Refactor out file helpers into fs.ts

src/utils/cost.ts

@@ -0,0 +1,24 @@
+import { ModelInfo } from "../shared/api"
+
+export function calculateApiCost(
+	modelInfo: ModelInfo,
+	inputTokens: number,
+	outputTokens: number,
+	cacheCreationInputTokens?: number,
+	cacheReadInputTokens?: number
+): number {
+	const modelCacheWritesPrice = modelInfo.cacheWritesPrice
+	let cacheWritesCost = 0
+	if (cacheCreationInputTokens && modelCacheWritesPrice) {
+		cacheWritesCost = (modelCacheWritesPrice / 1_000_000) * cacheCreationInputTokens
+	}
+	const modelCacheReadsPrice = modelInfo.cacheReadsPrice
+	let cacheReadsCost = 0
+	if (cacheReadInputTokens && modelCacheReadsPrice) {
+		cacheReadsCost = (modelCacheReadsPrice / 1_000_000) * cacheReadInputTokens
+	}
+	const baseInputCost = (modelInfo.inputPrice / 1_000_000) * inputTokens
+	const outputCost = (modelInfo.outputPrice / 1_000_000) * outputTokens
+	const totalCost = cacheWritesCost + cacheReadsCost + baseInputCost + outputCost
+	return totalCost
+}