using System;
using System.Collections.Generic;

namespace NightclubArcadia.Skills
{
    /// <summary>
    /// Transient state modifiers (third of three modifier sources). Pure state — no check math.
    /// Use skillId "*" to apply to every skill.
    /// </summary>
    public sealed class SkillStateModifiers
    {
        readonly Dictionary<string, Dictionary<string, int>> _bySource =
            new Dictionary<string, Dictionary<string, int>>(StringComparer.Ordinal);

        public void Set(string sourceKey, string skillId, int delta)
        {
            if (string.IsNullOrEmpty(sourceKey))
            {
                throw new ArgumentException("Source key is required.", nameof(sourceKey));
            }

            if (string.IsNullOrEmpty(skillId))
            {
                throw new ArgumentException("Skill id is required.", nameof(skillId));
            }

            if (!_bySource.TryGetValue(sourceKey, out var map))
            {
                map = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase);
                _bySource[sourceKey] = map;
            }

            map[skillId] = delta;
        }

        public void Clear(string sourceKey)
        {
            if (string.IsNullOrEmpty(sourceKey))
            {
                return;
            }

            _bySource.Remove(sourceKey);
        }

        public int TotalFor(string skillId)
        {
            if (string.IsNullOrEmpty(skillId))
            {
                return 0;
            }

            var total = 0;
            foreach (var map in _bySource.Values)
            {
                if (map.TryGetValue(skillId, out var specific))
                {
                    total += specific;
                }

                if (map.TryGetValue("*", out var wildcard))
                {
                    total += wildcard;
                }
            }

            return total;
        }
    }
}