Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

2026-08-21 18:30:13 +08:00
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+package handler
+
+import (
+	"strings"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/gin-gonic/gin"
+)
+
+// ──────────────────────────────────────────────────────────
+// Canonical inbound / upstream endpoint paths.
+// All normalization and derivation reference this single set
+// of constants — add new paths HERE when a new API surface
+// is introduced.
+// ──────────────────────────────────────────────────────────
+
+const (
+	EndpointMessages             = "/v1/messages"
+	EndpointChatCompletions      = "/v1/chat/completions"
+	EndpointEmbeddings           = "/v1/embeddings"
+	EndpointAlphaSearch          = "/v1/alpha/search"
+	EndpointResponses            = "/v1/responses"
+	EndpointResponsesCompact     = "/v1/responses/compact"
+	EndpointResponsesInputTokens = "/v1/responses/input_tokens"
+	EndpointImagesGenerations    = "/v1/images/generations"
+	EndpointImagesEdits          = "/v1/images/edits"
+	EndpointImageTasks           = "/v1/images/tasks"
+	EndpointVideosGenerations    = "/v1/videos/generations"
+	EndpointVideosEdits          = "/v1/videos/edits"
+	EndpointVideosExtensions     = "/v1/videos/extensions"
+	EndpointVideos               = "/v1/videos"
+	EndpointGeminiModels         = "/v1beta/models"
+)
+
+const EndpointAntigravityGenerateContent = "/v1internal:streamGenerateContent"
+
+// gin.Context keys used by the middleware and helpers below.
+const (
+	ctxKeyInboundEndpoint        = "_gateway_inbound_endpoint"
+	ctxKeyActualUpstreamEndpoint = "_gateway_actual_upstream_endpoint"
+)
+
+// ──────────────────────────────────────────────────────────
+// Normalization functions
+// ──────────────────────────────────────────────────────────
+
+// NormalizeInboundEndpoint maps a raw request path (which may carry
+// prefixes like /antigravity, /openai) to its canonical form.
+//
+//	"/antigravity/v1/messages"   → "/v1/messages"
+//	"/v1/chat/completions"       → "/v1/chat/completions"
+//	"/openai/v1/responses/foo"   → "/v1/responses"
+//	"/v1beta/models/gemini:gen"  → "/v1beta/models"
+//
+// The OpenAI Responses API is also exposed via a few bare/alias
+// routes that do not carry a "/v1/" prefix (top-level bare route and
+// the Codex direct route). "/responses/compact" (and "/backend-api/
+// codex/responses/compact") is a distinct client endpoint — the
+// "compact" client — and is normalized to its OWN canonical inbound
+// endpoint, EndpointResponsesCompact, rather than being folded into
+// the root Responses endpoint. Any other subpath under the bare/alias
+// roots (i.e. not "compact" itself or nested under it) remains a
+// subresource suffix of the root Responses endpoint:
+//
+//	"/v1/responses/compact"                         → EndpointResponsesCompact
+//	"/v1/responses/compact/detail"                  → EndpointResponsesCompact
+//	"/openai/v1/responses/compact"                  → EndpointResponsesCompact
+//	"/openai/v1/responses/compact/detail"           → EndpointResponsesCompact
+//	"/responses/compact"                            → EndpointResponsesCompact
+//	"/responses/compact/detail"                     → EndpointResponsesCompact
+//	"/backend-api/codex/responses/compact"          → EndpointResponsesCompact
+//	"/backend-api/codex/responses/compact/detail"   → EndpointResponsesCompact
+//	"/v1/responses"                                 → EndpointResponses
+//	"/openai/v1/responses"                          → EndpointResponses
+//	"/responses"                                    → EndpointResponses
+//	"/backend-api/codex/responses"                  → EndpointResponses
+//
+// The compact check MUST be evaluated before the root Responses check,
+// otherwise "/v1/responses" (a prefix of "/v1/responses/compact")
+// would erroneously match first.
