feat(internal): add backoff retry mechanism

.gitignore

@@ -13,4 +13,5 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+*.DS_store
 examples/.DS_Store

batchofferrequests.go

@@ -0,0 +1,45 @@
+package duffel
+
+import (
+	"context"
+)
+
+type (
+	BatchOfferRequestClient interface {
+		CreateBatchOfferRequest(ctx context.Context, requestInput CreateBatchOfferRequestInput) (*BatchOfferRequest, error)
+		GetBatchOfferRequest(ctx context.Context, id string) (*BatchOfferRequest, error)
+	}
+
+	CreateBatchOfferRequestInput struct {
+		// The passengers who want to travel. If you specify an age for a passenger, the type may differ for the same passenger in different offers due to airline's different rules. e.g. one airline may treat a 14 year old as an adult, and another as a young adult. You may only specify an age or a type – not both.
+		Passengers []OfferRequestPassenger `json:"passengers" url:"-"`
+		// The slices that make up this offer request. One-way journeys can be expressed using one slice, whereas return trips will need two.
+		Slices []OfferRequestSlice `json:"slices" url:"-"`
+		// The cabin that the passengers want to travel in
+		CabinClass CabinClass `json:"cabin_class" url:"-"`
+		// The maximum number of connections within any slice of the offer. For example 0 means a direct flight which will have a single segment within each slice and 1 means a maximum of two segments within each slice of the offer.
+		MaxConnections *int `json:"max_connections,omitempty" url:"-"`
+		// The maximum amount of time in milliseconds to wait for each airline to respond
+		SupplierTimeout int `json:"-" url:"supplier_timeout,omitempty"`
+	}
+
+	BatchOfferRequest struct {
+		TotalBatches     int      `json:"total_batches"`
+		RemainingBatches int      `json:"remaining_batches"`
+		ID               string   `json:"id"`
+		Offers           []Offer  `json:"offers,omitempty"`
+		CreatedAt        DateTime `json:"created_at"`
+	}
+)
+
+func (a *API) CreateBatchOfferRequest(ctx context.Context, requestInput CreateBatchOfferRequestInput) (*BatchOfferRequest, error) {
+	return newRequestWithAPI[CreateBatchOfferRequestInput, BatchOfferRequest](a).
+		Post("/air/batch_offer_requests", &requestInput).
+		Single(ctx)
+}
+
+func (a *API) GetBatchOfferRequest(ctx context.Context, id string) (*BatchOfferRequest, error) {
+	return newRequestWithAPI[EmptyPayload, BatchOfferRequest](a).
+		Getf("/air/batch_offer_requests/%s", id).
+		Single(ctx)
+}

batchofferrequests_test.go

@@ -0,0 +1,76 @@
+package duffel
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"gopkg.in/h2non/gock.v1"
+)
+
+func TestCreateBatchOfferRequest(t *testing.T) {
+	defer gock.Off()
+	a := assert.New(t)
+	gock.New("https://api.duffel.com").
+		Post("/air/batch_offer_requests").
+		Reply(200).
+		SetHeader("Ratelimit-Limit", "5").
+		SetHeader("Ratelimit-Remaining", "5").
+		SetHeader("Ratelimit-Reset", time.Now().Format(time.RFC1123)).
+		SetHeader("Date", time.Now().Format(time.RFC1123)).
+		File("fixtures/200-create-batch-offer-request.json")
+
+	ctx := context.TODO()
+
+	client := New("duffel_test_123")
+	data, err := client.CreateBatchOfferRequest(ctx, CreateBatchOfferRequestInput{
+		Passengers: []OfferRequestPassenger{
+			{
+				FamilyName: "Earhardt",
+				GivenName:  "Amelia",
+				Type:       PassengerTypeAdult,
+			},
+			{
+				Age: 14,
+			},
+		},
+		CabinClass: CabinClassEconomy,
+		Slices: []OfferRequestSlice{
+			{
+				DepartureDate: Date(time.Now().AddDate(0, 0, 7)),
+				Origin:        "JFK",
+				Destination:   "AUS",
+			},
+		},
+	})
+	a.NoError(err)
+	a.NotNil(data)
+
+	a.Equal(7, data.RemainingBatches)
+	a.Equal(7, data.TotalBatches)
+}
+
+func TestGetBatchOfferRequest(t *testing.T) {
+	defer gock.Off()
+	a := assert.New(t)
+	gock.New("https://api.duffel.com").
+		Get("/air/batch_offer_requests/orq_0000AhTmH2Thpl6RrM97qK").
+		Reply(200).
+		SetHeader("Ratelimit-Limit", "5").
+		SetHeader("Ratelimit-Remaining", "5").
+		SetHeader("Ratelimit-Reset", time.Now().Format(time.RFC1123)).
+		SetHeader("Date", time.Now().Format(time.RFC1123)).
+		File("fixtures/200-get-batch-offer-request.json")
+
+	ctx := context.TODO()
+
+	client := New("duffel_test_123")
+
+	data, err := client.GetBatchOfferRequest(ctx, "orq_0000AhTmH2Thpl6RrM97qK")
+	a.NoError(err)
+	a.NotNil(data)
+
+	a.Equal(2, data.TotalBatches)
+	a.Equal(2, data.RemainingBatches)
+}

