package server

import (
	"context"
	"fmt"
	"log/slog"
	"net"
	"net/http"
	"os"
	"sync"
	"time"

	"github.com/google/uuid"
	"github.com/labstack/echo/v5"
	"github.com/labstack/echo/v5/middleware"
	"github.com/pkg/errors"

	"github.com/usememos/memos/internal/profile"
	storepb "github.com/usememos/memos/proto/gen/store"
	apiv1 "github.com/usememos/memos/server/router/api/v1"
	"github.com/usememos/memos/server/router/fileserver"
	"github.com/usememos/memos/server/router/frontend"
	mcprouter "github.com/usememos/memos/server/router/mcp"
	"github.com/usememos/memos/server/router/rss"
	"github.com/usememos/memos/server/runner/s3presign"
	"github.com/usememos/memos/store"
)

const shutdownTimeout = 10 * time.Second

type Server struct {
	Secret  string
	Profile *profile.Profile
	Store   *store.Store

	echoServer *echo.Echo
	httpServer *http.Server
	sseHub     *apiv1.SSEHub

	backgroundRunnerCancels []context.CancelFunc
	backgroundRunnerWG      sync.WaitGroup
}

func NewServer(ctx context.Context, profile *profile.Profile, store *store.Store) (*Server, error) {
	s := &Server{
		Store:   store,
		Profile: profile,
	}

	echoServer := echo.New()
	echoServer.Use(middleware.Recover())
	s.echoServer = echoServer

	instanceBasicSetting, err := s.getOrUpsertInstanceBasicSetting(ctx)
	if err != nil {
		return nil, errors.Wrap(err, "failed to get instance basic setting")
	}

	secret := "usememos"
	if !profile.Demo {
		secret = instanceBasicSetting.SecretKey
	}
	s.Secret = secret

	// Register healthz endpoint.
	echoServer.GET("/healthz", func(c *echo.Context) error {
		return c.String(http.StatusOK, "Service ready.")
	})

	// Serve frontend static files.
	frontend.NewFrontendService(profile, store).Serve(ctx, echoServer)

	rootGroup := echoServer.Group("")

	apiV1Service := apiv1.NewAPIV1Service(s.Secret, profile, store)
	s.sseHub = apiV1Service.SSEHub

	// Register HTTP file server routes BEFORE gRPC-Gateway to ensure proper range request handling for Safari.
	// This uses native HTTP serving (http.ServeContent) instead of gRPC for video/audio files.
	fileServerService := fileserver.NewFileServerService(s.Profile, s.Store, s.Secret)
	fileServerService.RegisterRoutes(echoServer)

	// Create and register RSS routes (needs markdown service from apiV1Service).
	rss.NewRSSService(s.Profile, s.Store, apiV1Service.MarkdownService).RegisterRoutes(rootGroup)

	// Register gRPC gateway as api v1 (includes SSE endpoint on CORS-enabled group).
	if err := apiV1Service.RegisterGateway(ctx, echoServer); err != nil {
		return nil, errors.Wrap(err, "failed to register gRPC gateway")
	}

	// Register MCP server.
	mcpService := mcprouter.NewMCPService(s.Profile, s.Store, s.Secret, apiV1Service)
	mcpService.RegisterRoutes(echoServer)

	return s, nil
}

func (s *Server) Start(ctx context.Context) error {
	var address, network string
	if len(s.Profile.UNIXSock) == 0 {
		address = fmt.Sprintf("%s:%d", s.Profile.Addr, s.Profile.Port)
		network = "tcp"
	} else {
		address = s.Profile.UNIXSock
		network = "unix"
	}
	listener, err := net.Listen(network, address)
	if err != nil {
		return errors.Wrap(err, "failed to listen")
	}

	if network == "unix" {
		if err := os.Chmod(address, 0660); err != nil {
			_ = listener.Close()
			return errors.Wrap(err, "failed to chmod socket")
		}
	}

