File size: 4,059 Bytes
bf9e111 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 | package amp
import (
"bytes"
"net/http"
"strings"
"github.com/gin-gonic/gin"
log "github.com/sirupsen/logrus"
"github.com/tidwall/gjson"
"github.com/tidwall/sjson"
)
// ResponseRewriter wraps a gin.ResponseWriter to intercept and modify the response body
// It's used to rewrite model names in responses when model mapping is used
type ResponseRewriter struct {
gin.ResponseWriter
body *bytes.Buffer
originalModel string
isStreaming bool
}
// NewResponseRewriter creates a new response rewriter for model name substitution
func NewResponseRewriter(w gin.ResponseWriter, originalModel string) *ResponseRewriter {
return &ResponseRewriter{
ResponseWriter: w,
body: &bytes.Buffer{},
originalModel: originalModel,
}
}
// Write intercepts response writes and buffers them for model name replacement
func (rw *ResponseRewriter) Write(data []byte) (int, error) {
// Detect streaming on first write
if rw.body.Len() == 0 && !rw.isStreaming {
contentType := rw.Header().Get("Content-Type")
rw.isStreaming = strings.Contains(contentType, "text/event-stream") ||
strings.Contains(contentType, "stream")
}
if rw.isStreaming {
n, err := rw.ResponseWriter.Write(rw.rewriteStreamChunk(data))
if err == nil {
if flusher, ok := rw.ResponseWriter.(http.Flusher); ok {
flusher.Flush()
}
}
return n, err
}
return rw.body.Write(data)
}
// Flush writes the buffered response with model names rewritten
func (rw *ResponseRewriter) Flush() {
if rw.isStreaming {
if flusher, ok := rw.ResponseWriter.(http.Flusher); ok {
flusher.Flush()
}
return
}
if rw.body.Len() > 0 {
if _, err := rw.ResponseWriter.Write(rw.rewriteModelInResponse(rw.body.Bytes())); err != nil {
log.Warnf("amp response rewriter: failed to write rewritten response: %v", err)
}
}
}
// modelFieldPaths lists all JSON paths where model name may appear
var modelFieldPaths = []string{"model", "modelVersion", "response.modelVersion", "message.model"}
// rewriteModelInResponse replaces all occurrences of the mapped model with the original model in JSON
// It also suppresses "thinking" blocks if "tool_use" is present to ensure Amp client compatibility
func (rw *ResponseRewriter) rewriteModelInResponse(data []byte) []byte {
// 1. Amp Compatibility: Suppress thinking blocks if tool use is detected
// The Amp client struggles when both thinking and tool_use blocks are present
if gjson.GetBytes(data, `content.#(type=="tool_use")`).Exists() {
filtered := gjson.GetBytes(data, `content.#(type!="thinking")#`)
if filtered.Exists() {
originalCount := gjson.GetBytes(data, "content.#").Int()
filteredCount := filtered.Get("#").Int()
if originalCount > filteredCount {
var err error
data, err = sjson.SetBytes(data, "content", filtered.Value())
if err != nil {
log.Warnf("Amp ResponseRewriter: failed to suppress thinking blocks: %v", err)
} else {
log.Debugf("Amp ResponseRewriter: Suppressed %d thinking blocks due to tool usage", originalCount-filteredCount)
// Log the result for verification
log.Debugf("Amp ResponseRewriter: Resulting content: %s", gjson.GetBytes(data, "content").String())
}
}
}
}
if rw.originalModel == "" {
return data
}
for _, path := range modelFieldPaths {
if gjson.GetBytes(data, path).Exists() {
data, _ = sjson.SetBytes(data, path, rw.originalModel)
}
}
return data
}
// rewriteStreamChunk rewrites model names in SSE stream chunks
func (rw *ResponseRewriter) rewriteStreamChunk(chunk []byte) []byte {
if rw.originalModel == "" {
return chunk
}
// SSE format: "data: {json}\n\n"
lines := bytes.Split(chunk, []byte("\n"))
for i, line := range lines {
if bytes.HasPrefix(line, []byte("data: ")) {
jsonData := bytes.TrimPrefix(line, []byte("data: "))
if len(jsonData) > 0 && jsonData[0] == '{' {
// Rewrite JSON in the data line
rewritten := rw.rewriteModelInResponse(jsonData)
lines[i] = append([]byte("data: "), rewritten...)
}
}
}
return bytes.Join(lines, []byte("\n"))
}
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