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package main

import (
	"bytes"
	"crypto/ed25519"
	"encoding/base64"
	"encoding/binary"
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"strings"
	"time"
)

var pubKey ed25519.PublicKey
var privKey ed25519.PrivateKey
var id string
var servers []string

// Post new server list to DHT
func dhtPost(s string) {
	buf := new(bytes.Buffer)
	err := binary.Write(buf, binary.LittleEndian, time.Now().Unix())
	if err != nil {
		panic(err)
	}
	_, err = buf.WriteString(strings.Join(servers, "\n"))
	if err != nil {
		panic(err)
	}
	var message []byte
	_, err = buf.Read(message)
	if err != nil {
		panic(err)
	}
	_, err = buf.Write(ed25519.Sign(privKey, message))
	if err != nil {
		panic(err)
	}
	fmt.Println(http.Post(s+"/dht/"+id, "application/octet-stream", buf))
}

func main() {
	flag.Parse()

	if flag.Arg(0) == "setup" {
		// Create keys
		pubKey, privKey, err := ed25519.GenerateKey(nil)
		if err != nil {
			panic(err)
		}
		err = os.WriteFile("pubkey", pubKey, 0644)
		if err != nil {
			panic(err)
		}
		err = os.WriteFile("privkey", privKey, 0600)
		if err != nil {
			panic(err)
		}
		// Create servers file
		_, err = os.Create("servers")
		if err != nil {
			panic(err)
		}
		fmt.Printf("Success! Your user ID: %s\n", base64.RawURLEncoding.EncodeToString(pubKey))
		return
	}

	pubKeyBytes, err := os.ReadFile("pubkey")
	if err != nil {
		panic(err)
	}
	pubKey = ed25519.PublicKey(pubKeyBytes)
	privKeyBytes, err := os.ReadFile("privkey")
	if err != nil {
		panic(err)
	}
	privKey = ed25519.PrivateKey(privKeyBytes)
	serversBytes, err := os.ReadFile("servers")
	if err != nil {
		panic(err)
	}
	id = base64.RawURLEncoding.EncodeToString(pubKey)
	servers = strings.Split(string(serversBytes), "\n")
	if servers[0] == "" {
		servers = servers[1:]
	}
	fmt.Println(id, servers)

	if flag.Arg(0) == "add" {
		// Add server
		servers = append(servers, flag.Arg(1))
		dhtPost(flag.Arg(1))
		http.Get(flag.Arg(1) + "/user/" + id)
		if servers[0] != flag.Arg(1) {
			http.Get(servers[0] + "/user/" + id)
		}
		err := os.WriteFile("servers", []byte(strings.Join(servers, "\n")), 0644)
		if err != nil {
			panic(err)
		}
	} else if flag.Arg(0) == "remove" {
		// Remove server
		for i := range servers {
			if servers[i] == flag.Arg(1) {
				servers = append(servers[:i], servers[i+1:]...)
				break
			}
		}
		if len(servers) > 0 {
			dhtPost(servers[0])
			http.Get(servers[0] + "/user/" + id)
		} else {
			dhtPost(flag.Arg(1))
		}
		http.Get(flag.Arg(1) + "/user/" + id)
		err := os.WriteFile("servers", []byte(strings.Join(servers, "\n")), 0644)
		if err != nil {
			panic(err)
		}
	} else if flag.Arg(0) == "primary" {
		// Make server a primary
		for i := range servers {
			if i > 0 && servers[i] == flag.Arg(1) {
				servers[i] = servers[0]
				servers[0] = flag.Arg(i)
				dhtPost(flag.Arg(i))
				http.Get(servers[0] + "/user/" + id)
				http.Get(servers[i] + "/user/" + id)
				break
			}
		}
		err := os.WriteFile("servers", []byte(strings.Join(servers, "\n")), 0644)
		if err != nil {
			panic(err)
		}
	} else if flag.Arg(0) == "get" {
		user := flag.Arg(1)
		filename := flag.Arg(2)
		response, _ := http.Get(servers[0] + "/storage/" + user + "/" + filename)
		responseBodyBytes, _ := io.ReadAll(response.Body)
		os.WriteFile(user + "/" + filename, responseBodyBytes, 0644)
	} else if flag.Arg(0) == "post" {
		filename := flag.Arg(1)
		file, _ := os.Open(filename)
		http.Post(
			servers[0] + "/storage/" + id + "/" + filename,
			"application/octet-stream",
			file,
		)
	}
}