import { describe, it, expect } from "vitest";
import { firstFileName, fileNames, hasFile } from "./file-fields";

/**
 * Regression guard for the "No signed copy on file" bug.
 *
 * `delivery_notes.signed_copy` is a PB file field with `maxSelect: 1`.
 * We WRITE it as an array (`signed_copy: [file]`), but PocketBase
 * RETURNS a bare STRING when exactly one file is attached. Verified
 * against the live record on DN26100403 after a real upload:
 *
 *     typeof        : string
 *     Array.isArray : false
 *     value         : "image_ar52u2hjfq.jpg"
 *     value[0]      : "i"
 *
 * Every read site that assumed `string[]` therefore failed, and none
 * of them threw: `Array.isArray(x) ? x[0] : null` returns null, so the
 * app reported "No signed copy on file" for a note that had just been
 * signed, scanned and uploaded. `x[0]` in a tooltip returned the first
 * LETTER of the filename. One site called `.join(", ")` on the string,
 * which does throw.
 *
 * These tests pin the real shapes PB returns, so the string case can
 * never be quietly dropped again.
 */

describe("firstFileName", () => {
  it("reads a bare string — the shape PB actually returns for one file", () => {
    expect(firstFileName("image_ar52u2hjfq.jpg")).toBe("image_ar52u2hjfq.jpg");
  });

  it("reads an array, for the shape we WRITE or for several files", () => {
    expect(firstFileName(["a.jpg"])).toBe("a.jpg");
    expect(firstFileName(["a.jpg", "b.jpg"])).toBe("a.jpg");
  });

  it("skips empty entries rather than returning ''", () => {
    expect(firstFileName(["", "b.jpg"])).toBe("b.jpg");
    expect(firstFileName("")).toBeNull();
  });

  it("is null for nothing attached", () => {
    expect(firstFileName(null)).toBeNull();
    expect(firstFileName(undefined)).toBeNull();
    expect(firstFileName([])).toBeNull();
  });

  it("does NOT index into the string — the bug this replaces", () => {
    // `"image_x.jpg"[0]` is "i". Any read site doing that was showing
    // the first character of the filename as though it were the file.
    const value: string = "image_ar52u2hjfq.jpg";
    expect(value[0]).toBe("i");
    expect(firstFileName(value)).toBe("image_ar52u2hjfq.jpg");
  });
});

describe("fileNames", () => {
  it("normalises both shapes to an array", () => {
    expect(fileNames("a.jpg")).toEqual(["a.jpg"]);
    expect(fileNames(["a.jpg", "b.jpg"])).toEqual(["a.jpg", "b.jpg"]);
    expect(fileNames(null)).toEqual([]);
    expect(fileNames([])).toEqual([]);
  });

  it("would have thrown on the string form before — .join on a string", () => {
    // This is the deliveries page crash: `dn.signed_copy.join(", ")`.
    const value = "image_ar52u2hjfq.jpg" as unknown as string[];
    expect(() => value.join(", ")).toThrow();
    expect(fileNames("image_ar52u2hjfq.jpg").join(", ")).toBe("image_ar52u2hjfq.jpg");
  });
});

describe("hasFile", () => {
  it("is truthy for either shape", () => {
    expect(hasFile("a.jpg")).toBe(true);
    expect(hasFile(["a.jpg"])).toBe(true);
  });

  it("is falsy when empty", () => {
    expect(hasFile(null)).toBe(false);
    expect(hasFile("")).toBe(false);
    expect(hasFile([])).toBe(false);
    expect(hasFile(undefined)).toBe(false);
  });
});