using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using ClosedXML.Excel;
using DeclarationAutomatization.Models;

namespace DeclarationAutomatization.Services;

public class Sheet1ImportService
{
    private const string SheetName = "Лист1";
    private const string ItogoMarker = "ИТОГО";

    public List<Sheet1Group> ReadSheet1(string filePath)
    {
        using var workbook = new XLWorkbook(filePath);

        IXLWorksheet? sheet = null;
        foreach (var ws in workbook.Worksheets)
        {
            if (ws.Name.Equals(SheetName, StringComparison.OrdinalIgnoreCase))
            { sheet = ws; break; }
        }

        if (sheet == null)
            throw new InvalidOperationException($"Лист '{SheetName}' не найден в файле: {filePath}");

        var groups = new List<Sheet1Group>();
        int sequentialNumber = 1;
        int lastRow = sheet.LastRowUsed()?.RowNumber() ?? 1;

        for (int r = 1; r <= lastRow; r++)
        {
            var row = sheet.Row(r);
            if (!IsItogoRow(row)) continue;

            var group = BuildGroup(row, sequentialNumber);
            if (group != null)
            {
                groups.Add(group);
                sequentialNumber++;
            }
        }

        return groups;
    }

    private static bool IsItogoRow(IXLRow row)
    {
        foreach (var cell in row.CellsUsed())
        {
            if (cell.GetString().Contains(ItogoMarker, StringComparison.OrdinalIgnoreCase))
                return true;
        }
        return false;
    }

    private static Sheet1Group? BuildGroup(IXLRow row, int sequentialNumber)
    {
        string tnVed = FindTnVed(row);
        if (string.IsNullOrWhiteSpace(tnVed)) return null;

        string description = row.Cell(2).GetString().Trim();
        if (string.IsNullOrWhiteSpace(description))
            description = row.Cell(3).GetString().Trim();

        string countryId = FindCountryId(row);

        decimal qty    = ParseDecimal(row.Cell(9));
        decimal amount = ParseDecimal(row.Cell(10));
        decimal gross  = ParseDecimal(row.Cell(11));
        decimal net    = ParseDecimal(row.Cell(12));

        return new Sheet1Group
        {
            SequentialNumber = sequentialNumber,
            Description = description,
            TnVed = tnVed,
            CountryId = countryId,
            Quantity = qty,
            AmountWithVat = amount,
            GrossWeight = gross,
            NetWeight = net,
        };
    }

    private static string FindTnVed(IXLRow row)
    {
        foreach (var cell in row.CellsUsed())
        {
            var val = cell.GetString().Trim();
            if (Regex.IsMatch(val, @"^\d{10}$"))
                return val;
        }
        return "";
    }

    private static string FindCountryId(IXLRow row)
    {
        foreach (var cell in row.CellsUsed())
        {
            var val = cell.GetString().Trim();
            if (Regex.IsMatch(val, @"^[A-Z]{2}$"))
                return val;
        }
        return "";
    }

    private static decimal ParseDecimal(IXLCell cell)
    {
        if (cell.IsEmpty()) return 0;
        try
        {
            var val = cell.GetString().Trim().Replace(',', '.');
            return decimal.TryParse(val, System.Globalization.NumberStyles.Any,
                System.Globalization.CultureInfo.InvariantCulture, out var d) ? d : 0;
        }
        catch { return 0; }
    }
}