package main

import (
	"bytes"
	"crypto/ed25519"
	"encoding/json"
	"encoding/pem"
	"fmt"
	"log"
	_ "monitor-site/migrations"
	"net/http"
	"net/http/httputil"
	"net/url"
	"os"
	"strings"
	"time"

	"github.com/labstack/echo/v5"
	"github.com/pocketbase/pocketbase"
	"github.com/pocketbase/pocketbase/apis"
	"github.com/pocketbase/pocketbase/core"
	"github.com/pocketbase/pocketbase/models"
	"github.com/pocketbase/pocketbase/plugins/migratecmd"
	"github.com/pocketbase/pocketbase/tools/cron"
	"golang.org/x/crypto/ssh"
)

var app *pocketbase.PocketBase
var serverConnections = make(map[string]Server)

func main() {
	app = pocketbase.New()

	// loosely check if it was executed using "go run"
	isGoRun := strings.HasPrefix(os.Args[0], os.TempDir())

	// enable auto creation of migration files when making collection changes in the Admin UI
	migratecmd.MustRegister(app, app.RootCmd, migratecmd.Config{
		// (the isGoRun check is to enable it only during development)
		Automigrate: isGoRun,
	})

	// serve site
	app.OnBeforeServe().Add(func(e *core.ServeEvent) error {
		switch isGoRun {
		case true:
			proxy := httputil.NewSingleHostReverseProxy(&url.URL{
				Scheme: "http",
				Host:   "localhost:5173",
			})
			e.Router.Any("/*", echo.WrapHandler(proxy))
			e.Router.Any("/", echo.WrapHandler(proxy))
		default:
			e.Router.GET("/*", apis.StaticDirectoryHandler(os.DirFS("./site/dist"), true))
		}
		return nil
	})

	// set up cron job to delete records older than 30 days
	app.OnBeforeServe().Add(func(e *core.ServeEvent) error {
		scheduler := cron.New()
		scheduler.MustAdd("delete old records", "* 2 * * *", func() {
			// log.Println("Deleting old records...")
			// Get the current time
			now := time.Now().UTC()
			// Subtract one month
			oneMonthAgo := now.AddDate(0, 0, -30)
			// Format the time as a string
			timeString := oneMonthAgo.Format("2006-01-02 15:04:05")
			// collections to be cleaned
			collections := []string{"system_stats", "container_stats"}

			for _, collection := range collections {
				records, err := app.Dao().FindRecordsByFilter(
					collection,
					fmt.Sprintf("created <= \"%s\"", timeString), // filter
					"", // sort
					-1, // limit
					0,  // offset
				)
				if err != nil {
					log.Println(err)
					return
				}
				// delete records
				for _, record := range records {
					if err := app.Dao().DeleteRecord(record); err != nil {
						log.Fatal(err)
					}
				}
			}
		})
		scheduler.Start()
		return nil
	})

	// create ssh key if it doesn't exist
	app.OnBeforeServe().Add(func(e *core.ServeEvent) error {
		e.Router.GET("/getkey", func(c echo.Context) error {
			requestData := apis.RequestInfo(c)
			if requestData.Admin == nil {
				return apis.NewForbiddenError("Forbidden", nil)
			}
			key, err := os.ReadFile("./pb_data/id_ed25519.pub")
			if err != nil {
				return err
			}
			return c.JSON(http.StatusOK, map[string]string{"key": strings.TrimSuffix(string(key), "\n")})
		})
		return nil
	})

	// start ticker for server updates
	app.OnBeforeServe().Add(func(e *core.ServeEvent) error {
		go serverUpdateTicker()
		return nil
	})

	// immediately create connection for new servers
	app.OnRecordAfterCreateRequest("systems").Add(func(e *core.RecordCreateEvent) error {
		go updateServer(e.Record)
		return nil
	})

	if err := app.Start(); err != nil {
		log.Fatal(err)
	}
}

func serverUpdateTicker() {
	ticker := time.NewTicker(60 * time.Second)
	for range ticker.C {
		updateServers()
	}
}

func updateServers() {
	// serverCount := len(serverConnections)
	// fmt.Println("server count: ", serverCount)
	query := app.Dao().RecordQuery("systems").
		OrderBy("updated ASC").
		// todo get total count of servers and divide by 4 or something
		Limit(5)

	records := []*models.Record{}
	if err := query.All(&records); err != nil {
		app.Logger().Error("Failed to get servers: ", "err", err.Error())
		// return nil, err
	}

