using Dapper;
using GB5Shared.DTO.Framework.Criteria;

namespace PayRollDAL.CustomeCode.Periodic
{
    /// <summary>
    /// Builds a parameterized WHERE-fragment + DynamicParameters bag from a flattened CriteriaDTO,
    /// mirroring GB4's PeriodicDAL.GetPeriodicandaddonCriteria* helpers (HQL-based ApplyCriteria)
    /// without string-concatenating criteria VALUES into SQL — only column names are chosen per
    /// map (fixed, code-controlled), values are always bound via @p{N} parameters.
    /// </summary>
    public static class PeriodicCriteriaHelper
    {
        /// <summary>
        /// fieldToColumn: logical CriteriaDTO field name (case-insensitive) -> SQL column expression.
        /// Only fields present in the map AND present in the parsed criteria produce a filter.
        /// </summary>
        public static (string Filter, DynamicParameters Params) Build(
            CriteriaDTO? criteriaDTO,
            IReadOnlyDictionary<string, string> fieldToColumn)
        {
            var parameters = new DynamicParameters();
            if (criteriaDTO == null)
                return ("", parameters);

            var flat = CriteriaParser.Parse(criteriaDTO);
            if (flat.Count == 0)
                return ("", parameters);

            var sb = new System.Text.StringBuilder();
            int i = 0;
            foreach (var kv in fieldToColumn)
            {
                if (!flat.TryGetValue(kv.Key, out var value) || value == null)
                    continue;

                string paramName = $"CritP{i++}";
                sb.Append(" AND ").Append(kv.Value).Append(" = @").Append(paramName);
                parameters.Add(paramName, value);
            }

            return (sb.ToString(), parameters);
        }
    }
}