import test from 'node:test';
import assert from 'node:assert/strict';
import {
  enrichTokenStateForBilling,
  estimateAccumulatedCostUsd,
  loadCostEstimateConfig,
  pickSessionAccumulatedCost,
  resolveBillingTokenState,
} from './billing-token-state.mjs';
import { computeDeltaCostCents } from './billing.mjs';

test('pickSessionAccumulatedCost reads snake_case and camelCase', () => {
  assert.equal(pickSessionAccumulatedCost({ accumulated_cost: 0.12 }), 0.12);
  assert.equal(pickSessionAccumulatedCost({ accumulatedCost: 0.34 }), 0.34);
  assert.equal(pickSessionAccumulatedCost({}), null);
});

test('estimateAccumulatedCostUsd uses DeepSeek-ish defaults', () => {
  const estimate = estimateAccumulatedCostUsd(
    { accumulatedInputTokens: 1_000_000, accumulatedOutputTokens: 10_000 },
    { enabled: true, inputUsdPer1M: 0.27, outputUsdPer1M: 1.1 },
  );
  assert.equal(estimate, 0.281);
});

test('enrichTokenStateForBilling prefers upstream cost over estimate', () => {
  const enriched = enrichTokenStateForBilling(
    { accumulatedInputTokens: 1000, accumulatedOutputTokens: 100, accumulatedCost: 0.05 },
    {},
    { H5_USE_BACKEND_COST: '1' },
  );
  assert.equal(enriched.accumulatedCost, 0.05);
});

test('enrichTokenStateForBilling fills session cost when Finish omits it', () => {
  const enriched = enrichTokenStateForBilling(
    { accumulatedInputTokens: 1000, accumulatedOutputTokens: 100 },
    { sessionCost: { accumulated_cost: 0.08 } },
    { H5_USE_BACKEND_COST: '1' },
  );
  assert.equal(enriched.accumulatedCost, 0.08);
});

test('enrichTokenStateForBilling estimates when cost mode enabled and upstream missing', () => {
  const enriched = enrichTokenStateForBilling(
    { accumulatedInputTokens: 1_000_000, accumulatedOutputTokens: 0 },
    {},
    {
      H5_USE_BACKEND_COST: '1',
      H5_COST_ESTIMATE_FROM_TOKENS: '1',
      H5_COST_ESTIMATE_INPUT_USD_PER_1M: '0.27',
      H5_COST_ESTIMATE_OUTPUT_USD_PER_1M: '1.1',
    },
  );
  assert.equal(enriched.accumulatedCost, 0.27);
});

test('loadCostEstimateConfig disables estimate when cost mode off', () => {
  const cfg = loadCostEstimateConfig({ H5_USE_BACKEND_COST: '0' });
  assert.equal(cfg.enabled, false);
});

test('resolveBillingTokenState fetches session before estimating', async () => {
  let fetched = false;
  const resolved = await resolveBillingTokenState(
    { accumulatedInputTokens: 1000, accumulatedOutputTokens: 100 },
    {
      sessionId: '20260710_11',
      fetchSession: async (sessionId) => {
        fetched = true;
        assert.equal(sessionId, '20260710_11');
        return { accumulated_cost: 0.42 };
      },
    },
    { H5_USE_BACKEND_COST: '1' },
  );
  assert.equal(fetched, true);
  assert.equal(resolved.accumulatedCost, 0.42);
});

test('enriched cost drives 1.2x billing instead of flat fallback', () => {
  const previous = { lastInputTokens: 224853, lastOutputTokens: 6685, lastAccumulatedCost: null };
  const tokenState = enrichTokenStateForBilling(
    { accumulatedInputTokens: 2908661, accumulatedOutputTokens: 15349 },
    {},
    {
      H5_USE_BACKEND_COST: '1',
      H5_COST_ESTIMATE_FROM_TOKENS: '1',
      H5_COST_ESTIMATE_INPUT_USD_PER_1M: '0.27',
      H5_COST_ESTIMATE_OUTPUT_USD_PER_1M: '1.1',
    },
  );
  const previousCost = estimateAccumulatedCostUsd(
    { accumulatedInputTokens: 224853, accumulatedOutputTokens: 6685 },
    loadCostEstimateConfig({
      H5_USE_BACKEND_COST: '1',
      H5_COST_ESTIMATE_FROM_TOKENS: '1',
      H5_COST_ESTIMATE_INPUT_USD_PER_1M: '0.27',
      H5_COST_ESTIMATE_OUTPUT_USD_PER_1M: '1.1',
    }),
  );
  const costCents = computeDeltaCostCents(
    { ...previous, lastAccumulatedCost: previousCost },
    tokenState,
    {
      useBackendCost: true,
      usdCnyRate: 7.2,
      marginMultiplier: 1.2,
      inputCentsPer1k: 2,
      outputCentsPer1k: 6,
      minBillCents: 1,
    },
  );
  assert.ok(costCents < 1000, `expected cost-mode charge under ¥10, got ${costCents} cents`);
});