import { CloudWatchClient, PutMetricDataCommand, StandardUnit, type MetricDatum } from '@aws-sdk/client-cloudwatch'; import { calculateCost, DEFAULT_COST_DECIMAL_PLACES, getNormalizedPricing, parseUsage, resolveModelKey } from '@portfolio/chat-contract';

const ENABLED = process.env.OPENAI_COST_METRICS_ENABLED === 'true'; const NAMESPACE = process.env.OPENAI_COST_METRIC_NAMESPACE || 'PortfolioChat/OpenAI'; const METRIC_NAME = process.env.OPENAI_COST_METRIC_NAME || 'EstimatedCost'; const MODEL_DIMENSION_NAME = 'Model';

let cwClient: CloudWatchClient | null = null; let loggedPublishFailure = false;

function getCloudWatchClient(): CloudWatchClient { cwClient ??= new CloudWatchClient({}); return cwClient; }

function isRecord(value: unknown): value is Record<string, unknown> { return typeof value === 'object' && value !== null; }

export async function recordOpenAICostFromUsage(payload: unknown) { if (!ENABLED) return;

const payloadRecord = isRecord(payload) ? payload : null; const model = typeof payloadRecord?.model === 'string' ? payloadRecord.model : undefined; const usageCandidate = payloadRecord?.usage ?? payload;

const parsed = parseUsage(usageCandidate); if (!parsed) return;

const resolvedModelKey = resolveModelKey(model); const pricing = getNormalizedPricing(resolvedModelKey ?? model); if (!pricing) { console.warn(No pricing found for model "${model ?? 'unknown'}". Skipping cost metric publish until MODEL_PRICING is updated.); return; }

const cost = calculateCost(parsed, pricing);

if (!Number.isFinite(cost) || cost <= 0) { return; }

try { const client = getCloudWatchClient(); const value = Number(cost.toFixed(DEFAULT_COST_DECIMAL_PLACES)); const metricData: MetricDatum[] = [ { MetricName: METRIC_NAME, Value: value, Unit: StandardUnit.None, }, ];

const modelDimensionValue = resolvedModelKey ?? model ?? 'unknown'; if (modelDimensionValue) { metricData.push({ MetricName: METRIC_NAME, Value: value, Unit: StandardUnit.None, Dimensions: [ { Name: MODEL_DIMENSION_NAME, Value: modelDimensionValue, }, ], }); }

await client.send(
  new PutMetricDataCommand({
    Namespace: NAMESPACE,
    MetricData: metricData,
  })
);

} catch (error) { if (!loggedPublishFailure) { loggedPublishFailure = true; console.warn('Failed to publish OpenAI cost metric (suppressing future logs):', error); } } }