using ClosedXML.Excel;
using InnovEnergy.App.Backend.DataTypes;

namespace InnovEnergy.App.Backend.Services;

public static class ExcelDataParser
{
    // Column headers from the ESS Link Cloud Excel export
    private const string ColDateTime           = "Data time";
    private const string ColPvToday            = "PV Generated Energy Today";
    private const string ColLoadToday          = "Load Consumption Today";
    private const string ColGridImportToday    = "Purchased Energy Today";
    private const string ColGridExportToday    = "Feed in energy Today";
    private const string ColBattChargedToday   = "Daily Battery Charged";
    private const string ColBattDischargedToday = "Battery Discharged Today";

    /// <summary>
    /// Parses an ESS Link Cloud Excel export file and returns one DailyEnergyData per day.
    /// Takes the last row of each day (where "Today" cumulative values are highest).
    /// </summary>
    public static List<DailyEnergyData> Parse(string filePath)
    {
        if (!File.Exists(filePath))
            throw new FileNotFoundException($"Excel file not found: {filePath}");

        using var workbook  = new XLWorkbook(filePath);
        var       worksheet = workbook.Worksheet(1);
        var       lastRow   = worksheet.LastRowUsed()?.RowNumber() ?? 0;

        if (lastRow < 2)
            throw new InvalidOperationException("Excel file has no data rows.");

        // Find column indices by header name (row 1)
        var headerRow = worksheet.Row(1);
        var colMap    = new Dictionary<string, int>();

        for (var col = 1; col <= worksheet.LastColumnUsed()?.ColumnNumber(); col++)
        {
            var header = headerRow.Cell(col).GetString().Trim();
            if (!string.IsNullOrEmpty(header))
                colMap[header] = col;
        }

        // Validate required columns exist
        var requiredCols = new[] { ColDateTime, ColPvToday, ColLoadToday, ColGridImportToday, ColGridExportToday, ColBattChargedToday, ColBattDischargedToday };
        foreach (var rc in requiredCols)
        {
            if (!colMap.ContainsKey(rc))
                throw new InvalidOperationException($"Required column '{rc}' not found in Excel file. Available: {string.Join(", ", colMap.Keys)}");
        }

        // Read all rows, group by date, keep last row per day
        var dailyLastRows = new SortedDictionary<string, DailyEnergyData>();

        for (var row = 2; row <= lastRow; row++)
        {
            var dateTimeStr = worksheet.Row(row).Cell(colMap[ColDateTime]).GetString().Trim();
            if (string.IsNullOrEmpty(dateTimeStr)) continue;

            // Extract date portion (first 10 chars: "2026-02-10")
            var date = dateTimeStr.Length >= 10 ? dateTimeStr[..10] : dateTimeStr;

            var data = new DailyEnergyData
            {
                Date              = date,
                PvProduction      = GetDouble(worksheet, row, colMap[ColPvToday]),
                LoadConsumption   = GetDouble(worksheet, row, colMap[ColLoadToday]),
                GridImport        = GetDouble(worksheet, row, colMap[ColGridImportToday]),
                GridExport        = GetDouble(worksheet, row, colMap[ColGridExportToday]),
                BatteryCharged    = GetDouble(worksheet, row, colMap[ColBattChargedToday]),
                BatteryDischarged = GetDouble(worksheet, row, colMap[ColBattDischargedToday]),
            };

            // Always overwrite — last row of the day has the final cumulative values
            dailyLastRows[date] = data;
        }

        Console.WriteLine($"[ExcelDataParser] Parsed {dailyLastRows.Count} days from {filePath}");
        return dailyLastRows.Values.ToList();
    }

    private static double GetDouble(IXLWorksheet ws, int row, int col)
    {
        var cell = ws.Row(row).Cell(col);
        if (cell.IsEmpty()) return 0;
        return cell.TryGetValue<double>(out var val) ? Math.Round(val, 4) : 0;
    }
}