import * as path from "node:path";
import type { ImpactCascadeResult } from "./types.js";

const MAX_SYMBOLS = 5;

function displayList(items: string[], maxFiles: number, map?: (item: string) => string): string[] {
	return items.slice(0, maxFiles).map((item) => (map ? map(item) : item));
}

export function formatImpactCascade(
	result: ImpactCascadeResult,
	maxFiles = 4,
): string | undefined {
	if (
		result.changedSymbols.length === 0 &&
		result.neighborFiles.length === 0 &&
		result.riskFlags.length === 0
	) {
		return undefined;
	}

	const lines: string[] = ["🕸️ Impact cascade from edited file:"];
	if (result.changedSymbols.length > 0) {
		const shown = result.changedSymbols.slice(0, MAX_SYMBOLS);
		const suffix =
			result.changedSymbols.length > shown.length
				? ` (+${result.changedSymbols.length - shown.length} more)`
				: "";
		lines.push(`Changed symbols: ${shown.join(", ")}${suffix}`);
	}
	if (result.directImporters.length > 0) {
		lines.push(
			`Direct importers: ${displayList(result.directImporters, maxFiles, (item) => path.basename(item)).join(", ")}`,
		);
	}
	if (result.directCallers.length > 0) {
		lines.push(
			`Direct callers: ${displayList(result.directCallers, maxFiles, (item) => path.basename(item)).join(", ")}`,
		);
	}
	if (result.neighborFiles.length > 0) {
		lines.push(
			`Check next: ${displayList(result.neighborFiles, maxFiles, (item) => path.basename(item)).join(", ")}`,
		);
	}
	if (result.riskFlags.length > 0) {
		lines.push(`Risk: ${result.riskFlags.join(", ")}`);
	}

	return lines.join("\n");
}