marco.pms.api/Marco.Pms.Services/Extensions/QueryableExtensions.cs

using Marco.Pms.Model.Filters;
using System.Data;
using System.Linq.Dynamic.Core;

namespace Marco.Pms.Services.Extensions
{
    /// <summary>
    /// Enterprise-grade extension methods for applying dynamic filters and sorting to IQueryable sources.
    /// </summary>
    public static class QueryableExtensions
    {
        public static IQueryable<T> ApplyCustomFilters<T>(this IQueryable<T> query, AdvanceFilter? filter, string defaultSortColumn)
        {
            // 1. Apply Advanced Filters (Arithmetic/Logic)
            if (filter?.AdvanceFilters != null && filter.AdvanceFilters.Any())
            {
                foreach (var advanceFilter in filter.AdvanceFilters)
                {
                    if (string.IsNullOrWhiteSpace(advanceFilter.Column)) continue;

                    string op = advanceFilter.Opration.ToLower().Trim();
                    string predicate = "";

                    // Map your custom strings to Dynamic LINQ operators
                    switch (op)
                    {
                        case "greater than": predicate = $"{advanceFilter.Column} > @0"; break;
                        case "less than": predicate = $"{advanceFilter.Column} < @0"; break;
                        case "equal to": predicate = $"{advanceFilter.Column} == @0"; break;
                        case "not equal": predicate = $"{advanceFilter.Column} != @0"; break;
                        case "greater or equal": predicate = $"{advanceFilter.Column} >= @0"; break;
                        case "smaller or equal": predicate = $"{advanceFilter.Column} <= @0"; break;
                        default: continue;
                    }

                    if (!string.IsNullOrEmpty(predicate))
                    {
                        // Dynamic LINQ handles type conversion (string "100" to int 100) automatically
                        query = query.Where(predicate, advanceFilter.Value);
                    }
                }
            }

            // 2. Apply Sorting
            if (filter?.SortFilters != null && filter.SortFilters.Any())
            {
                // Build a comma-separated sort string: "Column1 desc, Column2 asc"
                var sortExpressions = new List<string>();
                foreach (var sort in filter.SortFilters)
                {
                    string direction = sort.SortDescending ? "desc" : "asc";
                    sortExpressions.Add($"{sort.Column} {direction}");
                }

                query = query.OrderBy(string.Join(", ", sortExpressions));
            }
            else
            {
                // Default sorting
                query = query.OrderBy($"{defaultSortColumn} desc");
            }


            // 3.Apply GroupBy
            if (!string.IsNullOrEmpty(filter?.GroupByColumn))
            {
                query.GroupBy(filter.GroupByColumn, "it")
                .Select("new (Key, it as Items)"); // Reshape to { Key: "Value", Items: [...] }
            }
            return query;
        }

        /// <summary>
        /// Applies search filters to the given IQueryable.
        /// </summary>
        /// <typeparam name="T">The type of the elements in the IQueryable.</typeparam>
        /// <param name="query">The IQueryable to apply the filters to.</param>
        /// <param name="searchFilters">The list of search filters to apply.</param>
        /// <returns>The filtered IQueryable.</returns>
        public static IQueryable<T> ApplySearchFilters<T>(this IQueryable<T> query, List<SearchItem> searchFilters)
        {
            // Apply search filters to the query
            if (searchFilters.Any())
            {
                foreach (var search in searchFilters)
                {
                    if (string.IsNullOrWhiteSpace(search.Column) || string.IsNullOrWhiteSpace(search.Value)) continue;

                    // Generates: x.Column.Contains("Value")
                    // Case insensitive logic can be handled here if needed
                    query = query.Where($"{search.Column}.Contains(@0)", search.Value);
                }
            }
            return query;
        }

        /// <summary>
        /// Applies group by filters to the given IQueryable.
        /// </summary>
        /// <typeparam name="T">The type of the elements in the IQueryable.</typeparam>
        /// <param name="query">The IQueryable to apply the filters to.</param>
        /// <param name="groupByColumn">The column to group by.</param>
        /// <returns>The grouped IQueryable.</returns>
        public static IQueryable<T> ApplyGroupByFilters<T>(this IQueryable<T> query, string groupByColumn)
        {
            // Group the query by the specified column and reshape the result to { Key: "Value", Items: [...] }
            query.GroupBy(groupByColumn, "it")
                .Select("new (Key, it as Items)");
            return query;
        }

        /// <summary>
        /// Applies list filters to the given IQueryable.
        /// </summary>
        /// <typeparam name="T">The type of the elements in the IQueryable.</typeparam>
        /// <param name="query">The IQueryable to apply the filters to.</param>
        /// <param name="filters">The list of filters to apply.</param>
        /// <returns>The filtered IQueryable.</returns>
        public static IQueryable<T> ApplyListFilters<T>(this IQueryable<T> query, List<ListDynamicFilter> filters)
        {
            // Check if there are any filters
            if (filters == null || !filters.Any()) return query;

            // Apply filters to the query
            foreach (var filter in filters)
            {
                // Skip if column is empty or values are null or empty
                if (string.IsNullOrWhiteSpace(filter.Column) || filter.Values == null || !filter.Values.Any()) continue;

                // Apply filter to the query
                query = query.Where($"@0.Contains({filter.Column})", filter.Values);
            }

            // Return the filtered query
            return query;
        }

        /// <summary>
        /// Applies date filters to the given IQueryable.
        /// </summary>
        /// <typeparam name="T">The type of the elements in the IQueryable.</typeparam>
        /// <param name="query">The IQueryable to apply the filters to.</param>
        /// <param name="dateFilter">The date filter to apply.</param>
        /// <returns>The filtered IQueryable.</returns>
        public static IQueryable<T> ApplyDateFilter<T>(this IQueryable<T> query, DateDynamicFilter dateFilter)
        {
            // Check if date filter is null or column is empty
            if (dateFilter == null || string.IsNullOrWhiteSpace(dateFilter.Column)) return query;

            // Convert start and end values to date
            var startValue = dateFilter.StartValue.Date;
            var endValue = dateFilter.EndValue.Date.AddDays(1);

            // Apply a filter to include items with a date greater than or equal to the start value
            query = query.Where($"{dateFilter.Column} >= @0", startValue);

            // Apply a filter to include items with a date less than or equal to the end value
            query = query.Where($"{dateFilter.Column} < @0", endValue);

            // Return the filtered IQueryable
            return query;
        }
    }
}