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

backend/internal/web/embed_on.go

@@ -0,0 +1,395 @@
+//go:build embed
+
+package web
+
+import (
+	"bytes"
+	"context"
+	"embed"
+	"encoding/json"
+	htmlpkg "html"
+	"io"
+	"io/fs"
+	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/server/middleware"
+	"github.com/gin-gonic/gin"
+)
+
+const (
+	// NonceHTMLPlaceholder is the placeholder for nonce in HTML script tags
+	NonceHTMLPlaceholder = "__CSP_NONCE_VALUE__"
+)
+
+//go:embed all:dist
+var frontendFS embed.FS
+
+// PublicSettingsProvider is an interface to fetch public settings
+type PublicSettingsProvider interface {
+	GetPublicSettingsForInjection(ctx context.Context) (any, error)
+}
+
+// FrontendServer serves the embedded frontend with settings injection
+type FrontendServer struct {
+	distFS      fs.FS
+	fileServer  http.Handler
+	baseHTML    []byte
+	cache       *HTMLCache
+	settings    PublicSettingsProvider
+	overrideDir string // local file override directory
+}
+
+// NewFrontendServer creates a new frontend server with settings injection
+func NewFrontendServer(settingsProvider PublicSettingsProvider) (*FrontendServer, error) {
+	distFS, err := fs.Sub(frontendFS, "dist")
+	if err != nil {
+		return nil, err
+	}
+
+	// Read base HTML once
+	file, err := distFS.Open("index.html")
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = file.Close() }()
+
+	baseHTML, err := io.ReadAll(file)
+	if err != nil {
+		return nil, err
+	}
+
+	cache := NewHTMLCache()
+	cache.SetBaseHTML(baseHTML)
+
+	return &FrontendServer{
+		distFS:      distFS,
+		fileServer:  http.FileServer(http.FS(distFS)),
+		baseHTML:    baseHTML,
+		cache:       cache,
+		settings:    settingsProvider,
+		overrideDir: filepath.Join("data", "public"),
+	}, nil
+}
+
+// InvalidateCache invalidates the HTML cache (call when settings change)
+func (s *FrontendServer) InvalidateCache() {
+	if s != nil && s.cache != nil {
+		s.cache.Invalidate()
+	}
+}
+
+// Middleware returns the Gin middleware handler
+func (s *FrontendServer) Middleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		path := c.Request.URL.Path
+
+		// Skip API routes
+		if shouldBypassEmbeddedFrontend(path) {
+			c.Next()
+			return
+		}
+
+		cleanPath := strings.TrimPrefix(path, "/")
+		if cleanPath == "" {
+			cleanPath = "index.html"
+		}
+
+		// For index.html or SPA routes, serve with injected settings
+		if cleanPath == "index.html" || !s.fileExists(cleanPath) {
+			s.serveIndexHTML(c)
+			return
+		}
+
+		// Try local override first
+		if s.tryServeOverride(c, cleanPath) {
+			return
+		}
+
+		// Serve static files normally (hashed assets get long-lived cache headers)
+		applyStaticAssetCacheHeaders(c.Writer.Header(), cleanPath)
+		s.fileServer.ServeHTTP(c.Writer, c.Request)
+		c.Abort()
+	}
+}
+
+func (s *FrontendServer) fileExists(path string) bool {
+	file, err := s.distFS.Open(path)
+	if err != nil {
+		return false
+	}
+	_ = file.Close()
+	return true
+}
+
+// tryServeOverride checks if a local override file exists and serves it.
+// Files in overrideDir take precedence over embedded files.
