import type { WorkflowJSON } from '@n8n/workflow-sdk';

import { collectStrings, extractJsonColumnRefs, nodeHasName, unique } from './column-ref-utils';

export interface AgentInputColumns {
	agentNodeName: string;
	inputColumns: string[];
}

const FALLBACK_COLUMN = 'input';

export function analyzeAgentInputColumns(
	workflow: WorkflowJSON,
	agentNodeName: string,
): AgentInputColumns {
	const node = (workflow.nodes ?? []).find((n) => nodeHasName(n) && n.name === agentNodeName);
	if (!node) {
		throw new Error(`Agent node "${agentNodeName}" not found in workflow`);
	}

	const refs = unique(
		collectStrings(node.parameters).flatMap((text) => extractJsonColumnRefs(text)),
	);

	if (refs.length === 0) {
		return { agentNodeName, inputColumns: [FALLBACK_COLUMN] };
	}
	return { agentNodeName, inputColumns: refs };
}