+func NormalizeInboundEndpoint(path string) string {
+	path = strings.TrimSpace(path)
+	switch {
+	case strings.Contains(path, EndpointResponsesInputTokens) || isResponsesInputTokensAliasPath(path):
+		return EndpointResponsesInputTokens
+	case strings.Contains(path, EndpointEmbeddings):
+		return EndpointEmbeddings
+	case strings.Contains(path, EndpointAlphaSearch) || isBareOrSubpathOf(strings.TrimRight(path, "/"), "/alpha/search") || isBareOrSubpathOf(strings.TrimRight(path, "/"), "/backend-api/codex/alpha/search"):
+		return EndpointAlphaSearch
+	case strings.Contains(path, EndpointChatCompletions):
+		return EndpointChatCompletions
+	case strings.Contains(path, EndpointMessages):
+		return EndpointMessages
+	case strings.Contains(path, EndpointImagesGenerations) || strings.Contains(path, "/images/generations"):
+		return EndpointImagesGenerations
+	case strings.Contains(path, EndpointImagesEdits) || strings.Contains(path, "/images/edits"):
+		return EndpointImagesEdits
+	case strings.Contains(path, EndpointImageTasks) || strings.Contains(path, "/images/tasks/"):
+		return EndpointImageTasks
+	case strings.Contains(path, EndpointVideosGenerations) || strings.Contains(path, "/videos/generations"):
+		return EndpointVideosGenerations
+	case strings.Contains(path, EndpointVideosEdits) || strings.Contains(path, "/videos/edits"):
+		return EndpointVideosEdits
+	case strings.Contains(path, EndpointVideosExtensions) || strings.Contains(path, "/videos/extensions"):
+		return EndpointVideosExtensions
+	case strings.Contains(path, EndpointVideos) || strings.Contains(path, "/videos/"):
+		return EndpointVideos
+	case strings.Contains(path, EndpointResponsesCompact) || isResponsesCompactAliasPath(path):
+		return EndpointResponsesCompact
+	case strings.Contains(path, EndpointResponses) || isResponsesRootAliasPath(path):
+		return EndpointResponses
+	case strings.Contains(path, EndpointGeminiModels):
+		return EndpointGeminiModels
+	default:
+		return path
+	}
+}
+
+func isResponsesInputTokensAliasPath(path string) bool {
+	trimmed := strings.TrimRight(strings.TrimSpace(path), "/")
+	if trimmed == "" {
+		return false
+	}
+	return isBareOrSubpathOf(trimmed, "/responses/input_tokens") ||
+		isBareOrSubpathOf(trimmed, "/backend-api/codex/responses/input_tokens")
+}
+
+// isResponsesCompactAliasPath reports whether path is the bare/alias
+// "compact" client endpoint — i.e. it is rooted at "/responses/compact"
+// or "/backend-api/codex/responses/compact" (bare routes that serve
+// the OpenAI Responses API "compact" client without a "/v1/" prefix),
+// or any subpath nested under either of those roots:
+//
+//   - "/responses/compact"                   (bare route, compact client)
+//   - "/responses/compact/*subpath"          (nested, e.g. "/responses/compact/detail")
+//   - "/backend-api/codex/responses/compact" (Codex direct route, compact client)
+//   - "/backend-api/codex/responses/compact/*subpath" (nested, e.g.
+//     "/backend-api/codex/responses/compact/detail")
+//
+// This MUST be checked before isResponsesRootAliasPath, since
+// "/responses" is a prefix of "/responses/compact".
