Commit bd1da30

@@ -0,0 +1,2 @@
+env.sh
+

@@ -0,0 +1,3 @@
+export AMAZING_ASSOCIATE_TAG=XXXXXX-20
+export AMAZING_ACCESS_KEY=XXXXXXXXXXXXXXXXXXX
+export AMAZING_SECRET_KEY=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

@@ -0,0 +1,158 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"github.com/bryfry/amazing"
+)
+
+var (
+	isbn           string
+	checkNeighbors bool
+)
+
+func init() {
+	flag.StringVar(&isbn, "i", "", "isbn number to validate")
+	flag.BoolVar(&checkNeighbors, "n", false, "check neighbor isbns")
+	flag.Parse()
+}
+
+func main() {
+	fmt.Println("Checking for valid ISBN:", isbn)
+	isbn := strings.Replace(isbn, "-", "", -1)
+
+	valid, err := ValidISBN10(isbn)
+	if err != nil || !valid {
+		fmt.Println("Not Valid ISBN-10: ", err)
+		isbn, err = CreateValidISBN10(isbn)
+		if err != nil {
+			fmt.Println("Failed to create a Valid ISBN10:", err)
+		}
+		fmt.Println("Looking up expected ISBN-10:", isbn)
+	}
+	url, err := ISBN10URL(isbn)
+	if err != nil {
+		fmt.Println("Amazon Error:", err)
+	}
+	fmt.Println("ISBN-10:", isbn, url)
+
+	if checkNeighbors {
+		ISBN10Neighbors(isbn)
+	}
+
+}
+
+func ISBN10Neighbors(isbn string) {
+	fmt.Println("-----   Neighbor ISBNs  -----")
+	for i := 0; i < 10; i++ {
+		isbn, err := CreateValidISBN10(isbn[:8] + strconv.Itoa(i))
+		if err != nil {
+			fmt.Println("ISBN-10:", isbn, err)
+			continue
+		}
+		url, err := ISBN10URL(isbn)
+		if err != nil {
+			fmt.Println(isbn)
+			continue
+		}
+		fmt.Println(isbn, url)
+	}
+
+	fmt.Println("----- ----- ----- ----- -----")
+
+}
+
+func ISBN10URL(isbn string) (string, error) {
+	client, err := amazing.NewAmazingFromEnv("US")
+	if err != nil {
+		return "", err
+	}
+
+	params := url.Values{
+		"IdType":      []string{"ISBN"},
+		"ItemId":      []string{isbn},
+		"Operation":   []string{"ItemLookup"},
+		"SearchIndex": []string{"All"},
+	}
+
+	result, err := client.ItemLookup(params)
+	if err != nil {
+		return "", err
+	}
+
+	if len(result.AmazonItems.Request.Errors) > 0 {
+		return "", errors.New(result.AmazonItems.Request.Errors[0].Error())
+	}
+
+	u, _ := url.Parse(result.AmazonItems.Items[0].DetailPageURL)
+	return strings.Split((u.Host + u.Path), "?")[0], nil
+}
+
+var ISBN10LengthError = errors.New("Incorrect Length")
+
+func ValidISBN10(isbn string) (bool, error) {
+	if len(isbn) != 10 {
+		return false, ISBN10LengthError
+	}
+	expected, err := CheckDigitISBN10(isbn)
+	if err != nil {
+		return false, err
+	}
+	recieved := strings.ToUpper(string(isbn[9]))
+	if expected != recieved {
+		return false, errors.New(fmt.Sprintf("Invalid check digit: expected (%s) received (%s)", expected, recieved))
+	}
+	return true, nil
+}
+
+func CheckDigitISBN10(isbn string) (string, error) {
+	if len(isbn) != 9 && len(isbn) != 10 {
+		return "", ISBN10LengthError
+	} else if len(isbn) == 10 {
+		isbn = isbn[:9] // Ignore check digit if provided
+	}
+	sum := 0
+	for i, r := range isbn {
+		d, err := isbnAtoi(string(r))
+		if err != nil {
+			return "", errors.New(fmt.Sprintf("Digit parsing failed (location %d: %s)", i, string(r)))
+		}
+		sum = sum + (10-i)*d
+	}
+	return isbnItoa(11 - (sum % 11)), nil
+}
+
+func CreateValidISBN10(isbn string) (string, error) {
+	if len(isbn) > 10 {
+		return "", ISBN10LengthError
+	}
+	cd, err := CheckDigitISBN10(isbn)
+	if err != nil {
+		return "", err
+	}
+	isbn = isbn[:9] + cd
+	return isbn, nil
+}
+
+func isbnAtoi(digit string) (int, error) {
+	if digit == "X" || digit == "x" {
+		return 10, nil
+	} else {
+		return strconv.Atoi(digit)
+	}
+}
+
+func isbnItoa(digit int) string {
+	if digit == 10 {
+		return "X"
+	}
+	if digit == 11 {
+		return "0"
+	}
+	return strconv.Itoa(digit)
+}