import { describe, expect, it } from "vitest";
import {
  applyMigrations,
  CURRENT_SAVE_VERSION,
  migrateSave,
  saveDocumentSchema,
  type SaveMigration,
} from "../src/index";
import { fullSave } from "./save-fixture";

describe("save document (Step 14.2)", () => {
  it("validates a fully populated save", () => {
    expect(saveDocumentSchema.safeParse(fullSave()).success).toBe(true);
    expect(CURRENT_SAVE_VERSION).toBe(1);
  });

  it("rejects an invalid save with a readable error naming the field", () => {
    const broken = fullSave() as unknown as { company: { credits: unknown } };
    broken.company.credits = "lots";
    const result = migrateSave(broken);
    expect(result.ok).toBe(false);
    if (!result.ok) {
      expect(result.error).toContain("The save is damaged");
      expect(result.error).toContain("company.credits");
    }
  });

  it("rejects things that aren't saves, and saves from a newer build", () => {
    expect(migrateSave("hello")).toEqual({ ok: false, error: "The save isn't a save document." });
    expect(migrateSave({ company: {} })).toEqual({
      ok: false,
      error: "The save has no valid saveVersion.",
    });
    const future = migrateSave({ ...fullSave(), saveVersion: CURRENT_SAVE_VERSION + 1 });
    expect(future.ok).toBe(false);
    if (!future.ok) expect(future.error).toContain("newer version");
  });

  it("migrates a version-1 save to a valid current save", () => {
    const result = migrateSave(JSON.parse(JSON.stringify(fullSave())));
    expect(result).toEqual({ ok: true, save: fullSave() });
  });

  it("chains migrations in order, one version at a time", () => {
    const seen: number[] = [];
    const migrations: SaveMigration[] = [
      { from: 2, migrate: (s) => (seen.push(2), { ...s, extra: [...(s.extra as number[]), 2] }) },
      { from: 1, migrate: (s) => (seen.push(1), { ...s, extra: [1] }) },
    ];
    const result = applyMigrations({ saveVersion: 1 }, migrations, 3);
    expect(result).toEqual({ ok: true, save: { saveVersion: 3, extra: [1, 2] } });
    expect(seen).toEqual([1, 2]);
    expect(applyMigrations({ saveVersion: 1 }, [], 2)).toEqual({
      ok: false,
      error: "No migration from save version 1.",
    });
  });
});