package servers

import (
	"context"
	"errors"
	"fmt"
	"github.com/gin-contrib/pprof"
	"github.com/gin-gonic/gin"
	ginprometheus "github.com/zsais/go-gin-prometheus"
	"gogs.tyduyong.com/duyong/dy-admin/internal/iam/config"
	"gogs.tyduyong.com/duyong/dy-pkg/app/middleware"
	"gogs.tyduyong.com/duyong/dy-pkg/app/response"
	"gogs.tyduyong.com/duyong/dy-pkg/app/version"
	"gogs.tyduyong.com/duyong/dy-pkg/logs"
	"log"
	"net"
	"net/http"
	"strconv"
	"strings"
	"time"
)

// CertKey 证书结构
type CertKey struct {
	// CertFile is a file containing a PEM-encoded certificate, and possibly the complete certificate chain
	CertFile string
	// KeyFile is a file containing a PEM-encoded private key for the certificate specified by CertFile
	KeyFile string
}

// SecureServeInfo 开启https时的结构
type SecureServeInfo struct {
	BindAddress string
	BindPort    int
	CertKey     CertKey
}

func (s *SecureServeInfo) Address() string {
	return net.JoinHostPort(s.BindAddress, strconv.Itoa(s.BindPort))
}

// httpAPIServer Http&Https封装
type httpAPIServer struct {
	*gin.Engine
	middlewares                  []string
	healthz                      bool
	enableMetrics                bool
	enableProfiling              bool
	insecureAddress              string
	secureInfo                   *SecureServeInfo
	insecureServer, secureServer *http.Server
}

// newHttpServer 构建http服务配置
func newHttpServer(cfg *config.Config) *httpAPIServer {
	gin.SetMode(cfg.ServerRunOptions.Mode)
	httpServer := &httpAPIServer{
		Engine:          gin.New(),
		middlewares:     cfg.ServerRunOptions.Middlewares,
		healthz:         cfg.ServerRunOptions.Healthz,
		enableMetrics:   cfg.FeatureOptions.EnableMetrics,
		enableProfiling: cfg.FeatureOptions.EnableProfiling,
		insecureAddress: net.JoinHostPort(cfg.InsecureServeOptions.BindAddress, strconv.Itoa(cfg.InsecureServeOptions.BindPort)),
		secureInfo: &SecureServeInfo{
			BindAddress: cfg.SecureServingOptions.BindAddress,
			BindPort:    cfg.SecureServingOptions.BindPort,
			CertKey: CertKey{
				CertFile: cfg.SecureServingOptions.ServerCert.CertKey.CertFile,
				KeyFile:  cfg.SecureServingOptions.ServerCert.CertKey.KeyFile,
			},
		},
	}

	httpServer.Setup()
	httpServer.InstallMiddlewares()
	httpServer.InstallAPIs()

	return httpServer
}

func (s *httpAPIServer) Setup() {
	gin.DebugPrintRouteFunc = func(httpMethod, absolutePath, handlerName string, nuHandlers int) {
		logs.Infof("%-6s %-s --> %s (%d handlers)", httpMethod, absolutePath, handlerName, nuHandlers)
	}
}

// InstallMiddlewares 根据配置，选定路由中间件
func (s *httpAPIServer) InstallMiddlewares() {
	// 必选中间件
	s.Use(middleware.RequestID())
	s.Use(middleware.Context())

	// install custom middlewares
	for _, m := range s.middlewares {
		mw, ok := middleware.Middlewares[m]
		if !ok {
			logs.Warnf("can not find middleware: %s", m)

			continue
		}

		logs.Infof("install middleware: %s", m)
		s.Use(mw)
	}
}

// InstallAPIs 根据配置，设置制定的接口
func (s *httpAPIServer) InstallAPIs() {
	// 健康检查接口
	if s.healthz {
		s.GET("/healthz", func(c *gin.Context) {
			response.WriteResponse(c, nil, map[string]string{"status": "ok"})
		})
	}

	// 监控接口
	if s.enableMetrics {
		prometheus := ginprometheus.NewPrometheus("gin")
		prometheus.Use(s.Engine)
	}

	// install pprof handler
	if s.enableProfiling {
		pprof.Register(s.Engine)
	}

	s.GET("/version", func(c *gin.Context) {
		response.WriteResponse(c, nil, version.Get())
	})
}

// Run 启动服务
func (s *httpAPIServer) Run() {

	s.insecureServer = &http.Server{
		Addr:    s.insecureAddress,
		Handler: s,
	}

	s.secureServer = &http.Server{
		Addr:    s.secureInfo.Address(),
		Handler: s,
	}

	go func() {
		logs.Infof("Start to listening the incoming requests on http address: %s", s.insecureAddress)

		if err := s.insecureServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			logs.Fatal(err.Error())
			return
		}

		logs.Infof("Server on %s stopped", s.insecureAddress)
	}()

	go func() {
		key, cert := s.secureInfo.CertKey.KeyFile, s.secureInfo.CertKey.CertFile
		if cert == "" || key == "" || s.secureInfo.BindPort == 0 {
			return
		}

		logs.Infof("Start to listening the incoming requests on https address: %s", s.secureInfo.Address())

		if err := s.secureServer.ListenAndServeTLS(cert, key); err != nil && !errors.Is(err, http.ErrServerClosed) {
			logs.Fatal(err.Error())
			return
		}

		logs.Infof("Server on %s stopped", s.secureInfo.Address())
	}()

	// Ping the server to make sure the router is working.
	go func() {
		if s.healthz {
			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
			defer cancel()
			if s.healthz {
				if err := s.ping(ctx); err != nil {
					return
				}
			}
		}
	}()

	return
}

// Close 关闭服务
func (s *httpAPIServer) Close() {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	if err := s.secureServer.Shutdown(ctx); err != nil {
		logs.Warnf("Shutdown secure server failed: %s", err.Error())
	}

	if err := s.insecureServer.Shutdown(ctx); err != nil {
		logs.Warnf("Shutdown insecure server failed: %s", err.Error())
	}
}

func (s *httpAPIServer) ping(ctx context.Context) error {
	url := fmt.Sprintf("http://%s/healthz", s.insecureAddress)
	if strings.Contains(s.insecureAddress, "0.0.0.0") {
		url = fmt.Sprintf("http://127.0.0.1:%s/healthz", strings.Split(s.insecureAddress, ":")[1])
	}

	for {

		req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
		if err != nil {
			return err
		}

		resp, err := http.DefaultClient.Do(req)
		if err == nil && resp.StatusCode == http.StatusOK {
			logs.Info("The router has been deployed successfully.")

			resp.Body.Close()

			return nil
		}

		// Sleep for a second to continue the next ping.
		logs.Info("Waiting for the router, retry in 1 second.")
		time.Sleep(1 * time.Second)

		select {
		case <-ctx.Done():
			log.Fatal("can not ping http server with in the specified time interval.")
		default:
		}
	}
}