import { IDataObject, INodeExecutionData, jsonParse } from 'n8n-workflow';
import { difference, get, intersection, isEmpty, isEqual, isNull, omit, set, union } from 'lodash';

type PairToMatch = {
	field1: string;
	field2: string;
};

type EntryMatches = {
	entry: INodeExecutionData;
	matches: INodeExecutionData[];
};

type CompareFunction = <T, U>(a: T, b: U) => boolean;

function compareItems(
	item1: INodeExecutionData,
	item2: INodeExecutionData,
	fieldsToMatch: PairToMatch[],
	resolve: string,
	skipFields: string[],
	isEntriesEqual: CompareFunction,
) {
	const keys = {} as IDataObject;
	fieldsToMatch.forEach((field) => {
		keys[field.field1] = item1.json[field.field1];
	});

	const keys1 = Object.keys(item1.json);
	const keys2 = Object.keys(item2.json);
	const intersectionKeys = intersection(keys1, keys2);

	const same = intersectionKeys.reduce((acc, key) => {
		if (isEntriesEqual(item1.json[key], item2.json[key])) {
			acc[key] = item1.json[key];
		}
		return acc;
	}, {} as IDataObject);

	const sameKeys = Object.keys(same);
	const allUniqueKeys = union(keys1, keys2);
	const differentKeys = difference(allUniqueKeys, sameKeys);

	const different: IDataObject = {};
	const skipped: IDataObject = {};

	differentKeys.forEach((key) => {
		switch (resolve) {
			case 'preferInput1':
				different[key] = item1.json[key] ?? null;
				break;
			case 'preferInput2':
				different[key] = item2.json[key] ?? null;
				break;
			default:
				const input1 = item1.json[key] ?? null;
				const input2 = item2.json[key] ?? null;
				if (skipFields.includes(key)) {
					skipped[key] = { input1, input2 };
				} else {
					different[key] = { input1, input2 };
				}
		}
	});

	return {
		json: { keys, same, different, ...(!isEmpty(skipped) && { skipped }) },
	} as INodeExecutionData;
}

function combineItems(
	item1: INodeExecutionData,
	item2: INodeExecutionData,
	prefer: string,
	except: string,
	disableDotNotation: boolean,
) {
	let exceptFields: string[];
	const [entry, match] = prefer === 'input1' ? [item1, item2] : [item2, item1];

	if (except && Array.isArray(except) && except.length) {
		exceptFields = except;
	} else {
		exceptFields = except ? except.split(',').map((field) => field.trim()) : [];
	}

	exceptFields.forEach((field) => {
		entry.json[field] = match.json[field];
		if (disableDotNotation) {
			entry.json[field] = match.json[field];
		} else {
			const value = get(match.json, field) ?? null;
			set(entry, `json.${field}`, value);
		}
	});

	return entry;
}

function findAllMatches(
	data: INodeExecutionData[],
	lookup: IDataObject,
	disableDotNotation: boolean,
	isEntriesEqual: CompareFunction,
) {
	return data.reduce((acc, entry2, i) => {
		if (entry2 === undefined) return acc;

		for (const key of Object.keys(lookup)) {
			const excpectedValue = lookup[key];
			let entry2FieldValue;

			if (disableDotNotation) {
				entry2FieldValue = entry2.json[key];
			} else {
				entry2FieldValue = get(entry2.json, key);
			}

			if (!isEntriesEqual(excpectedValue, entry2FieldValue)) {
				return acc;
			}
		}

		return acc.concat({
			entry: entry2,
			index: i,
		});
	}, [] as IDataObject[]);
}

function findFirstMatch(
	data: INodeExecutionData[],
	lookup: IDataObject,
	disableDotNotation: boolean,
	isEntriesEqual: CompareFunction,
) {
	const index = data.findIndex((entry2) => {
		if (entry2 === undefined) return false;

		for (const key of Object.keys(lookup)) {
			const excpectedValue = lookup[key];
			let entry2FieldValue;

			if (disableDotNotation) {
				entry2FieldValue = entry2.json[key];
			} else {
				entry2FieldValue = get(entry2.json, key);
			}

			if (!isEntriesEqual(excpectedValue, entry2FieldValue)) {
				return false;
			}
		}

		return true;
	});
	if (index === -1) return [];

