/**
 * Consolidated nodes tool — list, search, describe, type-definition, suggested, explore-resources.
 */
import { Tool } from '@n8n/agents';
import {
	AI_CONNECTION_TYPES,
	NodeSearchEngine,
	categoryList,
	suggestedNodesData,
	type SearchableNodeType,
} from '@n8n/ai-utilities/node-catalog';
import { z } from 'zod';

import { sanitizeInputSchema } from '../agent/sanitize-mcp-schemas';
import type { InstanceAiContext } from '../types';
import { pickPreferredChatModelNode } from './nodes/preferred-chat-model';
import { buildCredentialMap } from './workflows/resolve-credentials';

// ── Action schemas ──────────────────────────────────────────────────────────

const NODE_TYPE_ID_DESCRIPTION = 'Node type ID, e.g. "n8n-nodes-base.httpRequest"';
const METHOD_NAME_DESCRIPTION =
	'Exact method name from the node\'s @searchListMethod/@loadOptionsMethod annotation — read it via `action: "type-definition"` first, never guess.';
const METHOD_TYPE_DESCRIPTION =
	'"listSearch" for @searchListMethod (supports filter/pagination); "loadOptions" for @loadOptionsMethod. Match the annotation.';
const CURRENT_NODE_PARAMETERS_DESCRIPTION =
	'Current node parameters for dependent lookups — e.g. sheetsSearch needs documentId { __rl: true, mode: "id", value: "<spreadsheetId>" }. Check displayOptions in the type definition.';
const NODE_TYPES_ARRAY_DESCRIPTION =
	'Node type IDs for node-level lookups (max 5). For split nodes (e.g. Slack, Gmail, Google Sheets), pass the object form WITH resource/operation (or mode) discriminators when you know them — a bare string errors with the resource→operations index for resource/operation nodes, and returns all mode variants for mode-split nodes.';

const listAction = z.object({
	action: z.literal('list').describe('List available node types'),
	query: z
		.string()
		.optional()
		.describe('Search query to filter by name or description (e.g. "slack", "http")'),
	gatewayCreditsOnly: z
		.boolean()
		.optional()
		.describe(
			'When true, return only nodes supported by Gateway credits (each carries an `aiGateway` field with minVersion/operations). Use to answer "which nodes support Gateway credits?".',
		),
});

const searchAction = z.object({
	action: z
		.literal('search')
		.describe(
			'Search node types by name or AI connection type. Use for service-specific discovery — short service names like "Gmail" or "Slack", not full task phrases.',
		),
	query: z
		.string()
		.optional()
		.describe('Search query to filter by name or description (e.g. "slack", "http")'),
	connectionType: z
		.enum(AI_CONNECTION_TYPES)
		.optional()
		.describe('Filter results by AI sub-node connection type.'),
	limit: z
		.number()
		.optional()
		.default(10)
		.describe('Maximum number of results to return (default: 10)'),
});

const describeAction = z.object({
	action: z.literal('describe').describe('Get detailed description of a node type'),
	nodeType: z.string().describe(NODE_TYPE_ID_DESCRIPTION),
});

const nodeRequestObjectSchema = z.object({
	nodeType: z.string().describe(NODE_TYPE_ID_DESCRIPTION),
	version: z.string().optional().describe('Version, e.g. "4.3" or "v43"'),
	resource: z.string().optional().describe('Resource discriminator for split nodes'),
	operation: z.string().optional().describe('Operation discriminator for split nodes'),
	mode: z.string().optional().describe('Mode discriminator for split nodes'),
});

export const nodeRequestSchema = z.union([
	z.string().describe(NODE_TYPE_ID_DESCRIPTION),
	nodeRequestObjectSchema,
]);

export type NodeTypeRequest = z.infer<typeof nodeRequestSchema>;

const typeDefinitionAction = z.object({
	action: z
		.literal('type-definition')
		.describe(
			'Get TypeScript type definitions for nodes — exact parameter names, enum values, credential types, display conditions, and `@builderHint` annotations.',
		),
	nodeTypes: z.array(nodeRequestSchema).min(1).max(5).describe(NODE_TYPES_ARRAY_DESCRIPTION),
});

const suggestedAction = z.object({
	action: z
		.literal('suggested')
		.describe(
			'Get curated node recommendations by category. Call first when the workflow fits a known category.',
		),
	categories: z
		.array(z.string())
		.min(1)
		.max(3)
		.describe(`Workflow technique categories: ${categoryList.join(', ')}`),
});

const exploreResourcesAction = z.object({
	action: z
		.literal('explore-resources')
		.describe("Query live credential-backed resource lists for a node's RLC parameters"),
	nodeType: z.string().describe(NODE_TYPE_ID_DESCRIPTION),
	version: z.number().describe('Node version, e.g. 4.7'),
	methodName: z.string().describe(METHOD_NAME_DESCRIPTION),
	methodType: z.enum(['listSearch', 'loadOptions']).describe(METHOD_TYPE_DESCRIPTION),
	credentialType: z.string().describe('Credential type key, e.g. "googleSheetsOAuth2Api"'),
	credentialId: z.string().describe('Credential ID from list-credentials'),
	filter: z.string().optional().describe('Search/filter text to narrow results'),
	paginationToken: z
		.string()
		.optional()
		.describe('Pagination token from a previous call to get more results'),
	currentNodeParameters: z
		.record(z.unknown())
		.optional()
		.describe(CURRENT_NODE_PARAMETERS_DESCRIPTION),
});

