using ClosedXML.Excel;
using RhSolutions.SkuParser.Models;

namespace RhSolutions.SkuParser.Services;

public class ExcelParser : ISkuParser
{
	public IEnumerable<ProductQuantity> ParseProducts(IFormFile file)
	{
		using XLWorkbook workbook = new(file.OpenReadStream());
		IXLWorksheet ws = workbook.Worksheet(1);

		var leftTop = ws.FirstCellUsed()?.Address;
		var rightBottom = ws.LastCellUsed()?.Address;
		if (new object?[] { leftTop, rightBottom }.Any(x => x == null))
		{
			throw new ArgumentException($"Таблица пуста: {file.FileName}");
		}

		var lookupRange = ws.Range(leftTop, rightBottom).RangeUsed();
		var columns = lookupRange.Columns();

		var skuColumnQuantity = columns
			.Select(column => new
			{
				Column = column,
				Products = column.CellsUsed()
					.Select(cell => !cell.HasFormula && Product.TryParse(cell.Value.ToString(), out Product? p) ? p : null)
			})
			.Select(c => new { c.Column, SkuCount = c.Products.Count(p => p != null) })
			.Aggregate((l, r) => l.SkuCount > r.SkuCount ? l : r);
		var skuColumn = skuColumnQuantity.SkuCount > 0 ? skuColumnQuantity.Column : null;

		if (skuColumn == null)
		{
			throw new ArgumentException($"Столбец с артикулом не определен: {file.FileName}");
		}

		var quantityColumn = lookupRange.Columns().Skip(skuColumn.ColumnNumber())
			.Select(column => new
			{
				Column = column,
				IsColumnWithNumbers = column.CellsUsed()
					.Count(cell => cell.Value.IsNumber == true) > column.CellsUsed().Count() / 4
			})
			.First(x => x.IsColumnWithNumbers)
			.Column;

		if (quantityColumn == null)
		{
			throw new ArgumentException($"Столбец с количеством не определен: {file.FileName}");
		}

		List<ProductQuantity> result = new();
		var rows = quantityColumn.CellsUsed().Select(x => x.Address.RowNumber);
		
		foreach (var row in rows)
		{
			var quantity = quantityColumn.Cell(row).Value;
			var sku = skuColumn.Cell(row).Value;
			
			if (quantity.IsNumber 
				&& Product.TryParse(sku.ToString(), out Product? p))
			{
				ProductQuantity pq = new()
				{
					Product = p!,
					Quantity = quantity.GetNumber()
				};
				result.Add(pq);
			}
		}

		return result;
	}
}