client.go

@@ -10,10 +10,12 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
 	"strings"
+	"time"
 
 	"github.com/segmentio/encoding/json"
 )
@@ -95,25 +97,72 @@ func (c *client[R, T]) makeRequest(ctx context.Context, resourceName string, met
 		fmt.Printf("REQUEST:\n%s\n", string(b))
 	}
 
-	resp, err := c.httpDoer.Do(req)
-	if err != nil {
-		return nil, err
-	}
+	do := func(c *client[R, T], req *http.Request, reuse bool) (*http.Response, error) {
+		if reuse && req.Body != nil {
+			// In a way when we use retry functionality we have to copy
+			// request and pass it to c.httpDoer.Do, but req.Clone() doesn't really deep clone Body
+			// and we have to clone body manually as in httputil.DumpRequestOut
+			//
+			// Issue https://github.com/golang/go/issues/36095
+			var b bytes.Buffer
+			b.ReadFrom(req.Body)
+			req.Body = ioutil.NopCloser(&b)
+
+			cloneReq := req.Clone(ctx)
+			cloneReq.Body = ioutil.NopCloser(bytes.NewReader(b.Bytes()))
+			req = cloneReq
+		}
 
-	if c.options.Debug {
-		b, err := httputil.DumpResponse(resp, true)
+		resp, err := c.httpDoer.Do(req)
 		if err != nil {
 			return nil, err
 		}
-		fmt.Printf("RESPONSE:\n%s\n", string(b))
+
+		if c.options.Debug {
+			b, err := httputil.DumpResponse(resp, true)
+			if err != nil {
+				return nil, err
+			}
+			fmt.Printf("RESPONSE:\n%s\n", string(b))
+		}
+
+		if resp.StatusCode >= 400 {
+			err = decodeError(resp)
+			return nil, err
+		}
+		return resp, nil
 	}
 
-	if resp.StatusCode > 399 {
-		err = decodeError(resp)
-		return nil, err
+	if c.retry == nil {
+		// Do single request without using backoff retry mechanism
+		return do(c, req, false)
 	}
 
-	return resp, nil
+	for {
+		resp, err := do(c, req, true)
+
+		var isMatchedCond bool
+		for _, cond := range c.options.Retry.Conditions {
+			if ok := cond(resp, err); ok {
+				isMatchedCond = true
+				break
+			}
+		}
+		if isMatchedCond {
+			// Get next duration internval, sleep and make another request
+			// till nextDuration != stopBackoff
+			nextDuration := c.retry.next()
+			if nextDuration == stopBackoff {
+				c.retry.reset()
+				return resp, err
+			}
+			time.Sleep(nextDuration)
+			continue
+		}
+
+		// Break retries mechanism if conditions weren't matched
+		return resp, err
+	}
 }
 