	for _, record := range records {
		updateServer(record)
	}
}

func updateServer(record *models.Record) {
	var server Server
	// check if server connection data exists
	if _, ok := serverConnections[record.Id]; ok {
		server = serverConnections[record.Id]
	} else {
		// create server connection struct
		server = Server{
			Ip:   record.Get("ip").(string),
			Port: record.Get("port").(string),
		}
		client, err := getServerConnection(&server)
		if err != nil {
			app.Logger().Error("Failed to connect:", "err", err.Error(), "server", server.Ip, "port", server.Port)
			// todo update record to not connected
			record.Set("active", false)
			delete(serverConnections, record.Id)
			return
		}
		server.Client = client
		serverConnections[record.Id] = server
	}
	// get server stats from agent
	systemData, err := requestJson(&server)
	if err != nil {
		app.Logger().Error("Failed to get server stats: ", "err", err.Error())
		record.Set("active", false)
		if server.Client != nil {
			server.Client.Close()
		}
		delete(serverConnections, record.Id)
		return
	}
	// update system record
	record.Set("active", true)
	record.Set("stats", systemData.System)
	if err := app.Dao().SaveRecord(record); err != nil {
		app.Logger().Error("Failed to update record: ", "err", err.Error())
	}
	// add new system_stats record
	system_stats, _ := app.Dao().FindCollectionByNameOrId("system_stats")
	system_stats_record := models.NewRecord(system_stats)
	system_stats_record.Set("system", record.Id)
	system_stats_record.Set("stats", systemData.System)
	if err := app.Dao().SaveRecord(system_stats_record); err != nil {
		app.Logger().Error("Failed to save record: ", "err", err.Error())
	}
	// add new container_stats record
	if len(systemData.Containers) > 0 {
		container_stats, _ := app.Dao().FindCollectionByNameOrId("container_stats")
		container_stats_record := models.NewRecord(container_stats)
		container_stats_record.Set("system", record.Id)
		container_stats_record.Set("stats", systemData.Containers)
		if err := app.Dao().SaveRecord(container_stats_record); err != nil {
			app.Logger().Error("Failed to save record: ", "err", err.Error())
		}
	}
}

func getServerConnection(server *Server) (*ssh.Client, error) {
	// app.Logger().Debug("new ssh connection", "server", server.Ip)
	key, err := getSSHKey()
	if err != nil {
		app.Logger().Error("Failed to get SSH key: ", "err", err.Error())
		return nil, err
	}
	time.Sleep(time.Second)

	// Create the Signer for this private key.
	signer, err := ssh.ParsePrivateKey(key)
	if err != nil {
		return nil, err
	}

	config := &ssh.ClientConfig{
		User: "u",
		Auth: []ssh.AuthMethod{
			ssh.PublicKeys(signer),
		},
		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
		Timeout:         5 * time.Second,
	}

	client, err := ssh.Dial("tcp", fmt.Sprintf("%s:%s", server.Ip, server.Port), config)
	if err != nil {
		return nil, err
	}

	return client, nil
}

func requestJson(server *Server) (SystemData, error) {
	session, err := server.Client.NewSession()
	if err != nil {
		return SystemData{}, err
	}
	defer session.Close()

	// Create a buffer to capture the output
	var outputBuffer bytes.Buffer
	session.Stdout = &outputBuffer

	if err := session.Shell(); err != nil {
		return SystemData{}, err
	}

	err = session.Wait()
	if err != nil {
		return SystemData{}, err
	}

	// Unmarshal the output into our struct
	var systemData SystemData
	err = json.Unmarshal(outputBuffer.Bytes(), &systemData)
	if err != nil {
		return SystemData{}, err
	}

	return systemData, nil
}

func getSSHKey() ([]byte, error) {
	// check if the key pair already exists
	existingKey, err := os.ReadFile("./pb_data/id_ed25519")
	if err == nil {
		return existingKey, nil
	}

	// Generate the Ed25519 key pair
	pubKey, privKey, err := ed25519.GenerateKey(nil)
	if err != nil {
		// app.Logger().Error("Error generating key pair:", "err", err.Error())
		return nil, err
	}

	// Get the private key in OpenSSH format
	privKeyBytes, err := ssh.MarshalPrivateKey(privKey, "")
	if err != nil {
		// app.Logger().Error("Error marshaling private key:", "err", err.Error())
		return nil, err
	}

	// Save the private key to a file
	privateFile, err := os.Create("./pb_data/id_ed25519")
	if err != nil {
		// app.Logger().Error("Error creating private key file:", "err", err.Error())
		return nil, err
	}
	defer privateFile.Close()

	if err := pem.Encode(privateFile, privKeyBytes); err != nil {
		// app.Logger().Error("Error writing private key to file:", "err", err.Error())
		return nil, err
	}

	// Generate the public key in OpenSSH format
	publicKey, err := ssh.NewPublicKey(pubKey)
	if err != nil {
		return nil, err
	}

	pubKeyBytes := ssh.MarshalAuthorizedKey(publicKey)

	// Save the public key to a file
	publicFile, err := os.Create("./pb_data/id_ed25519.pub")
	if err != nil {
		return nil, err
	}
	defer publicFile.Close()

	if _, err := publicFile.Write(pubKeyBytes); err != nil {
		return nil, err
	}

	app.Logger().Info("ed25519 SSH key pair generated successfully.")
	app.Logger().Info("Private key saved to: pb_data/id_ed25519")
	app.Logger().Info("Public key saved to: pb_data/id_ed25519.pub")

	existingKey, err = os.ReadFile("./pb_data/id_ed25519")
	if err == nil {
		return existingKey, nil
	}
	return nil, err
}