import { test } from "node:test";
import assert from "node:assert/strict";
import { duplicateAddresses, describeConflicts } from "../src/lifecycle/invariants.ts";

/**
 * The fault this defends against, in the shape it actually occurred: two gateways declared
 * with the same public address became two router containers, both holding it on one segment.
 */

test("two machines holding one address on one segment is a conflict", () => {
  const conflicts = duplicateAddresses([
    { machine: "gw-home", segment: "isp-home", address: "198.51.100.7/24" },
    { machine: "gw-devices", segment: "isp-home", address: "198.51.100.7/24" },
    { machine: "transit", segment: "isp-home", address: "198.51.100.254/24" },
  ]);
  assert.equal(conflicts.length, 1);
  assert.equal(conflicts[0]?.address, "198.51.100.7");
  assert.deepEqual(conflicts[0]?.machines, ["gw-devices", "gw-home"]);
  assert.match(describeConflicts(conflicts), /198\.51\.100\.7 is held by gw-devices and gw-home/);
});

test("the same address on different segments is NOT a conflict", () => {
  // Every private network has its own `.1`. Reporting that would make the check useless.
  assert.deepEqual(
    duplicateAddresses([
      { machine: "gw-a", segment: "home", address: "10.99.1.1/24" },
      { machine: "gw-b", segment: "cafe", address: "10.99.1.1/24" },
    ]),
    [],
  );
});

test("one machine holding an address twice is not two machines", () => {
  // A machine multi-homed onto the same segment, or an address read back from two places.
  assert.deepEqual(
    duplicateAddresses([
      { machine: "gw", segment: "isp", address: "198.51.100.7/24" },
      { machine: "gw", segment: "isp", address: "198.51.100.7" },
    ]),
    [],
  );
});

test("the prefix length is not part of the address", () => {
  // The same address declared /24 in one place and /16 in another is still one address.
  const conflicts = duplicateAddresses([
    { machine: "a", segment: "isp", address: "198.51.100.7/24" },
    { machine: "b", segment: "isp", address: "198.51.100.7/16" },
  ]);
  assert.equal(conflicts.length, 1);
});

test("both families are checked", () => {
  const conflicts = duplicateAddresses([
    { machine: "a", segment: "isp", address: "2001:db8:b::7/48" },
    { machine: "b", segment: "isp", address: "2001:db8:b::7/48" },
  ]);
  assert.equal(conflicts.length, 1);
  assert.equal(conflicts[0]?.address, "2001:db8:b::7");
});