	return [{ entry: data[index], index }];
}

const parseStringAndCompareToObject = (str: string, arr: IDataObject) => {
	try {
		const parsedArray = jsonParse(str);
		return isEqual(parsedArray, arr);
	} catch (error) {
		return false;
	}
};

function isFalsy<T>(value: T) {
	if (isNull(value)) return true;
	if (typeof value === 'string' && value === '') return true;
	if (Array.isArray(value) && value.length === 0) return true;
	return false;
}

const fuzzyCompare =
	(options: IDataObject) =>
	<T, U>(item1: T, item2: U) => {
		//Fuzzy compare is disabled, so we do strict comparison
		if (!options.fuzzyCompare) return isEqual(item1, item2);

		//Both types are the same, so we do strict comparison
		if (!isNull(item1) && !isNull(item2) && typeof item1 === typeof item2) {
			return isEqual(item1, item2);
		}

		//Null, empty strings, empty arrays all treated as the same
		if (isFalsy(item1) && isFalsy(item2)) return true;

		//When a field is missing in one branch and isFalsy() in another, treat them as matching
		if (isFalsy(item1) && item2 === undefined) return true;
		if (item1 === undefined && isFalsy(item2)) return true;

		//Compare numbers and strings representing that number
		if (typeof item1 === 'number' && typeof item2 === 'string') {
			return item1.toString() === item2;
		}

		if (typeof item1 === 'string' && typeof item2 === 'number') {
			return item1 === item2.toString();
		}

		//Compare objects/arrays and their stringified version
		if (!isNull(item1) && typeof item1 === 'object' && typeof item2 === 'string') {
			return parseStringAndCompareToObject(item2, item1 as IDataObject);
		}

		if (!isNull(item2) && typeof item1 === 'string' && typeof item2 === 'object') {
			return parseStringAndCompareToObject(item1, item2 as IDataObject);
		}

		//Compare booleans and strings representing the boolean (’true’, ‘True’, ‘TRUE’)
		if (typeof item1 === 'boolean' && typeof item2 === 'string') {
			if (item1 === true && item2.toLocaleLowerCase() === 'true') return true;
			if (item1 === false && item2.toLocaleLowerCase() === 'false') return true;
		}

		if (typeof item2 === 'boolean' && typeof item1 === 'string') {
			if (item2 === true && item1.toLocaleLowerCase() === 'true') return true;
			if (item2 === false && item1.toLocaleLowerCase() === 'false') return true;
		}

		//Compare booleans and the numbers/string 0 and 1
		if (typeof item1 === 'boolean' && typeof item2 === 'number') {
			if (item1 === true && item2 === 1) return true;
			if (item1 === false && item2 === 0) return true;
		}

		if (typeof item2 === 'boolean' && typeof item1 === 'number') {
			if (item2 === true && item1 === 1) return true;
			if (item2 === false && item1 === 0) return true;
		}

		if (typeof item1 === 'boolean' && typeof item2 === 'string') {
			if (item1 === true && item2 === '1') return true;
			if (item1 === false && item2 === '0') return true;
		}

		if (typeof item2 === 'boolean' && typeof item1 === 'string') {
			if (item2 === true && item1 === '1') return true;
			if (item2 === false && item1 === '0') return true;
		}

		return isEqual(item1, item2);
	};

export function findMatches(
	input1: INodeExecutionData[],
	input2: INodeExecutionData[],
	fieldsToMatch: PairToMatch[],
	options: IDataObject,
) {
	const data1 = [...input1];
	const data2 = [...input2];

	const isEntriesEqual = fuzzyCompare(options);
	const disableDotNotation = (options.disableDotNotation as boolean) || false;
	const multipleMatches = (options.multipleMatches as string) || 'first';
	const skipFields = ((options.skipFields as string) || '').split(',').map((field) => field.trim());

	const filteredData = {
		matched: [] as EntryMatches[],
		unmatched1: [] as INodeExecutionData[],
		unmatched2: [] as INodeExecutionData[],
	};

	const matchedInInput2 = new Set<number>();

	matchesLoop: for (const entry of data1) {
		const lookup: IDataObject = {};

