumber(r) && r != 'X'
+	}
+
+	isbn = strings.TrimLeftFunc(isbn, isNotNumber)
+	isbn = strings.TrimRightFunc(isbn, isNotNumberOrX)
+	isbn = strings.Replace(isbn, "-", "", -1)
+	isbn = strings.Replace(isbn, " ", "", -1)
+
+	if len(isbn) > 13 {
+		isbn = isbn[:13]
+	}
+	return isbn
+}
+
+func validChecksum(isbn string) bool {
+	if len(isbn) == 10 {
+		return rune(isbn[9]) == checkDigit10(isbn)
+	}
+	return rune(isbn[12]) == checkDigit13(isbn)
+}
+
+func toISBN13(isbn string) string {
+	if len(isbn) == 13 {
+		return isbn
+	}
+
+	isbn = "978" + isbn
+	return isbn[:12] + string(checkDigit13(isbn))
+}
+
+func checkDigit10(isbn string) rune {
+	acc := 0
+	for i, r := range isbn[:9] {
+		acc += (10 - i) * int(r-'0')
+	}
+	check := (11 - (acc % 11)) % 11
+
+	if check == 10 {
+		return 'X'
+	}
+	return rune(check + '0')
+}
+
+func checkDigit13(isbn string) rune {
+	acc := 0
+	for i, r := range isbn[:12] {
+		n := int(r - '0')
+		if i%2 == 1 {
+			n = 3 * n
+		}
+		acc += n
+	}
+	check := (10 - (acc % 10)) % 10
+	return rune(check + '0')
+}
diff --git a/parser/isbn_test.go b/parser/isbn_test.go
new file mode 100644
index 0000000..ad404d9
--- /dev/null
+++ b/parser/isbn_test.go
@@ -0,0 +1,26 @@
+package parser
+
+import "testing"
+
+func TestISBN(t *testing.T) {
+	isbn_test := [][]string{
+		[]string{"", ""},
+		[]string{"978074341", ""},
+		[]string{"9780743412395", ""},
+		[]string{"9780743412391", "9780743412391"},
+		[]string{"0-688-12189-6", "9780688121891"},
+		[]string{"033026155X", "9780330261555"},
+		[]string{"033026155x", "9780330261555"},
+		[]string{"0307756432", "9780307756435"},
+		[]string{"urn:isbn:978-3-8387-0337-4:", "9783838703374"},
+		[]string{"EPUB9788865971468-113465", "9788865971468"},
+	}
+
+	for _, isbn := range isbn_test {
+		src := isbn[0]
+		dst := isbn[1]
+		if res := ISBN(src); res != dst {
+			t.Error("ISBN parse failed: ", src, " => ", res, " (expected ", dst, ")")
+		}
+	}
+}
diff --git a/parser/parser.go b/parser/parser.go
index d26f6b9..63556b9 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -4,7 +4,7 @@ import (
 	"regexp"
 	"strings"
 
-	"git.gitorious.org/go-pkg/epubgo.git"
+	"github.com/meskio/epubgo"
 )
 
 type MetaData map[string]interface{}
@@ -33,7 +33,10 @@ func EpubMetadata(epub *epubgo.Epub) MetaData {
 			attr, _ := epub.MetadataAttr(m)
 			for i, d := range data {
 				if attr[i]["scheme"] == "ISBN" {
-					metadata["isbn"] = d
+					isbn := ISBN(d)
+					if isbn != "" {
+						metadata["isbn"] = isbn
+					}
 				}
 			}
 		default: