using System.IO;

namespace RhSolutions.Services;

public class GuessReader : IReader
{
    private readonly Application _application;
    private ProgressBar _progressBar;

    public GuessReader(Application application)
    {
        _application = application;
    }

    public Dictionary<Product, double> ReadProducts(Range range)
    {
        _progressBar = new("Ищу колонку с артикулами...", range.Columns.Count);
        int? productColumnIndex = null;

        for (int column = 1; column < range.Columns.Count + 1; column++)
        {
            _progressBar.Update();
            if (IsProductColumn(range.Columns[column]))
            {
                productColumnIndex = column;
                break;
            }
        }

        if (productColumnIndex == null)
        {
            throw new ArgumentException("Колонка с артикулом не определена");
        }

        int? amountColumnIndex = null;
        int currentIndex = productColumnIndex.Value + 1;
        _progressBar = new("Ищу колонку с количеством...", range.Columns.Count);

        while (currentIndex > 0)
        {
            _progressBar.Update();
            if (currentIndex > range.Columns.Count + 1)
            {
                currentIndex = productColumnIndex.Value - 1;
                continue;
            }
            if (currentIndex > productColumnIndex)
            {
                if (IsAmountColumn(range.Columns[currentIndex]))
                {
                    amountColumnIndex = currentIndex;
                    break;
                }
                else currentIndex++;
            }
            else
            {
                if (IsAmountColumn(range.Columns[currentIndex]))
                {
                    amountColumnIndex = currentIndex;
                    break;
                }
                else currentIndex--;
            }
        }

        if (amountColumnIndex == null)
        {
            throw new ArgumentException("Колонка с количеством не определена");
        }

        else
        {
            return GetDictionaryFromColumns(range.Columns[productColumnIndex],
                range.Columns[amountColumnIndex]);
        }
    }

    private bool IsProductColumn(Range column)
    {
        int successCounter = 0;
        var cells = column.Value2;

        if (cells == null)
        {
            return false;
        }

        for (int row = 1; row < column.Rows.Count + 1; row++)
        {            
            object currentCell = column.Rows.Count == 1 ? cells : cells[row, 1];
            if (currentCell == null)
            {
                continue;
            }

            if (ProductSku.TryParse(currentCell.ToString(), out _))
            {
                successCounter++;
            }

            if (successCounter > 2)
            {
                return true;
            }
        }

        return successCounter > 0;
    }

    private bool IsAmountColumn(Range column)
    {
        int successCounter = 0;
        var cells = column.Value2;
        double maxValue = 30000;

        if (cells == null)
        {
            return false;
        }

        if (column.Rows.Count == 1)
        {
            double? value = cells as double?;

            return value != null
                && value != 0
                && value < maxValue;
        }

        else
        {
            for (int row = 1; row < column.Rows.Count + 1; row++)
            {
                object currentCell = cells[row, 1];
                double? value = currentCell as double?;

                if (value == null 
                    || value == 0 
                    || value > maxValue)
                {
                    continue;
                }

                if (++successCounter > 3)
                {
                    return true;
                }
            }
        }
        return successCounter > 1;
    }

    private Dictionary<Product, double> GetDictionaryFromColumns(Range productColumn, Range amountColumn)
    {
        Dictionary<Product, double> result = new();
        var firstRowIndex = 1;
        var lastRowIndex = amountColumn.Worksheet
            .Cells[amountColumn.Worksheet.Rows.Count, amountColumn.Column]
            .End[XlDirection.xlUp].Row; 
        _progressBar = new("Заполняю словарь значений...", lastRowIndex);
        Worksheet worksheet = amountColumn.Worksheet;

        for (int row = firstRowIndex; row < lastRowIndex + 1; row++)
        {
            _progressBar.Update();
            object currentAmountCell = worksheet.Cells[row, amountColumn.Column].Value2;
            object currentProductCell = worksheet.Cells[row, productColumn.Column].Value2;
            double? amountValue = currentAmountCell as double?;

            if (amountValue == null || amountValue == 0 || currentProductCell == null)
            {
                continue;
            }

            if (ProductSku.TryParse(currentProductCell.ToString(), out IEnumerable<ProductSku> skus))
            {
                Product p = new(skus.First())
                {
                    Name = "Распознанный артикул"
                };
                if (result.ContainsKey(p))
                {
                    result[p] += amountValue.Value;
                }
                else
                {
                    result.Add(p, amountValue.Value);
                }
            }
        }
        return result;
    }

    public List<(string, Dictionary<Product, double>)> ReadProducts(IEnumerable<Worksheet> worksheets)
    {
        List<(string, Dictionary<Product, double>)> result = new();
        foreach (Worksheet worksheet in worksheets)
        {
            string wbName = Path.GetFileNameWithoutExtension(
                worksheet.Parent.Name);
            Range range = worksheet.UsedRange;
            var productsDict = ReadProducts(range);
            result.Add((wbName, productsDict));
        }
        return result;
    }

    public List<(string, Dictionary<Product, double>)> ReadProducts(string[] files)
    {
        _progressBar = new("Открываю исходные файлы...", files.Length);
        List<Worksheet> worksheets = new();

        _application.ScreenUpdating = false;
        foreach (string file in files)
        {
            Workbook wb = _application.Workbooks.Open(file);
            worksheets.Add(wb.ActiveSheet);
            _progressBar.Update();
        }
        _application.ScreenUpdating = true;
        var result = ReadProducts(worksheets);
        foreach (var ws in worksheets)
        {
            ws.Parent.Close();
        }
        return result;
    }

    public void Dispose()
    {
        _progressBar?.Dispose();
    }
}