feat: Unify the SSE processing logic (#1800)

plugins/wasm-go/extensions/ai-proxy/provider/provider.go

@@ -149,6 +149,10 @@ type StreamingResponseBodyHandler interface {
 	OnStreamingResponseBody(ctx wrapper.HttpContext, name ApiName, chunk []byte, isLastChunk bool, log wrapper.Log) ([]byte, error)
 }
 
+type StreamingEventHandler interface {
+	OnStreamingEvent(ctx wrapper.HttpContext, name ApiName, event StreamEvent, log wrapper.Log) ([]StreamEvent, error)
+}
+
 type ApiNameHandler interface {
 	GetApiName(path string) ApiName
 }
@@ -575,6 +579,81 @@ func doGetMappedModel(model string, modelMapping map[string]string, log wrapper.
 	return ""
 }
 
+func ExtractStreamingEvents(ctx wrapper.HttpContext, chunk []byte, log wrapper.Log) []StreamEvent {
+	body := chunk
+	if bufferedStreamingBody, has := ctx.GetContext(ctxKeyStreamingBody).([]byte); has {
+		body = append(bufferedStreamingBody, chunk...)
+	}
+
+	eventStartIndex, lineStartIndex, valueStartIndex := -1, -1, -1
+
+	defer func() {
+		if eventStartIndex >= 0 && eventStartIndex < len(body) {
+			// Just in case the received chunk is not a complete event.
+			ctx.SetContext(ctxKeyStreamingBody, body[eventStartIndex:])
+		} else {
+			ctx.SetContext(ctxKeyStreamingBody, nil)
+		}
+	}()
+
+	// Sample Qwen event response:
+	//
+	// event:result
+	// :HTTP_STATUS/200
+	// data:{"output":{"choices":[{"message":{"content":"你好！","role":"assistant"},"finish_reason":"null"}]},"usage":{"total_tokens":116,"input_tokens":114,"output_tokens":2},"request_id":"71689cfc-1f42-9949-86e8-9563b7f832b1"}
+	//
+	// event:error
+	// :HTTP_STATUS/400
+	// data:{"code":"InvalidParameter","message":"Preprocessor error","request_id":"0cbe6006-faec-9854-bf8b-c906d75c3bd8"}
+	//
+
+	var events []StreamEvent
+
+	currentKey := ""
+	currentEvent := &StreamEvent{}
+	i, length := 0, len(body)
+	for i = 0; i < length; i++ {
+		ch := body[i]
+		if ch != '\n' {
+			if lineStartIndex == -1 {
+				if eventStartIndex == -1 {
+					eventStartIndex = i
+				}
+				lineStartIndex = i
+				valueStartIndex = -1
+			}
+			if valueStartIndex == -1 {
+				if ch == ':' {
+					valueStartIndex = i + 1
+					currentKey = string(body[lineStartIndex:valueStartIndex])
+				}
+			} else if valueStartIndex == i && ch == ' ' {
+				// Skip leading spaces in data.
+				valueStartIndex = i + 1
+			}
+			continue
+		}
+
+		if lineStartIndex != -1 {
+			value := string(body[valueStartIndex:i])
+			currentEvent.SetValue(currentKey, value)
+		} else {
+			// Extra new line. The current event is complete.
+			events = append(events, *currentEvent)
+			// Reset event parsing state.
+			eventStartIndex = -1
+			currentEvent = &StreamEvent{}
+		}
+
+		// Reset line parsing state.
+		lineStartIndex = -1
+		valueStartIndex = -1
+		currentKey = ""
+	}
+
+	return events
+}
+
 func (c *ProviderConfig) isSupportedAPI(apiName ApiName) bool {
 	_, exist := c.capabilities[string(apiName)]
 	return exist