refactor split gateway handler helpers

backend/internal/handler/gateway_handler_intercept.go

@@ -0,0 +1,197 @@
+package handler
+
+import (
+	"crypto/rand"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/gin-gonic/gin"
+)
+
+type InterceptType int
+
+const (
+	InterceptTypeNone InterceptType = iota
+	InterceptTypeWarmup
+	InterceptTypeSuggestionMode
+	InterceptTypeMaxTokensOneHaiku
+)
+
+func isHaikuModel(model string) bool {
+	return strings.Contains(strings.ToLower(model), "haiku")
+}
+
+func isMaxTokensOneHaikuRequest(model string, maxTokens int, isStream bool) bool {
+	return maxTokens == 1 && isHaikuModel(model) && !isStream
+}
+
+func detectInterceptType(body []byte, model string, maxTokens int, isStream bool, isClaudeCodeClient bool) InterceptType {
+	if isClaudeCodeClient && isMaxTokensOneHaikuRequest(model, maxTokens, isStream) {
+		return InterceptTypeMaxTokensOneHaiku
+	}
+
+	bodyStr := string(body)
+	hasSuggestionMode := strings.Contains(bodyStr, "[SUGGESTION MODE:")
+	hasWarmupKeyword := strings.Contains(bodyStr, "title") || strings.Contains(bodyStr, "Warmup")
+
+	if !hasSuggestionMode && !hasWarmupKeyword {
+		return InterceptTypeNone
+	}
+
+	var req struct {
+		Messages []struct {
+			Role    string `json:"role"`
+			Content []struct {
+				Type string `json:"type"`
+				Text string `json:"text"`
+			} `json:"content"`
+		} `json:"messages"`
+		System []struct {
+			Text string `json:"text"`
+		} `json:"system"`
+	}
+	if err := json.Unmarshal(body, &req); err != nil {
+		return InterceptTypeNone
+	}
+
+	if hasSuggestionMode && len(req.Messages) > 0 {
+		lastMsg := req.Messages[len(req.Messages)-1]
+		if lastMsg.Role == "user" && len(lastMsg.Content) > 0 &&
+			lastMsg.Content[0].Type == "text" &&
+			strings.HasPrefix(lastMsg.Content[0].Text, "[SUGGESTION MODE:") {
+			return InterceptTypeSuggestionMode
+		}
+	}
+
+	if hasWarmupKeyword {
+		for _, msg := range req.Messages {
+			for _, content := range msg.Content {
+				if content.Type == "text" {
+					if strings.Contains(content.Text, "Please write a 5-10 word title for the following conversation:") ||
+						content.Text == "Warmup" {
+						return InterceptTypeWarmup
+					}
+				}
+			}
+		}
+		for _, sys := range req.System {
+			if strings.Contains(sys.Text, "nalyze if this message indicates a new conversation topic. If it does, extract a 2-3 word title") {
+				return InterceptTypeWarmup
+			}
+		}
+	}
+
+	return InterceptTypeNone
+}
+
+func sendMockInterceptStream(c *gin.Context, model string, interceptType InterceptType) {
+	c.Header("Content-Type", "text/event-stream")
+	c.Header("Cache-Control", "no-cache")
+	c.Header("Connection", "keep-alive")
+	c.Header("X-Accel-Buffering", "no")
+
+	var msgID string
+	var outputTokens int
+	var textDeltas []string
+
+	switch interceptType {
+	case InterceptTypeSuggestionMode:
+		msgID = "msg_mock_suggestion"
+		outputTokens = 1
+		textDeltas = []string{""}
+	default:
+		msgID = "msg_mock_warmup"
+		outputTokens = 2
+		textDeltas = []string{"New", " Conversation"}
+	}
+
+	messageStartJSON := `{"type":"message_start","message":{"id":` + strconv.Quote(msgID) + `,"type":"message","role":"assistant","model":` + strconv.Quote(model) + `,"content":[],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":10,"output_tokens":0}}}`
+
+	events := []string{
+		`event: message_start` + "\n" + `data: ` + string(messageStartJSON),
+		`event: content_block_start` + "\n" + `data: {"content_block":{"text":"","type":"text"},"index":0,"type":"content_block_start"}`,
+	}
+
+	for _, text := range textDeltas {
+		deltaJSON := `{"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":` + strconv.Quote(text) + `}}`
+		events = append(events, `event: content_block_delta`+"\n"+`data: `+string(deltaJSON))
+	}
+
+	messageDeltaJSON := `{"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},"usage":{"input_tokens":10,"output_tokens":` + strconv.Itoa(outputTokens) + `}}`
+
+	events = append(events,
+		`event: content_block_stop`+"\n"+`data: {"index":0,"type":"content_block_stop"}`,
+		`event: message_delta`+"\n"+`data: `+string(messageDeltaJSON),
+		`event: message_stop`+"\n"+`data: {"type":"message_stop"}`,
+	)
+
+	for _, event := range events {
+		_, _ = c.Writer.WriteString(event + "\n\n")
+		c.Writer.Flush()
+		time.Sleep(20 * time.Millisecond)
+	}
+}
+
+func generateRealisticMsgID() string {
+	const charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+	const idLen = 24
+	randomBytes := make([]byte, idLen)
+	if _, err := rand.Read(randomBytes); err != nil {
+		return fmt.Sprintf("msg_bdrk_%d", time.Now().UnixNano())
+	}
+	b := make([]byte, idLen)
+	for i := range b {
+		b[i] = charset[int(randomBytes[i])%len(charset)]
+	}
+	return "msg_bdrk_" + string(b)
+}
+
+func sendMockInterceptResponse(c *gin.Context, model string, interceptType InterceptType) {
+	var msgID, text, stopReason string
+	var outputTokens int
+
+	switch interceptType {
+	case InterceptTypeSuggestionMode:
+		msgID = "msg_mock_suggestion"
+		text = ""
+		outputTokens = 1
+		stopReason = "end_turn"
+	case InterceptTypeMaxTokensOneHaiku:
+		msgID = generateRealisticMsgID()
+		text = "#"
+		outputTokens = 1
+		stopReason = "max_tokens"
+	default:
+		msgID = "msg_mock_warmup"
+		text = "New Conversation"
+		outputTokens = 2
+		stopReason = "end_turn"
+	}
+
+	response := gin.H{
+		"model":         model,
+		"id":            msgID,
+		"type":          "message",
+		"role":          "assistant",
+		"content":       []gin.H{{"type": "text", "text": text}},
+		"stop_reason":   stopReason,
+		"stop_sequence": nil,
+		"usage": gin.H{
+			"input_tokens":                10,
+			"cache_creation_input_tokens": 0,
+			"cache_read_input_tokens":     0,
+			"cache_creation": gin.H{
+				"ephemeral_5m_input_tokens": 0,
+				"ephemeral_1h_input_tokens": 0,
+			},
+			"output_tokens": outputTokens,
+			"total_tokens":  10 + outputTokens,
+		},
+	}
+
+	c.JSON(http.StatusOK, response)
+}