co-mono/packages/coding-agent/src/tui/footer.ts

import type { AgentState } from "@mariozechner/pi-agent";
import type { AssistantMessage } from "@mariozechner/pi-ai";
import { visibleWidth } from "@mariozechner/pi-tui";
import chalk from "chalk";

/**
 * Footer component that shows pwd, token stats, and context usage
 */
export class FooterComponent {
	private state: AgentState;

	constructor(state: AgentState) {
		this.state = state;
	}

	updateState(state: AgentState): void {
		this.state = state;
	}

	render(width: number): string[] {
		// Calculate cumulative usage from all assistant messages
		let totalInput = 0;
		let totalOutput = 0;
		let totalCacheRead = 0;
		let totalCacheWrite = 0;
		let totalCost = 0;

		for (const message of this.state.messages) {
			if (message.role === "assistant") {
				const assistantMsg = message as AssistantMessage;
				totalInput += assistantMsg.usage.input;
				totalOutput += assistantMsg.usage.output;
				totalCacheRead += assistantMsg.usage.cacheRead;
				totalCacheWrite += assistantMsg.usage.cacheWrite;
				totalCost += assistantMsg.usage.cost.total;
			}
		}

		// Get last assistant message for context percentage calculation (skip aborted messages)
		const lastAssistantMessage = this.state.messages
			.slice()
			.reverse()
			.find((m) => m.role === "assistant" && m.stopReason !== "aborted") as AssistantMessage | undefined;

		// Calculate context percentage from last message (input + output + cacheRead + cacheWrite)
		const contextTokens = lastAssistantMessage
			? lastAssistantMessage.usage.input +
				lastAssistantMessage.usage.output +
				lastAssistantMessage.usage.cacheRead +
				lastAssistantMessage.usage.cacheWrite
			: 0;
		const contextWindow = this.state.model?.contextWindow || 0;
		const contextPercent = contextWindow > 0 ? ((contextTokens / contextWindow) * 100).toFixed(1) : "0.0";

		// Format token counts (similar to web-ui)
		const formatTokens = (count: number): string => {
			if (count < 1000) return count.toString();
			if (count < 10000) return (count / 1000).toFixed(1) + "k";
			return Math.round(count / 1000) + "k";
		};

		// Replace home directory with ~
		let pwd = process.cwd();
		const home = process.env.HOME || process.env.USERPROFILE;
		if (home && pwd.startsWith(home)) {
			pwd = "~" + pwd.slice(home.length);
		}

		// Truncate path if too long to fit width
		const maxPathLength = Math.max(20, width - 10); // Leave some margin
		if (pwd.length > maxPathLength) {
			const start = pwd.slice(0, Math.floor(maxPathLength / 2) - 2);
			const end = pwd.slice(-(Math.floor(maxPathLength / 2) - 1));
			pwd = `${start}...${end}`;
		}

		// Build stats line
		const statsParts = [];
		if (totalInput) statsParts.push(`↑${formatTokens(totalInput)}`);
		if (totalOutput) statsParts.push(`↓${formatTokens(totalOutput)}`);
		if (totalCacheRead) statsParts.push(`R${formatTokens(totalCacheRead)}`);
		if (totalCacheWrite) statsParts.push(`W${formatTokens(totalCacheWrite)}`);
		if (totalCost) statsParts.push(`$${totalCost.toFixed(3)}`);
		statsParts.push(`${contextPercent}%`);

		const statsLeft = statsParts.join(" ");

		// Add model name on the right side
		let modelName = this.state.model?.id || "no-model";
		const statsLeftWidth = visibleWidth(statsLeft);
		const modelWidth = visibleWidth(modelName);

		// Calculate available space for padding (minimum 2 spaces between stats and model)
		const minPadding = 2;
		const totalNeeded = statsLeftWidth + minPadding + modelWidth;

		let statsLine: string;
		if (totalNeeded <= width) {
			// Both fit - add padding to right-align model
			const padding = " ".repeat(width - statsLeftWidth - modelWidth);
			statsLine = statsLeft + padding + modelName;
		} else {
			// Need to truncate model name
			const availableForModel = width - statsLeftWidth - minPadding;
			if (availableForModel > 3) {
				// Truncate model name to fit
				modelName = modelName.substring(0, availableForModel);
				const padding = " ".repeat(width - statsLeftWidth - visibleWidth(modelName));
				statsLine = statsLeft + padding + modelName;
			} else {
				// Not enough space for model name at all
				statsLine = statsLeft;
			}
		}

		// Return two lines: pwd and stats
		return [chalk.gray(pwd), chalk.gray(statsLine)];
	}
}