+func (s *FrontendServer) tryServeOverride(c *gin.Context, cleanPath string) bool {
+	if s.overrideDir == "" {
+		return false
+	}
+	filePath := filepath.Join(s.overrideDir, filepath.Clean("/"+cleanPath))
+	info, err := os.Stat(filePath)
+	if err != nil || info.IsDir() {
+		return false
+	}
+	c.File(filePath)
+	c.Abort()
+	return true
+}
+
+func (s *FrontendServer) serveIndexHTML(c *gin.Context) {
+	// Get nonce from context (generated by SecurityHeaders middleware)
+	nonce := middleware.GetNonceFromContext(c)
+
+	// Check cache first
+	cached := s.cache.Get()
+	if cached != nil {
+		// Check If-None-Match for 304 response
+		if match := c.GetHeader("If-None-Match"); match == cached.ETag {
+			c.Status(http.StatusNotModified)
+			c.Abort()
+			return
+		}
+
+		// Replace nonce placeholder with actual nonce before serving
+		content := replaceNoncePlaceholder(cached.Content, nonce)
+
+		c.Header("ETag", cached.ETag)
+		c.Header("Cache-Control", "no-cache") // Must revalidate
+		c.Data(http.StatusOK, "text/html; charset=utf-8", content)
+		c.Abort()
+		return
+	}
+
+	// Cache miss - fetch settings and render
+	ctx, cancel := context.WithTimeout(c.Request.Context(), 2*time.Second)
+	defer cancel()
+
+	settings, err := s.settings.GetPublicSettingsForInjection(ctx)
+	if err != nil {
+		// Fallback: serve without injection
+		c.Data(http.StatusOK, "text/html; charset=utf-8", s.baseHTML)
+		c.Abort()
+		return
+	}
+
+	settingsJSON, err := json.Marshal(settings)
+	if err != nil {
+		// Fallback: serve without injection
+		c.Data(http.StatusOK, "text/html; charset=utf-8", s.baseHTML)
+		c.Abort()
+		return
+	}
+
+	rendered := s.injectSettings(settingsJSON)
+	s.cache.Set(rendered, settingsJSON)
+
+	// Replace nonce placeholder with actual nonce before serving
+	content := replaceNoncePlaceholder(rendered, nonce)
+
+	cached = s.cache.Get()
+	if cached != nil {
+		c.Header("ETag", cached.ETag)
+	}
+	c.Header("Cache-Control", "no-cache")
+	c.Data(http.StatusOK, "text/html; charset=utf-8", content)
+	c.Abort()
+}
+
+func (s *FrontendServer) injectSettings(settingsJSON []byte) []byte {
+	// Create the script tag to inject with nonce placeholder
+	// The placeholder will be replaced with actual nonce at request time
+	script := []byte(`<script nonce="` + NonceHTMLPlaceholder + `">window.__APP_CONFIG__=` + string(settingsJSON) + `;</script>`)
+
+	// Inject before </head>
+	headClose := []byte("</head>")
+	result := bytes.Replace(s.baseHTML, headClose, append(script, headClose...), 1)
+
+	// Apply custom branding before the browser paints the static defaults.
+	result = injectSiteTitle(result, settingsJSON)
+	result = injectSiteFavicon(result, settingsJSON)
+
+	return result
+}
+
+// injectSiteFavicon replaces the static favicon with a configured, browser-safe image URL.
+func injectSiteFavicon(html, settingsJSON []byte) []byte {
+	var cfg struct {
+		SiteLogo string `json:"site_logo"`
+	}
+	if err := json.Unmarshal(settingsJSON, &cfg); err != nil {
+		return html
+	}
+
+	logoURL := safeImageURL(cfg.SiteLogo)
+	if logoURL == "" {
+		return html
+	}
+
+	linkStart := bytes.Index(html, []byte(`<link rel="icon"`))
+	if linkStart == -1 {
+		return html
+	}
+	linkEndOffset := bytes.IndexByte(html[linkStart:], '>')
+	if linkEndOffset == -1 {
+		return html
+	}
+	linkEnd := linkStart + linkEndOffset + 1
+	replacement := []byte(`<link rel="icon" href="` + htmlpkg.EscapeString(logoURL) + `" />`)
+
+	var buf bytes.Buffer
+	buf.Write(html[:linkStart])
+	buf.Write(replacement)
+	buf.Write(html[linkEnd:])
+	return buf.Bytes()
+}
+
+func safeImageURL(value string) string {
+	trimmed := strings.TrimSpace(value)
+	if trimmed == "" {
+		return ""
+	}
+	if strings.HasPrefix(trimmed, "/") && !strings.HasPrefix(trimmed, "//") {
+		return trimmed
+	}
+	if strings.HasPrefix(strings.ToLower(trimmed), "data:image/") {
+		return trimmed
+	}
+
+	parsed, err := url.Parse(trimmed)
+	if err != nil || (parsed.Scheme != "http" && parsed.Scheme != "https") || parsed.Host == "" {
+		return ""
+	}
+	return trimmed
+}
+
+// injectSiteTitle replaces the static <title> in HTML with the configured site name.
+// This ensures the browser tab shows the correct title before JS executes.