const fullInputSchema = sanitizeInputSchema(
	z.discriminatedUnion('action', [
		listAction,
		searchAction,
		describeAction,
		typeDefinitionAction,
		suggestedAction,
		exploreResourcesAction,
	]),
);

type FullInput = z.infer<typeof fullInputSchema>;

interface SearchEngineCache {
	nodeTypes?: SearchableNodeType[];
	nodeCount?: number;
	engine?: NodeSearchEngine;
}

// ── Handlers ────────────────────────────────────────────────────────────────

async function handleList(
	context: InstanceAiContext,
	input: Extract<FullInput, { action: 'list' }>,
) {
	const nodes = await context.nodeService.listAvailable({
		query: input.query,
		gatewayCreditsOnly: input.gatewayCreditsOnly,
	});
	return { nodes };
}

async function handleSearch(
	context: InstanceAiContext,
	input: Extract<FullInput, { action: 'search' }>,
	cache: SearchEngineCache,
) {
	const nodeTypes = await context.nodeService.listSearchable();
	let engine = cache.engine;
	if (!engine || cache.nodeTypes !== nodeTypes || cache.nodeCount !== nodeTypes.length) {
		cache.nodeTypes = nodeTypes;
		cache.nodeCount = nodeTypes.length;
		engine = new NodeSearchEngine(nodeTypes);
		cache.engine = engine;
	}

	let results;
	if (input.connectionType) {
		results = engine.searchByConnectionType(input.connectionType, input.limit, input.query);
	} else if (input.query) {
		results = engine.searchByName(input.query, input.limit);
	} else {
		return { results: [], totalResults: 0 };
	}

	// Enrich results with discriminator info (resources/operations) when available
	const enriched = await Promise.all(
		results.map(async (r) => {
			if (!context.nodeService.listDiscriminators) return r;
			const disc = await context.nodeService.listDiscriminators(r.name);
			if (!disc) return r;
			return { ...r, discriminators: disc };
		}),
	);

	// Steer the language model subnode toward a provider the user already has a
	// credential for, so the builder stops defaulting to OpenAI when only another
	// provider is configured. Only hits the credential list when relevant.
	const hasLanguageModelRequirement = enriched.some((r) =>
		r.subnodeRequirements?.some((req) => req.connectionType === 'ai_languageModel'),
	);
	if (!hasLanguageModelRequirement) {
		return { results: enriched, totalResults: enriched.length };
	}

	const credentialMap = await buildCredentialMap(context.credentialService);
	const suggestedModelNode = pickPreferredChatModelNode(credentialMap.keys());
	if (!suggestedModelNode) {
		return { results: enriched, totalResults: enriched.length };
	}

	const withSuggestions = enriched.map((r) =>
		r.subnodeRequirements
			? {
					...r,
					subnodeRequirements: r.subnodeRequirements.map((req) =>
						req.connectionType === 'ai_languageModel'
							? { ...req, suggestedNode: suggestedModelNode }
							: req,
					),
				}
			: r,
	);

	return {
		results: withSuggestions,
		totalResults: withSuggestions.length,
	};
}

async function handleDescribe(
	context: InstanceAiContext,
	input: Extract<FullInput, { action: 'describe' }>,
) {
	try {
		const desc = await context.nodeService.getDescription(input.nodeType);
		return { found: true, ...desc };
	} catch {
		return {
			found: false,
			error: `Node type "${input.nodeType}" not found. Use the search action to discover available node types.`,
			name: input.nodeType,
			displayName: '',
			description: '',
			properties: [],
			inputs: [],
			outputs: [],
		};
	}
}

/**
 * Resolve TypeScript type definitions for a validated list of node requests.
 * Used by the consolidated `nodes` tool's `type-definition` action.
 */
async function resolveNodeTypeDefinitions(
	context: InstanceAiContext,
	nodeTypes: NodeTypeRequest[],
) {
	if (!context.nodeService.getNodeTypeDefinition) {
		return {
			definitions: nodeTypes.map((req) => ({
				nodeType: typeof req === 'string' ? req : req.nodeType,
				content: '',
				error: 'Node type definitions are not available.',
			})),
		};
	}

	const definitions = await Promise.all(
		nodeTypes.map(async (req) => {
			const nodeType = typeof req === 'string' ? req : req.nodeType;
			const options = typeof req === 'string' ? undefined : req;

			const result = await context.nodeService.getNodeTypeDefinition!(nodeType, options);

			if (!result) {
				return {
					nodeType,
					content: '',
					error: `No type definition found for '${nodeType}'.`,
				};
			}

			if (result.error) {
				return {
					nodeType,
					content: '',
					error: result.error,
				};
			}

			return {
				nodeType,
				version: result.version,
				content: result.content,
				...(result.builderHint ? { builderHint: result.builderHint } : {}),
				...(result.deprecated ? { deprecated: true } : {}),
			};
		}),
	);

