using Microsoft.EntityFrameworkCore;
using UtopiaCanteenSystem.Data;
using UtopiaCanteenSystem.Models;

namespace UtopiaCanteenSystem.Services;

/// <summary>
/// Fetches lunch menu from local SQLite cache (lunch_menu_week → lunch_menu_item → menu_item).
/// </summary>
public class MenuLookupService : IMenuLookupService
{
    private readonly IDbContextFactory<AppDbContext> _dbFactory;

    public MenuLookupService(IDbContextFactory<AppDbContext> dbFactory)
    {
        _dbFactory = dbFactory;
    }

    public async Task<IReadOnlyList<HrmsMenuItem>> GetMenuItemsForSiteAsync(int siteIdNumeric, CancellationToken cancellationToken = default)
    {
        return await GetMenuItemsForSiteAndDateAsync(
            siteIdNumeric,
            DateTime.Today,
            "NonManagement",
            "no-active-meal-session",
            cancellationToken).ConfigureAwait(false);
    }

    public async Task<IReadOnlyList<HrmsMenuItem>> GetMenuItemsForSiteAndDateAsync(
        int siteIdNumeric,
        DateTime menuDateLocal,
        string gradeType,
        string mealName,
        CancellationToken cancellationToken = default)
    {
        if (siteIdNumeric <= 0)
            return Array.Empty<HrmsMenuItem>();

        await using var db = await _dbFactory.CreateDbContextAsync(cancellationToken).ConfigureAwait(false);

        if (!await db.MenuItemCache.AnyAsync(cancellationToken).ConfigureAwait(false))
            return Array.Empty<HrmsMenuItem>();

        var menuDate = menuDateLocal.Date;
        var itemFor = HrmsMenuItemForMapping.FromGradeType(gradeType);
        var meal = mealName?.Trim() ?? string.Empty;

        var query =
            from w in db.LunchMenuWeekCache.AsNoTracking()
            join li in db.LunchMenuItemCache.AsNoTracking() on w.HrmsId equals li.LunchMenuWeekHrmsId
            join mi in db.MenuItemCache.AsNoTracking() on li.MenuItemHrmsId equals mi.HrmsId
            where w.LocationSiteId == siteIdNumeric
                  && w.WeekStartDate != null
                  && w.WeekEndDate != null
                  && menuDate >= w.WeekStartDate.Value.Date
                  && menuDate <= w.WeekEndDate.Value.Date
                  && li.MenuDate != null
                  && li.MenuDate.Value.Date == menuDate
                  && li.MealName == meal
                  && mi.ItemFor == itemFor
            orderby mi.ItemName
            select new HrmsMenuItem
            {
                MenuItemId = (int)mi.HrmsId,
                ItemName = mi.ItemName,
                ItemType = mi.ItemType,
                Price = mi.Price,
                MenuDate = li.MenuDate != null ? li.MenuDate.Value.ToString("yyyy-MM-dd") : string.Empty,
                DayOfWeek = li.DayOfWeek,
                MealName = li.MealName
            };

        return await query.ToListAsync(cancellationToken).ConfigureAwait(false);
    }
}