using MySqlConnector;
using UtopiaCanteenSystem.Models;

namespace UtopiaCanteenSystem.Services;

/// <summary>
/// Meal schedule CRUD against production HRMS MySQL table hrms.meal_schedule.
/// Uses IConfigService.GetHrmsLookupConnectionString() (same DB as employee lookup).
/// Schema: id (bigint), meal_name (varchar), start_time (time), end_time (time), created_at, updated_at, location_site_id (int).
/// No is_active column; all rows are treated as active.
/// </summary>
public class ProductionMealScheduleService : IMealScheduleService
{
    private readonly IConfigService _configService;
    private const string TableRef = "`hrms`.`meal_schedule`";

    public ProductionMealScheduleService(IConfigService configService)
    {
        _configService = configService;
    }

    /// <inheritdoc />
    public IReadOnlyList<MealSchedule> GetActiveSchedulesForSite(string siteId)
    {
        var connStr = _configService.GetHrmsLookupConnectionString();
        if (string.IsNullOrWhiteSpace(connStr))
            return Array.Empty<MealSchedule>();

        var siteIdInt = SiteIdStringToInt(siteId);
        var list = new List<MealSchedule>();
        try
        {
            using var conn = new MySqlConnection(connStr);
            conn.Open();
            var sql = $"SELECT id, meal_name, start_time, end_time, created_at, updated_at, location_site_id FROM {TableRef} WHERE location_site_id = @siteId ORDER BY start_time";
            using var cmd = new MySqlCommand(sql, conn);
            cmd.Parameters.AddWithValue("@siteId", siteIdInt);
            using var r = cmd.ExecuteReader();
            while (r.Read())
                list.Add(ReadRow(r));
        }
        catch
        {
            return Array.Empty<MealSchedule>();
        }
        return list;
    }

    /// <inheritdoc />
    public async Task<IReadOnlyList<MealSchedule>> GetAllSchedulesAsync(CancellationToken cancellationToken = default)
    {
        var connStr = _configService.GetHrmsLookupConnectionString();
        if (string.IsNullOrWhiteSpace(connStr))
            return Array.Empty<MealSchedule>();

        var list = new List<MealSchedule>();
        await using var conn = new MySqlConnection(connStr);
        await conn.OpenAsync(cancellationToken).ConfigureAwait(false);
        var sql = $"SELECT id, meal_name, start_time, end_time, created_at, updated_at, location_site_id FROM {TableRef} ORDER BY location_site_id, start_time";
        await using var cmd = new MySqlCommand(sql, conn);
        await using var r = await cmd.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false);
        while (await r.ReadAsync(cancellationToken).ConfigureAwait(false))
            list.Add(ReadRow(r));
        return list;
    }

    /// <inheritdoc />
    public async Task<long> CreateAsync(MealSchedule schedule, CancellationToken cancellationToken = default)
    {
        var connStr = _configService.GetHrmsLookupConnectionString();
        if (string.IsNullOrWhiteSpace(connStr))
            throw new InvalidOperationException("HRMS MySQL connection string not configured.");

        var utc = DateTime.UtcNow;
        var mealName = MealSessionToName(schedule.MealSession);
        var siteIdInt = SiteIdStringToInt(schedule.LocationSiteId);

        await using var conn = new MySqlConnection(connStr);
        await conn.OpenAsync(cancellationToken).ConfigureAwait(false);
        var sql = $@"INSERT INTO {TableRef} (meal_name, start_time, end_time, created_at, updated_at, location_site_id)
                    VALUES (@mealName, @startTime, @endTime, @createdAt, @updatedAt, @siteId)";
        await using var cmd = new MySqlCommand(sql, conn);
        cmd.Parameters.AddWithValue("@mealName", mealName);
        cmd.Parameters.AddWithValue("@startTime", schedule.StartTime?.Trim() ?? "00:00:00");
        cmd.Parameters.AddWithValue("@endTime", schedule.EndTime?.Trim() ?? "23:59:59");
        cmd.Parameters.AddWithValue("@createdAt", utc);
        cmd.Parameters.AddWithValue("@updatedAt", utc);
        cmd.Parameters.AddWithValue("@siteId", siteIdInt);
        await cmd.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false);
        return cmd.LastInsertedId;
    }

