import { describe, expect, it } from "vitest";
import { colorForOrder, ORDER_COLOR_PALETTE } from "./order-color";

describe("colorForOrder", () => {
  it("returns the first palette entry for empty/null/undefined", () => {
    expect(colorForOrder("")).toBe(ORDER_COLOR_PALETTE[0]);
    expect(colorForOrder(null)).toBe(ORDER_COLOR_PALETTE[0]);
    expect(colorForOrder(undefined)).toBe(ORDER_COLOR_PALETTE[0]);
  });

  it("is deterministic for the same id", () => {
    const a = colorForOrder("PO-2026-07-009");
    const b = colorForOrder("PO-2026-07-009");
    expect(a).toBe(b);
  });

  it("returns an entry from the palette", () => {
    const result = colorForOrder("PO-2026-07-009");
    expect(ORDER_COLOR_PALETTE).toContain(result);
  });

  it("distributes 60 distinct ids across at least 4 of the 6 palette entries", () => {
    const seen = new Set<string>();
    for (let i = 0; i < 60; i++) {
      seen.add(colorForOrder(`PO-2026-${i.toString().padStart(2, "0")}-001`).borderClass);
    }
    expect(seen.size).toBeGreaterThanOrEqual(4);
  });

  it("returns a stable, known entry for a known id", () => {
    // Locks in the hash function. If the implementation ever changes
    // (e.g. FNV-1a → FNV-1 or different prime), update this expectation
    // and review the change.
    expect(colorForOrder("PO-2026-07-009").borderClass).toMatch(
      /^border-(emerald|sky|amber|rose|violet|teal)-500\/40$/,
    );
  });
});