import { NodeConnectionType } from 'n8n-workflow';
import type {
	INodeTypeBaseDescription,
	IExecuteFunctions,
	INodeExecutionData,
	INodeType,
	INodeTypeDescription,
	IDataObject,
} from 'n8n-workflow';

import { loadSummarizationChain } from 'langchain/chains';
import type { BaseLanguageModel } from 'langchain/dist/base_language';
import type { Document } from 'langchain/document';
import type { TextSplitter } from 'langchain/text_splitter';
import { RecursiveCharacterTextSplitter } from 'langchain/text_splitter';
import { N8nJsonLoader } from '../../../../utils/N8nJsonLoader';
import { N8nBinaryLoader } from '../../../../utils/N8nBinaryLoader';
import { getTemplateNoticeField } from '../../../../utils/sharedFields';
import { REFINE_PROMPT_TEMPLATE, DEFAULT_PROMPT_TEMPLATE } from '../prompt';
import { getChainPromptsArgs } from '../helpers';

function getInputs(parameters: IDataObject) {
	const chunkingMode = parameters?.chunkingMode;
	const operationMode = parameters?.operationMode;
	const inputs = [
		{ displayName: '', type: NodeConnectionType.Main },
		{
			displayName: 'Model',
			maxConnections: 1,
			type: NodeConnectionType.AiLanguageModel,
			required: true,
		},
	];

	if (operationMode === 'documentLoader') {
		inputs.push({
			displayName: 'Document',
			type: NodeConnectionType.AiDocument,
			required: true,
			maxConnections: 1,
		});
		return inputs;
	}

	if (chunkingMode === 'advanced') {
		inputs.push({
			displayName: 'Text Splitter',
			type: NodeConnectionType.AiTextSplitter,
			required: false,
			maxConnections: 1,
		});
		return inputs;
	}
	return inputs;
}

export class ChainSummarizationV2 implements INodeType {
	description: INodeTypeDescription;

