first commit

shortener/shortener.go

@@ -0,0 +1,35 @@
+package shortener
+
+import (
+	"crypto/sha256"
+	"fmt"
+	"math/big"
+
+	"github.com/itchyny/base58-go"
+)
+
+func sha256Of(input string) []byte {
+	algorithm := sha256.New()
+	algorithm.Write([]byte(input))
+	return algorithm.Sum(nil)
+}
+
+func base58Encoded(bytes []byte) (string, error) {
+	encoded, err := base58.BitcoinEncoding.Encode(bytes)
+	if err != nil {
+		return "", err
+	}
+
+	return string(encoded), nil
+}
+
+func GenerateShortLink(originUrl string, userId string) (string, error) {
+	urlHashByte := sha256Of(originUrl + userId)
+	generateNumber := new(big.Int).SetBytes(urlHashByte).Uint64()
+	result, err := base58Encoded([]byte(fmt.Sprintf("%d", generateNumber)))
+	if err != nil {
+		return "", err
+	}
+
+	return result, nil
+}

shortener/shortener_test.go

@@ -0,0 +1,26 @@
+package shortener
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+const userId = "7c729139-7ff4-445f-976b-2d842f55cb0e"
+
+func TestGenerateShortLink(t *testing.T) {
+	link1 := "https://www.baidu.com/"
+	short1, err := GenerateShortLink(link1, userId)
+	assert.NoError(t, err)
+	assert.Equal(t, short1, "egtq236P5f3")
+
+	link2 := "https://www.163.com/"
+	short2, err := GenerateShortLink(link2, userId)
+	assert.NoError(t, err)
+	assert.Equal(t, short2, "DiCqg9YpV89")
+
+	link3 := "https://www.qq.com/"
+	short3, err := GenerateShortLink(link3, userId)
+	assert.NoError(t, err)
+	assert.Equal(t, short3, "4QhQ62cZem1")
+}