	// Start Echo server directly (no cmux needed - all traffic is HTTP).
	s.httpServer = &http.Server{Handler: s.echoServer}
	go func() {
		if err := s.httpServer.Serve(listener); err != nil && err != http.ErrServerClosed {
			slog.Error("failed to start echo server", "error", err)
		}
	}()
	s.startBackgroundRunners(ctx)

	return nil
}

func (s *Server) Shutdown(ctx context.Context) {
	ctx, cancel := context.WithTimeout(ctx, shutdownTimeout)
	defer cancel()

	slog.Info("server shutting down")

	s.stopBackgroundRunners()
	s.closeLongLivedConnections()
	s.shutdownHTTPServer(ctx)
	s.waitBackgroundRunners(ctx)

	// Close database connection.
	if err := s.Store.Close(); err != nil {
		slog.Error("failed to close database", slog.String("error", err.Error()))
	}

	slog.Info("memos stopped properly")
}

func (s *Server) startBackgroundRunners(ctx context.Context) {
	// Create a separate context for each background runner
	// This allows us to control cancellation for each runner independently
	s3Context, s3Cancel := context.WithCancel(ctx)

	// Store the cancel function so we can properly shut down runners
	s.backgroundRunnerCancels = append(s.backgroundRunnerCancels, s3Cancel)

	// Create and start S3 presign runner
	s3presignRunner := s3presign.NewRunner(s.Store)
	s3presignRunner.RunOnce(ctx)

	// Start continuous S3 presign runner
	s.backgroundRunnerWG.Add(1)
	go func() {
		defer s.backgroundRunnerWG.Done()
		s3presignRunner.Run(s3Context)
		slog.Info("s3presign runner stopped")
	}()

	slog.Info("background runners started")
}

func (s *Server) stopBackgroundRunners() {
	for _, cancelFunc := range s.backgroundRunnerCancels {
		if cancelFunc != nil {
			cancelFunc()
		}
	}
}

func (s *Server) waitBackgroundRunners(ctx context.Context) {
	done := make(chan struct{})
	go func() {
		s.backgroundRunnerWG.Wait()
		close(done)
	}()

	select {
	case <-done:
	case <-ctx.Done():
		select {
		case <-done:
			return
		default:
		}
		slog.Error("failed to stop background runners", slog.String("error", ctx.Err().Error()))
	}
}

func (s *Server) closeLongLivedConnections() {
	// Long-lived SSE requests do not finish on their own during http.Server.Shutdown.
	if s.sseHub != nil {
		s.sseHub.Close()
	}
}

func (s *Server) shutdownHTTPServer(ctx context.Context) {
	if s.httpServer == nil {
		return
	}
	if err := s.httpServer.Shutdown(ctx); err != nil {
		slog.Error("failed to shutdown server", slog.String("error", err.Error()))
		if closeErr := s.httpServer.Close(); closeErr != nil && closeErr != http.ErrServerClosed {
			slog.Error("failed to close server", slog.String("error", closeErr.Error()))
		}
	}
}

func (s *Server) getOrUpsertInstanceBasicSetting(ctx context.Context) (*storepb.InstanceBasicSetting, error) {
	instanceBasicSetting, err := s.Store.GetInstanceBasicSetting(ctx)
	if err != nil {
		return nil, errors.Wrap(err, "failed to get instance basic setting")
	}
	modified := false
	if instanceBasicSetting.SecretKey == "" {
		instanceBasicSetting.SecretKey = uuid.NewString()
		modified = true
	}
	if modified {
		instanceSetting, err := s.Store.UpsertInstanceSetting(ctx, &storepb.InstanceSetting{
			Key:   storepb.InstanceSettingKey_BASIC,
			Value: &storepb.InstanceSetting_BasicSetting{BasicSetting: instanceBasicSetting},
		})
		if err != nil {
			return nil, errors.Wrap(err, "failed to upsert instance setting")
		}
		instanceBasicSetting = instanceSetting.GetBasicSetting()
	}
	return instanceBasicSetting, nil
}