package server

import (
	"context"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"

	fiberzap "github.com/gofiber/contrib/fiberzap/v2"
	"github.com/gofiber/contrib/swagger"
	"github.com/gofiber/fiber/v2"
	middleware "github.com/oapi-codegen/fiber-middleware"
	"gitlab.mareshq.com/hq/backoffice/backoffice-api/internal/api"
	"go.uber.org/zap"
)

type Server struct {
	ready ready
}

func NewServer() *Server {
	return &Server{}
}

func (s *Server) Run() {
	shutdownCtx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	logger, err := zap.NewProduction()
	if err != nil {
		logger.Fatal("failed to initialize logger", zap.Error(err))
	}
	defer logger.Sync()
	sugaredLogger := logger.Sugar()

	fiberConfig := fiber.Config{
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 5 * time.Second,
		IdleTimeout:  5 * time.Second,

		DisableStartupMessage: true,
	}

	app := fiber.New(fiberConfig)

	app.Get("/", func(c *fiber.Ctx) error {
		return c.SendStatus(fiber.StatusNotFound)
	})

	app.Get("/livez", func(c *fiber.Ctx) error {
		return c.SendStatus(fiber.StatusOK)
	})

	app.Get("/readyz", func(c *fiber.Ctx) error {
		if s.ready.isReady() {
			return c.SendStatus(fiber.StatusOK)
		}

		return c.SendStatus(fiber.StatusServiceUnavailable)
	})

	// TODO: add /metrics endpoint

	app.Use(fiberzap.New(fiberzap.Config{
		Logger: logger,
	}))

	swaggerConfig := swagger.Config{
		BasePath: "/",
		FilePath: "./api/v1/openapi.yaml",
		Path:     "/swagger",
		Title:    "Swagger API Docs",
	}

	app.Use(swagger.New(swaggerConfig))

	app = registerAPIHandlers(app, sugaredLogger)

	<-shutdownCtx.Done()
	stop()
	s.ready.notReady()

	// wait till Pod is signaling not ready (no new requests)
	time.Sleep(5 * time.Second)

	shutdownBegan := time.Now()

	sugaredLogger.Info("Shutdown signal recieved. Shutting down gracefully...")

	// * Gracefully shut down fiber server
	// * If does not shutdown within `gracefulShutdownPeriod`, force shutdown
	// ! Does not close keep-alive connections
	// ! fiber.Config{ReadTimeout} must be set and non-zero and greater than the `gracefulShutdownPeriod`
	// TODO: make shutdown timeout configurable
	err = app.ShutdownWithTimeout(time.Second * 10)
	if err != nil {
		sugaredLogger.Errorw("Error during shutdown", "error", err)
	}

	sugaredLogger.Infof("Shutdown completed in %v", time.Since(shutdownBegan))
}

func registerAPIHandlers(fiberApp *fiber.App, logger *zap.SugaredLogger) *fiber.App {
	swagger, err := api.GetSwagger()
	if err != nil {
		logger.Fatalf("Error getting swagger: %v", err)
	}

	// TODO: validate this. Copied from example
	// See: https://github.com/deepmap/oapi-codegen/blob/master/examples/petstore-expanded/fiber/petstore.go#L41
	// Clear out the servers array in the swagger spec, that skips validating
	// that server names match. We don't know how this thing will be run.
	swagger.Servers = nil

	fiberApp.Use(middleware.OapiRequestValidator(swagger))

	api.RegisterHandlers(fiberApp)

	return fiberApp
}

type ready struct {
	ready bool
	lock  sync.Mutex
}

func (r *ready) setReady() {
	r.lock.Lock()
	defer r.lock.Unlock()
	r.ready = true
}

func (r *ready) isReady() bool {
	r.lock.Lock()
	defer r.lock.Unlock()
	return r.ready
}

func (r *ready) notReady() {
	r.lock.Lock()
	defer r.lock.Unlock()
	r.ready = false
}