+func injectSiteTitle(html, settingsJSON []byte) []byte {
+	var cfg struct {
+		SiteName string `json:"site_name"`
+	}
+	if err := json.Unmarshal(settingsJSON, &cfg); err != nil || cfg.SiteName == "" {
+		return html
+	}
+
+	// Find and replace the existing <title>...</title>
+	titleStart := bytes.Index(html, []byte("<title>"))
+	titleEnd := bytes.Index(html, []byte("</title>"))
+	if titleStart == -1 || titleEnd == -1 || titleEnd <= titleStart {
+		return html
+	}
+
+	newTitle := []byte("<title>" + htmlpkg.EscapeString(cfg.SiteName) + " - AI API Gateway</title>")
+	var buf bytes.Buffer
+	buf.Write(html[:titleStart])
+	buf.Write(newTitle)
+	buf.Write(html[titleEnd+len("</title>"):])
+	return buf.Bytes()
+}
+
+// replaceNoncePlaceholder replaces the nonce placeholder with actual nonce value
+func replaceNoncePlaceholder(html []byte, nonce string) []byte {
+	return bytes.ReplaceAll(html, []byte(NonceHTMLPlaceholder), []byte(nonce))
+}
+
+// ServeEmbeddedFrontend returns a middleware for serving embedded frontend
+// This is the legacy function for backward compatibility when no settings provider is available
+func ServeEmbeddedFrontend() gin.HandlerFunc {
+	distFS, err := fs.Sub(frontendFS, "dist")
+	if err != nil {
+		panic("failed to get dist subdirectory: " + err.Error())
+	}
+	fileServer := http.FileServer(http.FS(distFS))
+	overrideDir := filepath.Join("data", "public")
+
+	return func(c *gin.Context) {
+		path := c.Request.URL.Path
+
+		if shouldBypassEmbeddedFrontend(path) {
+			c.Next()
+			return
+		}
+
+		cleanPath := strings.TrimPrefix(path, "/")
+		if cleanPath == "" {
+			cleanPath = "index.html"
+		}
+
+		if file, err := distFS.Open(cleanPath); err == nil {
+			_ = file.Close()
+			// Try local override first
+			if tryServeOverrideFile(c, overrideDir, cleanPath) {
+				return
+			}
+			applyStaticAssetCacheHeaders(c.Writer.Header(), cleanPath)
+			fileServer.ServeHTTP(c.Writer, c.Request)
+			c.Abort()
+			return
+		}
+
+		serveIndexHTML(c, distFS)
+	}
+}
+
+// tryServeOverrideFile is a standalone version of tryServeOverride for legacy usage.
+func tryServeOverrideFile(c *gin.Context, overrideDir, cleanPath string) bool {
+	if overrideDir == "" {
+		return false
+	}
+	filePath := filepath.Join(overrideDir, filepath.Clean("/"+cleanPath))
+	info, err := os.Stat(filePath)
+	if err != nil || info.IsDir() {
+		return false
+	}
+	c.File(filePath)
+	c.Abort()
+	return true
+}
+
+func shouldBypassEmbeddedFrontend(path string) bool {
+	trimmed := strings.TrimSpace(path)
+	return strings.HasPrefix(trimmed, "/api/") ||
+		strings.HasPrefix(trimmed, "/v1/") ||
+		strings.HasPrefix(trimmed, "/v1beta/") ||
+		strings.HasPrefix(trimmed, "/backend-api/") ||
+		strings.HasPrefix(trimmed, "/antigravity/") ||
+		strings.HasPrefix(trimmed, "/setup/") ||
+		trimmed == "/health" ||
+		trimmed == "/models" ||
+		trimmed == "/responses" ||
+		strings.HasPrefix(trimmed, "/responses/") ||
+		trimmed == "/alpha/search" ||
+		strings.HasPrefix(trimmed, "/images/") ||
+		strings.HasPrefix(trimmed, "/videos/")
+}
+
+func serveIndexHTML(c *gin.Context, fsys fs.FS) {
+	file, err := fsys.Open("index.html")
+	if err != nil {
+		c.String(http.StatusNotFound, "Frontend not found")
+		c.Abort()
+		return
+	}
+	defer func() { _ = file.Close() }()
+
+	content, err := io.ReadAll(file)
+	if err != nil {
+		c.String(http.StatusInternalServerError, "Failed to read index.html")
+		c.Abort()
+		return
+	}
+
+	c.Data(http.StatusOK, "text/html; charset=utf-8", content)
+	c.Abort()
+}
+
+func HasEmbeddedFrontend() bool {
+	_, err := frontendFS.ReadFile("dist/index.html")
+	return err == nil
+}