fix: fixing SSE support

controller/relay.go

 package controller
 
 import (
+	"bufio"
+	"bytes"
 	"fmt"
 	"github.com/gin-gonic/gin"
 	"io"
 	"net/http"
 	"one-api/common"
+	"strings"
 )
 
 func Relay(c *gin.Context) {
@@ -30,18 +33,8 @@ func Relay(c *gin.Context) {
 	//req.Header.Del("Accept-Encoding")
 	req.Header.Set("Authorization", c.Request.Header.Get("Authorization"))
 	req.Header.Set("Content-Type", c.Request.Header.Get("Content-Type"))
-	acceptHeader := c.Request.Header.Get("Accept")
-	if acceptHeader != "" {
-		req.Header.Set("Accept", acceptHeader)
-	}
-	connectionHeader := c.Request.Header.Get("Connection")
-	if connectionHeader != "" {
-		req.Header.Set("Connection", connectionHeader)
-	}
-	lastEventIDHeader := c.Request.Header.Get("Last-Event-ID")
-	if lastEventIDHeader != "" {
-		req.Header.Set("Last-Event-ID", lastEventIDHeader)
-	}
+	req.Header.Set("Accept", c.Request.Header.Get("Accept"))
+	req.Header.Set("Connection", c.Request.Header.Get("Connection"))
 	client := &http.Client{}
 
 	resp, err := client.Do(req)
@@ -54,17 +47,57 @@ func Relay(c *gin.Context) {
 		})
 		return
 	}
+	defer resp.Body.Close()
+	scanner := bufio.NewScanner(resp.Body)
+	scanner.Split(func(data []byte, atEOF bool) (advance int, token []byte, err error) {
+		if atEOF && len(data) == 0 {
+			return 0, nil, nil
+		}
+
+		if i := strings.Index(string(data), "\n\n"); i >= 0 {
+			return i + 2, data[0:i], nil
+		}
+
+		if atEOF {
+			return len(data), data, nil
+		}
+
+		return 0, nil, nil
+	})
+	dataChan := make(chan string)
+	stopChan := make(chan bool)
+	go func() {
+		for scanner.Scan() {
+			data := scanner.Text()
+			dataChan <- data
+		}
+		stopChan <- true
+	}()
 	for k, v := range resp.Header {
 		c.Writer.Header().Set(k, v[0])
 	}
-	_, err = io.Copy(c.Writer, resp.Body)
-	if err != nil {
-		c.JSON(http.StatusOK, gin.H{
-			"error": gin.H{
-				"message": err.Error(),
-				"type":    "one_api_error",
-			},
-		})
-		return
-	}
+	c.Stream(func(w io.Writer) bool {
+		select {
+		case data := <-dataChan:
+			//fmt.Println(data)
+			//c.Data(http.StatusOK, "text/event-stream", []byte(data))
+			//c.Render(-1, common.Event{Data: data})
+			//c.SSEvent("", data)
+			//w.Write([]byte(data))
+			//w.(http.Flusher).Flush()
+			//c.Writer.Write(append([]byte(data), []byte("\n\n")...))
+			outputBytes := bytes.NewBufferString(data)
+			w.Write(outputBytes.Bytes())
+			if strings.HasPrefix(data, "data: ") {
+				w.Write([]byte("\n\n"))
+			}
+			//w.Write(append(outputBytes.Bytes(), []byte("\n\n")...))
+			w.(http.Flusher).Flush()
+			//fmt.Println(data)
+			return true
+		case <-stopChan:
+			return false
+		}
+	})
+	return
 }