import get from 'lodash/get';
import isEqual from 'lodash/isEqual';
import lt from 'lodash/lt';
import pick from 'lodash/pick';
import { NodeOperationError } from 'n8n-workflow';
import type { IExecuteFunctions, INodeExecutionData, INodeProperties } from 'n8n-workflow';

import { compareItems, flattenKeys, updateDisplayOptions } from '@utils/utilities';

import { prepareFieldsArray, typeToNumber } from '../../helpers/utils';
import { disableDotNotationBoolean } from '../common.descriptions';

const properties: INodeProperties[] = [
	{
		displayName: 'Compare',
		name: 'compare',
		type: 'options',
		options: [
			{
				name: 'All Fields',
				value: 'allFields',
			},
			{
				name: 'All Fields Except',
				value: 'allFieldsExcept',
			},
			{
				name: 'Selected Fields',
				value: 'selectedFields',
			},
		],
		default: 'allFields',
		description: 'The fields of the input items to compare to see if they are the same',
	},
	{
		displayName: 'Fields To Exclude',
		name: 'fieldsToExclude',
		type: 'string',
		placeholder: 'e.g. email, name',
		requiresDataPath: 'multiple',
		description: 'Fields in the input to exclude from the comparison',
		default: '',
		displayOptions: {
			show: {
				compare: ['allFieldsExcept'],
			},
		},
	},
	{
		displayName: 'Fields To Compare',
		name: 'fieldsToCompare',
		type: 'string',
		placeholder: 'e.g. email, name',
		requiresDataPath: 'multiple',
		description: 'Fields in the input to add to the comparison',
		default: '',
		displayOptions: {
			show: {
				compare: ['selectedFields'],
			},
		},
	},
	{
		displayName: 'Options',
		name: 'options',
		type: 'collection',
		placeholder: 'Add Field',
		default: {},
		displayOptions: {
			show: {
				compare: ['allFieldsExcept', 'selectedFields'],
			},
		},
		options: [
			disableDotNotationBoolean,
			{
				displayName: 'Remove Other Fields',
				name: 'removeOtherFields',
				type: 'boolean',
				default: false,
				description:
					'Whether to remove any fields that are not being compared. If disabled, will keep the values from the first of the duplicates.',
			},
		],
	},
];

const displayOptions = {
	show: {
		resource: ['itemList'],
		operation: ['removeDuplicates'],
	},
};

export const description = updateDisplayOptions(displayOptions, properties);

export async function execute(
	this: IExecuteFunctions,
	items: INodeExecutionData[],
): Promise<INodeExecutionData[]> {
	const compare = this.getNodeParameter('compare', 0) as string;
	const disableDotNotation = this.getNodeParameter(
		'options.disableDotNotation',
		0,
		false,
	) as boolean;
	const removeOtherFields = this.getNodeParameter('options.removeOtherFields', 0, false) as boolean;
	const nodeVersion = this.getNode().typeVersion;

	let keys = disableDotNotation
		? Object.keys(items[0].json)
		: Object.keys(flattenKeys(items[0].json));

	for (const item of items) {
		for (const key of disableDotNotation
			? Object.keys(item.json)
			: Object.keys(flattenKeys(item.json))) {
			if (!keys.includes(key)) {
				keys.push(key);
			}
		}
	}

	if (compare === 'allFieldsExcept') {
		const fieldsToExclude = prepareFieldsArray(
			this.getNodeParameter('fieldsToExclude', 0, '') as string,
			'Fields To Exclude',
		);

		if (!fieldsToExclude.length) {
			throw new NodeOperationError(
				this.getNode(),
				'No fields specified. Please add a field to exclude from comparison',
			);
		}
		if (!disableDotNotation) {
			keys = Object.keys(flattenKeys(items[0].json));
		}
		keys = keys.filter((key) => !fieldsToExclude.includes(key));
	}
	if (compare === 'selectedFields') {
		const fieldsToCompare = prepareFieldsArray(
			this.getNodeParameter('fieldsToCompare', 0, '') as string,
			'Fields To Compare',
		);
		if (!fieldsToCompare.length) {
			throw new NodeOperationError(
				this.getNode(),
				'No fields specified. Please add a field to compare on',
			);
		}
		if (!disableDotNotation) {
			keys = Object.keys(flattenKeys(items[0].json));
		}
		keys = fieldsToCompare.map((key) => key.trim());
	}

	// This solution is O(nlogn)
	// add original index to the items
	const newItems = items.map(
		(item, index) =>
			({
				json: { ...item.json, __INDEX: index },
				pairedItem: { item: index },
			}) as INodeExecutionData,
	);

	//sort items using the compare keys
	newItems.sort((a, b) => {
		let result = 0;

		for (const key of keys) {
			const a_value = disableDotNotation ? a.json[key] : get(a.json, key);
			const b_value = disableDotNotation ? b.json[key] : get(b.json, key);

			if (nodeVersion >= 3.1) {
				const a_value_tnum = typeToNumber(a_value);
				const b_value_tnum = typeToNumber(b_value);
				if (a_value_tnum !== b_value_tnum) {
					result = a_value_tnum - b_value_tnum;
					break;
				}
			}

			const equal = isEqual(a_value, b_value);

			if (!equal) {
				const lessThan = lt(a_value, b_value);
				result = lessThan ? -1 : 1;
				break;
			}
		}
		return result;
	});

	for (const key of keys) {
		let type: any = undefined;
		for (const item of newItems) {
			if (key === '') {
				throw new NodeOperationError(this.getNode(), 'Name of field to compare is blank');
			}
			const value = !disableDotNotation ? get(item.json, key) : item.json[key];
			if (value === undefined && disableDotNotation && key.includes('.')) {
				throw new NodeOperationError(
					this.getNode(),
					`'${key}' field is missing from some input items`,
					{
						description:
							"If you're trying to use a nested field, make sure you turn off 'disable dot notation' in the node options",
					},
				);
			} else if (value === undefined) {
				throw new NodeOperationError(
					this.getNode(),
					`'${key}' field is missing from some input items`,
				);
			}
			if (nodeVersion < 3.1 && type !== undefined && value !== undefined && type !== typeof value) {
				throw new NodeOperationError(this.getNode(), `'${key}' isn't always the same type`, {
					description: 'The type of this field varies between items',
				});
			} else {
				type = typeof value;
			}
		}
	}

	// collect the original indexes of items to be removed
	const removedIndexes: number[] = [];
	let temp = newItems[0];
	for (let index = 1; index < newItems.length; index++) {
		if (compareItems(newItems[index], temp, keys, disableDotNotation)) {
			removedIndexes.push(newItems[index].json.__INDEX as unknown as number);
		} else {
			temp = newItems[index];
		}
	}

	let returnData = items.filter((_, index) => !removedIndexes.includes(index));

	if (removeOtherFields) {
		returnData = returnData.map((item, index) => ({
			json: pick(item.json, ...keys),
			pairedItem: { item: index },
		}));
	}

	return returnData;
}