using GB5Shared.DTO.Ice;
using IceImportDAL.DTO.IceImportPipeline;

namespace IceImportBLL.HierarchyMapper;

public class HierarchyMapper : IHierarchyMapper
{
    // MENTITY.ENTITYID sentinel meaning "Addon entity" — MICEMAPDETAILS rows whose
    // DestinationMemberEntityId is this value carry an IceMapDetailsAddonFields (physical column
    // name) instead of a normal DBFIELDID/DataType=5 mapping. Mirrors IceImportPipeline's own
    // identical constant (duplicated per class, same convention as EntityLookupService.GcmEntityId).
    private const int AddonEntityId = -1399999424;

    public List<MappedEntityRowDTO> BuildHierarchy(
        Dictionary<int, List<ResolvedCandidateRow>> resolvedRowsByEntity,
        IceMapDTO mapDefinition)
    {
        // IceMapEntityId is the POCO-side MICEMAP.ENTITYID; IceMapDetails' DestinationMemberEntityId
        // is always the DTO-side entity (joined via MENTITYMEMBERS). Must compare via the resolved
        // link (IceMapRootEntityId), not IceMapEntityId directly — see IceMapDTO's doc comment.
        var rootEntityId = mapDefinition.IceMapRootEntityId;

        if (!resolvedRowsByEntity.TryGetValue(rootEntityId, out var rootCandidates) || rootCandidates.Count == 0)
            return new List<MappedEntityRowDTO>();

        var roots = rootCandidates.Select(c => c.Row).ToList();

        // Last-write-wins is fine here — CorrelationIndex values are expected to be unique per
        // root row (either distinct positional indices, or distinct JSON __ROWINDEX__ values).
        var rootByIndex = new Dictionary<int, MappedEntityRowDTO>();
        foreach (var candidate in rootCandidates)
            rootByIndex[candidate.CorrelationIndex] = candidate.Row;

        foreach (var (childEntityId, childCandidates) in resolvedRowsByEntity)
        {
            if (childEntityId == rootEntityId) continue;

            foreach (var candidate in childCandidates)
            {
                if (!rootByIndex.TryGetValue(candidate.CorrelationIndex, out var parentRow))
                    continue; // no matching parent row at this correlation index — drop silently is
                              // not acceptable; caller surfaces this via RequiredFieldValidator/row
                              // count mismatches instead of HierarchyMapper inventing a parent.

                if (!parentRow.Children.TryGetValue(childEntityId, out var list))
                {
                    list = new List<MappedEntityRowDTO>();
                    parentRow.Children[childEntityId] = list;
                }

                list.Add(candidate.Row);
            }
        }

        return roots;
    }

    public string? GetParentIdFieldName(IceMapDTO mapDefinition, int childEntityId)
        => mapDefinition.IceMapDetailsArray
            .FirstOrDefault(d => d.DestinationMemberEntityId == childEntityId && d.IceMapDetailsValueType == 6)
            ?.DestinationMemberMemberName;

    public string? GetFirstParentIdFieldName(IceMapDTO mapDefinition, int childEntityId)
        => mapDefinition.IceMapDetailsArray
            .FirstOrDefault(d => d.DestinationMemberEntityId == childEntityId && d.IceMapDetailsValueType == 11)
            ?.DestinationMemberMemberName;

    public List<ObjectListRelationshipDTO> GetObjectListRelationships(IceMapDTO mapDefinition)
    {
        var result = new List<ObjectListRelationshipDTO>();

        // Addon: check for the presence of any field row hardcoded to the AddonEntityId sentinel
        // FIRST (e.g. BONUSAPPL/INCAPPL's own DestinationMemberEntityId=-1399999424) — the DataType=5
        // marker representing the Addon object as a whole (e.g. EmployeeAddOn) has its OWN,
        // different, real EntityId/EntityPocoToDtoLinkId, so it can never be found by resolving the
        // marker's link the way BOM-style relationships are. If no such field exists at all, this
        // map has no Addon and the BOM-style detection below runs unchanged.
        var hasAddonFields = mapDefinition.IceMapDetailsArray
            .Any(d => d.DestinationMemberEntityId == AddonEntityId);

        if (hasAddonFields)
        {
            // Find the DataType=5 marker (whatever it's named, e.g. EmployeeAddOn) and emit ONE
            // relationship for the whole Addon object, keyed by the AddonEntityId sentinel directly
            // — not the marker's own (unrelated) resolved link. Individual field names (BONUSAPPL,
            // INCAPPL, ...) come from each field row's own IceMapDetailsAddonFields elsewhere in the
            // pipeline (AddonFieldAccumulator) — this DTO only carries the ONE containing member name.
            var addonMarker = mapDefinition.IceMapDetailsArray
                .FirstOrDefault(d => d.DestinationMemberDataType == 5);

            if (addonMarker is not null && !string.IsNullOrWhiteSpace(addonMarker.DestinationMemberMemberName))
            {
                result.Add(new ObjectListRelationshipDTO(
                    addonMarker.DestinationMemberEntityId, AddonEntityId,
                    addonMarker.DestinationMemberMemberName!, addonMarker.DestinationMemberMemberName!));
            }

            return result;
        }

        var listMemberRows = mapDefinition.IceMapDetailsArray
            .Where(d => d.IceMapDetailsValueType == 0 && d.DestinationMemberDataType == 5)
            .ToList();

        foreach (var row in listMemberRows)
        {
            var listMemberName = row.DestinationMemberMemberName;
            if (string.IsNullOrWhiteSpace(listMemberName)) continue;

            // row.EntityId is POCO-side (mirrors IceMapDTO.IceMapEntityId's own POCO/DTO split) —
            // the actual DTO-side child entity, matching every other DestinationMemberEntityId
            // value in this map, is EntityPocoToDtoLinkId. != 0, not > 0 — entity ids here are
            // routinely large negative numbers (see IceMapDTO.IceMapRootEntityId's identical
            // convention).
            var childEntityId = row.EntityPocoToDtoLinkId != 0 ? row.EntityPocoToDtoLinkId : row.EntityId;

            var groupingField = mapDefinition.IceMapDetailsArray
                .FirstOrDefault(d => d.DestinationMemberEntityId == childEntityId && d.IceMapDetailsIsFilterField == 0)
                ?.IceMapDetailsSourceFieldName;

            if (string.IsNullOrWhiteSpace(groupingField)) continue;

            result.Add(new ObjectListRelationshipDTO(
                row.DestinationMemberEntityId, childEntityId, listMemberName!, groupingField!));
        }

        return result;
    }
}