	constructor(baseDescription: INodeTypeBaseDescription) {
		this.description = {
			...baseDescription,
			version: [2],
			defaults: {
				name: 'Summarization Chain',
				color: '#909298',
			},
			// eslint-disable-next-line n8n-nodes-base/node-class-description-inputs-wrong-regular-node
			inputs: `={{ ((parameter) => { ${getInputs.toString()}; return getInputs(parameter) })($parameter) }}`,
			outputs: [NodeConnectionType.Main],
			credentials: [],
			properties: [
				getTemplateNoticeField(1951),
				{
					displayName: 'Data to Summarize',
					name: 'operationMode',
					noDataExpression: true,
					type: 'options',
					description: 'How to pass data into the summarization chain',
					default: 'nodeInputJson',
					options: [
						{
							name: 'Use Node Input (JSON)',
							value: 'nodeInputJson',
							description: 'Summarize the JSON data coming into this node from the previous one',
						},
						{
							name: 'Use Node Input (Binary)',
							value: 'nodeInputBinary',
							description: 'Summarize the binary data coming into this node from the previous one',
						},
						{
							name: 'Use Document Loader',
							value: 'documentLoader',
							description: 'Use a loader sub-node with more configuration options',
						},
					],
				},
				{
					displayName: 'Chunking Strategy',
					name: 'chunkingMode',
					noDataExpression: true,
					type: 'options',
					description: 'Chunk splitting strategy',
					default: 'simple',
					options: [
						{
							name: 'Simple (Define Below)',
							value: 'simple',
						},
						{
							name: 'Advanced',
							value: 'advanced',
							description: 'Use a splitter sub-node with more configuration options',
						},
					],
					displayOptions: {
						show: {
							'/operationMode': ['nodeInputJson', 'nodeInputBinary'],
						},
					},
				},
				{
					displayName: 'Characters Per Chunk',
					name: 'chunkSize',
					description:
						'Controls the max size (in terms of number of characters) of the final document chunk',
					type: 'number',
					default: 1000,
					displayOptions: {
						show: {
							'/chunkingMode': ['simple'],
						},
					},
				},
				{
					displayName: 'Chunk Overlap (Characters)',
					name: 'chunkOverlap',
					type: 'number',
					description: 'Specifies how much characters overlap there should be between chunks',
					default: 200,
					displayOptions: {
						show: {
							'/chunkingMode': ['simple'],
						},
					},
				},
				{
					displayName: 'Options',
					name: 'options',
					type: 'collection',
					default: {},
					placeholder: 'Add Option',
					options: [
						{
							displayName: 'Input Data Field Name',
							name: 'binaryDataKey',
							type: 'string',
							default: 'data',
							description:
								'The name of the field in the agent or chain’s input that contains the binary file to be processed',
							displayOptions: {
								show: {
									'/operationMode': ['nodeInputBinary'],
								},
							},
						},
						{
							displayName: 'Summarization Method and Prompts',
							name: 'summarizationMethodAndPrompts',
							type: 'fixedCollection',
							default: {
								values: {
									summarizationMethod: 'map_reduce',
									prompt: DEFAULT_PROMPT_TEMPLATE,
									combineMapPrompt: DEFAULT_PROMPT_TEMPLATE,
								},
							},
							placeholder: 'Add Option',
							typeOptions: {},
							options: [
								{
									name: 'values',
									displayName: 'Values',
									values: [
										{
											displayName: 'Summarization Method',
											name: 'summarizationMethod',
											type: 'options',
											description: 'The type of summarization to run',
											default: 'map_reduce',
											options: [
												{
													name: 'Map Reduce (Recommended)',
													value: 'map_reduce',
													description:
														'Summarize each document (or chunk) individually, then summarize those summaries',
												},
												{
													name: 'Refine',
													value: 'refine',
													description:
														'Summarize the first document (or chunk). Then update that summary based on the next document (or chunk), and repeat.',
												},
												{
													name: 'Stuff',
													value: 'stuff',
													description:
														'Pass all documents (or chunks) at once. Ideal for small datasets.',
												},
											],
										},
										{
											displayName: 'Final Prompt to Combine',
											name: 'combineMapPrompt',
											type: 'string',
											hint: 'The prompt to combine individual summaries',
											displayOptions: {
												hide: {
													'/options.summarizationMethodAndPrompts.values.summarizationMethod': [
														'stuff',
														'refine',
													],
												},
											},
											default: DEFAULT_PROMPT_TEMPLATE,
											typeOptions: {
												rows: 9,
											},
										},
										{
											displayName: 'Individual Summary Prompt',
											name: 'prompt',
											type: 'string',
											default: DEFAULT_PROMPT_TEMPLATE,
											hint: 'The prompt to summarize an individual document (or chunk)',
											displayOptions: {
												hide: {
													'/options.summarizationMethodAndPrompts.values.summarizationMethod': [
														'stuff',
														'refine',
													],
												},
											},
											typeOptions: {
												rows: 9,
											},
										},
										{
											displayName: 'Prompt',
											name: 'prompt',
											type: 'string',
											default: DEFAULT_PROMPT_TEMPLATE,
											displayOptions: {
												hide: {
													'/options.summarizationMethodAndPrompts.values.summarizationMethod': [
														'refine',
														'map_reduce',
													],
												},
											},
											typeOptions: {
												rows: 9,
											},
										},
										{
											displayName: 'Subsequent (Refine) Prompt',
											name: 'refinePrompt',
											type: 'string',
											displayOptions: {
												hide: {
													'/options.summarizationMethodAndPrompts.values.summarizationMethod': [
														'stuff',
														'map_reduce',
													],
												},
											},
											default: REFINE_PROMPT_TEMPLATE,
											hint: 'The prompt to refine the summary based on the next document (or chunk)',
											typeOptions: {
												rows: 9,
											},
										},
										{
											displayName: 'Initial Prompt',
											name: 'refineQuestionPrompt',
											type: 'string',
											displayOptions: {
												hide: {
													'/options.summarizationMethodAndPrompts.values.summarizationMethod': [
														'stuff',
														'map_reduce',
													],
												},
											},
											default: DEFAULT_PROMPT_TEMPLATE,
											hint: 'The prompt for the first document (or chunk)',
											typeOptions: {
												rows: 9,
											},
										},
									],
								},
							],
						},
					],
				},
			],
		};
	}

