feat: add marshal function

Add Marshal function, for now, only supporting structs.

Author: mapaiva

errors.go

@@ -0,0 +1,8 @@
+package vcard
+
+import "errors"
+
+var (
+	// ErrUnsupportedType indicates that an unsupported interface type was sent for conversion.
+	ErrUnsupportedType = errors.New("unsupported type")
+)

prop/prop.go

@@ -59,3 +59,57 @@ const (
 	Interest     = "INTEREST"
 	OrgDirectory = "ORG-DIRECTORY"
 )
+
+var (
+	Props = map[string]string{
+		Adr:          "ADR",
+		Anniversary:  "ANNIVERSARY",
+		BDay:         "BDAY",
+		CalAdrURI:    "CALADRURI",
+		CalURI:       "CALURI",
+		Categories:   "CATEGORIES",
+		Class:        "CLASS",
+		ClientPIDMap: "CLIENTPIDMAP",
+		Email:        "EMAIL",
+		FbURL:        "FBURL",
+		Fn:           "FN",
+		Gender:       "GENDER",
+		Geo:          "GEO",
+		Key:          "KEY",
+		Kind:         "KIND",
+		Lang:         "LANG",
+		Logo:         "LOGO",
+		Mailer:       "MAILER",
+		Member:       "MEMBER",
+		N:            "N",
+		Name:         "NAME",
+		Nickname:     "NICKNAME",
+		Note:         "NOTE",
+		Org:          "ORG",
+		Photo:        "PHOTO",
+		ProdID:       "PRODID",
+		Profile:      "PROFILE",
+		Related:      "RELATED",
+		Rev:          "REV",
+		Role:         "ROLE",
+		Sound:        "SOUND",
+		Source:       "SOURCE",
+		Tel:          "TEL",
+		Title:        "TITLE",
+		Tz:           "TZ",
+		UID:          "UID",
+		URL:          "URL",
+		Version:      "VERSION",
+		XML:          "XML",
+
+		// Additional properties
+		BirthPlace:   "BIRTHPLACE",
+		DeathPlace:   "DEATHPLACE",
+		DeathDate:    "DEATHDATE",
+		Expertise:    "EXPERTISE",
+		Hobby:        "HOBBY",
+		IMPP:         "IMPP",
+		Interest:     "INTEREST",
+		OrgDirectory: "ORG-DIRECTORY",
+	}
+)

vcard.go

@@ -3,6 +3,8 @@ package vcard
 
 import (
 	"bufio"
+	"bytes"
+	"fmt"
 	"io"
 	"os"
 	"reflect"
@@ -14,6 +16,9 @@ import (
 const (
 	// VCardTagName represents the tag name used inside the struct VCard.
 	VCardTagName = "vcard"
+
+	// VCardVersion represents the supported version of vCard.
+	VCardVersion = "2.1"
 )
 
 // VCard represents a single vCard with its fields.
@@ -112,6 +117,48 @@ func GetVCardsByReader(r io.Reader) ([]VCard, error) {
 	return vcList, nil
 }
 
+// Marshal returns the vCard encoding of v.
+func Marshal(v interface{}) ([]byte, error) {
+	switch reflect.TypeOf(v).Kind() {
+	case reflect.Struct:
+		return marshalStruct(v)
+	}
+
+	return nil, ErrUnsupportedType
+}
+
+func marshalStruct(v interface{}) ([]byte, error) {
+	elem := reflect.ValueOf(v)
+	buffer := new(bytes.Buffer)
+
+	buffer.WriteString(prop.Begin + "\n")
+
+	buffer.WriteString(prop.Version)
+	buffer.WriteString(":")
+	buffer.WriteString(VCardVersion + "\n")
+
+	for i := 0; i < elem.NumField(); i++ {
+		f := elem.Field(i)
+		if f.Kind() != reflect.String {
+			continue // No non string field is supported yet
+		}
+
+		sf := elem.Type().Field(i)
+		tag := sf.Tag.Get(VCardTagName)
+		if tag != "" && f.CanInterface() {
+			if property, ok := prop.Props[tag]; ok {
+				buffer.WriteString(property)
+				buffer.WriteString(":")
+				buffer.WriteString(fmt.Sprintf("%s\n", f.Interface()))
+			}
+		}
+	}
+
+	buffer.WriteString(prop.End + "\n")
+
+	return buffer.Bytes(), nil
+}
+
 func readVCFProperty(vc *VCard, line string) {
 	if line == prop.Begin || line == prop.End || len(strings.Trim(line, " \t")) == 0 {
 		return

vcard_test.go

@@ -1,18 +1,18 @@
-package vcard
+package vcard_test
 
 import (
 	"bytes"
 	"testing"
 
+	"github.com/mapaiva/vcard-go"
 	"github.com/stretchr/testify/assert"
 )
 
-func TestVCardsByReader(t *testing.T) {
+func TestGetVCardsByReader(t *testing.T) {
 	assert := assert.New(t)
 
 	t.Run("Test if it returns the expected fields given a valid reader", func(t *testing.T) {
-		r := bytes.NewBuffer([]byte(`
-BEGIN:VCARD
+		r := bytes.NewBuffer([]byte(`BEGIN:VCARD
 VERSION:2.1
 N:Prefect;Ford;
 FN:Ford Prefect
@@ -26,7 +26,7 @@ EMAIL;PREF:[email protected]
 END:VCARD
 		`))
 
-		cards, err := GetVCardsByReader(r)
+		cards, err := vcard.GetVCardsByReader(r)
 
 		assert.Nil(err)
 		assert.NotNil(cards)
@@ -39,3 +39,44 @@ END:VCARD
 		assert.Equal(cards[1].Email, "[email protected]")
 	})
 }
+
+func TestMarshal(t *testing.T) {
+	assert := assert.New(t)
+
+	type vCard struct {
+		StructuredName string `vcard:"N"`
+		FormattedName  string `vcard:"FN"`
+		Email          string `vcard:"EMAIL"`
+	}
+
+	t.Run("Should marshal a struct into a vcard record encoding", func(t *testing.T) {
+		expected := []byte(`BEGIN:VCARD
+VERSION:2.1
+N:Prefect;Ford;
+FN:Ford Prefect
+EMAIL:[email protected]
+END:VCARD
+`)
+		card, err := vcard.Marshal(vCard{
+			StructuredName: "Prefect;Ford;",
+			FormattedName:  "Ford Prefect",
+			Email:          "[email protected]",
+		})
+
+		assert.Nil(err)
+		assert.Equal(string(expected), string(card))
+	})
+
+	t.Run("Should return error trying to marshal a slice", func(t *testing.T) {
+		_, err := vcard.Marshal([]vCard{
+			{
+
+				StructuredName: "Prefect;Ford;",
+				FormattedName:  "Ford Prefect",
+				Email:          "[email protected]",
+			},
+		})
+
+		assert.Equal(vcard.ErrUnsupportedType, err)
+	})
+}