import { describe, expect, it } from "vitest";
import { countChanges, findNextChangeIndex, findPreviousChangeIndex } from "./diffNavigation";
import { DiffLine } from "./diffApi";

const lines: DiffLine[] = [
  { op: "equal", text: "a" },
  { op: "delete", text: "b" },
  { op: "equal", text: "c" },
  { op: "equal", text: "d" },
  { op: "insert", text: "e" },
  { op: "equal", text: "f" },
];

describe("diffNavigation", () => {
  it("findNextChangeIndex springt zur naechsten Aenderung nach dem aktuellen Index", () => {
    expect(findNextChangeIndex(lines, -1)).toBe(1);
    expect(findNextChangeIndex(lines, 1)).toBe(4);
    expect(findNextChangeIndex(lines, 4)).toBe(-1);
  });

  it("findPreviousChangeIndex springt zur vorherigen Aenderung", () => {
    expect(findPreviousChangeIndex(lines, 6)).toBe(4);
    expect(findPreviousChangeIndex(lines, 4)).toBe(1);
    expect(findPreviousChangeIndex(lines, 1)).toBe(-1);
  });

  it("countChanges zaehlt alle Nicht-equal-Zeilen", () => {
    expect(countChanges(lines)).toBe(2);
  });

  it("liefert -1 bei einer Liste ohne Aenderungen", () => {
    const noChanges: DiffLine[] = [{ op: "equal", text: "x" }];
    expect(findNextChangeIndex(noChanges, -1)).toBe(-1);
    expect(countChanges(noChanges)).toBe(0);
  });
});