package email

import (
	"context"
	"encoding/base64"
	"net/mail"
	"strings"
	"testing"
	"time"
)

func testFrom() mail.Address {
	return mail.Address{Address: "no-reply@example.com"}
}

func TestLoginAuthChallengeResponse(t *testing.T) {
	a := &loginAuth{username: "user", password: "pass"}
	mech, initial, err := a.Start(nil)
	if err != nil {
		t.Fatalf("Start: %v", err)
	}
	if mech != "LOGIN" || initial != nil {
		t.Fatalf("unexpected Start result: %q %v", mech, initial)
	}
	resp, err := a.Next([]byte("Username:"), true)
	if err != nil || string(resp) != "user" {
		t.Fatalf("username challenge: %q %v", resp, err)
	}
	resp, err = a.Next([]byte("Password"), true)
	if err != nil || string(resp) != "pass" {
		t.Fatalf("password challenge: %q %v", resp, err)
	}
	if _, err := a.Next([]byte("Bogus"), true); err == nil {
		t.Fatal("expected error on unexpected challenge")
	}
}

func TestPlainAuthSendsCredentialsInClear(t *testing.T) {
	// Internal relays advertise only PLAIN over an unencrypted connection;
	// stdlib smtp.PlainAuth refuses that (ErrUnencryptedConnection), so the
	// sender uses the cleartext-capable plainAuth instead.
	a := &plainAuth{username: "user", password: "pass"}
	mech, initial, err := a.Start(nil)
	if err != nil {
		t.Fatalf("Start: %v", err)
	}
	if mech != "PLAIN" {
		t.Fatalf("mechanism = %q, want PLAIN", mech)
	}
	want := "\x00user\x00pass"
	if string(initial) != want {
		t.Fatalf("initial response = %q, want %q", initial, want)
	}
	if resp, err := a.Next(nil, false); err != nil || resp != nil {
		t.Fatalf("Next(done) = %q %v, want nil nil", resp, err)
	}
	if _, err := a.Next(nil, true); err == nil {
		t.Fatal("expected error on unexpected challenge")
	}
}

func TestNewSMTPValidation(t *testing.T) {
	if _, err := NewSMTP(SMTPConfig{Port: 587}); err == nil ||
		!strings.Contains(err.Error(), "missing host") {
		t.Fatalf("want missing-host error, got %v", err)
	}
	if _, err := NewSMTP(SMTPConfig{Host: "relay.internal", Port: 0, DefaultFrom: testFrom()}); err == nil ||
		!strings.Contains(err.Error(), "port") {
		t.Fatalf("want invalid-port error, got %v", err)
	}
	s, err := NewSMTP(SMTPConfig{
		Host:        "relay.internal",
		Port:        25,
		SSL:         false,
		DefaultFrom: testFrom(),
		Timeout:     time.Second,
	})
	if err != nil {
		t.Fatalf("NewSMTP: %v", err)
	}
	smtpS, ok := s.(*smtpSender)
	if !ok {
		t.Fatalf("unexpected sender type %T", s)
	}
	if smtpS.ssl || smtpS.addr != "relay.internal:25" {
		t.Fatalf("unexpected config: %+v", smtpS)
	}
}

func TestBuildMessageMultipartAlternative(t *testing.T) {
	msg := Message{
		From:     mail.Address{Name: "go-auth", Address: "no-reply@example.com"},
		To:       []mail.Address{{Name: "Ada", Address: "ada@example.com"}},
		Subject:  "Reset your password — Åke & Östen",
		TextBody: "Hello Ada,\nreset link: https://auth.example/reset?token=abc\n",
		HTMLBody: "<p>Hello Ada,</p><p>reset link: https://auth.example/reset?token=abc</p>",
		Headers:  map[string]string{"List-Unsubscribe": "<https://auth.example/unsub>"},
	}
	raw, err := buildMessage(msg)
	if err != nil {
		t.Fatal(err)
	}
	out := string(raw)

