Add support for segment management in API client (App and Track)

README.md

@@ -388,6 +388,11 @@ if err := track.TrackCtx(ctx, "5", "purchase", map[string]interface{}{
 }
 ```
 
+## Segments API
+
+We also provide a client for managing customer segments through the Segments API. For more details on how to use it, refer to the [Segments API README](./SEGMENTS.md).
+
+
 ## Contributing
 
 1. Fork it

SEGMENTS.md

@@ -0,0 +1,176 @@
+# Customer.io Segments API Methods
+
+This document explains how to use the new methods added for managing customer segments in Customer.io. These methods enable you to list, create, delete segments, and manage customers in segments.
+
+## Usage
+
+### Available Methods
+
+1. **Create Segment**
+
+   Creates a new segment in Customer.io.
+
+    ```go
+    request := &CreateSegmentRequest{
+		Segment: Segment{
+			Name: "New Segment",
+		},
+	}
+
+	resp, err := cio.CreateSegment(context.Background(), request)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Printf("Segment created: ID: %d, Name: %s", resp.Segment.ID, resp.Segment.Name)
+    ```
+
+2. **List Segments**
+
+   Retrieves a list of all customer segments.
+
+    ```go
+    segments, err := cio.ListSegments(context.Background())
+    if err != nil {
+        log.Fatal(err)
+    }
+
+    for _, segment := range segments.Segments {
+        log.Printf("Segment ID: %d, Name: %s", segment.ID, segment.Name)
+    }
+    ```
+
+3. **Get Segment by ID**
+
+   Retrieves a specific segment by its ID.
+
+    ```go
+    segmentID := 1234
+	resp, err := cio.GetSegment(context.Background(), segmentID)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Printf("Segment ID: %d, Name: %s", resp.Segment.ID, resp.Segment.Name)
+    ```
+
+4. **Delete Segment**
+
+   Deletes a segment by its ID.
+
+    ```go
+    segmentID := 1234
+    err := cio.DeleteSegment(context.Background(), segmentID)
+    if err != nil {
+        log.Fatal(err)
+    }
+
+    log.Println("Segment deleted successfully")
+    ```
+
+5. **Get Segment Dependencies**
+
+   Retrieves dependencies for a specific segment.
+
+    ```go
+    segmentID := 1234
+    dependencies, err := cio.GetSegmentDependencies(context.Background(), segmentID)
+    if err != nil {
+        log.Fatal(err)
+    }
+
+    log.Printf("Segment dependencies: %v", dependencies)
+    ```
+
+6. **Get Segment Customer Count**
+
+   Retrieves the number of customers in a specific segment.
+
+    ```go
+    segmentID := 1234
+    count, err := cio.GetSegmentCustomerCount(context.Background(), segmentID)
+    if err != nil {
+        log.Fatal(err)
+    }
+
+    log.Printf("Customer count in segment %d: %d", segmentID, count.Count)
+    ```
+
+7. **List Customers in a Segment**
+
+   Retrieves a list of customers in a specific segment.
+
+    ```go
+    segmentID := 1234
+	customers, err := cio.ListCustomersInSegment(context.Background(), segmentID)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	for _, customer := range customers.Identifiers {
+		log.Printf("Customer ID: %d", customer.ID)
+	}
+    ```
+
+### Managing Customers in Segments
+
+You can add or remove customers from segments using the following methods:
+
+1. **Add People to Segment**
+
+   Adds a list of customer IDs to a segment.
+
+    ```go
+    segmentID := 1234
+	customerIDs := []string{"customer_1", "customer_2"}
+
+	err := track.AddPeopleToSegment(context.Background(), segmentID, customerIDs)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Println("Customers added to segment successfully")
+    ```
+
+2. **Remove People from Segment**
+
+   Removes a list of customer IDs from a segment.
+
+    ```go
+    segmentID := 1234
+	customerIDs := []string{"customer_1", "customer_2"}
+
+	err := track.RemovePeopleFromSegment(context.Background(), segmentID, customerIDs)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Println("Customers removed from segment successfully")
+    ```
+
+## Example: Creating a Segment and Adding Customers
+
+```go
+func main() {
+    // Create a new segment
+	request := &CreateSegmentRequest{
+		Segment: Segment{
+			Name: "VIP Customers",
+		},
+	}
+	resp, err := cio.CreateSegment(context.Background(), request)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Printf("Created segment: %s (ID: %d)", resp.Segment.Name, resp.Segment.ID)
+
+	// Add customers to the new segment
+	customerIDs := []string{"customer_1", "customer_2"}
+	err = track.AddPeopleToSegment(context.Background(), resp.Segment.ID, customerIDs)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Println("Customers added to the segment successfully")
+}

api.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"io"
 	"io/ioutil"
 	"net/http"
 )
@@ -32,12 +33,17 @@ func NewAPIClient(key string, opts ...option) *APIClient {
 }
 
 func (c *APIClient) doRequest(ctx context.Context, verb, requestPath string, body interface{}) ([]byte, int, error) {
-	b, err := json.Marshal(body)
-	if err != nil {
-		return nil, 0, err
+	var requestBody io.Reader
+
+	if body != nil {
+		b, err := json.Marshal(body)
+		if err != nil {
+			return nil, 0, err
+		}
+		requestBody = bytes.NewBuffer(b)
 	}
 
-	req, err := http.NewRequest(verb, c.URL+requestPath, bytes.NewBuffer(b))
+	req, err := http.NewRequest(verb, c.URL+requestPath, requestBody)
 	if err != nil {
 		return nil, 0, err
 	}