import { describe, expect, it } from "vitest";
import { reconcileUserEdits } from "./media-ingest-cluster.js";

const computed = [
  { key: "session:a1", assetIds: ["a1", "a2", "a3"] },
  { key: "session:b1", assetIds: ["b1", "b2"] },
  { key: "session:c1", assetIds: ["c1", "c2", "c3"] },
];

const keys = (clusters: Array<{ key: string; assetIds: string[] }>) =>
  clusters.map((cluster) => [cluster.key, cluster.assetIds]);

describe("reconcileUserEdits", () => {
  it("passes computed clusters through when the user edited nothing", () => {
    expect(reconcileUserEdits(computed, [], "session")).toEqual(computed);
  });

  it("never re-adds the assets of a merged collection to computed clusters", () => {
    // The user merged a1.. and b1.. into the a1 collection.
    const merged = { clusterKey: "session:a1", assetIds: ["a1", "a2", "a3", "b1", "b2"] };
    expect(keys(reconcileUserEdits(computed, [merged], "session"))).toEqual([
      ["session:c1", ["c1", "c2", "c3"]],
    ]);
  });

  it("keeps both halves of a split and places new assets outside them", () => {
    // Split c1 | c2 c3; a later sync adds c4 to the computed session.
    const grown = [
      ...computed.slice(0, 2),
      { key: "session:c1", assetIds: ["c1", "c2", "c3", "c4"] },
    ];
    const kept = { clusterKey: "session:c1", assetIds: ["c1"] };
    const splitOff = { clusterKey: null, assetIds: ["c2", "c3"] };
    expect(keys(reconcileUserEdits(grown, [kept, splitOff], "session"))).toEqual([
      ["session:a1", ["a1", "a2", "a3"]],
      ["session:b1", ["b1", "b2"]],
      ["session:c1", ["c1", "c4"]],
    ]);
    // When the kept half is not a subset any more it freezes; c4 gets its own key.
    const moved = [...computed.slice(0, 2), { key: "session:c0", assetIds: ["c0", "c4"] }];
    expect(
      keys(reconcileUserEdits(moved, [{ ...kept, assetIds: ["c1", "c9"] }], "session")),
    ).toEqual([
      ["session:a1", ["a1", "a2", "a3"]],
      ["session:b1", ["b1", "b2"]],
      ["session:c0", ["c0", "c4"]],
    ]);
  });

  it("lets a renamed collection follow its cluster, even when the cluster key changes", () => {
    const renamed = { clusterKey: "session:a1", assetIds: ["a1", "a2"] };
    const earlier = [
      { key: "session:a0", assetIds: ["a0", "a1", "a2", "a3"] },
      ...computed.slice(1),
    ];
    expect(keys(reconcileUserEdits(earlier, [renamed], "session"))).toEqual([
      ["session:a1", ["a0", "a1", "a2", "a3"]],
      ["session:b1", ["b1", "b2"]],
      ["session:c1", ["c1", "c2", "c3"]],
    ]);
  });

  it("re-keys a cluster that lost its first asset to a split-off collection", () => {
    const splitOff = { clusterKey: null, assetIds: ["a1"] };
    expect(keys(reconcileUserEdits(computed, [splitOff], "theme"))).toEqual([
      ["theme:a2", ["a2", "a3"]],
      ["session:b1", ["b1", "b2"]],
      ["session:c1", ["c1", "c2", "c3"]],
    ]);
  });

  it("ignores empty user collections", () => {
    expect(
      reconcileUserEdits(computed, [{ clusterKey: "session:a1", assetIds: [] }], "session"),
    ).toEqual(computed);
  });
});