Merge pull request #3497 from JRBaggins/fix/openai-count-tokens-bridge

Bridge OpenAI count_tokens to responses input_tokens

backend/internal/handler/openai_gateway_count_tokens.go

@@ -0,0 +1,145 @@
+package handler
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/domain"
+	pkghttputil "github.com/Wei-Shaw/sub2api/internal/pkg/httputil"
+	middleware2 "github.com/Wei-Shaw/sub2api/internal/server/middleware"
+	"github.com/Wei-Shaw/sub2api/internal/service"
+
+	"github.com/gin-gonic/gin"
+	"go.uber.org/zap"
+)
+
+// CountTokens handles Anthropic-compatible POST /v1/messages/count_tokens for OpenAI groups.
+// It validates billing and routes to an OpenAI token-count bridge without taking concurrency slots
+// or recording usage.
+func (h *OpenAIGatewayHandler) CountTokens(c *gin.Context) {
+	apiKey, ok := middleware2.GetAPIKeyFromContext(c)
+	if !ok {
+		h.anthropicErrorResponse(c, http.StatusUnauthorized, "authentication_error", "Invalid API key")
+		return
+	}
+
+	subject, ok := middleware2.GetAuthSubjectFromContext(c)
+	if !ok {
+		h.anthropicErrorResponse(c, http.StatusInternalServerError, "api_error", "User context not found")
+		return
+	}
+	reqLog := requestLogger(
+		c,
+		"handler.openai_gateway.count_tokens",
+		zap.Int64("user_id", subject.UserID),
+		zap.Int64("api_key_id", apiKey.ID),
+		zap.Any("group_id", apiKey.GroupID),
+	)
+
+	if apiKey.Group != nil && !apiKey.Group.AllowMessagesDispatch {
+		h.anthropicErrorResponse(c, http.StatusForbidden, "permission_error",
+			"This group does not allow /v1/messages dispatch")
+		return
+	}
+
+	if !h.ensureResponsesDependencies(c, reqLog) {
+		return
+	}
+
+	body, err := pkghttputil.ReadRequestBodyWithPrealloc(c.Request)
+	if err != nil {
+		if maxErr, ok := extractMaxBytesError(err); ok {
+			h.anthropicErrorResponse(c, http.StatusRequestEntityTooLarge, "invalid_request_error", buildBodyTooLargeMessage(maxErr.Limit))
+			return
+		}
+		h.anthropicErrorResponse(c, http.StatusBadRequest, "invalid_request_error", "Failed to read request body")
+		return
+	}
+	if len(body) == 0 {
+		h.anthropicErrorResponse(c, http.StatusBadRequest, "invalid_request_error", "Request body is empty")
+		return
+	}
+
+	bodyRef := service.NewRequestBodyRef(body)
+	parsedReq, err := service.ParseGatewayRequest(bodyRef, domain.PlatformAnthropic)
+	if err != nil {
+		h.anthropicErrorResponse(c, http.StatusBadRequest, "invalid_request_error", "Failed to parse request body")
+		return
+	}
+	if parsedReq.Model == "" {
+		h.anthropicErrorResponse(c, http.StatusBadRequest, "invalid_request_error", "model is required")
+		return
+	}
+
+	reqModel := parsedReq.Model
+	routingModel := service.NormalizeOpenAICompatRequestedModel(reqModel)
+	preferredMappedModel := resolveOpenAIMessagesDispatchMappedModel(apiKey, reqModel)
+	reqLog = reqLog.With(zap.String("model", reqModel), zap.Bool("stream", parsedReq.Stream))
+
+	setOpsRequestContext(c, reqModel, false)
+	setOpsEndpointContext(c, "", int16(service.RequestTypeFromLegacy(false, false)))
+
+	channelMapping, _ := h.gatewayService.ResolveChannelMappingAndRestrict(c.Request.Context(), apiKey.GroupID, reqModel)
+	mappedBodyForMessages := newOpenAIModelMappedBodyCache(body, h.gatewayService.ReplaceModelInBody)
+
+	subscription, _ := middleware2.GetSubscriptionFromContext(c)
+	if err := h.billingCacheService.CheckBillingEligibility(c.Request.Context(), apiKey.User, apiKey, apiKey.Group, subscription, service.QuotaPlatform(c.Request.Context(), apiKey)); err != nil {
+		reqLog.Info("openai_count_tokens.billing_eligibility_check_failed", zap.Error(err))
+		status, code, message, retryAfter := billingErrorDetails(err)
+		if retryAfter > 0 {
+			c.Header("Retry-After", strconv.Itoa(retryAfter))
+		}
+		h.anthropicErrorResponse(c, status, code, message)
+		return
+	}
+
+	requestStart := time.Now()
+	sessionHash := h.gatewayService.GenerateSessionHash(c, body)
+	currentRoutingModel := routingModel
+	if preferredMappedModel != "" {
+		currentRoutingModel = preferredMappedModel
+	}
+	selection, _, err := h.gatewayService.SelectAccountWithSchedulerForCapability(
+		c.Request.Context(),
+		apiKey.GroupID,
+		"",
+		sessionHash,
+		currentRoutingModel,
+		nil,
+		service.OpenAIUpstreamTransportAny,
+		service.OpenAIEndpointCapabilityChatCompletions,
+		false,
+		openAICompatibleRequestPlatform(apiKey),
+	)
+	service.SetOpsLatencyMs(c, service.OpsAuthLatencyMsKey, time.Since(requestStart).Milliseconds())
+	if err != nil {
+		reqLog.Warn("openai_count_tokens.account_select_failed", zap.Error(err))
+		cls := classifyNoAccountErrorFromGin(c, h.gatewayService, apiKey, currentRoutingModel, reqModel, service.PlatformOpenAI)
+		if !cls.ModelNotFound {
+			markOpsRoutingCapacityLimitedIfNoAvailable(c, err)
+		}
+		h.anthropicErrorResponse(c, cls.Status, cls.ErrType, cls.Message)
+		return
+	}
+	if selection == nil || selection.Account == nil {
+		cls := classifyNoAccountErrorFromGin(c, h.gatewayService, apiKey, currentRoutingModel, reqModel, service.PlatformOpenAI)
+		if !cls.ModelNotFound {
+			markOpsRoutingCapacityLimited(c)
+		}
+		h.anthropicErrorResponse(c, cls.Status, cls.ErrType, cls.Message)
+		return
+	}
+
+	account := selection.Account
+	setOpsSelectedAccount(c, account.ID, account.Platform)
+	if selection.Acquired && selection.ReleaseFunc != nil {
+		defer selection.ReleaseFunc()
+	}
+	forwardBody := mappedBodyForMessages(channelMapping.Mapped, channelMapping.MappedModel)
+	defaultMappedModel := preferredMappedModel
+
+	if err := h.gatewayService.ForwardCountTokensAsAnthropic(c.Request.Context(), c, account, forwardBody, defaultMappedModel); err != nil {
+		reqLog.Error("openai_count_tokens.forward_failed", zap.Int64("account_id", account.ID), zap.Error(err))
+	}
+}