chitchat/client/main.go

package main

import (
	"bytes"
	"fmt"
	"io"
	"math/rand/v2"
	"net/http"
	"os"
	"strings"
	"time"
)

/*
Connect:
1. Client A: Create URL with public key and ID to reach on
2. Client B: Parses URL, generate AES key, upload key to storage
3. Client A: Polls for storage on server
*/

func get(id string) ([]byte, error) {
	res, err := http.Get(fmt.Sprintf("http://localhost:3000/store/%s", id))
	if err != nil {
		return nil, err
	}

	defer res.Body.Close()

	if res.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("failed to get")
	}

	data, err := io.ReadAll(res.Body)
	if err != nil {
		return nil, err
	}

	return data, nil
}

func put(id string, data []byte) error {
	req, err := http.NewRequest(
		http.MethodPut,
		fmt.Sprintf("http://localhost:3000/store/%s", id),
		bytes.NewReader(data),
	)
	if err != nil {
		return err
	}

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}

	defer res.Body.Close()
	if res.StatusCode != http.StatusNoContent {
		return fmt.Errorf("failed to get")
	}

	return nil
}

func randomId() string {
	var charset = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")

	runes := make([]rune, 512)
	for i := range runes {
		runes[i] = charset[rand.IntN(len(charset))]
	}

	return string(runes)
}

func connect() (string, string) {
	// link: chitchat:<temporary-id>
	var selfId, partnerId string
	selfId = randomId()

	fmt.Printf("Your ID:    %s\n", selfId)
	fmt.Printf("Partner ID: ")
	fmt.Scanln(&partnerId)

	partnerId = strings.TrimSpace(partnerId)
	return selfId, partnerId
}

func pollPartner(partnerId string) {
	var message string

	for {
		time.Sleep(5 * time.Second)

		data, err := get(partnerId)
		if err != nil {
			fmt.Printf("Failed to poll: %s\n", err)
			continue
		}

		partnerId, message, _ = strings.Cut(string(data), ":")
		fmt.Printf("%s\n", message)
	}
}

func pollInput(selfId string) {
	var message string

	for {
		fmt.Scanln(&message)
		nextId := randomId()
		data := fmt.Sprintf("%s:%s", nextId, message)

		err := put(selfId, []byte(data))
		if err != nil {
			fmt.Printf("Failed to put: %s\n", err)
			continue
		}

		selfId = nextId
	}
}

func run() error {
	selfId, partnerId := connect()
	if partnerId == "" {
		fmt.Printf("Waiting for partner to connect to you...\n")

		for {
			time.Sleep(5 * time.Second)

			data, err := get(selfId)
			if err != nil {
				fmt.Printf("Partner hasn't connected: %s\n", err)
				continue
			}

			partnerId = string(data)
			break
		}
	} else {
		err := put(partnerId, []byte(selfId))
		if err != nil {
			return fmt.Errorf("failed to put next id: %w", err)
		}
	}

	fmt.Printf("Your ID:    %s\n", selfId)
	fmt.Printf("Partner ID: %s\n", partnerId)

	fmt.Printf("Chat away!\n")

	go pollInput(partnerId)
	go pollPartner(selfId)
	for {
	}

	return nil
}

func main() {
	err := run()
	if err != nil {
		fmt.Printf("%s\n", err)
		os.Exit(1)
	}
}