	return { definitions };
}

async function handleTypeDefinition(
	context: InstanceAiContext,
	input: Extract<FullInput, { action: 'type-definition' }>,
) {
	// Native tool validation uses the flattened top-level schema (required for
	// Anthropic's `type: "object"` constraint), which makes every variant field
	// optional. Re-assert the variant contract so missing/invalid inputs return
	// a structured error the model can self-correct from, instead of crashing
	// downstream on `input.nodeTypes.map`.
	const parsed = typeDefinitionAction.safeParse(input);
	if (!parsed.success) {
		return {
			definitions: [],
			error: parsed.error.issues
				.map((i) => `${i.path.join('.') || '<root>'}: ${i.message}`)
				.join('; '),
		};
	}

	return await resolveNodeTypeDefinitions(context, parsed.data.nodeTypes);
}

// eslint-disable-next-line @typescript-eslint/require-await
async function handleSuggested(input: Extract<FullInput, { action: 'suggested' }>) {
	const results: Array<{
		category: string;
		description: string;
		patternHint: string;
		suggestedNodes: Array<{ name: string; note?: string }>;
	}> = [];
	const unknownCategories: string[] = [];

	for (const cat of input.categories) {
		const data = suggestedNodesData[cat];
		if (data) {
			results.push({
				category: cat,
				description: data.description,
				patternHint: data.patternHint,
				suggestedNodes: data.nodes,
			});
		} else {
			unknownCategories.push(cat);
		}
	}

	return { results, unknownCategories };
}

async function handleExploreResources(
	context: InstanceAiContext,
	input: Extract<FullInput, { action: 'explore-resources' }>,
) {
	if (!context.nodeService.exploreResources) {
		return {
			results: [],
			error: 'Resource exploration is not available.',
		};
	}

	try {
		const result = await context.nodeService.exploreResources(input);
		return {
			results: result.results,
			paginationToken: result.paginationToken,
			...(result.builderHint ? { builderHint: result.builderHint } : {}),
		};
	} catch (error) {
		return {
			results: [],
			error: error instanceof Error ? error.message : String(error),
		};
	}
}

// ── Tool factory ────────────────────────────────────────────────────────────

export function createNodesTool(
	context: InstanceAiContext,
	surface: 'full' | 'orchestrator' = 'full',
) {
	const searchEngineCache: SearchEngineCache = {};

	if (surface === 'orchestrator') {
		const orchestratorExploreAction = z.object({
			action: z
				.literal('explore-resources')
				.describe("Query real resources for a node's RLC parameters"),
			nodeType: z.string().describe('Node type ID, e.g. "n8n-nodes-base.httpRequest"'),
			version: z.number().describe('Node version, e.g. 4.7'),
			methodName: z.string().describe(METHOD_NAME_DESCRIPTION),
			methodType: z.enum(['listSearch', 'loadOptions']).describe(METHOD_TYPE_DESCRIPTION),
			credentialType: z.string().describe('Credential type key, e.g. "googleSheetsOAuth2Api"'),
			credentialId: z.string().describe('Credential ID from list-credentials'),
			filter: z.string().optional().describe('Search/filter text to narrow results'),
			paginationToken: z
				.string()
				.optional()
				.describe('Pagination token from a previous call to get more results'),
			currentNodeParameters: z
				.record(z.unknown())
				.optional()
				.describe(CURRENT_NODE_PARAMETERS_DESCRIPTION),
		});

		const orchestratorInputSchema = sanitizeInputSchema(
			z.discriminatedUnion('action', [typeDefinitionAction, orchestratorExploreAction]),
		);

		type OrchestratorInput = z.infer<typeof orchestratorInputSchema>;

		return new Tool('nodes')
			.description(
				"Read node type definitions or query real resources for a node's RLC parameters " +
					'(e.g. list Google Sheets, OpenAI models, Slack channels). Use `type-definition` ' +
					'first to read `@searchListMethod` / `@loadOptionsMethod` annotations, then ' +
					'`explore-resources` with the real method name and a credential.',
			)
			.input(orchestratorInputSchema)
			.handler(async (input: OrchestratorInput) => {
				switch (input.action) {
					case 'type-definition':
						return await handleTypeDefinition(context, input);
					case 'explore-resources':
						return await handleExploreResources(context, input);
				}
			})
			.build();
	}

	return new Tool('nodes')
		.description(
			'Work with n8n node types. Use `suggested` for known workflow categories, `search` for service-specific discovery, `type-definition` before configuring nodes, and `explore-resources` for live credential-backed lists.',
		)
		.input(fullInputSchema)
		.handler(async (input: FullInput) => {
			switch (input.action) {
				case 'list':
					return await handleList(context, input);
				case 'search':
					return await handleSearch(context, input, searchEngineCache);
				case 'describe':
					return await handleDescribe(context, input);
				case 'type-definition':
					return await handleTypeDefinition(context, input);
				case 'suggested':
					return await handleSuggested(input);
				case 'explore-resources':
					return await handleExploreResources(context, input);
			}
		})
		.build();
}