package openplatform

import (
	"database/sql"
	"encoding/json"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"
)

type StandaloneConfig struct {
	StaticDir        string
	SessionTTL       time.Duration
	RequestTimeout   time.Duration
	Release          string
	TDengine         *sql.DB
	TDengineDatabase string
}

func NewStandaloneServer(db *sql.DB, cfg StandaloneConfig) http.Handler {
	repository := NewMySQLRepository(db)
	if cfg.TDengine != nil {
		repository.WithTDengine(cfg.TDengine, cfg.TDengineDatabase)
	}
	service := NewService(repository)
	portal := NewPortalService(db, cfg.SessionTTL)
	external := NewExternalHandler(service, portal)

	api := http.NewServeMux()
	api.HandleFunc("GET /healthz", func(w http.ResponseWriter, _ *http.Request) {
		writeStandaloneJSON(w, http.StatusOK, map[string]any{
			"status":  "ok",
			"service": "open-platform-api",
			"release": strings.TrimSpace(cfg.Release),
		})
	})
	api.Handle("/", external)

	handler := standaloneStatic(cfg.StaticDir, api)
	handler = WithDocs(handler)
	handler = standaloneSecurityHeaders(handler)
	timeout := cfg.RequestTimeout
	if timeout <= 0 {
		timeout = 10 * time.Second
	}
	return http.TimeoutHandler(handler, timeout, `{"error":{"code":"REQUEST_TIMEOUT","message":"请求处理超时"}}`)
}

func standaloneStatic(dir string, fallback http.Handler) http.Handler {
	dir = strings.TrimSpace(dir)
	if dir == "" {
		return fallback
	}
	files := http.FileServer(http.Dir(dir))
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if isStandaloneAPIRoute(r.URL.Path) {
			fallback.ServeHTTP(w, r)
			return
		}
		clean := filepath.Clean("/" + r.URL.Path)
		path := filepath.Join(dir, clean)
		if info, err := os.Stat(path); err == nil && !info.IsDir() {
			if clean == "/index.html" {
				w.Header().Set("Cache-Control", "no-cache")
			} else if strings.HasPrefix(clean, "/assets/") {
				w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
			}
			files.ServeHTTP(w, r)
			return
		}
		w.Header().Set("Cache-Control", "no-cache")
		http.ServeFile(w, r, filepath.Join(dir, "index.html"))
	})
}

func isStandaloneAPIRoute(path string) bool {
	return path == "/healthz" ||
		strings.HasPrefix(path, "/api/") ||
		strings.HasPrefix(path, "/portal-api/") ||
		strings.HasPrefix(path, "/open-api/")
}

func standaloneSecurityHeaders(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("X-Content-Type-Options", "nosniff")
		w.Header().Set("X-Frame-Options", "DENY")
		w.Header().Set("Referrer-Policy", "strict-origin-when-cross-origin")
		w.Header().Set("Permissions-Policy", "camera=(), microphone=(), geolocation=()")
		w.Header().Set("Content-Security-Policy", "default-src 'self'; script-src 'self'; style-src 'self' https://fonts.googleapis.com; font-src https://fonts.gstatic.com; img-src 'self' data:; connect-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'none'; form-action 'self'")
		next.ServeHTTP(w, r)
	})
}

func writeStandaloneJSON(w http.ResponseWriter, status int, body any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("Cache-Control", "no-store")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(body)
}