import {MemoryCache} from './memory-cache.ts';
import {extractMetadata, Memory, MemoryNode} from './memory.ts';

export function buildMemoryGraph(memories: Memory[] | MemoryCache): MemoryNode[] {
	const mems = memories instanceof MemoryCache ? memories.memories : memories;
	const nameSet = new Set(mems.map(m => m.name));
	const ghosts = new Set<string>();

	const nodes: MemoryNode[] = mems.map(m => {
		const {links, backlinks} = extractMetadata(m.content);
		return {
			name: m.name,
			missing: false,
			links,
			backlinks,
		};
	});

	for (const node of nodes) {
		for (const link of node.links) {
			if (!nameSet.has(link)) ghosts.add(link);
		}
	}

	return [
		...nodes,
		...[...ghosts].map(name => ({
			name,
			missing: true,
			links: [],
			backlinks: nodes
				.filter(n => n.links.includes(name))
				.map(n => n.name),
		}))
	];
}

export function renderMemoryGraph(nodes) {
	if (!nodes.length) return 'No memories yet.';

	const groups = new Map();
	for (const node of nodes) {
		const [prefix, ...rest] = node.name.split('/');
		const group = rest.length ? prefix : 'Root';
		const label = rest.length ? rest.join('/') : node.name;
		if (!groups.has(group)) groups.set(group, []);
		groups.get(group).push({...node, label});
	}

	const ghostCount = nodes.filter(n => n.missing).length;
	const lines = [`Memory Graph (${nodes.length} nodes, ${ghostCount} ghost${ghostCount === 1 ? '' : 's'})`, ''];

	for (const group of [...groups.keys()].sort()) {
		const items = groups.get(group).sort((a, b) => a.label.localeCompare(b.label));
		lines.push(`${group}/`);
		items.forEach((n, i) => {
			const last = i === items.length - 1;
			const branch = last ? '└─' : '├─';
			const pad = last ? '  ' : '│ ';
			const tag = n.missing ? ' (ghost)' : '';
			lines.push(`  ${branch} ${n.label}${tag}`);
			if (n.links.length) lines.push(`  ${pad}   → ${n.links.join(', ')}`);
			if (n.backlinks.length) lines.push(`  ${pad}   ← ${n.backlinks.join(', ')}`);
		});
		lines.push('');
	}

	return lines.join('\n').trimEnd();
}