import { ClineMessage } from "./ExtensionMessage"

interface ApiMetrics {
	totalTokensIn: number
	totalTokensOut: number
	totalCacheWrites?: number
	totalCacheReads?: number
	totalCost: number
	contextTokens: number // Total tokens in conversation (last message's tokensIn + tokensOut)
}

/**
 * Calculates API metrics from an array of ClineMessages.
 *
 * This function processes 'api_req_started' messages that have been combined with their
 * corresponding 'api_req_finished' messages by the combineApiRequests function.
 * It extracts and sums up the tokensIn, tokensOut, cacheWrites, cacheReads, and cost from these messages.
 *
 * @param messages - An array of ClineMessage objects to process.
 * @returns An ApiMetrics object containing totalTokensIn, totalTokensOut, totalCacheWrites, totalCacheReads, and totalCost.
 *
 * @example
 * const messages = [
 *   { type: "say", say: "api_req_started", text: '{"request":"GET /api/data","tokensIn":10,"tokensOut":20,"cost":0.005}', ts: 1000 }
 * ];
 * const { totalTokensIn, totalTokensOut, totalCost } = getApiMetrics(messages);
 * // Result: { totalTokensIn: 10, totalTokensOut: 20, totalCost: 0.005 }
 */
export function getApiMetrics(messages: ClineMessage[]): ApiMetrics {
	const result: ApiMetrics = {
		totalTokensIn: 0,
		totalTokensOut: 0,
		totalCacheWrites: undefined,
		totalCacheReads: undefined,
		totalCost: 0,
		contextTokens: 0,
	}

	// Find the last api_req_started message that has valid token information
	const lastApiReq = [...messages].reverse().find((message) => {
		if (message.type === "say" && message.say === "api_req_started" && message.text) {
			try {
				const parsedData = JSON.parse(message.text)
				return typeof parsedData.tokensIn === "number" && typeof parsedData.tokensOut === "number"
			} catch {
				return false
			}
		}
		return false
	})

	messages.forEach((message) => {
		if (message.type === "say" && message.say === "api_req_started" && message.text) {
			try {
				const parsedData = JSON.parse(message.text)
				const { tokensIn, tokensOut, cacheWrites, cacheReads, cost } = parsedData

				if (typeof tokensIn === "number") {
					result.totalTokensIn += tokensIn
				}
				if (typeof tokensOut === "number") {
					result.totalTokensOut += tokensOut
				}
				if (typeof cacheWrites === "number") {
					result.totalCacheWrites = (result.totalCacheWrites ?? 0) + cacheWrites
				}
				if (typeof cacheReads === "number") {
					result.totalCacheReads = (result.totalCacheReads ?? 0) + cacheReads
				}
				if (typeof cost === "number") {
					result.totalCost += cost
				}

				// If this is the last api request, use its tokens for context size
				if (message === lastApiReq) {
					// Only update context tokens if both input and output tokens are non-zero
					if (tokensIn > 0 && tokensOut > 0) {
						result.contextTokens = tokensIn + tokensOut
					}
				}
			} catch (error) {
				console.error("Error parsing JSON:", error)
			}
		}
	})

	return result
}