import { expect, test } from "bun:test";
import { defineEntitlements, defineMeter, definePacks } from "../src/index.ts";

test("resolves fallback entitlements and features", async () => {
  const entitlements = defineEntitlements({
    plans: () => [
      { code: "free", name: "Free", features: [], allowance: 10 },
      { code: "pro", name: "Pro", features: ["schedule"], allowance: 100 },
    ],
    subscriptionFor: async () => "pro",
    fallback: "free",
  });
  expect(await entitlements.enabled("u1", "schedule")).toBe(true);
  expect(await entitlements.allowance("u1")).toBe(100);
});

test("packs are immutable and selected only by code", () => {
  const packs = definePacks([{ code: "small", units: 100, label: "Small" }]);
  expect(packs.get("constructor")).toBeUndefined();
  expect(packs.get("small")?.units).toBe(100);
});

test("meter distinguishes refusals from storage faults", async () => {
  const meter = defineMeter({
    store: {
      balance: async () => 5,
      reserve: async (_subject, units) => units <= 5,
      write: async () => {
        throw new Error("offline");
      },
    },
  });
  expect(await meter.reserve("u1", 6, "send")).toEqual({
    ok: false,
    reason: "insufficient balance",
  });
  expect(await meter.grant("u1", 5, "plan")).toEqual({
    ok: false,
    reason: "offline",
    fault: true,
  });
});

test("adjust accepts signed non-zero amounts while other additions stay positive", async () => {
  const writes: number[] = [];
  const meter = defineMeter({
    store: {
      balance: async () => 0,
      reserve: async () => true,
      write: async (_subject, units) => {
        writes.push(units);
      },
    },
  });
  expect(await meter.adjust("u1", -25, "correction")).toEqual({ ok: true });
  expect(await meter.adjust("u1", 10, "correction")).toEqual({ ok: true });
  expect(await meter.adjust("u1", 0, "correction")).toEqual({
    ok: false,
    reason: "units adjustment must be a non-zero whole number",
  });
  expect(await meter.grant("u1", -1, "invalid")).toEqual({
    ok: false,
    reason: "units must be a positive whole number",
  });
  expect(writes).toEqual([-25, 10]);
});