package utility

import (
	"context"
	"fmt"
	"io"
	"net"
	"net/textproto"
	"strings"
	"testing"
	"time"
)

func TestExternalRequestTimeoutDefaults(t *testing.T) {
	for _, value := range []string{"", "invalid", "0s", "-1s"} {
		if got := ExternalRequestTimeout(value); got != DefaultExternalRequestTimeout {
			t.Errorf("invalid timeout %q resolved to %v", value, got)
		}
	}
	if got := ExternalRequestTimeout(" 30s "); got != 30*time.Second {
		t.Fatalf("configured timeout ignored: %v", got)
	}
}

func startSMTPTestServer(t *testing.T, handle func(net.Conn)) string {
	t.Helper()
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	done := make(chan struct{})
	go func() {
		defer close(done)
		conn, err := listener.Accept()
		if err != nil {
			return
		}
		defer conn.Close()
		_ = conn.SetDeadline(time.Now().Add(2 * time.Second))
		handle(conn)
	}()
	t.Cleanup(func() {
		_ = listener.Close()
		select {
		case <-done:
		case <-time.After(3 * time.Second):
			t.Error("SMTP server connection was not released")
		}
	})
	return listener.Addr().String()
}

func TestSMTPSuccessAndRejectedRecipient(t *testing.T) {
	for _, reject := range []bool{false, true} {
		t.Run(fmt.Sprintf("reject=%t", reject), func(t *testing.T) {
			address := startSMTPTestServer(t, func(conn net.Conn) {
				peer := textproto.NewConn(conn)
				_ = peer.PrintfLine("220 localhost ready")
				for {
					line, err := peer.ReadLine()
					if err != nil {
						return
					}
					switch {
					case strings.HasPrefix(line, "EHLO"), strings.HasPrefix(line, "HELO"), strings.HasPrefix(line, "MAIL"):
						_ = peer.PrintfLine("250 OK")
					case strings.HasPrefix(line, "RCPT"):
						if reject {
							_ = peer.PrintfLine("550 recipient rejected")
							return
						}
						_ = peer.PrintfLine("250 OK")
					case line == "DATA":
						_ = peer.PrintfLine("354 send message")
						if _, err := peer.ReadDotBytes(); err != nil {
							return
						}
						_ = peer.PrintfLine("250 accepted")
					case line == "QUIT":
						_ = peer.PrintfLine("221 bye")
						return
					}
				}
			})
			err := SendSMTP(context.Background(), SMTPOptions{
				Address: address, Host: "localhost", From: "xxx@example.com",
				To: []string{"xxx@example.com"}, Data: []byte("Subject: test\r\n\r\nmessage\r\n"), Timeout: time.Second,
			})
			if (err != nil) != reject {
				t.Fatalf("unexpected SMTP result: rejected=%t error=%v", reject, err)
			}
		})
	}
}

func TestSMTPTimeoutInterruptsGreetingTLSAndProtocol(t *testing.T) {
	for _, scenario := range []string{"greeting", "tls", "mail", "starttls"} {
		t.Run(scenario, func(t *testing.T) {
			address := startSMTPTestServer(t, func(conn net.Conn) {
				if scenario == "greeting" || scenario == "tls" {
					_, _ = io.Copy(io.Discard, conn)
					return
				}
				peer := textproto.NewConn(conn)
				_ = peer.PrintfLine("220 localhost ready")
				if _, err := peer.ReadLine(); err != nil {
					return
				}
				if scenario == "starttls" {
					_ = peer.PrintfLine("250-localhost")
					_ = peer.PrintfLine("250 STARTTLS")
					if _, err := peer.ReadLine(); err != nil {
						return
					}
					_ = peer.PrintfLine("220 start TLS")
				} else {
					_ = peer.PrintfLine("250 OK")
				}
				_, _ = io.Copy(io.Discard, conn)
			})
			started := time.Now()
			err := SendSMTP(context.Background(), SMTPOptions{
				Address: address, Host: "localhost", SSL: scenario == "tls", From: "xxx@example.com",
				To: []string{"xxx@example.com"}, Data: []byte("message"), Timeout: 70 * time.Millisecond,
			})
			if err == nil || time.Since(started) > time.Second {
				t.Fatalf("SMTP stall was not interrupted: %v", err)
			}
		})
	}
}

func TestSMTPHonorsEarlierParentDeadline(t *testing.T) {
	address := startSMTPTestServer(t, func(conn net.Conn) {
		_, _ = io.Copy(io.Discard, conn)
	})
	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
	defer cancel()
	started := time.Now()
	err := SendSMTP(ctx, SMTPOptions{Address: address, Host: "localhost", Timeout: 10 * time.Second})
	if err == nil || time.Since(started) > time.Second {
		t.Fatalf("parent deadline was not honored: %v", err)
	}
}