using System;
using System.Threading;
using System.Threading.Tasks;
using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.ListQuery;
using GB5Shared.QueryExecutor;
using MMDAL.DTO.Allocation;
using Newtonsoft.Json;
using static GB5Shared.GB5Constant.Constant;

namespace MMBLL.Allocation
{
    // ─────────────────────────────────────────────────────────────────────
    //  PendingAllocationBLL  – Pattern B (routed) query router
    //
    //  Routing logic:
    //    Read 'objectheadertypeid' and 'allitemsview'/'multiprocess' from
    //    the CriteriaDTO, then dispatch to the correct query variant via
    //    IListDispatcher (which resolves the IListHandler from DI).
    //
    //  Discriminator fields (read from CriteriaDTO via CriteriaRouterHelper):
    //    objectheadertypeid  = EntityConstant.OBJECTMMHEAD  → MM document variants
    //    objectheadertypeid  = EntityConstant.OBJECTINDENT  → Indent variants
    //    allitemsview        = "true"                       → detail-level MM view
    //    multiprocess        = "true"                       → multi-process indent view
    //
    //  Default (no discriminator or unknown value): PendingMMDocumentsQuery
    // ─────────────────────────────────────────────────────────────────────
    public sealed class PendingAllocationBLL : IPendingAllocationBLL
    {
        private readonly IListDispatcher _dispatcher;
        private readonly IListHandler<PendingAllocationSelectListQuery, PendingAllocationSelectListDTO> _selectListHandler;

        public PendingAllocationBLL(
            IListDispatcher dispatcher,
            IListHandler<PendingAllocationSelectListQuery, PendingAllocationSelectListDTO> selectListHandler)
        {
            _dispatcher = dispatcher;
            _selectListHandler = selectListHandler;
        }

        public async Task<string> GetPendingAllocations(
            CriteriaDTO criteria,
            string?     searchText,
            int         pageOffset,
            int         pageSize,
            LoginDTO    login,
            CancellationToken ct = default)
        {
            // Merge query-param search text and paging into the criteria body.
            // searchText=null means legacy client already embedded it in the body.
            var merged = CriteriaRouterHelper.WithSearchAndPaging(
                criteria, searchText, pageOffset, pageSize);

            // Read discriminator fields from the merged criteria
            var flat         = CriteriaRouterHelper.Flatten(merged);
            int headTypeId   = CriteriaRouterHelper.GetInt(flat, "objectheadertypeid");
            bool allItems    = string.Equals(
                CriteriaRouterHelper.GetStr(flat, "allitemsview"), "true",
                StringComparison.OrdinalIgnoreCase);
            bool multiProc   = string.Equals(
                CriteriaRouterHelper.GetStr(flat, "multiprocess"), "true",
                StringComparison.OrdinalIgnoreCase);

            PagedResult<PendingAllocationListDTO> result;

            if (headTypeId == EntityConstant.OBJECTINDENT)
            {
                if (multiProc)
                {
                    var c = CriteriaBinder.Bind<PendingIndentMultiProcessCriteria>(merged);
                    result = await _dispatcher.DispatchAsync(
                        new PendingIndentMultiProcessQuery(c), login, ct).ConfigureAwait(false);
                }
                else
                {
                    var c = CriteriaBinder.Bind<PendingIndentCriteria>(merged);
                    result = await _dispatcher.DispatchAsync(
                        new PendingIndentsQuery(c), login, ct).ConfigureAwait(false);
                }
            }
            else
            {
                // Default: OBJECTMMHEAD (or when objectheadertypeid is absent)
                if (allItems)
                {
                    var c = CriteriaBinder.Bind<PendingMMAllItemsCriteria>(merged);
                    result = await _dispatcher.DispatchAsync(
                        new PendingMMAllItemsQuery(c), login, ct).ConfigureAwait(false);
                }
                else
                {
                    var c = CriteriaBinder.Bind<PendingMMDocumentCriteria>(merged);
                    result = await _dispatcher.DispatchAsync(
                        new PendingMMDocumentsQuery(c), login, ct).ConfigureAwait(false);
                }
            }

            return JsonConvert.SerializeObject(result.Items);
        }

        // ─────────────────────────────────────────────────────────────────
        //  GetSelectListTPendingAllocation  – Pattern A (direct) — single
        //  query variant, no routing/discriminator needed, so the typed
        //  IListHandler is injected and called directly instead of going
        //  through IListDispatcher.
        // ─────────────────────────────────────────────────────────────────
        public async Task<string> GetSelectListTPendingAllocation(
            CriteriaDTO criteria,
            string?     searchText,
            int         pageOffset,
            int         pageSize,
            LoginDTO    login,
            CancellationToken ct = default)
        {
            var merged = CriteriaRouterHelper.WithSearchAndPaging(
                criteria, searchText, pageOffset, pageSize);

            var c = CriteriaBinder.Bind<PendingAllocationSelectListCriteria>(merged);

            var result = await _selectListHandler.HandleAsync(
                new PendingAllocationSelectListQuery(c), login, ct).ConfigureAwait(false);

            return JsonConvert.SerializeObject(result.Items);
        }
    }
}