fix moonshot usage compatible problem (#1568)

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

@@ -3,12 +3,15 @@ package provider
 import (
 	"errors"
 	"fmt"
+	"net/http"
+	"strings"
+
 	"github.com/alibaba/higress/plugins/wasm-go/extensions/ai-proxy/util"
 	"github.com/alibaba/higress/plugins/wasm-go/pkg/wrapper"
 	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
 	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
 	"github.com/tidwall/gjson"
-	"net/http"
+	"github.com/tidwall/sjson"
 )
 
 // moonshotProvider is the provider for Moonshot AI service.
@@ -149,3 +152,99 @@ func (m *moonshotProvider) sendRequest(method, path, body, apiKey string, callba
 		return errors.New("unsupported method: " + method)
 	}
 }
+
+func (m *moonshotProvider) OnStreamingResponseBody(ctx wrapper.HttpContext, name ApiName, chunk []byte, isLastChunk bool, log wrapper.Log) ([]byte, error) {
+	receivedBody := chunk
+	if bufferedStreamingBody, has := ctx.GetContext(ctxKeyStreamingBody).([]byte); has {
+		receivedBody = append(bufferedStreamingBody, chunk...)
+	}
+
+	eventStartIndex, lineStartIndex, valueStartIndex := -1, -1, -1
+
+	defer func() {
+		if eventStartIndex >= 0 && eventStartIndex < len(receivedBody) {
+			// Just in case the received chunk is not a complete event.
+			ctx.SetContext(ctxKeyStreamingBody, receivedBody[eventStartIndex:])
+		} else {
+			ctx.SetContext(ctxKeyStreamingBody, nil)
+		}
+	}()
+
+	var responseBuilder strings.Builder
+	currentKey := ""
+	currentEvent := &streamEvent{}
+	i, length := 0, len(receivedBody)
+	for i = 0; i < length; i++ {
+		ch := receivedBody[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(receivedBody[lineStartIndex:valueStartIndex])
+				}
+			} else if valueStartIndex == i && ch == ' ' {
+				// Skip leading spaces in data.
+				valueStartIndex = i + 1
+			}
+			continue
+		}
+
+		if lineStartIndex != -1 {
+			value := string(receivedBody[valueStartIndex:i])
+			currentEvent.setValue(currentKey, value)
+		} else {
+			// Extra new line. The current event is complete.
+			log.Debugf("processing event: %v", currentEvent)
+			m.convertStreamEvent(&responseBuilder, currentEvent, log)
+			// Reset event parsing state.
+			eventStartIndex = -1
+			currentEvent = &streamEvent{}
+		}
+
+		// Reset line parsing state.
+		lineStartIndex = -1
+		valueStartIndex = -1
+		currentKey = ""
+	}
+
+	modifiedResponseChunk := responseBuilder.String()
+	log.Debugf("=== modified response chunk: %s", modifiedResponseChunk)
+	return []byte(modifiedResponseChunk), nil
+}
+
+func (m *moonshotProvider) convertStreamEvent(responseBuilder *strings.Builder, event *streamEvent, log wrapper.Log) error {
+	if event.Data == streamEndDataValue {
+		m.appendStreamEvent(responseBuilder, event)
+		return nil
+	}
+
+	if gjson.Get(event.Data, "choices.0.usage").Exists() {
+		usageStr := gjson.Get(event.Data, "choices.0.usage").Raw
+		newData, err := sjson.Delete(event.Data, "choices.0.usage")
+		if err != nil {
+			log.Errorf("convert usage event error: %v", err)
+			return err
+		}
+		newData, err = sjson.SetRaw(newData, "usage", usageStr)
+		if err != nil {
+			log.Errorf("convert usage event error: %v", err)
+			return err
+		}
+		event.Data = newData
+	}
+	m.appendStreamEvent(responseBuilder, event)
+	return nil
+}
+
+func (m *moonshotProvider) appendStreamEvent(responseBuilder *strings.Builder, event *streamEvent) {
+	responseBuilder.WriteString(streamDataItemKey)
+	responseBuilder.WriteString(event.Data)
+	responseBuilder.WriteString("\n\n")
+}