package mailparser

import (
	"strings"
	"testing"
)

func TestRepairUTF8(t *testing.T) {
	tests := []struct {
		name string
		in   string
		want string
	}{
		{"pure ascii untouched", "Passwort geaendert", "Passwort geaendert"},
		{"valid utf8 untouched", "Passwort geändert – ok", "Passwort geändert – ok"},
		{"windows1252 umlauts", "Passwort ge\xe4ndert", "Passwort geändert"},
		{"windows1252 sharp s", "Mini-Fu\xdfball", "Mini-Fußball"},
		{"cp1252 en dash 0x96", "Netbook f\xfcr 207 Euro \x96 jetzt", "Netbook für 207 Euro – jetzt"},
		{"cp1252 registered 0xae", "NVIDIA\xae Karten", "NVIDIA® Karten"},
		{"mixed valid utf8 and latin1", "Gr\xfc\xdfe – ünd", "Grüße – ünd"},
		{"empty", "", ""},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			if got := RepairUTF8(tc.in); got != tc.want {
				t.Errorf("RepairUTF8(%q) = %q, want %q", tc.in, got, tc.want)
			}
		})
	}
}

func TestNeedsCharsetRepair(t *testing.T) {
	if NeedsCharsetRepair("Passwort geändert") {
		t.Error("valid UTF-8 must not be flagged for repair")
	}
	if !NeedsCharsetRepair("Passwort ge\xe4ndert") {
		t.Error("raw Latin-1 byte must be flagged for repair")
	}
}

// A Subject header with raw 8-bit bytes and no RFC 2047 encoded-word must be
// decoded via the Windows-1252 fallback instead of ending up as invalid UTF-8.
func TestParseRawEightBitSubject(t *testing.T) {
	raw := "From: a@example.com\r\n" +
		"Subject: Passwort f\xfcr WoltLab ge\xe4ndert\r\n" +
		"Content-Type: text/plain\r\n\r\n" +
		"Gr\xfc\xdfe\r\n"

	pm, err := Parse([]byte(raw))
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	if pm.Subject != "Passwort für WoltLab geändert" {
		t.Errorf("Subject = %q", pm.Subject)
	}
	if !strings.Contains(pm.TextBody, "Grüße") {
		t.Errorf("TextBody = %q", pm.TextBody)
	}
}

// A correctly encoded UTF-8 mail must survive the repair unchanged.
func TestParseValidUTF8NotMangled(t *testing.T) {
	raw := "From: a@example.com\r\n" +
		"Subject: =?UTF-8?Q?Gr=C3=BC=C3=9Fe?=\r\n" +
		"Content-Type: text/plain; charset=UTF-8\r\n\r\n" +
		"Schöne Grüße – äöüß\r\n"

	pm, err := Parse([]byte(raw))
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	if pm.Subject != "Grüße" {
		t.Errorf("Subject = %q", pm.Subject)
	}
	if !strings.Contains(pm.TextBody, "Schöne Grüße – äöüß") {
		t.Errorf("TextBody = %q", pm.TextBody)
	}
}