// Package server provides the HTTP server and lifecycle management.
package server

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

	"github.com/getsentry/sentry-go"
	"github.com/go-chi/chi/v5"
	"go.uber.org/fx"
	"sneak.berlin/go/pixa/internal/config"
	"sneak.berlin/go/pixa/internal/globals"
	"sneak.berlin/go/pixa/internal/handlers"
	"sneak.berlin/go/pixa/internal/logger"
	"sneak.berlin/go/pixa/internal/middleware"
)

// Shutdown configuration constants.
const (
	ShutdownTimeout    = 5 * time.Second
	SentryFlushTimeout = 2 * time.Second
)

// Params defines dependencies for Server.
type Params struct {
	fx.In
	Logger     *logger.Logger
	Globals    *globals.Globals
	Config     *config.Config
	Middleware *middleware.Middleware
	Handlers   *handlers.Handlers
}

// Server is the main HTTP server.
type Server struct {
	log           *slog.Logger
	config        *config.Config
	globals       *globals.Globals
	mw            *middleware.Middleware
	h             *handlers.Handlers
	startupTime   time.Time
	exitCode      int
	sentryEnabled bool
	ctx           context.Context
	cancelFunc    context.CancelFunc
	httpServer    *http.Server
	router        *chi.Mux
}

// New creates a new Server instance.
func New(lc fx.Lifecycle, params Params) (*Server, error) {
	s := &Server{
		log:     params.Logger.Get(),
		config:  params.Config,
		globals: params.Globals,
		mw:      params.Middleware,
		h:       params.Handlers,
	}

	lc.Append(fx.Hook{
		OnStart: func(_ context.Context) error {
			s.startupTime = time.Now()
			go s.Run()

			return nil
		},
		OnStop: func(_ context.Context) error {
			if s.cancelFunc != nil {
				s.cancelFunc()
			}

			return nil
		},
	})

	return s, nil
}

// Run starts the server.
func (s *Server) Run() {
	s.enableSentry()
	s.serve()
}

func (s *Server) enableSentry() {
	s.sentryEnabled = false

	if s.config.SentryDSN == "" {
		return
	}

	err := sentry.Init(sentry.ClientOptions{
		Dsn:     s.config.SentryDSN,
		Release: fmt.Sprintf("%s-%s", s.globals.Appname, s.globals.Version),
	})
	if err != nil {
		s.log.Error("sentry init failure", "error", err)
		os.Exit(1)
	}
	s.log.Info("sentry error reporting activated")
	s.sentryEnabled = true
}

func (s *Server) serve() int {
	s.ctx, s.cancelFunc = context.WithCancel(context.Background())

	go func() {
		c := make(chan os.Signal, 1)
		signal.Ignore(syscall.SIGPIPE)
		signal.Notify(c, os.Interrupt, syscall.SIGTERM)
		sig := <-c
		s.log.Info("signal received", "signal", sig)
		if s.cancelFunc != nil {
			s.cancelFunc()
		}
	}()

	go s.serveUntilShutdown()

	<-s.ctx.Done()
	s.cleanShutdown()

	return s.exitCode
}

func (s *Server) cleanShutdown() {
	s.exitCode = 0
	ctxShutdown, shutdownCancel := context.WithTimeout(context.Background(), ShutdownTimeout)
	defer shutdownCancel()

	if s.httpServer != nil {
		if err := s.httpServer.Shutdown(ctxShutdown); err != nil {
			s.log.Error("server clean shutdown failed", "error", err)
		}
	}

	if s.sentryEnabled {
		sentry.Flush(SentryFlushTimeout)
	}
}

// MaintenanceMode returns whether maintenance mode is enabled.
func (s *Server) MaintenanceMode() bool {
	return s.config.MaintenanceMode
}