fix(import): a deleted DXCC entity is not re-stamped from cty.dat

Reported with a Logger32 export: the record said <DXCC:3>151 and OpsLog
stored 54.

cty.dat answers one question — where is this callsign TODAY — and that is
the wrong question for a log. R1MVI was Malyj Vysotskij Island, entity
151, until the ARRL deleted it in 2012; the same call resolves to European
Russia today. Forcing the lookup onto a 2004 contact therefore destroys a
credit that can NEVER be worked again, because the place no longer counts.

So the ADIF's number wins whenever it names a deleted entity, and nothing
is corrected on those records at all — the country name and the zones of a
deleted entity are equally beyond what a present-day prefix table knows.
The list is the ADIF specification's own enumeration, sixty-odd entities
that only change when the ARRL deletes another one.

The guard sits in the forced path, so it also covers the grid's 'Update
from cty.dat' on a selection — the other way an operator could have lost
the same credits, one right-click at a time.

internal/dxcc/deleted.go

@@ -0,0 +1,97 @@
+package dxcc
+
+// The DELETED DXCC entities, and why a lookup table needs to know about them.
+//
+// cty.dat answers one question: what entity is this callsign in TODAY. That is
+// the right answer for a spot and the wrong one for a log. R1MVI was Malyj
+// Vysotskij Island, entity 151, until the ARRL deleted it in February 2012;
+// today the same callsign resolves to European Russia, 54. A 2004 contact
+// re-stamped from cty.dat therefore loses the entity it was made with — and
+// with it a DXCC credit that cannot be worked again, because the place no
+// longer counts.
+//
+// Reported by an operator importing a Logger32 export: his ADIF said
+// <DXCC:3>151 and OpsLog stored 54.
+//
+// So this list exists to be able to say "that number belongs to something that
+// no longer exists, leave it alone". It is the ADIF specification's own
+// enumeration of deleted entities, and it does not change except when the ARRL
+// deletes another one.
+var deletedEntities = map[int]string{
+	2:   "Abu Ail Is.",
+	8:   "Aldabra",
+	19:  "Bajo Nuevo",
+	23:  "Blenheim Reef",
+	25:  "British North Borneo",
+	26:  "British Somaliland",
+	28:  "Canal Zone",
+	30:  "Celebe & Molucca Is.",
+	39:  "Comoros",
+	42:  "Damao, Diu",
+	44:  "Desroches",
+	55:  "Farquhar",
+	57:  "French Equatorial Africa",
+	58:  "French Indo-China",
+	59:  "French West Africa",
+	67:  "French India",
+	68:  "Kuwait/Saudi Arabia Neutral Zone",
+	81:  "Germany",
+	85:  "Bonaire, Curacao",
+	93:  "Geyser Reef",
+	101: "Goa",
+	102: "Gold Coast, Togoland",
+	113: "Ifni",
+	115: "Italian Somaliland",
+	119: "Java",
+	127: "Kamaran Is.",
+	128: "Karelo-Finnish Republic",
+	134: "Kingman Reef",
+	139: "Kuria Muria I.",
+	151: "Malyj Vysotskij I.",
+	154: "Yemen Arab Republic",
+	155: "Malaya",
+	164: "Manchuria",
+	178: "Minerva Reef",
+	183: "Netherlands Borneo",
+	184: "Netherlands New Guinea",
+	186: "Newfoundland, Labrador",
+	193: "Okinawa (Ryukyu Is.)",
+	194: "Okino Tori-shima",
+	196: "Palestine",
+	200: "Portuguese Timor",
+	208: "Ruanda-Urundi",
+	210: "Saar",
+	218: "Czechoslovakia",
+	220: "Sarawak",
+	226: "Saudi Arabia/Iraq Neutral Zone",
+	228: "Serrana Bank & Roncador Cay",
+	229: "German Democratic Republic",
+	231: "Sikkim",
+	243: "People's Democratic Rep. of Yemen",
+	244: "Southern Sudan",
+	255: "St. Maarten, Saba, St. Eustatius",
+	258: "Sumatra",
+	261: "Swan Is.",
+	264: "Tangier",
+	267: "Territory of New Guinea",
+	268: "Tibet",
+	271: "Trieste",
+	307: "Zanzibar",
+	488: "Walvis Bay",
+	493: "Penguin Is.",
+}
+
+// IsDeleted reports whether a DXCC entity number names an entity the ARRL has
+// deleted.
+//
+// The one thing every caller does with a true answer is the same: stop. A
+// deleted entity cannot be looked up from a callsign, cannot be worked again,
+// and cannot be corrected by anything that only knows about today.
+func IsDeleted(n int) bool {
+	_, ok := deletedEntities[n]
+	return ok
+}
+
+// DeletedName is what entity n was called, or "" if it is not a deleted entity.
+// Used to say WHICH entity was preserved rather than only that one was.
+func DeletedName(n int) string { return deletedEntities[n] }

internal/dxcc/deleted_test.go

@@ -0,0 +1,46 @@
+package dxcc
+
+import "testing"
+
+// The contact that reported this: R1MVI, worked in 2004 on Malyj Vysotskij
+// Island, entity 151, deleted in February 2012. cty.dat resolves that callsign
+// to European Russia (54) today, so anything that re-stamps an old QSO from a
+// callsign has to know to stop here.
+func TestMalyjVysotskijIsKnownDeleted(t *testing.T) {
+	if !IsDeleted(151) {
+		t.Fatal("151 (Malyj Vysotskij I.) must be known as deleted — the whole guard hangs on it")
+	}
+	if got := DeletedName(151); got == "" {
+		t.Error("a deleted entity should be able to say what it was called")
+	}
+}
+
+// The guard must not fire on entities that are alive, or every log would freeze
+// at whatever DXCC number it was imported with — including the wrong ones.
+func TestLiveEntitiesAreNotTreatedAsDeleted(t *testing.T) {
+	live := map[int]string{
+		54:  "European Russia — what R1MVI resolves to today",
+		227: "France",
+		291: "United States",
+		339: "Japan",
+		1:   "Canada",
+	}
+	for n, what := range live {
+		if IsDeleted(n) {
+			t.Errorf("%d (%s) must not be listed as deleted", n, what)
+		}
+	}
+	if got := DeletedName(54); got != "" {
+		t.Errorf("DeletedName(54) = %q, want empty", got)
+	}
+}
+
+// A few more from the ADIF enumeration, so a careless edit to the table is
+// caught rather than discovered by an operator whose credits moved.
+func TestSomeOtherDeletedEntities(t *testing.T) {
+	for _, n := range []int{218 /* Czechoslovakia */, 229 /* German DR */, 255 /* St. Maarten, Saba, St. Eustatius */, 28 /* Canal Zone */} {
+		if !IsDeleted(n) {
+			t.Errorf("%d should be a deleted entity", n)
+		}
+	}
+}