	async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
		this.logger.verbose('Executing Summarization Chain V2');
		const operationMode = this.getNodeParameter('operationMode', 0, 'nodeInputJson') as
			| 'nodeInputJson'
			| 'nodeInputBinary'
			| 'documentLoader';
		const chunkingMode = this.getNodeParameter('chunkingMode', 0, 'simple') as
			| 'simple'
			| 'advanced';

		const model = (await this.getInputConnectionData(
			NodeConnectionType.AiLanguageModel,
			0,
		)) as BaseLanguageModel;

		const items = this.getInputData();
		const returnData: INodeExecutionData[] = [];

		for (let itemIndex = 0; itemIndex < items.length; itemIndex++) {
			const summarizationMethodAndPrompts = this.getNodeParameter(
				'options.summarizationMethodAndPrompts.values',
				itemIndex,
				{},
			) as {
				prompt?: string;
				refineQuestionPrompt?: string;
				refinePrompt?: string;
				summarizationMethod: 'map_reduce' | 'stuff' | 'refine';
				combineMapPrompt?: string;
			};

			const chainArgs = getChainPromptsArgs(
				summarizationMethodAndPrompts.summarizationMethod ?? 'map_reduce',
				summarizationMethodAndPrompts,
			);

			const chain = loadSummarizationChain(model, chainArgs);
			const item = items[itemIndex];

			let processedDocuments: Document[];

			// Use dedicated document loader input to load documents
			if (operationMode === 'documentLoader') {
				const documentInput = (await this.getInputConnectionData(
					NodeConnectionType.AiDocument,
					0,
				)) as N8nJsonLoader | Array<Document<Record<string, unknown>>>;

				const isN8nLoader =
					documentInput instanceof N8nJsonLoader || documentInput instanceof N8nBinaryLoader;

				processedDocuments = isN8nLoader
					? await documentInput.processItem(item, itemIndex)
					: documentInput;

				const response = await chain.call({
					input_documents: processedDocuments,
				});

				returnData.push({ json: { response } });
			}

			// Take the input and use binary or json loader
			if (['nodeInputJson', 'nodeInputBinary'].includes(operationMode)) {
				let textSplitter: TextSplitter | undefined;

				switch (chunkingMode) {
					// In simple mode we use recursive character splitter with default settings
					case 'simple':
						const chunkSize = this.getNodeParameter('chunkSize', itemIndex, 1000) as number;
						const chunkOverlap = this.getNodeParameter('chunkOverlap', itemIndex, 200) as number;

						textSplitter = new RecursiveCharacterTextSplitter({ chunkOverlap, chunkSize });
						break;

					// In advanced mode user can connect text splitter node so we just retrieve it
					case 'advanced':
						textSplitter = (await this.getInputConnectionData(
							NodeConnectionType.AiTextSplitter,
							0,
						)) as TextSplitter | undefined;
						break;
					default:
						break;
				}

				let processor: N8nJsonLoader | N8nBinaryLoader;
				if (operationMode === 'nodeInputBinary') {
					const binaryDataKey = this.getNodeParameter(
						'options.binaryDataKey',
						itemIndex,
						'data',
					) as string;
					processor = new N8nBinaryLoader(this, 'options.', binaryDataKey, textSplitter);
				} else {
					processor = new N8nJsonLoader(this, 'options.', textSplitter);
				}

				const processedItem = await processor.processItem(item, itemIndex);
				const response = await chain.call({
					input_documents: processedItem,
				});
				returnData.push({ json: { response } });
			}
		}

		return this.prepareOutputData(returnData);
	}
}