google mail API [[[WIP]]]

googleapi/README.md

@@ -0,0 +1,54 @@
+
+Google OAuth Setup (to send mails)
+==================================
+
+
+ - Login @ https://console.cloud.google.com
+
+ - GMail API akivieren: https://console.cloud.google.com/apis/library/gmail.googleapis.com?
+
+ - Create new Project (aka 'BackendMailAPI') @ https://console.cloud.google.com/projectcreate
+   User Type: Intern
+   Anwendungsname: 'BackendMailAPI'
+   Support-Email: ...
+   Authorisierte Domains: 'heydyno.de' (or project domain)
+   Kontakt-Email: ...
+   
+
+ - Unter "Anmeldedaten" neuer OAuth Client erstellen @ https://console.cloud.google.com/apis/credentials
+   Anwendungstyp: Web
+   Name: 'BackendMailOAuth'
+   Redirect-Uri: 'http://localhost/oauth'
+   Client-ID und Client-Key merken
+
+ - Open in Browser:
+   https://accounts.google.com/o/oauth2/v2/auth?redirect_uri=http://localhost/oauth&prompt=consent&response_type=code&client_id={...}&scope=https://www.googleapis.com/auth/gmail.send&access_type=offline
+   Code aus redirected URI merken
+
+ - Code via request einlösen (und refresh_roken merken):
+
+```
+curl --request POST \
+  --url https://oauth2.googleapis.com/token \
+  --data code={...} \
+  --data redirect_uri=http://localhost/oauth \
+  --data client_id={...} \
+  --data client_secret={...} \
+  --data grant_type=authorization_code \
+  --data scope=https://www.googleapis.com/auth/gmail.send
+```
+
+ - Fertig, mit `client_id`, `client_secret` und `refresh_token` kann das package benutzt werden
+
+
+
+
+
+
+
+
+
+
+
+
+

googleapi/attachment.go

@@ -0,0 +1,41 @@
+package googleapi
+
+import (
+	"encoding/base64"
+	"fmt"
+)
+
+type MailAttachment struct {
+	IsInline    bool
+	ContentType *string
+	Filename    *string
+	Data        []byte
+}
+
+func (a MailAttachment) dump() []string {
+	res := make([]string, 0, 4)
+
+	if a.ContentType != nil {
+		res = append(res, "Content-Type: "+*a.ContentType+"; charset=UTF-8")
+	}
+
+	res = append(res, "Content-Transfer-Encoding: base64")
+
+	if a.IsInline {
+		if a.Filename != nil {
+			res = append(res, fmt.Sprintf("Content-Disposition: inline;filename=\"%s\"", *a.Filename))
+		} else {
+			res = append(res, "Content-Disposition: inline")
+		}
+	} else {
+		if a.Filename != nil {
+			res = append(res, fmt.Sprintf("Content-Disposition: attachment;filename=\"%s\"", *a.Filename))
+		} else {
+			res = append(res, "Content-Disposition: attachment")
+		}
+	}
+
+	res = append(res, base64.URLEncoding.EncodeToString(a.Data))
+
+	return res
+}

googleapi/body.go

@@ -0,0 +1,6 @@
+package googleapi
+
+type MailBody struct {
+	Plain *string
+	HTML  *string
+}

googleapi/oAuth.go

@@ -0,0 +1,83 @@
+package googleapi
+
+import (
+	"encoding/json"
+	"gogs.mikescher.com/BlackForestBytes/goext/langext"
+	"gogs.mikescher.com/BlackForestBytes/goext/timeext"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+)
+
+type GoogleOAuth interface {
+}
+
+type oauth struct {
+	clientID     string
+	clientSecret string
+	refreshToken string
+
+	lock        sync.RWMutex
+	accessToken *string
+	expiryDate  *time.Time
+}
+
+func NewGoogleOAuth(clientid string, clientsecret, refreshtoken string) GoogleOAuth {
+	return &oauth{
+		clientID:     clientid,
+		clientSecret: clientsecret,
+		refreshToken: refreshtoken,
+	}
+}
+
+func (c *oauth) AccessToken() (string, error) {
+	c.lock.RLock()
+	if c.accessToken != nil && c.expiryDate != nil && (*c.expiryDate).After(time.Now()) {
+		c.lock.RUnlock()
+		return *c.accessToken, nil // still valid
+	}
+	c.lock.RUnlock()
+
+	httpclient := http.Client{}
+
+	req, err := http.NewRequest(http.MethodPost, "https://oauth2.googleapis.com/token", nil)
+	if err != nil {
+		return "", err
+	}
+
+	req.URL.Query().Add("client_id", c.clientID)
+	req.URL.Query().Add("client_secret", c.clientSecret)
+	req.URL.Query().Add("grant_type", "refresh_token")
+	req.URL.Query().Add("refresh_token", c.refreshToken)
+
+	reqStartTime := time.Now()
+
+	res, err := httpclient.Do(req)
+
+	type response struct {
+		AccessToken string `json:"access_token"`
+		ExpiresIn   int    `json:"expires_in"`
+		Scope       string `json:"scope"`
+		TokenType   string `json:"token_type"`
+	}
+
+	var r response
+
+	data, err := io.ReadAll(res.Body)
+	if err != nil {
+		return "", err
+	}
+
+	err = json.Unmarshal(data, &r)
+	if err != nil {
+		return "", err
+	}
+
+	c.lock.Lock()
+	c.expiryDate = langext.Ptr(reqStartTime.Add(timeext.FromSeconds(r.ExpiresIn - 10)))
+	c.accessToken = langext.Ptr(r.AccessToken)
+	c.lock.Unlock()
+
+	return r.AccessToken, nil
+}

