import assert from "node:assert/strict";
import test from "node:test";
import { estimateFeature, membershipCost, weightedAverageMessages } from "../src/lib/pricing-simulation.ts";

const metric = (value: number | null) => ({ runs: value === null ? 0 : 1, avg: value, p50: value, p95: value, max: value });

test("normalizes a distribution whose weights do not sum to one", () => {
  assert.equal(weightedAverageMessages([{ weight: 1, monthlyMessages: 10 }, { weight: 1, monthlyMessages: 20 }]), 15);
});

test("billingLimit null is explicitly unlimited rather than zero", () => {
  const result = membershipCost([{ weight: 1, monthlyMessages: 10 }], 2, null);
  assert.equal(result.worstCostCny, null);
  assert.equal(result.unlimitedWorstCase, true);
});

test("zero model prices remain a measured zero cost", () => {
  const result = estimateFeature({
    featureKey: "chat.standard",
    creditCost: 10,
    usdToCny: 7,
    model: { modelTier: "standard", inputCostMicrousdPerMillion: 0, outputCostMicrousdPerMillion: 0 },
    usage: { hasData: true, metrics: { costMicrousd: metric(0), inputTokens: metric(100), outputTokens: metric(20), durationMs: metric(1000) } },
  });
  assert.equal(result.costMicrousd, 0);
  assert.equal(result.costCny, 0);
  assert.equal(result.marginPercent, 100);
  assert.equal(result.source, "ledger");
});

test("ledger with no data is not silently converted to zero", () => {
  const result = estimateFeature({
    featureKey: "report.full",
    creditCost: null,
    usdToCny: 7,
    model: null,
    usage: { hasData: false, metrics: { costMicrousd: metric(null), inputTokens: metric(null), outputTokens: metric(null), durationMs: metric(null) } },
  });
  assert.equal(result.costMicrousd, null);
  assert.equal(result.source, "unavailable");
});