import { describe, it, expect } from "vitest";
import { describeProgress } from "./downloadProgress";

const base = {
  status: "downloading" as const,
  progress: 0,
  bytesDownloaded: 0,
  fileSize: undefined as number | undefined,
  fileSizeEstimated: false,
};

// TRACES: UR-071 | DR-290 | UT-254
describe("describeProgress", () => {
  it("shows an indeterminate bar, not 0%, when the size is unknown", () => {
    // A transcode has no Content-Length and (before the estimate) no total:
    // 200 MB in, the bar read "0%". That is not progress information.
    const view = describeProgress({ ...base, bytesDownloaded: 200 * 1024 * 1024 });
    expect(view.kind).toBe("indeterminate");
    expect(view.percent).toBeNull();
    expect(view.label).toBe("200.0 MB");
  });

  it("marks an estimated total as approximate", () => {
    const view = describeProgress({
      ...base,
      progress: 0.42,
      bytesDownloaded: 420,
      fileSize: 1000,
      fileSizeEstimated: true,
    });
    expect(view.kind).toBe("estimated");
    expect(view.percent).toBe(42);
    expect(view.percentLabel).toBe("~42%");
    expect(view.label).toBe("420 B / ~1000 B");
  });

  it("reports an exact total plainly", () => {
    const view = describeProgress({
      ...base,
      progress: 0.5,
      bytesDownloaded: 512,
      fileSize: 1024,
    });
    expect(view.kind).toBe("exact");
    expect(view.percent).toBe(50);
    expect(view.percentLabel).toBe("50%");
    expect(view.label).toBe("512 B / 1.0 KB");
  });

  it("keeps a paused download's bar where it stopped", () => {
    const view = describeProgress({
      ...base,
      status: "paused",
      progress: 0.25,
      bytesDownloaded: 256,
      fileSize: 1024,
    });
    expect(view.kind).toBe("exact");
    expect(view.percent).toBe(25);
  });
});