add listmonk mailing list control (subscribe/usubscribe)

server/configurations/local.yaml

@@ -237,6 +237,14 @@ zoho:
     list-key:
     topic-ids:
 
+# Listmonk Campaigns config (optional)
+# Use case: Sending emails
+listmonk:
+    server-url:
+    username:
+    password:
+    list-ids:
+
 # Various low-level configuration options
 internal:
     # If false (the default), then museum will notify the external world of

server/pkg/controller/mailing_lists.go

@@ -6,29 +6,30 @@ import (
 	"strings"
 
 	"github.com/ente-io/museum/ente"
+	"github.com/ente-io/museum/pkg/external/listmonk"
 	"github.com/ente-io/museum/pkg/external/zoho"
 	"github.com/ente-io/stacktrace"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/viper"
 )
 
-// MailingListsController is used to keeping the external mailing lists in sync
+// ZohoMailingListsController is used to keeping the external mailing lists in sync
 // with customer email changes.
 //
-// MailingListsController contains methods for keeping external mailing lists in
+// ZohoMailingListsController contains methods for keeping external mailing lists in
 // sync when new users sign up, or update their email, or delete their account.
 // Currently, these mailing lists are hosted on Zoho Campaigns.
 //
 // See also: Syncing emails with Zoho Campaigns
-type MailingListsController struct {
+type ZohoMailingListsController struct {
 	zohoAccessToken string
 	zohoListKey     string
 	zohoTopicIds    string
 	zohoCredentials zoho.Credentials
 }
 
-// Return a new instance of MailingListsController
-func NewMailingListsController() *MailingListsController {
+// Return a new instance of ZohoMailingListsController
+func NewZohoMailingListsController() *ZohoMailingListsController {
 	zohoCredentials := zoho.Credentials{
 		ClientID:     viper.GetString("zoho.client-id"),
 		ClientSecret: viper.GetString("zoho.client-secret"),
@@ -57,7 +58,7 @@ func NewMailingListsController() *MailingListsController {
 	// we'll use the refresh token to create an access token on demand.
 	zohoAccessToken := viper.GetString("zoho.access_token")
 
-	return &MailingListsController{
+	return &ZohoMailingListsController{
 		zohoCredentials: zohoCredentials,
 		zohoListKey:     zohoListKey,
 		zohoTopicIds:    zohoTopicIds,
@@ -65,6 +66,31 @@ func NewMailingListsController() *MailingListsController {
 	}
 }
 
+// ListmonkMailingListsController is used to interact with the Listmonk API.
+//
+// It specifies BaseURL (URL of your listmonk server),
+// your listmonk Username and Password
+// and ListIDs (an array of integer values indicating the id of listmonk campaign mailing list
+// to which the subscriber needs to added)
+type ListmonkMailingListsController struct {
+	BaseURL  string
+	Username string
+	Password string
+	ListIDs  []int
+}
+
+// NewListmonkMailingListsController creates a new instance of ListmonkMailingListsController
+// with the API credentials provided in config file
+func NewListmonkMailingListsController() *ListmonkMailingListsController {
+	credentials := &ListmonkMailingListsController{
+		BaseURL:  viper.GetString("listmonk.server-url"),
+		Username: viper.GetString("listmonk.username"),
+		Password: viper.GetString("listmonk.password"),
+		ListIDs:  viper.GetIntSlice("listmonk.list-ids"),
+	}
+	return credentials
+}
+
 // Add the given email address to our default Zoho Campaigns list.
 //
 // It is valid to resubscribe an email that has previously been unsubscribe.
@@ -75,8 +101,8 @@ func NewMailingListsController() *MailingListsController {
 // that can be later updated or deleted via their API. So instead, we maintain
 // the email addresses of our customers in a Zoho Campaign "list", and subscribe
 // or unsubscribe them to this list.
-func (c *MailingListsController) Subscribe(email string) error {
-	if c.shouldSkip() {
+func (c *ZohoMailingListsController) Subscribe(email string) error {
+	if c.shouldSkipZoho() {
 		return stacktrace.Propagate(ente.ErrNotImplemented, "")
 	}
 
@@ -89,24 +115,26 @@ func (c *MailingListsController) Subscribe(email string) error {
 	//   any confirmations.
 	//
 	// https://www.zoho.com/campaigns/help/developers/contact-subscribe.html
-	return c.doListAction("listsubscribe", email)
+	return c.doListActionZoho("listsubscribe", email)
 }
 
 // Unsubscribe the given email address to our default Zoho Campaigns list.
 //
 // See: [Note: Syncing emails with Zoho Campaigns]
-func (c *MailingListsController) Unsubscribe(email string) error {
-	if c.shouldSkip() {
+func (c *ZohoMailingListsController) Unsubscribe(email string) error {
+	if c.shouldSkipZoho() {
 		return stacktrace.Propagate(ente.ErrNotImplemented, "")
 	}
 
 	// https://www.zoho.com/campaigns/help/developers/contact-unsubscribe.html
-	return c.doListAction("listunsubscribe", email)
+	return c.doListActionZoho("listunsubscribe", email)
 }
 
-func (c *MailingListsController) shouldSkip() bool {
+// shouldSkipZoho checks if the ZohoMailingListsController should be skipped
+// due to missing credentials.
+func (c *ZohoMailingListsController) shouldSkipZoho() bool {
 	if c.zohoCredentials.RefreshToken == "" {
-		log.Info("Skipping mailing list update because credentials are not configured")
+		log.Info("Skipping Zoho mailing list update because credentials are not configured")
 		return true
 	}
 	return false
@@ -114,7 +142,7 @@ func (c *MailingListsController) shouldSkip() bool {
 
