import type { QuietToolsConfig } from "./config";

export interface CompactPolicy {
	headLines: number;
	tailLines: number;
	maxChars: number;
}

export interface CompactResult {
	text: string;
	originalChars: number;
	originalLines: number;
	previewChars: number;
	previewLines: number;
}

export function countLines(text: string): number {
	if (text.length === 0) return 0;
	return text.endsWith("\n") ? text.split("\n").length - 1 : text.split("\n").length;
}

export function shouldCompact(text: string, config: QuietToolsConfig): boolean {
	return text.length > config.maxChars || countLines(text) > config.maxLines;
}

export function policyFor(config: QuietToolsConfig, isError: boolean): CompactPolicy {
	return isError
		? { headLines: config.errorHeadLines, tailLines: config.errorTailLines, maxChars: config.maxChars }
		: { headLines: config.headLines, tailLines: config.tailLines, maxChars: config.maxChars };
}

export function compactText(text: string, policy: CompactPolicy): CompactResult {
	const originalChars = text.length;
	const originalLines = countLines(text);
	const lines = text.split("\n");
	let preview: string;

	if (lines.length <= policy.headLines + policy.tailLines) {
		if (text.length <= policy.maxChars) {
			preview = text;
		} else {
			const headChars = Math.max(1, Math.floor(policy.maxChars * 0.6));
			const tailChars = Math.max(1, policy.maxChars - headChars);
			preview = `${text.slice(0, headChars)}\n\n... omitted ${text.length - headChars - tailChars} characters ...\n\n${text.slice(-tailChars)}`;
		}
	} else {
		const head = lines.slice(0, policy.headLines);
		const tail = lines.slice(-policy.tailLines);
		const omitted = lines.length - head.length - tail.length;
		preview = [...head, ``, `... omitted ${omitted} lines ...`, ``, ...tail].join("\n");
	}

	return {
		text: preview,
		originalChars,
		originalLines,
		previewChars: preview.length,
		previewLines: countLines(preview),
	};
}