import { json } from '@sveltejs/kit';
import { execSync } from 'child_process';

export async function GET({ url }) {
	try {
		const limit = url.searchParams.get('limit') || '50';
		const output = execSync(`hermes sessions list --limit ${limit} 2>/dev/null`, {
			timeout: 5000,
			encoding: 'utf-8'
		});

		const sessions = parseSessions(output);
		return json(sessions);
	} catch {
		return json([]);
	}
}

/**
 * Parse the plain-text output of `hermes sessions list`.
 *
 * Expected format (column-aligned with spaces):
 *   Title                            Preview                                  Last Active   ID
 *   ──────────────────────────────────────────────────────────────────────────────────────────────────────────────
 *   —                                create a way to connect to hermes via    2m ago        20260522_045714_48480d
 *   Self-Improvement and Token Eff   find me good self improvement skills.    45m ago       20260522_045210_2381af
 *
 * The ID column is always the last column and matches: YYYYMMDD_HHMMSS_[hex]
 * The "Last Active" column is second-to-last.
 */
function parseSessions(output: string) {
	const lines = output.split('\n').filter((l) => l.trim());
	const sessions: { id: string; title: string; preview: string; timestamp: number }[] = [];

	for (const line of lines) {
		// Skip header and separator lines
		if (line.startsWith('Title') || line.startsWith('──')) continue;

		// Match the session ID at the end: YYYYMMDD_HHMMSS_[hex]
		const idMatch = line.match(/(\d{8}_\d{6}_[0-9a-f]+)\s*$/);
		if (!idMatch) continue;

		const id = idMatch[1];
		const beforeId = line.slice(0, line.lastIndexOf(id)).trimEnd();

		// Match the "Last Active" column (relative time like "2m ago", "1h ago", "3d ago")
		const timeMatch = beforeId.match(/(\d+[smhdw]\s+ago)\s*$/);
		let timestamp = Date.now();
		let beforeTime = beforeId;
		if (timeMatch) {
			const timeStr = timeMatch[1];
			beforeTime = beforeId.slice(0, beforeId.lastIndexOf(timeStr)).trimEnd();
			timestamp = parseRelativeTime(timeStr);
		}

		// Everything before the time column is Title + Preview
		// Title is typically up to ~32 chars, Preview fills the rest
		// We'll split on the first long gap of spaces
		const parts = beforeTime.split(/\s{3,}/);
		let title = parts[0] || 'Untitled';
		let preview = parts.slice(1).join(' ') || '';

		// Clean up title (replace dash-only titles)
		if (/^[—\-]+$/.test(title)) title = 'Untitled';

		sessions.push({ id, title, preview, timestamp });
	}

	return sessions;
}

function parseRelativeTime(str: string): number {
	const now = Date.now();
	const match = str.match(/^(\d+)\s*([smhdw])\s+ago$/);
	if (!match) return now;
	const value = parseInt(match[1]);
	const unit = match[2];
	const multipliers: Record<string, number> = {
		s: 1000,
		m: 60 * 1000,
		h: 60 * 60 * 1000,
		d: 24 * 60 * 60 * 1000,
		w: 7 * 24 * 60 * 60 * 1000
	};
	return now - value * (multipliers[unit] || 0);
}