Add fields to ApiError struct (#32)

* Add fields to ApiError struct

* Add documentation comments

apierror.go

@@ -3,24 +3,78 @@ package replicate
 import (
 	"encoding/json"
 	"fmt"
+	"net/http"
+	"strings"
 )
 
 // APIError represents an error returned by the Replicate API
 type APIError struct {
-	Detail string `json:"detail"`
+	// Type is a URI that identifies the error type.
+	Type string `json:"type,omitempty"`
+
+	// Title is a short human-readable summary of the error.
+	Title string `json:"title,omitempty"`
+
+	// Status is the HTTP status code.
+	Status int `json:"status,omitempty"`
+
+	// Detail is a human-readable explanation of the error.
+	Detail string `json:"detail,omitempty"`
+
+	// Instance is a URI that identifies the specific occurrence of the error.
+	Instance string `json:"instance,omitempty"`
 }
 
-func unmarshalAPIError(data []byte) *APIError {
-	apiError := &APIError{}
-	err := json.Unmarshal(data, apiError)
+func unmarshalAPIError(resp *http.Response, data []byte) *APIError {
+	apiError := APIError{}
+	err := json.Unmarshal(data, &apiError)
 	if err != nil {
 		apiError.Detail = fmt.Sprintf("Unknown error: %s", err)
 	}
 
-	return apiError
+	if apiError.Status == 0 && resp != nil {
+		apiError.Status = resp.StatusCode
+	}
+
+	return &apiError
 }
 
-// Error implements the error interface
 func (e APIError) Error() string {
-	return fmt.Sprintf("Replicate API error: %s", e.Detail)
+	components := []string{}
+	if e.Type != "" {
+		components = append(components, e.Type)
+	}
+
+	if e.Title != "" {
+		components = append(components, e.Title)
+	}
+
+	if e.Detail != "" {
+		components = append(components, e.Detail)
+	}
+
+	output := strings.Join(components, ": ")
+	if output == "" {
+		output = "Unknown error"
+	}
+
+	if e.Instance != "" {
+		output = fmt.Sprintf("%s (%s)", output, e.Instance)
+	}
+
+	return output
+}
+
+func (e *APIError) WriteHTTPResponse(w http.ResponseWriter) {
+	status := http.StatusBadGateway
+	if e.Status != 0 {
+		status = e.Status
+	}
+
+	w.WriteHeader(status)
+	err := json.NewEncoder(w).Encode(e)
+	if err != nil {
+		err = fmt.Errorf("failed to write error response: %w", err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+	}
 }

client.go

@@ -186,7 +186,7 @@ func (r *Client) request(ctx context.Context, method, path string, body interfac
 		}
 
 		if response.StatusCode < 200 || response.StatusCode >= 400 {
-			apiError = unmarshalAPIError(responseBytes)
+			apiError = unmarshalAPIError(response, responseBytes)
 			if !r.shouldRetry(response, method) {
 				return apiError
 			}

client_test.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/replicate/replicate-go"
+
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -1148,19 +1149,11 @@ func TestAutomaticallyRetryGetRequests(t *testing.T) {
 			w.Header().Set("Retry-After", "0")
 			w.WriteHeader(status)
 
-			if status == http.StatusInternalServerError {
-				err := &replicate.APIError{
-					Detail: "Internal server error",
-				}
-				body, _ := json.Marshal(err)
-				w.Write(body)
-			} else if status == http.StatusTooManyRequests {
-				err := &replicate.APIError{
-					Detail: "Too many requests",
-				}
-				body, _ := json.Marshal(err)
-				w.Write(body)
+			err := replicate.APIError{
+				Detail: http.StatusText(status),
 			}
+			body, _ := json.Marshal(err)
+			w.Write(body)
 		}
 	}))
 	defer mockServer.Close()
@@ -1191,19 +1184,11 @@ func TestAutomaticallyRetryPostRequests(t *testing.T) {
 		w.Header().Set("Retry-After", "0")
 		w.WriteHeader(status)
 
-		if status == http.StatusInternalServerError {
-			err := &replicate.APIError{
-				Detail: "Internal server error",
-			}
-			body, _ := json.Marshal(err)
-			w.Write(body)
-		} else if status == http.StatusTooManyRequests {
-			err := &replicate.APIError{
-				Detail: "Too many requests",
-			}
-			body, _ := json.Marshal(err)
-			w.Write(body)
+		err := replicate.APIError{
+			Detail: http.StatusText(status),
 		}
+		body, _ := json.Marshal(err)
+		w.Write(body)
 	}))
 	defer mockServer.Close()
 
@@ -1224,7 +1209,7 @@ func TestAutomaticallyRetryPostRequests(t *testing.T) {
 	version := "5c7d5dc6dd8bf75c1acaa8565735e7986bc5b66206b55cca93cb72c9bf15ccaa"
 	_, err = client.CreatePrediction(ctx, version, input, &webhook, true)
 
-	assert.ErrorContains(t, err, "Internal server error")
+	assert.ErrorContains(t, err, http.StatusText(http.StatusInternalServerError))
 }
 
 func TestStream(t *testing.T) {

stream.go

@@ -179,7 +179,7 @@ func (r *Client) streamPrediction(ctx context.Context, prediction *Prediction, l
 
 					switch event.Type {
 					case "error":
-						errChan <- unmarshalAPIError([]byte(event.Data))
+						errChan <- unmarshalAPIError(nil, []byte(event.Data))
 					case "done":
 						close(done)
 						return