	for _, want := range []string{
		"From: \"go-auth\" <no-reply@example.com>",
		"To: \"Ada\" <ada@example.com>",
		"Subject: =?utf-8?q?",
		"MIME-Version: 1.0",
		"multipart/alternative;",
		"Content-Type: text/plain; charset=utf-8",
		"Content-Type: text/html; charset=utf-8",
		"List-Unsubscribe: <https://auth.example/unsub>",
		"Hello Ada,",
	} {
		if !strings.Contains(out, want) {
			t.Errorf("message missing %q\n%s", want, out)
		}
	}
	// The multipart must terminate properly.
	if !strings.Contains(out, "--alt-") || !strings.HasSuffix(out, "--\r\n") {
		t.Errorf("multipart envelope not closed properly:\n%s", out)
	}
}

func TestBuildMessageTextOnly(t *testing.T) {
	raw, err := buildMessage(Message{
		From:     testFrom(),
		To:       []mail.Address{{Address: "ada@example.com"}},
		Subject:  "hi",
		TextBody: "plain only",
	})
	if err != nil {
		t.Fatal(err)
	}
	out := string(raw)
	if strings.Contains(out, "multipart") {
		t.Errorf("text-only message must not be multipart:\n%s", out)
	}
	if !strings.Contains(out, "Content-Type: text/plain; charset=utf-8") {
		t.Errorf("missing text/plain content type:\n%s", out)
	}
}

func TestBuildMessageRejectsHeaderInjection(t *testing.T) {
	raw, err := buildMessage(Message{
		From:     testFrom(),
		To:       []mail.Address{{Address: "ada@example.com"}},
		Subject:  "hi",
		TextBody: "body",
		Headers:  map[string]string{"X-Evil": "a\r\nBcc: victim@example.com"},
	})
	if err != nil {
		t.Fatal(err)
	}
	if strings.Contains(string(raw), "Bcc: victim@example.com") {
		t.Error("CR/LF injection survived into the message")
	}
}

func TestBuildMessageAttachment(t *testing.T) {
	body, err := buildMessage(Message{
		From:     mail.Address{Name: "B2B Demo AB", Address: "faktura@demo.se"},
		To:       []mail.Address{{Address: "faktura@falk.se"}},
		Subject:  "Faktura INV-000001",
		TextBody: "Hej,\nFaktura bifogas.",
		Attachments: []Attachment{{
			Filename: "INV-000001.pdf",
			Content:  []byte("%PDF-1.4 fake"),
		}},
	})
	if err != nil {
		t.Fatalf("buildMessage: %v", err)
	}
	s := string(body)
	for _, want := range []string{
		"multipart/mixed;",
		`Content-Type: application/pdf; name="INV-000001.pdf"`,
		`Content-Disposition: attachment; filename="INV-000001.pdf"`,
		"Content-Transfer-Encoding: base64",
	} {
		if !strings.Contains(s, want) {
			t.Errorf("message missing %q", want)
		}
	}

	// The attachment payload round-trips: extract the base64 blob between the
	// attachment part header and the closing CRLF, decode, compare.
	idx := strings.Index(s, `Content-Disposition: attachment; filename="INV-000001.pdf"`)
	rest := s[idx:]
	lineEnd := strings.Index(rest, "\r\n\r\n")
	if lineEnd < 0 {
		t.Fatal("attachment part has no body separator")
	}
	b64line := strings.SplitN(rest[lineEnd+4:], "\r\n", 2)[0]
	decoded, err := base64.StdEncoding.DecodeString(strings.TrimSpace(b64line))
	if err != nil {
		t.Fatalf("decode attachment base64: %v", err)
	}
	if string(decoded) != "%PDF-1.4 fake" {
		t.Fatalf("attachment content = %q", decoded)
	}
}

func TestBuildMessageMissingBody(t *testing.T) {
	if _, err := buildMessage(Message{
		From: testFrom(), To: []mail.Address{{Address: "a@b"}}, Subject: "x",
	}); err == nil {
		t.Fatal("want missing-body error")
	}
}

func TestLogSenderNeverSends(t *testing.T) {
	s := NewLogSender(nil, testFrom())
	if err := s.Send(context.Background(), Message{
		From: testFrom(), To: []mail.Address{{Address: "a@b"}}, Subject: "x", TextBody: "y",
	}); err != nil {
		t.Fatalf("log sender: %v", err)
	}
	if s.DefaultFrom().Address != "no-reply@example.com" {
		t.Fatalf("DefaultFrom = %q", s.DefaultFrom().Address)
	}
}