googleapi/sendMail.go

@@ -0,0 +1,127 @@
+package googleapi
+
+import (
+	"gogs.mikescher.com/BlackForestBytes/goext/langext"
+	"mime"
+	"strings"
+	"time"
+)
+
+func (c *client) SendMail(from string, recipients []string, cc []string, bcc []string, subject string, body MailBody, attachments []MailAttachment) error {
+
+	data := make([]string, 0, 32)
+
+	data = append(data, "Date: "+time.Now().Format(time.RFC1123Z))
+	data = append(data, "From: "+mime.QEncoding.Encode("UTF-8", from))
+	data = append(data, "To: "+strings.Join(langext.ArrMap(recipients, func(v string) string { return mime.QEncoding.Encode("UTF-8", v) }), ", "))
+	if len(cc) > 0 {
+		data = append(data, "To: "+strings.Join(langext.ArrMap(cc, func(v string) string { return mime.QEncoding.Encode("UTF-8", v) }), ", "))
+	}
+	if len(bcc) > 0 {
+		data = append(data, "Bcc: "+strings.Join(langext.ArrMap(bcc, func(v string) string { return mime.QEncoding.Encode("UTF-8", v) }), ", "))
+	}
+	data = append(data, "Subject: "+mime.QEncoding.Encode("UTF-8", subject))
+
+	hasAttachments := len(attachments) > 0
+	hasInlineAttachments := langext.ArrAny(attachments, func(v MailAttachment) bool { return v.IsInline })
+	hasPlain := body.Plain != nil
+	hasHTML := body.HTML != nil
+
+	mixedBoundary := "--------------" + langext.MustRawHexUUID()
+	relatedBoundary := "--------------" + langext.MustRawHexUUID()
+	altBoundary := "--------------" + langext.MustRawHexUUID()
+
+	inlineAttachments := langext.ArrFilter(attachments, func(v MailAttachment) bool { return v.IsInline })
+	normalAttachments := langext.ArrFilter(attachments, func(v MailAttachment) bool { return !v.IsInline })
+
+	if hasInlineAttachments {
+		// "mixed+related"
+
+		data = append(data, "Content-Type: multipart/mixed; boundary="+mixedBoundary)
+		data = append(data, "")
+		data = append(data, mixedBoundary)
+
+		data = append(data, "Content-Type: multipart/related; boundary="+relatedBoundary)
+		data = append(data, "")
+
+		data = append(data, c.dumpHTMLBody(body, hasInlineAttachments, hasAttachments, relatedBoundary, altBoundary)...)
+		data = append(data, "")
+
+		for i, attachment := range inlineAttachments {
+			data = append(data, relatedBoundary)
+			data = append(data, attachment.dump()...)
+
+			if i < len(inlineAttachments)-1 {
+				data = append(data, "")
+			}
+		}
+
+		data = append(data, relatedBoundary)
+
+		for i, attachment := range normalAttachments {
+			data = append(data, mixedBoundary)
+			data = append(data, attachment.dump()...)
+
+			if i < len(inlineAttachments)-1 {
+				data = append(data, "")
+			}
+		}
+
+		data = append(data, mixedBoundary)
+
+	} else if hasAttachments {
+		// "mixed"
+
+		//TODO https://github.dev/muratgozel/MIMEText/blob/master/src/MIMEMessage.ts
+
+	} else if hasPlain && hasHTML {
+		// "alternative"
+
+		//TODO https://github.dev/muratgozel/MIMEText/blob/master/src/MIMEMessage.ts
+
+	} else {
+		// "plain"
+
+		//TODO https://github.dev/muratgozel/MIMEText/blob/master/src/MIMEMessage.ts
+
+	}
+
+}
+
+func (c *client) dumpHTMLBody(body MailBody, hasInlineAttachments bool, hasAttachments bool, boundary string, boundaryAlt string) []string {
+
+	data := make([]string, 0, 16)
+
+	if body.HTML != nil && body.Plain != nil && hasInlineAttachments {
+		data = append(data, boundary)
+		data = append(data, *body.HTML)
+	} else if body.HTML != nil && body.Plain != nil && hasAttachments {
+		data = append(data, boundary)
+		data = append(data, "Content-Type: multipart/alternative; boundary="+boundaryAlt)
+		data = append(data, "")
+		data = append(data, boundaryAlt)
+		data = append(data, *body.Plain)
+		data = append(data, "")
+		data = append(data, boundaryAlt)
+		data = append(data, *body.HTML)
+		data = append(data, "")
+		data = append(data, boundaryAlt)
+	} else if body.HTML != nil && body.Plain != nil {
+		data = append(data, boundary)
+		data = append(data, *body.Plain)
+		data = append(data, "")
+		data = append(data, boundary)
+		data = append(data, *body.HTML)
+	} else if body.HTML != nil {
+		data = append(data, boundary)
+		data = append(data, *body.HTML)
+	} else if body.Plain != nil {
+		data = append(data, boundary)
+		data = append(data, *body.Plain)
+	} else {
+		data = append(data, boundary)
+		data = append(data, "") // no content ?!?
+	}
+
+	return data
+}

googleapi/service.go

@@ -0,0 +1,14 @@
+package googleapi
+
+type GoogleClient interface {
+}
+
+type client struct {
+	oauth GoogleOAuth
+}
+
+func NewGoogleClient(oauth GoogleOAuth) GoogleClient {
+	return &client{
+		oauth: oauth,
+	}
+}