import { describe, expect, it } from "vitest";
import { diffSnapshots, type PageSnapshot, type SnapshotBlock } from "./version-diff.js";

const b = (id: string, text: string, extra: Partial<SnapshotBlock> = {}): SnapshotBlock => ({
  id,
  type: "PARAGRAPH",
  content: { text },
  properties: {},
  parentId: null,
  position: id,
  ...extra
});

const snap = (blocks: SnapshotBlock[], page: PageSnapshot["page"] = { title: "T", icon: null, description: null }): PageSnapshot => ({
  page,
  blocks
});

describe("version snapshot diff (T-150)", () => {
  it("identical snapshots → empty diff", () => {
    const s = snap([b("a", "one"), b("c", "three")]);
    const d = diffSnapshots(s, snap([...s.blocks]), 1, 2);
    expect(d.summary).toEqual({ added: 0, deleted: 0, modified: 0, moved: 0, unchanged: 2 });
    expect(Object.keys(d.page)).toHaveLength(0);
  });

  it("classifies added / deleted / modified / moved", () => {
    const from = snap([
      b("a", "one"),
      b("b", "two"),
      b("c", "three", { position: "c0" }),
      b("gone", "bye")
    ]);
    const to = snap([
      b("a", "ONE changed"),
      b("b", "two", { properties: { align: "center" } }),
      b("c", "three", { position: "z9" }),
      b("d", "new block")
    ]);
    const d = diffSnapshots(from, to, 1, 2);
    expect(d.summary).toEqual({ added: 1, deleted: 1, modified: 2, moved: 1, unchanged: 0 });
    expect(d.added.map((x) => x.id)).toEqual(["d"]);
    expect(d.deleted.map((x) => x.id)).toEqual(["gone"]);
    const byId = Object.fromEntries(d.modified.map((m) => [m.id, m.fields]));
    expect(byId).toEqual({ a: ["content"], b: ["properties"] });
    expect(d.moved).toEqual([{ id: "c", from: "c0", to: "z9" }]);
  });

  it("detects parent moves as modified (structure change), not moved", () => {
    const from = snap([b("a", "top")]);
    const to = snap([b("a", "top", { parentId: "toggle1" })]);
    const d = diffSnapshots(from, to, 1, 2);
    expect(d.modified).toEqual([{ id: "a", fields: ["parentId"] }]);
    expect(d.moved).toHaveLength(0);
  });

  it("compares page fields and reports from/to values", () => {
    const d = diffSnapshots(
      snap([], { title: "Old", icon: "x", description: null }),
      snap([], { title: "Old", icon: null, description: "new" }),
      1, 2
    );
    expect(d.page).toEqual({
      icon: { from: "x", to: null },
      description: { from: null, to: "new" }
    });
  });

  it("key order in content/properties objects does NOT count as a change", () => {
    const from = snap([b("a", "x", { properties: { b: 1, a: 2 } })]);
    const to = snap([b("a", "x", { properties: { a: 2, b: 1 } })]);
    expect(diffSnapshots(from, to, 1, 2).summary.modified).toBe(0);
  });

  it("type change is flagged", () => {
    const d = diffSnapshots(snap([b("a", "x")]), snap([b("a", "x", { type: "HEADING_1" })]), 1, 2);
    expect(d.modified).toEqual([{ id: "a", fields: ["type"] }]);
  });
});