/**
 * Direct unit tests for `session.ts`'s defensive guards. Each method below has
 * a guard for a state its normal callers never produce (an out-of-range index,
 * a missing overlay/buffer/policy/file-gateway, an empty match set, a zero-delta
 * hunk adjustment). The public key-handling flow can't reach those states, so
 * the guards are exercised by invoking the private method directly with the
 * edge input and asserting the method declines gracefully.
 */

import { assertEquals } from "@std/assert";
import { parseDocument, SAMPLE } from "./view-helpers.ts";
import { Session } from "../lib/view/session.ts";

function makeSession(): Session {
  return new Session(parseDocument(SAMPLE), {
    color: false,
    showLineNumbers: false,
  }, { width: 90, height: 24 });
}

/** The private surface these tests reach into. */
const priv = (s: Session) => s.accessForTestingOnly;

Deno.test("selectNode: an out-of-range index leaves the selection untouched", () => {
  const s = makeSession();
  priv(s).selectNode(-1);
  assertEquals(s.view().selected, null);
  priv(s).selectNode(s.doc.flatStructure.length + 5);
  assertEquals(s.view().selected, null);
});

Deno.test("moveCardSelection: a no-op when no info overlay is open", () => {
  const s = makeSession();
  priv(s).moveCardSelection(1);
  assertEquals(s.view().overlay, null);
});

Deno.test("revealMatch: a no-op when there are no matches", () => {
  const s = makeSession();
  const top = s.top;
  priv(s).revealMatch();
  assertEquals(s.top, top);
});

Deno.test("handleOverlayKey: a no-op when no overlay is open", () => {
  const s = makeSession();
  priv(s).handleOverlayKey({ name: "down" });
  assertEquals(s.view().overlay, null);
});

Deno.test("prepareContextEdit: a no-op on a plain file (no diff policy)", () => {
  const s = makeSession();
  priv(s).prepareContextEdit();
  assertEquals(s.view().overlay, null);
});

Deno.test("editStart: column 0 when there is no diff policy", () => {
  const s = makeSession();
  assertEquals(priv(s).editStart(), 0);
});

Deno.test("ensureCursorVisible: a no-op when there is no edit buffer", () => {
  const s = makeSession();
  const top = s.top;
  priv(s).ensureCursorVisible();
  assertEquals(s.top, top);
});

Deno.test("computeEditedFiles: empty when there is no source or buffer", () => {
  const s = makeSession();
  assertEquals(priv(s).computeEditedFiles(), []);
});

Deno.test("the file-picker helpers are no-ops without a file gateway", () => {
  const s = makeSession();
  priv(s).refreshPicker();
  priv(s).pickerUp();
  priv(s).activatePicked();
  priv(s).openPickedFile("/anywhere/main.ts");
  // The picker was never entered, so no overlay was opened.
  assertEquals(s.view().overlay, null);
});

Deno.test("adjustHunkCounts: a no-op with no diff policy", () => {
  const s = makeSession();
  const top = s.top;
  priv(s).adjustHunkCounts(0, 0);
  assertEquals(s.top, top);
});