From 878312fefd6ae1f8f7a5a23b24edcb088c2b12f2 Mon Sep 17 00:00:00 2001
From: Pavel Pogodaev <p.pogodaev@yadro.com>
Date: Tue, 19 Nov 2024 15:29:54 +0300
Subject: [PATCH] HW11 is completed

Signed-off-by: Pavel Pogodaev <p.pogodaev@yadro.com>
---
 hw11_telnet_client/.sync          |  0
 hw11_telnet_client/main.go        | 94 ++++++++++++++++++++++++++++++-
 hw11_telnet_client/telnet.go      | 63 ++++++++++++++++++++-
 hw11_telnet_client/telnet_test.go |  2 +-
 4 files changed, 153 insertions(+), 6 deletions(-)
 delete mode 100644 hw11_telnet_client/.sync

diff --git a/hw11_telnet_client/.sync b/hw11_telnet_client/.sync
deleted file mode 100644
index e69de29..0000000
diff --git a/hw11_telnet_client/main.go b/hw11_telnet_client/main.go
index 307acaf..939fe94 100644
--- a/hw11_telnet_client/main.go
+++ b/hw11_telnet_client/main.go
@@ -1,6 +1,96 @@
 package main
 
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+	"time"
+)
+
 func main() {
-	// Place your code here,
-	// P.S. Do not rush to throw context down, think think if it is useful with blocking operation?
+	flag.Parse()
+	port := os.Args[len(os.Args)-1]
+	host := os.Args[len(os.Args)-2]
+	duration := os.Args[len(os.Args)-3]
+
+	durVal, err := time.ParseDuration(duration)
+	if err != nil {
+		panic("wrong duration value " + duration)
+	}
+
+	in := &bytes.Buffer{}
+
+	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGTERM, syscall.SIGINT, os.Interrupt)
+	defer stop()
+
+	client := NewTelnetClient(host+":"+port, durVal, io.NopCloser(in), os.Stdout)
+	defer client.Close()
+
+	err = client.Connect()
+	if err != nil {
+		fmt.Printf("connection failed: %s\n", err)
+		return
+	}
+
+	var wg sync.WaitGroup
+
+	wg.Add(2)
+	go sendByTcp(ctx, stop, &wg, in, client)
+	go connectionHandler(ctx, &wg, client)
+
+	wg.Wait()
+}
+
+func sendByTcp(ctx context.Context, stop context.CancelFunc, wg *sync.WaitGroup, in *bytes.Buffer, t TelnetClient) {
+	go func() {
+		<-ctx.Done()
+		err := t.Close()
+		if err != nil {
+			fmt.Printf("failed to colse connection %s", err)
+		}
+		wg.Done()
+	}()
+
+	reader := bufio.NewReader(os.Stdin)
+	for {
+		resp, err := reader.ReadString('\n')
+		if err != nil {
+			stop()
+			return
+		}
+
+		in.WriteString(resp)
+		err = t.Send()
+		if err != nil {
+			fmt.Println(err)
+			return
+		}
+	}
+}
+
+func connectionHandler(ctx context.Context, wg *sync.WaitGroup, t TelnetClient) {
+	errCh := make(chan error)
+	defer func() {
+		wg.Done()
+	}()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case errCh <- t.Receive():
+			err := <-errCh
+			if err != nil {
+				fmt.Println(err)
+				return
+			}
+		}
+	}
 }
diff --git a/hw11_telnet_client/telnet.go b/hw11_telnet_client/telnet.go
index 369caa1..f89c634 100644
--- a/hw11_telnet_client/telnet.go
+++ b/hw11_telnet_client/telnet.go
@@ -1,7 +1,10 @@
 package main
 
 import (
+	"errors"
+	"fmt"
 	"io"
+	"net"
 	"time"
 )
 
@@ -12,10 +15,64 @@ type TelnetClient interface {
 	Receive() error
 }
 
+type ConnectionParams struct {
+	Address string
+	Timeout time.Duration
+	In      io.ReadCloser
+	Out     io.Writer
+	Conn    net.Conn
+}
+
 func NewTelnetClient(address string, timeout time.Duration, in io.ReadCloser, out io.Writer) TelnetClient {
-	// Place your code here.
+	return &ConnectionParams{
+		Address: address,
+		Timeout: timeout,
+		In:      in,
+		Out:     out,
+	}
+}
+
+func (c *ConnectionParams) Connect() error {
+	conn, err := net.DialTimeout("tcp", c.Address, c.Timeout)
+	if err != nil {
+		return fmt.Errorf("connection error: %w", err)
+	}
+
+	c.Conn = conn
+	fmt.Println("connected to ", c.Address)
+
 	return nil
 }
 
-// Place your code here.
-// P.S. Author's solution takes no more than 50 lines.
+func (c *ConnectionParams) Close() error {
+	if c.Conn != nil {
+		if err := c.Conn.Close(); err != nil {
+			return fmt.Errorf("close error: %w", err)
+		}
+	}
+
+	return nil
+}
+
+func (c *ConnectionParams) Send() error {
+	size, err := io.Copy(c.Conn, c.In)
+	if err != nil {
+		return fmt.Errorf("send error: %w", err)
+	}
+	fmt.Printf("sent %d bytes", size)
+	fmt.Println()
+
+	return nil
+}
+
+func (c *ConnectionParams) Receive() error {
+	_, err := io.Copy(c.Out, c.Conn)
+	if err != nil {
+		if errors.Is(err, io.EOF) {
+			return nil
+		}
+		return fmt.Errorf("receive error: %w", err)
+	}
+
+	return nil
+}
diff --git a/hw11_telnet_client/telnet_test.go b/hw11_telnet_client/telnet_test.go
index fb89f6d..eee771b 100644
--- a/hw11_telnet_client/telnet_test.go
+++ b/hw11_telnet_client/telnet_test.go
@@ -8,7 +8,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/require" //nolint:depguard
 )
 
 func TestTelnetClient(t *testing.T) {