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";
    private const string ColBattSoC             = "Battery 1 SoC";    // instantaneous %

    /// <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();
    }

    /// <summary>
    /// Parses hourly energy snapshots from the xlsx.
    /// For each hour of each day, finds the row nearest HH:00:00 and records the
    /// cumulative "Today" values at that moment. The caller (BehaviorAnalyzer) then
    /// diffs consecutive snapshots to get per-hour energy.
    /// </summary>
    public static List<HourlyEnergyData> ParseHourly(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.");

        // Build column map
        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;
        }

        // SoC column is optional — not all exports include it
        var hasSoC = colMap.ContainsKey(ColBattSoC);

        // Read all rows into memory as (DateTime, cumulative values) pairs
        var rawRows = new List<(DateTime Dt, double Pv, double Load, double GridIn, double BattChg, double BattDis, double SoC)>();

        for (var row = 2; row <= lastRow; row++)
        {
            var dtStr = worksheet.Row(row).Cell(colMap[ColDateTime]).GetString().Trim();
            if (string.IsNullOrEmpty(dtStr)) continue;
            if (!DateTime.TryParse(dtStr, out var dt)) continue;

            rawRows.Add((
                dt,
                GetDouble(worksheet, row, colMap[ColPvToday]),
                GetDouble(worksheet, row, colMap[ColLoadToday]),
                GetDouble(worksheet, row, colMap[ColGridImportToday]),
                GetDouble(worksheet, row, colMap[ColBattChargedToday]),
                GetDouble(worksheet, row, colMap[ColBattDischargedToday]),
                hasSoC ? GetDouble(worksheet, row, colMap[ColBattSoC]) : 0
            ));
        }

        if (rawRows.Count == 0) return new List<HourlyEnergyData>();

        // For each calendar hour that exists in the data, find the nearest row to HH:00:00
        // Group rows by (date, hour) and pick the one closest to the round hour
        var byHour = rawRows
            .GroupBy(r => new DateTime(r.Dt.Year, r.Dt.Month, r.Dt.Day, r.Dt.Hour, 0, 0))
            .OrderBy(g => g.Key)
            .Select(g =>
            {
                var roundHour = g.Key;
                var nearest   = g.OrderBy(r => Math.Abs((r.Dt - roundHour).TotalSeconds)).First();
                return (RoundHour: roundHour, Row: nearest);
            })
            .ToList();

        // Diff consecutive snapshots within the same day to get per-hour energy
        var result = new List<HourlyEnergyData>();

        for (var i = 1; i < byHour.Count; i++)
        {
            var prev = byHour[i - 1];
            var curr = byHour[i];

            // Only diff within the same day — don't carry over across midnight
            if (curr.RoundHour.Date != prev.RoundHour.Date) continue;

            // Cumulative "Today" values reset at midnight, so diff is always >= 0 within a day
            result.Add(new HourlyEnergyData
            {
                DateTime            = curr.RoundHour,
                Hour                = curr.RoundHour.Hour,
                DayOfWeek           = curr.RoundHour.DayOfWeek.ToString(),
                IsWeekend           = curr.RoundHour.DayOfWeek is DayOfWeek.Saturday or DayOfWeek.Sunday,
                PvKwh               = Math.Max(0, Math.Round(curr.Row.Pv    - prev.Row.Pv,    3)),
                LoadKwh             = Math.Max(0, Math.Round(curr.Row.Load  - prev.Row.Load,  3)),
                GridImportKwh       = Math.Max(0, Math.Round(curr.Row.GridIn - prev.Row.GridIn, 3)),
                BatteryChargedKwh   = Math.Max(0, Math.Round(curr.Row.BattChg - prev.Row.BattChg, 3)),
                BatteryDischargedKwh = Math.Max(0, Math.Round(curr.Row.BattDis - prev.Row.BattDis, 3)),
                BattSoC             = curr.Row.SoC,
            });
        }

        Console.WriteLine($"[ExcelDataParser] Parsed {result.Count} hourly records from {filePath}");
        return result;
    }

    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;
    }
}