using System.Collections.Concurrent;

namespace NeonSprawl.Server.Game.Factions;

/// <summary>Thread-safe in-memory append-only reputation delta audit log (NEO-135).</summary>
public sealed class InMemoryReputationDeltaStore : IReputationDeltaStore
{
    private readonly ConcurrentDictionary<string, ReputationDeltaRow> rowsById = new(StringComparer.Ordinal);

    private readonly ConcurrentDictionary<string, object> idLocks = new(StringComparer.Ordinal);

    /// <inheritdoc />
    public bool TryAppend(ReputationDeltaRow row)
    {
        if (!IsValidRow(row))
        {
            return false;
        }

        var normalized = row with
        {
            Id = row.Id.Trim(),
            PlayerId = FactionStandingIds.NormalizePlayerId(row.PlayerId),
            FactionId = FactionStandingIds.NormalizeFactionId(row.FactionId),
            SourceKind = row.SourceKind.Trim(),
            SourceId = row.SourceId.Trim(),
        };

        lock (idLocks.GetOrAdd(normalized.Id, _ => new object()))
        {
            if (rowsById.ContainsKey(normalized.Id))
            {
                return false;
            }

            rowsById[normalized.Id] = normalized;
            return true;
        }
    }

    /// <inheritdoc />
    public IReadOnlyList<ReputationDeltaRow> GetDeltasForPlayer(string playerId, int? limit = null)
    {
        var player = FactionStandingIds.NormalizePlayerId(playerId);
        if (player.Length == 0)
        {
            return [];
        }

        IEnumerable<ReputationDeltaRow> query = rowsById.Values
            .Where(r => string.Equals(r.PlayerId, player, StringComparison.Ordinal))
            .OrderBy(static r => r.RecordedAt)
            .ThenBy(static r => r.Id, StringComparer.Ordinal);

        if (limit is > 0)
        {
            query = query.Take(limit.Value);
        }

        return query.ToArray();
    }

    private static bool IsValidRow(ReputationDeltaRow row) =>
        row.Id.Trim().Length > 0 &&
        FactionStandingIds.NormalizePlayerId(row.PlayerId).Length > 0 &&
        FactionStandingIds.NormalizeFactionId(row.FactionId).Length > 0 &&
        row.SourceKind.Trim().Length > 0 &&
        row.SourceId.Trim().Length > 0;
}