/**
 * Model cost display extension - shows cost info in status bar.
 *
 * Format: "$X.XX (Y.YY) in" where Y.YY is cache write cost if present.
 *
 * Usage: pi -e ./model-cost.ts
 */

import type {
	ExtensionAPI,
	ModelSelectEvent,
	UIContext,
} from "@earendil-works/pi-coding-agent";

export default function (pi: ExtensionAPI) {
	const modelSelectHandler = async (
		event: ModelSelectEvent,
		ctx: UIContext,
	) => {
		const { model } = event;

		// Get cost data from model config
		const cost = getModelCost(model);

		if (cost) {
			ctx.ui.setStatus("model", cost);
		} else {
			ctx.ui.setStatus("model", "");
		}
	};

	pi.on("model_select", modelSelectHandler);
}

function getModelCost(model: any): string {
	if (!model?.cost) return "";

	const { input, output, cacheRead, cacheWrite } = model.cost;

	// Only show if there's actual cost data
	const hasCost =
		input !== 0 || output !== 0 || cacheRead !== 0 || cacheWrite !== 0;
	if (!hasCost) return "";

	// Format: "$X.XX (Y.YY) in"
	const parts: string[] = [];

	if (input !== 0) {
		const cachePrefix = cacheRead > 0 ? ` (↙${cacheRead}) ` : "";
		parts.push(`$${input}${cachePrefix}in`);
	}

	if (output !== 0) {
		const cachePrefix = cacheWrite > 0 ? ` (↗${cacheWrite}) ` : "";
		parts.push(`$${output}${cachePrefix}out`);
	}

	if (parts.length === 0) return "";

	return parts.join(" / ");
}