import * as React from 'react';

import omit from 'lodash/omit';
import pick from 'lodash/pick';
import set from 'lodash/set';
import unset from 'lodash/unset';
import { v4 as uuidv4 } from 'uuid';

import { useCalculateLineItemTaxAndTotals } from './use-calculate-line-item-tax-and-totals';
import { useLineItemData } from './use-line-item-data';
import { updatePosDataMeta } from './utils';
import { useLocalMutation } from '../../hooks/mutations/use-local-mutation';
import { useCurrentOrder } from '../contexts/current-order';

type LineItem = import('@wcpos/database').OrderDocument['line_items'][number];

/**
 *
 */
export const useUpdateLineItem = () => {
	const { currentOrder } = useCurrentOrder();
	const { localPatch } = useLocalMutation();
	const { calculateLineItemTaxesAndTotals } = useCalculateLineItemTaxAndTotals();
	const { getLineItemData } = useLineItemData();

	/**
	 * Applies updates to a line item based on provided changes.
	 */
	const applyChangesToLineItem = React.useCallback(
		(lineItem: LineItem, changes: Partial<LineItem>): LineItem => {
			const { price, regular_price, tax_status } = getLineItemData(lineItem);

			const newData = {
				...{ price, regular_price, tax_status },
				...pick(changes, ['price', 'regular_price', 'tax_status']),
			};

			let updatedItem = { ...lineItem };
			updatedItem = updatePosDataMeta(updatedItem, newData);

			const remainingChanges = omit(changes, ['price', 'regular_price', 'tax_status']);

			for (const key of Object.keys(remainingChanges)) {
				// Special case for nested changes, only meta_data at the moment
				const nestedKey = key.split('.');
				if (nestedKey.length === 1) {
					(updatedItem as any)[key] = remainingChanges[key];
				} else {
					set(updatedItem, nestedKey, remainingChanges[key]);
				}
			}

			return calculateLineItemTaxesAndTotals(updatedItem);
		},
		[calculateLineItemTaxesAndTotals, getLineItemData]
	);

	/**
	 * Update line item
	 *
	 * @TODO - what if more than one property is changed at once?
	 */
	const updateLineItem = React.useCallback(
		async (uuid: string, changes: Partial<LineItem>) => {
			const order = currentOrder.getLatest();
			const json = order.toMutableJSON();
			let updated = false;

			const updatedLineItems = json.line_items?.map((lineItem) => {
				if (
					updated ||
					!lineItem.meta_data?.some((m) => m.key === '_woocommerce_pos_uuid' && m.value === uuid)
				) {
					return lineItem;
				}

				const updatedItem = applyChangesToLineItem(lineItem, changes);
				updated = true;
				return updatedItem;
			});

			// if we have updated a line item, patch the order
			if (updated && updatedLineItems) {
				return localPatch({ document: order, data: { line_items: updatedLineItems } });
			}
		},
		[applyChangesToLineItem, currentOrder, localPatch]
	);

	/**
	 *
	 */
	const splitLineItem = React.useCallback(
		async (uuid: string) => {
			const order = currentOrder.getLatest();
			const lineItemIndex = order.line_items.findIndex((item) =>
				item.meta_data.some((meta) => meta.key === '_woocommerce_pos_uuid' && meta.value === uuid)
			);

			if (lineItemIndex === -1) {
				console.error('Line item not found');
				return;
			}

			const lineItemToSplit = order.line_items[lineItemIndex];

			if (lineItemToSplit.quantity <= 1) {
				console.error('Line item quantity must be greater than 1');
				return;
			}

			const lineItemToCopy = calculateLineItemTaxesAndTotals({ ...lineItemToSplit, quantity: 1 });
			const quantity = Math.floor(lineItemToSplit.quantity);
			const rawRemainder = lineItemToSplit.quantity - quantity;
			const remainder = parseFloat(rawRemainder.toFixed(6));
			const newLineItems = [{ ...lineItemToCopy }];
			unset(lineItemToCopy, 'id'); // remove id so it is treated as a new item

			for (let i = 1; i < quantity; i++) {
				const newItem = {
					...lineItemToCopy,
					meta_data: lineItemToCopy.meta_data.map((meta) =>
						meta.key === '_woocommerce_pos_uuid' ? { ...meta, value: uuidv4() } : meta
					),
				};
				newLineItems.push(newItem);
			}

			if (remainder > 0) {
				const remainderLineItem = calculateLineItemTaxesAndTotals({
					...lineItemToCopy,
					quantity: remainder,
				});
				const newItem = {
					...remainderLineItem,
					quantity: remainder,
					meta_data: remainderLineItem.meta_data.map((meta) =>
						meta.key === '_woocommerce_pos_uuid' ? { ...meta, value: uuidv4() } : meta
					),
				};
				newLineItems.push(newItem);
			}

			// Replace the original item with the new items in the order
			const updatedLineItems = [
				...order.line_items.slice(0, lineItemIndex),
				...newLineItems,
				...order.line_items.slice(lineItemIndex + 1),
			];

			return localPatch({ document: order, data: { line_items: updatedLineItems } });
		},
		[calculateLineItemTaxesAndTotals, currentOrder, localPatch]
	);

	return { updateLineItem, splitLineItem };
};