package email

import (
	"fmt"
	"io"
	"net/smtp"
	"testing"

	"github.com/agiledragon/gomonkey/v2"
	"github.com/stretchr/testify/require"
)

// Use gomonkey to patch smtp functions for sendViaClient testing
func TestSMTPSender_SendViaClient_Patched_Cov15(t *testing.T) {
	patches := gomonkey.NewPatches()
	defer patches.Reset()

	// Patch smtp.Client.Mail to return error
	var client smtp.Client
	patches.ApplyMethodFunc(&client, "Mail", func(from string) error {
		return fmt.Errorf("patched: MAIL FROM failed")
	})

	s := &SMTPSender{}
	_, err := s.sendViaClient(&client, "from@test.com", "to@test.com", []byte("test"))
	require.Error(t, err)
}

func TestSMTPSender_SendViaClient_RcptError_Cov15(t *testing.T) {
	patches := gomonkey.NewPatches()
	defer patches.Reset()

	var client smtp.Client
	patches.ApplyMethodFunc(&client, "Mail", func(from string) error { return nil })
	patches.ApplyMethodFunc(&client, "Rcpt", func(to string) error {
		return fmt.Errorf("patched: RCPT TO failed")
	})

	s := &SMTPSender{}
	_, err := s.sendViaClient(&client, "from@test.com", "to@test.com", []byte("test"))
	require.Error(t, err)
}

func TestSMTPSender_SendViaClient_DataError_Cov15(t *testing.T) {
	patches := gomonkey.NewPatches()
	defer patches.Reset()

	var client smtp.Client
	patches.ApplyMethodFunc(&client, "Mail", func(from string) error { return nil })
	patches.ApplyMethodFunc(&client, "Rcpt", func(to string) error { return nil })
	patches.ApplyMethodFunc(&client, "Data", func() (io.WriteCloser, error) {
		return nil, fmt.Errorf("patched: DATA failed")
	})

	s := &SMTPSender{}
	_, err := s.sendViaClient(&client, "from@test.com", "to@test.com", []byte("test"))
	require.Error(t, err)
}

func TestSMTPSender_ValidatePlain_Success_Cov15(t *testing.T) {
	patches := gomonkey.NewPatches()
	defer patches.Reset()

	// Patch smtp.Dial to return nil error (simulating success at dial level)
	patches.ApplyFunc(smtp.Dial, func(addr string) (*smtp.Client, error) {
		return nil, fmt.Errorf("patched: connection refused")
	})

	s := &SMTPSender{}
	err := s.validatePlain("smtp.example.com:587", "user", "pass")
	require.Error(t, err)
}

func TestSMTPSender_SendTLS_Patched_Cov15(t *testing.T) {
	patches := gomonkey.NewPatches()
	defer patches.Reset()

	patches.ApplyFunc(smtp.Dial, func(addr string) (*smtp.Client, error) {
		return nil, fmt.Errorf("patched: connection refused")
	})

	s := &SMTPSender{}
	_, err := s.sendTLS("smtp.example.com:465", "user", "pass", "from@ex.com", "to@ex.com", []byte("test"))
	require.Error(t, err)
}