+func isResponsesCompactAliasPath(path string) bool {
+	trimmed := strings.TrimRight(strings.TrimSpace(path), "/")
+	if trimmed == "" {
+		return false
+	}
+	return isBareOrSubpathOf(trimmed, "/responses/compact") || isBareOrSubpathOf(trimmed, "/backend-api/codex/responses/compact")
+}
+
+// isResponsesRootAliasPath reports whether path is one of the bare/alias
+// routes that serve the root OpenAI Responses API without a "/v1/"
+// prefix, or any non-"compact" subpath registered under them:
+//
+//   - "/responses"                    (top-level bare route)
+//   - "/responses/*subpath"           (any subpath other than "compact",
+//     since "compact" is its own distinct inbound endpoint)
+//   - "/backend-api/codex/responses"  (Codex direct route)
+//   - "/backend-api/codex/responses/*subpath" (any subpath other than
+//     "compact")
+//
+// Only the top-level bare route and the Codex direct route (and their
+// subpaths) are recognized here — this deliberately does NOT generalize
+// to any path merely ending in "/responses" (e.g. an unrelated
+// "/foo/responses" must not match).
+func isResponsesRootAliasPath(path string) bool {
+	trimmed := strings.TrimRight(strings.TrimSpace(path), "/")
+	if trimmed == "" {
+		return false
+	}
+	return isBareOrSubpathOf(trimmed, "/responses") || isBareOrSubpathOf(trimmed, "/backend-api/codex/responses")
+}
+
+// isBareOrSubpathOf reports whether path is exactly root, or a subpath
+// rooted at root (i.e. root followed by "/"). This anchors the match
+// at the start of path so it cannot match paths where root appears
+// nested under some other unrelated prefix.
+func isBareOrSubpathOf(path, root string) bool {
+	return path == root || strings.HasPrefix(path, root+"/")
+}
+
+// DeriveUpstreamEndpoint determines the upstream endpoint from the
+// account platform and the normalized inbound endpoint.
+//
+// Platform-specific rules:
+//   - OpenAI and Grok text compatibility routes forward to /v1/responses
+//     (with optional subpath such as /v1/responses/compact preserved from
+//     the raw URL); native endpoints such as embeddings and alpha search
+//     retain their paths. Grok raw Chat requests override this through the
+//     forwarding result consumed by resolveOpenAIUpstreamEndpoint.
+//   - Anthropic  → /v1/messages
+//   - Gemini     → /v1beta/models
+//   - Antigravity → /v1/messages (Claude) or gemini (Gemini)
+//   - Antigravity routes may target either Claude or Gemini, so the
+//     inbound endpoint is used to distinguish.
+func DeriveUpstreamEndpoint(inbound, rawRequestPath, platform string) string {
+	inbound = strings.TrimSpace(inbound)
+
+	switch platform {
+	case service.PlatformOpenAI, service.PlatformGrok:
+		if inbound == EndpointEmbeddings || inbound == EndpointAlphaSearch || inbound == EndpointResponsesInputTokens || inbound == EndpointImagesGenerations || inbound == EndpointImagesEdits || inbound == EndpointVideosGenerations || inbound == EndpointVideosEdits || inbound == EndpointVideosExtensions || inbound == EndpointVideos {
+			return inbound
+		}
+		// OpenAI forwards everything to the Responses API.
+		// Preserve subresource suffix (e.g. /v1/responses/compact,
+		// /v1/responses/compact/detail) as derived from the raw path.
+		if suffix := responsesSubpathSuffix(rawRequestPath); suffix != "" {
+			return EndpointResponses + suffix
+		}
+		// The raw path carried no derivable suffix (e.g. it was already
+		// normalized upstream, or the caller only has the canonical
+		// inbound endpoint available) — fall back to the canonical
+		// compact endpoint when that's what the inbound request was
+		// recognized as, so it isn't silently treated as the root
+		// Responses endpoint.
+		if inbound == EndpointResponsesCompact {
+			return EndpointResponsesCompact
+		}
+		return EndpointResponses
+
+	case service.PlatformAnthropic:
+		return EndpointMessages
+
+	case service.PlatformGemini:
+		return EndpointGeminiModels
+
+	case service.PlatformAntigravity:
+		// Antigravity accounts serve both Claude and Gemini.
+		if inbound == EndpointGeminiModels {
+			return EndpointGeminiModels
+		}
+		return EndpointMessages
+	}
+
+	// Unknown platform — fall back to inbound.