		fieldsToMatch.forEach((matchCase) => {
			let valueToCompare;
			if (disableDotNotation) {
				valueToCompare = entry.json[matchCase.field1];
			} else {
				valueToCompare = get(entry.json, matchCase.field1);
			}
			lookup[matchCase.field2] = valueToCompare;
		});

		for (const fieldValue of Object.values(lookup)) {
			if (fieldValue === undefined) {
				filteredData.unmatched1.push(entry);
				continue matchesLoop;
			}
		}

		const foundedMatches =
			multipleMatches === 'all'
				? findAllMatches(data2, lookup, disableDotNotation, isEntriesEqual)
				: findFirstMatch(data2, lookup, disableDotNotation, isEntriesEqual);

		const matches = foundedMatches.map((match) => match.entry) as INodeExecutionData[];
		foundedMatches.map((match) => matchedInInput2.add(match.index as number));

		if (matches.length) {
			filteredData.matched.push({ entry, matches });
		} else {
			filteredData.unmatched1.push(entry);
		}
	}

	data2.forEach((entry, i) => {
		if (!matchedInInput2.has(i)) {
			filteredData.unmatched2.push(entry);
		}
	});

	const same: INodeExecutionData[] = [];
	const different: INodeExecutionData[] = [];

	filteredData.matched.forEach((entryMatches) => {
		let entryCopy: INodeExecutionData | undefined;

		entryMatches.matches.forEach((match) => {
			let entryFromInput1 = entryMatches.entry.json;
			let entryFromInput2 = match.json;

			if (skipFields.length) {
				entryFromInput1 = omit(entryFromInput1, skipFields);
				entryFromInput2 = omit(entryFromInput2, skipFields);
			}

			let isItemsEqual = true;
			if (options.fuzzyCompare) {
				for (const key of Object.keys(entryFromInput1)) {
					if (!isEntriesEqual(entryFromInput1[key], entryFromInput2[key])) {
						isItemsEqual = false;
						break;
					}
				}
			} else {
				isItemsEqual = isEntriesEqual(entryFromInput1, entryFromInput2);
			}

			if (isItemsEqual) {
				if (!entryCopy) {
					if (options.fuzzyCompare && options.resolve === 'preferInput2') {
						entryCopy = match;
					} else {
						entryCopy = entryMatches.entry;
					}
				}
			} else {
				switch (options.resolve) {
					case 'preferInput1':
						different.push(entryMatches.entry);
						break;
					case 'preferInput2':
						different.push(match);
						break;
					case 'mix':
						different.push(
							combineItems(
								entryMatches.entry,
								match,
								options.preferWhenMix as string,
								options.exceptWhenMix as string,
								disableDotNotation,
							),
						);
						break;
					default:
						different.push(
							compareItems(
								entryMatches.entry,
								match,
								fieldsToMatch,
								options.resolve as string,
								skipFields,
								isEntriesEqual,
							),
						);
				}
			}
		});
		if (!isEmpty(entryCopy)) {
			same.push(entryCopy);
		}
	});

	return [filteredData.unmatched1, same, different, filteredData.unmatched2];
}

export function checkMatchFieldsInput(data: IDataObject[]) {
	if (data.length === 1 && data[0].field1 === '' && data[0].field2 === '') {
		throw new Error(
			'You need to define at least one pair of fields in "Fields to Match" to match on',
		);
	}
	for (const [index, pair] of data.entries()) {
		if (pair.field1 === '' || pair.field2 === '') {
			throw new Error(
				`You need to define both fields in "Fields to Match" for pair ${index + 1},
				 field 1 = '${pair.field1}'
				 field 2 = '${pair.field2}'`,
			);
		}
	}
	return data as PairToMatch[];
}

export function checkInput(
	input: INodeExecutionData[],
	fields: string[],
	disableDotNotation: boolean,
	inputLabel: string,
) {
	if (input.some((item) => isEmpty(item.json))) {
		input = input.filter((item) => !isEmpty(item.json));
	}
	if (input.length === 0) {
		return input;
	}
	for (const field of fields) {
		const isPresent = (input || []).some((entry) => {
			if (disableDotNotation) {
				return entry.json.hasOwnProperty(field);
			}
			return get(entry.json, field, undefined) !== undefined;
		});
		if (!isPresent) {
			throw new Error(`Field '${field}' is not present in any of items in '${inputLabel}'`);
		}
	}
	return input;
}