package smtp2shoutrrr

import (
	"net/mail"
	"strings"
	"testing"

	"github.com/stretchr/testify/require"
)

func readMessage(t *testing.T, raw string) *mail.Message {
	t.Helper()

	msg, err := mail.ReadMessage(strings.NewReader(raw))
	require.NoError(t, err)

	return msg
}

// Regression: this header reached log.Fatalf, which exits the process. The
// value is attacker-controlled and needs nothing but the ability to deliver a
// message.
func TestBodyRejectsMalformedContentType(t *testing.T) {
	for name, contentType := range map[string]string{
		"parameter without a value": "text/plain; charset",
		"duplicate parameter":       "text/plain; charset=utf-8; charset=ascii",
		"no media type":             ";",
		"unterminated quoted value": `multipart/mixed; boundary="unterminated`,
	} {
		t.Run(name, func(t *testing.T) {
			email := ReceivedEmail{
				Msg: readMessage(t, "Subject: Test\r\nContent-Type: "+contentType+"\r\n\r\nbody\r\n"),
			}

			body, err := email.Body()
			require.Error(t, err)
			require.ErrorIs(t, err, errMalformedMessage,
				"an unparseable header is permanent, so the sender must not be told to retry")
			require.Empty(t, body)
		})
	}
}

func TestBodyReadsMessageWithoutContentType(t *testing.T) {
	email := ReceivedEmail{Msg: readMessage(t, "Subject: Test\r\n\r\nplain body\r\n")}

	body, err := email.Body()
	require.NoError(t, err)
	require.Equal(t, "plain body\r\n", body)
}

func TestBodyPrefersPlainTextPartOverHTML(t *testing.T) {
	email := ReceivedEmail{Msg: readMessage(t, strings.Join([]string{
		"Subject: Test",
		`Content-Type: multipart/alternative; boundary="b"`,
		"",
		"--b",
		"Content-Type: text/html; charset=utf-8",
		"",
		"<p>html body</p>",
		"--b",
		"Content-Type: text/plain; charset=utf-8",
		"",
		"plain body",
		"--b--",
		"",
	}, "\r\n"))}

	body, err := email.Body()
	require.NoError(t, err)
	require.Equal(t, "plain body", body)
}

func TestBodyFallsBackToHTMLPart(t *testing.T) {
	email := ReceivedEmail{Msg: readMessage(t, strings.Join([]string{
		"Subject: Test",
		`Content-Type: multipart/alternative; boundary="b"`,
		"",
		"--b",
		"Content-Type: text/html; charset=utf-8",
		"",
		"<p>html body</p>",
		"--b--",
		"",
	}, "\r\n"))}

	body, err := email.Body()
	require.NoError(t, err)
	require.Equal(t, "<p>html body</p>", body)
}