import { describe, expect, it } from "vitest";

import { History, HISTORY_LIMIT } from "./history.js";
import type { BlockDto } from "./types.js";

function block(id: string, text: string, version = 1): BlockDto {
  return {
    id,
    type: "paragraph",
    content: { text },
    parentId: null,
    position: "1",
    version,
  };
}

describe("History (undo/redo, 100 steps)", () => {
  it("records, undoes and redoes", () => {
    const h = new History([block("a", "A")]);
    expect(h.canUndo).toBe(false);
    expect(h.canRedo).toBe(false);

    h.record(h.current(), [block("a", "AB")], "type");
    expect(h.canUndo).toBe(true);
    expect(h.depth).toBe(1);

    const undo = h.undo();
    expect(undo?.blocks.map((b) => (b.content as { text: string }).text)).toEqual(["A"]);
    expect(h.canRedo).toBe(true);

    const redo = h.redo();
    expect(redo?.blocks.map((b) => (b.content as { text: string }).text)).toEqual(["AB"]);
    expect(h.canRedo).toBe(false);
  });

  it("truncates the redo branch on a new edit after undo", () => {
    const h = new History([block("a", "A")]);
    h.record(h.current(), [block("a", "B")], "e1");
    h.record(h.current(), [block("a", "C")], "e2");
    h.undo(); // back to B
    h.record(h.current(), [block("a", "D")], "e3"); // new branch
    expect(h.canRedo).toBe(false);
    expect(h.depth).toBe(2);
  });

  it("coalesces consecutive same-label steps (typing burst)", () => {
    const h = new History([block("a", "A")]);
    h.record(h.current(), [block("a", "AB")], "type");
    h.record(h.current(), [block("a", "ABC")], "type");
    expect(h.depth).toBe(1); // one step, not two
    const undo = h.undo();
    expect(undo?.blocks.map((b) => (b.content as { text: string }).text)).toEqual(["A"]);
  });

  it("caps the undo stack at 100 steps", () => {
    const h = new History([block("a", "A")]);
    for (let i = 0; i < HISTORY_LIMIT + 10; i += 1) {
      h.record(h.current(), [block("a", `T${i}`)], `edit-${i}`);
    }
    expect(h.depth).toBe(HISTORY_LIMIT);
  });

  it("reset drops all history", () => {
    const h = new History([block("a", "A")]);
    h.record(h.current(), [block("a", "B")], "x");
    h.reset([block("b", "fresh")]);
    expect(h.canUndo).toBe(false);
    expect(h.canRedo).toBe(false);
    expect(h.current().map((b) => b.id)).toEqual(["b"]);
  });
});