+	return inbound
+}
+
+// responsesSubpathSuffix extracts the part after "/responses" in a raw
+// request path, e.g. "/openai/v1/responses/compact" → "/compact".
+// Returns "" when there is no meaningful suffix.
+func responsesSubpathSuffix(rawPath string) string {
+	trimmed := strings.TrimRight(strings.TrimSpace(rawPath), "/")
+	idx := strings.LastIndex(trimmed, "/responses")
+	if idx < 0 {
+		return ""
+	}
+	suffix := trimmed[idx+len("/responses"):]
+	if suffix == "" || suffix == "/" {
+		return ""
+	}
+	if !strings.HasPrefix(suffix, "/") {
+		return ""
+	}
+	return suffix
+}
+
+// ──────────────────────────────────────────────────────────
+// Middleware
+// ──────────────────────────────────────────────────────────
+
+// InboundEndpointMiddleware normalizes the request path and stores the
+// canonical inbound endpoint in gin.Context so that every handler in
+// the chain can read it via GetInboundEndpoint.
+//
+// Apply this middleware to all gateway route groups.
+func InboundEndpointMiddleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		path := ""
+		if c.Request != nil && c.Request.URL != nil {
+			path = c.Request.URL.Path
+		}
+		if path == "" {
+			path = c.FullPath()
+		}
+		c.Set(ctxKeyInboundEndpoint, NormalizeInboundEndpoint(path))
+		c.Next()
+	}
+}
+
+// ──────────────────────────────────────────────────────────
+// Context helpers — used by handlers before building
+// RecordUsageInput / RecordUsageLongContextInput.
+// ──────────────────────────────────────────────────────────
+
+// GetInboundEndpoint returns the canonical inbound endpoint stored by
+// InboundEndpointMiddleware. If the middleware did not run (e.g. in
+// tests), it falls back to normalizing c.Request.URL.Path on the fly
+// (preferring the raw request path over c.FullPath(), which collapses
+// wildcard route patterns such as "/v1/responses/*subpath" and would
+// otherwise mis-normalize concrete requests like "/v1/responses/compact"
+// to the root Responses endpoint).
+func GetInboundEndpoint(c *gin.Context) string {
+	if v, ok := c.Get(ctxKeyInboundEndpoint); ok {
+		if s, ok := v.(string); ok && s != "" {
+			return s
+		}
+	}
+	// Fallback: normalize on the fly.
+	path := ""
+	if c != nil {
+		if c.Request != nil && c.Request.URL != nil {
+			path = c.Request.URL.Path
+		}
+		if path == "" {
+			path = c.FullPath()
+		}
+	}
+	return NormalizeInboundEndpoint(path)
+}
+
+// GetUpstreamEndpoint derives the upstream endpoint from the context
+// and the account platform. Handlers call this after scheduling an
+// account, passing account.Platform.
+func GetUpstreamEndpoint(c *gin.Context, platform string) string {
+	if c != nil {
+		if value, ok := c.Get(ctxKeyActualUpstreamEndpoint); ok {
+			if endpoint, ok := value.(string); ok && endpoint != "" {
+				return endpoint
+			}
+		}
+	}
+	inbound := GetInboundEndpoint(c)
+	rawPath := ""
+	if c != nil && c.Request != nil && c.Request.URL != nil {
+		rawPath = c.Request.URL.Path
+	}
+	return DeriveUpstreamEndpoint(inbound, rawPath, platform)
+}
+
+func setActualUpstreamEndpoint(c *gin.Context, endpoint string) {
+	if c != nil {
+		c.Set(ctxKeyActualUpstreamEndpoint, strings.TrimSpace(endpoint))
+	}
+}
+
+func shouldUseAntigravityCompat(account *service.Account) bool {
+	return account != nil &&
+		account.Platform == service.PlatformAntigravity &&
+		account.Type == service.AccountTypeOAuth
+}