 // Both the listsubscribe and listunsubscribe Zoho Campaigns API endpoints work
 // similarly, so use this function to keep the common code.
-func (c *MailingListsController) doListAction(action string, email string) error {
+func (c *ZohoMailingListsController) doListActionZoho(action string, email string) error {
 	// Query escape the email so that any pluses get converted to %2B.
 	escapedEmail := url.QueryEscape(email)
 	contactInfo := fmt.Sprintf("{Contact+Email: \"%s\"}", escapedEmail)
@@ -158,3 +186,56 @@ func (c *MailingListsController) doListAction(action string, email string) error
 
 	return stacktrace.Propagate(err, "")
 }
+
+// Add or subscribe an email to listmonk mailing list
+func (c *ListmonkMailingListsController) Subscribe(email string) error {
+	if c.shouldSkipListmonk() {
+		return stacktrace.Propagate(ente.ErrNotImplemented, "")
+	}
+
+	data := map[string]interface{}{
+		"email": email,
+		"lists": c.ListIDs,
+	}
+
+	return listmonk.SendRequest("POST", c.BaseURL+"/api/subscribers", data,
+		c.Username, c.Password)
+}
+
+// Remove or unsubscribe an email from listmonk mailing list
+func (c *ListmonkMailingListsController) Unsubscribe(email string) error {
+	if c.shouldSkipListmonk() {
+		return stacktrace.Propagate(ente.ErrNotImplemented, "")
+	}
+
+	// Listmonk dosen't provide an endpoint for unsubscribing users from a particular list
+	// directly via their email
+	//
+	// Thus, fetching subscriberID through email address,
+	// and then calling endpoint to modify subscription in a list
+	id, err := listmonk.GetSubscriberID(c.BaseURL+"/api/subscribers", c.Username, c.Password, email)
+	if err != nil {
+		stacktrace.Propagate(err, "")
+	}
+	// API endpoint expects an array of subscriber id as paarmeter
+	subscriberID := []int{id}
+
+	data := map[string]interface{}{
+		"ids":             subscriberID,
+		"action":          "unsubscribe",
+		"target_list_ids": c.ListIDs,
+	}
+
+	return listmonk.SendRequest("PUT", c.BaseURL+"/api/subscribers/lists", data,
+		c.Username, c.Password)
+}
+
+// shouldSkipListmonk checks if the ListmonkMailingListsController should be skipped
+// due to missing credentials.
+func (c *ListmonkMailingListsController) shouldSkipListmonk() bool {
+	if c.BaseURL == "" || c.Username == "" || c.Password == "" {
+		log.Info("Skipping Listmonk mailing list because credentials are not configured")
+		return true
+	}
+	return false
+}

server/pkg/external/listmonk/api.go

@@ -0,0 +1,104 @@
+package listmonk
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+
+	"github.com/ente-io/stacktrace"
+)
+
+// GetSubscriberID returns subscriber id of the provided email address, else returns an error if email was not found
+func GetSubscriberID(endpoint string, username string, password string, subscriberEmail string) (int, error) {
+	// Struct for the received API response.
+	// Can define other fields as well that can be extracted from response JSON
+	type SubscriberResponse struct {
+		Data struct {
+			Results []struct {
+				ID int `json:"id"`
+			} `json:"results"`
+		} `json:"data"`
+	}
+
+	// Constructing query parameters
+	queryParams := url.Values{}
+	queryParams.Set("query", fmt.Sprintf("subscribers.email = '%s'", subscriberEmail))
+
+	// Constructing the URL with query parameters
+	endpointURL, err := url.Parse(endpoint)
+	if err != nil {
+		return 0, stacktrace.Propagate(err, "")
+	}
+	endpointURL.RawQuery = queryParams.Encode()
+
+	req, err := http.NewRequest("GET", endpointURL.String(), nil)
+	if err != nil {
+		return 0, stacktrace.Propagate(err, "")
+	}
+
+	req.SetBasicAuth(username, password)
+
+	// Sending the HTTP request
+	client := &http.Client{}
+	resp, err := client.Do(req)
+	if err != nil {
+		return 0, stacktrace.Propagate(err, "")
+	}
+	defer resp.Body.Close()
+
+	// Reading the response body
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return 0, stacktrace.Propagate(err, "")
+	}
+
+	// Parsing the JSON response
+	var subscriberResp SubscriberResponse
+	if err := json.Unmarshal(body, &subscriberResp); err != nil {
+		return 0, stacktrace.Propagate(err, "")
+	}
+
+	// Checking if there are any subscribers found
+	if len(subscriberResp.Data.Results) == 0 {
+		return 0, stacktrace.Propagate(err, "")
+	}
+
+	// Extracting the ID from the response
+	id := subscriberResp.Data.Results[0].ID
+
+	return id, nil
+}
+
+// SendRequest sends a request to the specified Listmonk API endpoint with the provided method and data
+// after authentication with the provided credentials (username, password)
+func SendRequest(method string, url string, data interface{}, username string, password string) error {
+	jsonData, err := json.Marshal(data)
+	if err != nil {
+		return stacktrace.Propagate(err, "")
+	}
+
+	client := &http.Client{}
+	req, err := http.NewRequest(method, url, bytes.NewBuffer(jsonData))
+	if err != nil {
+		return stacktrace.Propagate(err, "")
+	}
+
+	req.SetBasicAuth(username, password)
+	req.Header.Set("Content-Type", "application/json")
+
+	// Send request
+	resp, err := client.Do(req)
+	if err != nil {
+		return stacktrace.Propagate(err, "")
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return stacktrace.Propagate(err, "")
+	}
+
+	return nil
+}