using System;
using System.Collections.Generic;
using Lskj.CommandKernel;

namespace Lskj.AgentBridge
{
    public sealed class InMemoryPlanStore : IServerPlanStore
    {
        public const int MaximumPlans = 128;
        private readonly object _syncRoot = new object();
        private readonly Dictionary<string, CommandPlan> _plans =
            new Dictionary<string, CommandPlan>(StringComparer.OrdinalIgnoreCase);

        public void Save(CommandPlan plan)
        {
            if (plan == null) throw new ArgumentNullException("plan");
            if (string.IsNullOrWhiteSpace(plan.PlanId))
                throw new ArgumentException("计划 ID 不能为空。", "plan");
            lock (_syncRoot)
            {
                if (!_plans.ContainsKey(plan.PlanId)
                    && _plans.Count >= MaximumPlans)
                    throw new CommandKernelException(
                        "plan_store_capacity_exceeded",
                        "ERP 待执行计划已达到安全上限，请等待旧计划过期后重试。",
                        6);
                _plans[plan.PlanId] = plan;
            }
        }

        public bool TryGet(string planId, out CommandPlan plan)
        {
            if (string.IsNullOrWhiteSpace(planId))
            {
                plan = null;
                return false;
            }
            lock (_syncRoot)
            {
                return _plans.TryGetValue(planId, out plan);
            }
        }

        public void Remove(string planId)
        {
            if (string.IsNullOrWhiteSpace(planId)) return;
            lock (_syncRoot)
            {
                _plans.Remove(planId);
            }
        }

        public void PurgeExpired(DateTime utcNow)
        {
            lock (_syncRoot)
            {
                List<string> expired = new List<string>();
                foreach (KeyValuePair<string, CommandPlan> item in _plans)
                {
                    if (item.Value == null || item.Value.ExpiresAtUtc < utcNow)
                        expired.Add(item.Key);
                }
                foreach (string planId in expired) _plans.Remove(planId);
            }
        }
    }
}