 func (c *client[R, T]) buildRequestURL(resourceName string) (*url.URL, error) {

client_test.go

@@ -6,7 +6,9 @@ package duffel
 
 import (
 	"context"
+	"net/http"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"gopkg.in/h2non/gock.v1"
@@ -59,3 +61,27 @@ func TestClientErrorBadGateway(t *testing.T) {
 	a.Nil(data)
 	a.Equal("duffel: An internal server error occurred. Please try again later.", err.Error())
 }
+
+func TestClientRetry(t *testing.T) {
+	ctx := context.TODO()
+	a := assert.New(t)
+	gock.New("https://api.duffel.com/air/offer_requests").
+		Persist().
+		Reply(502).
+		AddHeader("Content-Type", "text/html").
+		File("fixtures/502-bad-gateway.html")
+	defer gock.Off()
+
+	client := New("duffel_test_123",
+		WithRetry(3, time.Second, time.Second*5, ExponentalBackoff),
+		WithRetryCondition(func(resp *http.Response, err error) bool {
+			return err != nil
+		}),
+	)
+	data, err := client.CreateOfferRequest(ctx, OfferRequestInput{
+		ReturnOffers: true,
+	})
+	a.Error(err)
+	a.Nil(data)
+	a.Equal("duffel: An internal server error occurred. Please try again later.", err.Error())
+}

duffel.go

@@ -17,6 +17,7 @@ const defaultHost = "https://api.duffel.com/"
 type (
 	Duffel interface {
 		OfferRequestClient
+		BatchOfferRequestClient
 		OfferClient
 		OrderClient
 		OrderChangeClient
@@ -66,6 +67,7 @@ type (
 		OperatingCarrier             Airline            `json:"operating_carrier"`
 		MarketingCarrierFlightNumber string             `json:"marketing_carrier_flight_number"`
 		MarketingCarrier             Airline            `json:"marketing_carrier"`
+		Stops                        []FlightStop       `json:"stops,omitempty"`
 		Duration                     Duration           `json:"duration"`
 		Distance                     Distance           `json:"distance,omitempty"`
 		DestinationTerminal          string             `json:"destination_terminal"`
@@ -75,6 +77,13 @@ type (
 		Aircraft                     Aircraft           `json:"aircraft"`
 	}
 
+	FlightStop struct {
+		ID             string   `json:"id"`
+		Duration       Duration `json:"duration"`
+		RawDepartingAt string   `json:"departing_at"`
+		Airport        Airport  `json:"airport"`
+	}
+
 	SegmentPassenger struct {
 		ID                      string     `json:"passenger_id"`
 		FareBasisCode           string     `json:"fare_basis_code"`
@@ -237,7 +246,16 @@ type (
 		Host      string
 		UserAgent string
 		HttpDoer  *http.Client
-		Debug     bool
+		Retry     struct {
+			MaxAttempts int
+			MinWaitTime time.Duration
+			MaxWaitTime time.Duration
+			// Conditions that will be applied on retry mechanism.
+			Conditions []RetryCond
+			// Retry function which describes backoff algorithm.
+			Fn RetryFunc
+		}
+		Debug bool
 	}
 
 	client[Req any, Resp any] struct {
@@ -246,6 +264,7 @@ type (
 		options       *Options
 		limiter       *rate.Limiter
 		rateLimit     *RateLimit
+		retry         *backoff
 		afterResponse []func(resp *http.Response)
 	}
 

fixtures/200-create-batch-offer-request.json

@@ -0,0 +1,10 @@
+{
+  "data": {
+      "remaining_batches": 7,
+      "total_batches": 7,
+      "client_key": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE3MTQ3MzU4NDAsImxpdmVfbW9kZSI6ZmFsc2UsIm9yZ2FuaXNhdGlvbl9pZCI6Im9yZ18wMDAwQU4xdXZobHNaQlF6RDhPSTFZIn0.1dOy3eTaUskIgfphTgAlW0aStrwklPModabSf-Znam0",
+      "created_at": "2024-05-02T11:30:40.589820Z",
+      "live_mode": false,
+      "id": "orq_0000AhTmH2Thpl6RrM97qK"
+  }
+}