package main

import (
	"bufio"
	"crypto/rand"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/fsnotify/fsnotify"
)

type Config struct {
	Port       int
	AuthCode   string
	Peers      []string
	PeerID     string
	OpenSearch OpenSearchConfig
}

type OpenSearchConfig struct {
	Domain string
}

var defaultConfig = Config{
	Port: 5000,
	OpenSearch: OpenSearchConfig{
		Domain: "localhost",
	},
}

const configFilePath = "config.json"

var config Config
var configLock sync.RWMutex

func main() {
	err := initConfig()
	if err != nil {
		fmt.Println("Error during initialization:", err)
		return
	}

	loadNodeConfig()
	go startFileWatcher()
	go checkMasterHeartbeat()

	if config.AuthCode == "" {
		config.AuthCode = generateStrongRandomString(64)
		fmt.Printf("Generated connection code: %s\n", config.AuthCode)
		saveConfig(config)
	}

	// Generate Host ID
	hostID, nodeErr := generateHostID()
	if nodeErr != nil {
		log.Fatalf("Failed to generate host ID: %v", nodeErr)
	}
	config.PeerID = hostID

	if len(config.Peers) > 0 {
		time.Sleep(2 * time.Second) // Give some time for connections to establish
		startElection()
	}

	go startNodeClient()

	runServer()
}

func initConfig() error {
	if _, err := os.Stat(configFilePath); os.IsNotExist(err) {
		return createConfig()
	}

	fmt.Println("Configuration file already exists.")
	config = loadConfig()
	return nil
}

func createConfig() error {
	reader := bufio.NewReader(os.Stdin)

	fmt.Println("Configuration file not found.")
	fmt.Print("Do you want to use default values? (yes/no): ")
	useDefaults, _ := reader.ReadString('\n')

	config := defaultConfig
	if useDefaults != "yes\n" {
		fmt.Print("Enter port (default 5000): ")
		portStr, _ := reader.ReadString('\n')
		if portStr != "\n" {
			port, err := strconv.Atoi(portStr[:len(portStr)-1])
			if err != nil {
				return err
			}
			config.Port = port
		}

		fmt.Print("Enter your domain address (e.g., domain.com): ")
		domain, _ := reader.ReadString('\n')
		if domain != "\n" {
			config.OpenSearch.Domain = domain[:len(domain)-1]
		}

		fmt.Print("Do you want to connect to other nodes? (yes/no): ")
		connectNodes, _ := reader.ReadString('\n')
		if strings.TrimSpace(connectNodes) == "yes" {
			fmt.Println("Enter peer addresses (comma separated, e.g., /ip4/127.0.0.1/tcp/5000,/ip4/127.0.0.1/tcp/5001): ")
			peersStr, _ := reader.ReadString('\n')
			if peersStr != "\n" {
				config.Peers = strings.Split(strings.TrimSpace(peersStr), ",")
			}
		}
	}

	if config.AuthCode == "" {
		config.AuthCode = generateStrongRandomString(64)
		fmt.Printf("Generated connection code: %s\n", config.AuthCode)
	}

	saveConfig(config)
	return nil
}

func saveConfig(config Config) {
	file, err := os.Create(configFilePath)
	if err != nil {
		fmt.Println("Error creating config file:", err)
		return
	}
	defer file.Close()

	configData, err := json.MarshalIndent(config, "", "  ")
	if err != nil {
		fmt.Println("Error marshalling config data:", err)
		return
	}

	_, err = file.Write(configData)
	if err != nil {
		fmt.Println("Error writing to config file:", err)
	}
}

func loadConfig() Config {
	configFile, err := os.Open(configFilePath)
	if err != nil {
		log.Fatalf("Error opening config file: %v", err)
	}
	defer configFile.Close()

	var config Config
	if err := json.NewDecoder(configFile).Decode(&config); err != nil {
		log.Fatalf("Error decoding config file: %v", err)
	}

	return config
}

func generateStrongRandomString(length int) string {
	bytes := make([]byte, length)
	_, err := rand.Read(bytes)
	if err != nil {
		log.Fatalf("Error generating random string: %v", err)
	}
	return base64.URLEncoding.EncodeToString(bytes)[:length]
}

func startFileWatcher() {
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		log.Fatal(err)
	}

	go func() {
		defer watcher.Close()
		for {
			select {
			case event, ok := <-watcher.Events:
				if !ok {
					return
				}
				if event.Op&fsnotify.Write == fsnotify.Write {
					log.Println("Modified file:", event.Name)
					configLock.Lock()
					config = loadConfig()
					configLock.Unlock()
					// Perform your logic here to handle the changes in the config file
				}
			case err, ok := <-watcher.Errors:
				if !ok {
					return
				}
				log.Println("Error:", err)
			}
		}
	}()

	err = watcher.Add(configFilePath)
	if err != nil {
		log.Fatal(err)
	}
}