    /// <inheritdoc />
    public async Task UpdateAsync(MealSchedule schedule, CancellationToken cancellationToken = default)
    {
        var connStr = _configService.GetHrmsLookupConnectionString();
        if (string.IsNullOrWhiteSpace(connStr))
            throw new InvalidOperationException("HRMS MySQL connection string not configured.");

        var utc = DateTime.UtcNow;
        var mealName = MealSessionToName(schedule.MealSession);
        var siteIdInt = SiteIdStringToInt(schedule.LocationSiteId);

        await using var conn = new MySqlConnection(connStr);
        await conn.OpenAsync(cancellationToken).ConfigureAwait(false);
        var sql = $@"UPDATE {TableRef} SET meal_name = @mealName, start_time = @startTime, end_time = @endTime, location_site_id = @siteId, updated_at = @updatedAt WHERE id = @id";
        await using var cmd = new MySqlCommand(sql, conn);
        cmd.Parameters.AddWithValue("@id", schedule.Id);
        cmd.Parameters.AddWithValue("@mealName", mealName);
        cmd.Parameters.AddWithValue("@startTime", schedule.StartTime?.Trim() ?? "00:00:00");
        cmd.Parameters.AddWithValue("@endTime", schedule.EndTime?.Trim() ?? "23:59:59");
        cmd.Parameters.AddWithValue("@siteId", siteIdInt);
        cmd.Parameters.AddWithValue("@updatedAt", utc);
        await cmd.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false);
    }

    /// <inheritdoc />
    public async Task DeleteAsync(long id, CancellationToken cancellationToken = default)
    {
        var connStr = _configService.GetHrmsLookupConnectionString();
        if (string.IsNullOrWhiteSpace(connStr))
            throw new InvalidOperationException("HRMS MySQL connection string not configured.");

        await using var conn = new MySqlConnection(connStr);
        await conn.OpenAsync(cancellationToken).ConfigureAwait(false);
        var sql = $"DELETE FROM {TableRef} WHERE id = @id";
        await using var cmd = new MySqlCommand(sql, conn);
        cmd.Parameters.AddWithValue("@id", id);
        await cmd.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false);
    }

    /// <summary>Read row: id (bigint), meal_name, start_time (time), end_time (time), created_at, updated_at, location_site_id (int).</summary>
    private static MealSchedule ReadRow(MySqlDataReader r)
    {
        return new MealSchedule
        {
            Id = r.GetInt64(0),
            MealSession = MealNameToSession(GetString(r, 1)),
            StartTime = GetTimeString(r, 2),
            EndTime = GetTimeString(r, 3),
            CreatedAt = GetDateTime(r, 4),
            UpdatedAt = GetDateTime(r, 5),
            LocationSiteId = IntToSiteIdString(r.IsDBNull(6) ? 0 : r.GetInt32(6)),
            IsActive = true
        };
    }

    private static string GetString(MySqlDataReader r, int i)
    {
        if (r.IsDBNull(i)) return "";
        return r.GetString(i) ?? "";
    }

    private static string GetTimeString(MySqlDataReader r, int i)
    {
        if (r.IsDBNull(i)) return "00:00:00";
        var v = r.GetValue(i);
        if (v is TimeSpan ts)
            return ts.ToString(@"hh\:mm\:ss");
        return v?.ToString()?.Trim() ?? "00:00:00";
    }

    private static DateTime GetDateTime(MySqlDataReader r, int i)
    {
        if (r.IsDBNull(i)) return DateTime.UtcNow;
        var dt = r.GetDateTime(i);
        return dt.Kind == DateTimeKind.Utc ? dt : DateTime.SpecifyKind(dt, DateTimeKind.Utc);
    }

    private static int MealNameToSession(string mealName)
    {
        if (string.IsNullOrWhiteSpace(mealName)) return 0;
        var n = mealName.Trim();
        if (n.Equals("Breakfast", StringComparison.OrdinalIgnoreCase) || n.Equals("BreakFast", StringComparison.OrdinalIgnoreCase)) return (int)MealSession.Breakfast;
        if (n.Equals("Lunch", StringComparison.OrdinalIgnoreCase)) return (int)MealSession.Lunch;
        if (n.Equals("Tea", StringComparison.OrdinalIgnoreCase)) return (int)MealSession.Tea;
        if (n.Equals("Dinner", StringComparison.OrdinalIgnoreCase)) return (int)MealSession.Dinner;
        return 0;
    }

    private static string MealSessionToName(int mealSession)
    {
        return mealSession switch
        {
            (int)MealSession.Breakfast => "Breakfast",
            (int)MealSession.Lunch => "Lunch",
            (int)MealSession.Tea => "Tea",
            (int)MealSession.Dinner => "Dinner",
            _ => "Breakfast"
        };
    }

    private static int SiteIdStringToInt(string siteId)
    {
        var s = (siteId ?? "").Trim();
        if (string.IsNullOrEmpty(s)) return 0;
        var digits = new string(s.Where(char.IsDigit).ToArray());
        return int.TryParse(digits, out var n) ? n : 0;
    }

    /// <summary>Normalize production location_site_id int to display string (e.g. 2 -> "02").</summary>
    private static string IntToSiteIdString(int siteIdInt)
    {
        if (siteIdInt <= 0) return "01";
        return siteIdInt <= 99 ? siteIdInt.ToString("D2") : siteIdInt.ToString();
    }
}