Add form builder (#235)

* add form builder

* cover VariImage

* test for closing errors

* simplify tests

* add audio api test coverage

* don't leak authToken when printed

* rename api->client

* fix test

client.go

@@ -0,0 +1,134 @@
+package openai
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+// Client is OpenAI GPT-3 API client.
+type Client struct {
+	config ClientConfig
+
+	requestBuilder    requestBuilder
+	createFormBuilder func(io.Writer) formBuilder
+}
+
+// NewClient creates new OpenAI API client.
+func NewClient(authToken string) *Client {
+	config := DefaultConfig(authToken)
+	return NewClientWithConfig(config)
+}
+
+// NewClientWithConfig creates new OpenAI API client for specified config.
+func NewClientWithConfig(config ClientConfig) *Client {
+	return &Client{
+		config:         config,
+		requestBuilder: newRequestBuilder(),
+		createFormBuilder: func(body io.Writer) formBuilder {
+			return newFormBuilder(body)
+		},
+	}
+}
+
+// NewOrgClient creates new OpenAI API client for specified Organization ID.
+//
+// Deprecated: Please use NewClientWithConfig.
+func NewOrgClient(authToken, org string) *Client {
+	config := DefaultConfig(authToken)
+	config.OrgID = org
+	return NewClientWithConfig(config)
+}
+
+func (c *Client) sendRequest(req *http.Request, v interface{}) error {
+	req.Header.Set("Accept", "application/json; charset=utf-8")
+	// Azure API Key authentication
+	if c.config.APIType == APITypeAzure {
+		req.Header.Set(AzureAPIKeyHeader, c.config.authToken)
+	} else {
+		// OpenAI or Azure AD authentication
+		req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", c.config.authToken))
+	}
+
+	// Check whether Content-Type is already set, Upload Files API requires
+	// Content-Type == multipart/form-data
+	contentType := req.Header.Get("Content-Type")
+	if contentType == "" {
+		req.Header.Set("Content-Type", "application/json; charset=utf-8")
+	}
+
+	if len(c.config.OrgID) > 0 {
+		req.Header.Set("OpenAI-Organization", c.config.OrgID)
+	}
+
+	res, err := c.config.HTTPClient.Do(req)
+	if err != nil {
+		return err
+	}
+
+	defer res.Body.Close()
+
+	if res.StatusCode < http.StatusOK || res.StatusCode >= http.StatusBadRequest {
+		var errRes ErrorResponse
+		err = json.NewDecoder(res.Body).Decode(&errRes)
+		if err != nil || errRes.Error == nil {
+			reqErr := RequestError{
+				StatusCode: res.StatusCode,
+				Err:        err,
+			}
+			return fmt.Errorf("error, %w", &reqErr)
+		}
+		errRes.Error.StatusCode = res.StatusCode
+		return fmt.Errorf("error, status code: %d, message: %w", res.StatusCode, errRes.Error)
+	}
+
+	if v != nil {
+		if err = json.NewDecoder(res.Body).Decode(v); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (c *Client) fullURL(suffix string) string {
+	// /openai/deployments/{engine}/chat/completions?api-version={api_version}
+	if c.config.APIType == APITypeAzure || c.config.APIType == APITypeAzureAD {
+		baseURL := c.config.BaseURL
+		baseURL = strings.TrimRight(baseURL, "/")
+		return fmt.Sprintf("%s/%s/%s/%s%s?api-version=%s",
+			baseURL, azureAPIPrefix, azureDeploymentsPrefix, c.config.Engine, suffix, c.config.APIVersion)
+	}
+
+	// c.config.APIType == APITypeOpenAI || c.config.APIType == ""
+	return fmt.Sprintf("%s%s", c.config.BaseURL, suffix)
+}
+
+func (c *Client) newStreamRequest(
+	ctx context.Context,
+	method string,
+	urlSuffix string,
+	body any) (*http.Request, error) {
+	req, err := c.requestBuilder.build(ctx, method, c.fullURL(urlSuffix), body)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Accept", "text/event-stream")
+	req.Header.Set("Cache-Control", "no-cache")
+	req.Header.Set("Connection", "keep-alive")
+
+	// https://learn.microsoft.com/en-us/azure/cognitive-services/openai/reference#authentication
+	// Azure API Key authentication
+	if c.config.APIType == APITypeAzure {
+		req.Header.Set(AzureAPIKeyHeader, c.config.authToken)
+	} else {
+		// OpenAI or Azure AD authentication
+		req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", c.config.authToken))
+	}
+	return req, nil
+}