chore: import upstream snapshot with attribution

ai/internal/openaiapi/stream.go

@@ -0,0 +1,117 @@
+package openaiapi
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"go-micro.dev/v6/ai"
+)
+
+// Stream opens an OpenAI-compatible chat completions SSE stream.
+func Stream(ctx context.Context, opts ai.Options, req *ai.Request, basePath string) (ai.Stream, error) {
+	messages := []map[string]any{{"role": "system", "content": req.SystemPrompt}}
+	for _, m := range req.Messages {
+		messages = append(messages, map[string]any{"role": m.Role, "content": m.Content})
+	}
+	if req.Prompt != "" {
+		messages = append(messages, map[string]any{"role": "user", "content": req.Prompt})
+	}
+	apiReq := map[string]any{
+		"model":          opts.Model,
+		"messages":       messages,
+		"stream":         true,
+		"stream_options": map[string]any{"include_usage": true},
+	}
+	if opts.MaxTokens > 0 {
+		apiReq["max_tokens"] = opts.MaxTokens
+	}
+	reqBody, err := json.Marshal(apiReq)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal stream request: %w", err)
+	}
+	apiURL := strings.TrimRight(opts.BaseURL, "/") + basePath
+	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, apiURL, bytes.NewReader(reqBody))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create stream request: %w", err)
+	}
+	httpReq.Header.Set("Content-Type", "application/json")
+	httpReq.Header.Set("Accept", "text/event-stream")
+	httpReq.Header.Set("Authorization", "Bearer "+opts.APIKey)
+
+	httpResp, err := http.DefaultClient.Do(httpReq)
+	if err != nil {
+		return nil, fmt.Errorf("stream API request failed: %w", err)
+	}
+	if httpResp.StatusCode != http.StatusOK {
+		defer httpResp.Body.Close()
+		respBody, _ := io.ReadAll(httpResp.Body)
+		return nil, fmt.Errorf("stream API error (%s): %s", httpResp.Status, string(respBody))
+	}
+	return &StreamReader{body: httpResp.Body, scanner: bufio.NewScanner(httpResp.Body)}, nil
+}
+
+// StreamReader reads OpenAI-compatible server-sent event chunks.
+type StreamReader struct {
+	body    io.ReadCloser
+	scanner *bufio.Scanner
+	closed  bool
+}
+
+func (s *StreamReader) Recv() (*ai.Response, error) {
+	for s.scanner.Scan() {
+		line := strings.TrimSpace(s.scanner.Text())
+		if line == "" || strings.HasPrefix(line, ":") {
+			continue
+		}
+		if !strings.HasPrefix(line, "data:") {
+			continue
+		}
+		data := strings.TrimSpace(strings.TrimPrefix(line, "data:"))
+		if data == "[DONE]" {
+			return nil, io.EOF
+		}
+		var chunk struct {
+			Choices []struct {
+				Delta struct {
+					Content string `json:"content"`
+				} `json:"delta"`
+			} `json:"choices"`
+			Usage *struct {
+				PromptTokens     int `json:"prompt_tokens"`
+				CompletionTokens int `json:"completion_tokens"`
+				TotalTokens      int `json:"total_tokens"`
+			} `json:"usage"`
+		}
+		if err := json.Unmarshal([]byte(data), &chunk); err != nil {
+			return nil, fmt.Errorf("failed to parse stream chunk: %w", err)
+		}
+		if len(chunk.Choices) > 0 && chunk.Choices[0].Delta.Content != "" {
+			return &ai.Response{Reply: chunk.Choices[0].Delta.Content}, nil
+		}
+		if chunk.Usage != nil {
+			return &ai.Response{Usage: ai.Usage{
+				InputTokens:  chunk.Usage.PromptTokens,
+				OutputTokens: chunk.Usage.CompletionTokens,
+				TotalTokens:  chunk.Usage.TotalTokens,
+			}}, nil
+		}
+	}
+	if err := s.scanner.Err(); err != nil {
+		return nil, err
+	}
+	return nil, io.EOF
+}
+
+func (s *StreamReader) Close() error {
+	if s.closed {
+		return nil
+	}
+	s.closed = true
+	return s.body.Close()
+}