using System;
using System.Collections.Generic;
using ArchestrA;
using ZB.MOM.WW.OtOpcUa.Historian.Aveva;
using ZB.MOM.WW.OtOpcUa.Host.Configuration;

namespace ZB.MOM.WW.OtOpcUa.Historian.Aveva.Tests
{
    /// <summary>
    ///     Fake Historian connection factory for tests. Controls whether connections
    ///     succeed, fail, or timeout without requiring the real Historian SDK runtime.
    /// </summary>
    internal sealed class FakeHistorianConnectionFactory : IHistorianConnectionFactory
    {
        /// <summary>
        ///     Exception thrown on every CreateAndConnect call unless a more specific rule in
        ///     <see cref="ServerBehaviors"/> or <see cref="OnConnect"/> fires first.
        /// </summary>
        public Exception? ConnectException { get; set; }

        public int ConnectCallCount { get; private set; }

        public Action<int>? OnConnect { get; set; }

        /// <summary>
        ///     Per-server-name override: if the requested <c>config.ServerName</c> has an entry
        ///     whose value is non-null, that exception is thrown instead of the global
        ///     <see cref="ConnectException"/>. Lets tests script cluster failover behavior like
        ///     "node A always fails; node B always succeeds".
        /// </summary>
        public Dictionary<string, Exception?> ServerBehaviors { get; } =
            new Dictionary<string, Exception?>(StringComparer.OrdinalIgnoreCase);

        /// <summary>
        ///     Ordered history of server names passed to CreateAndConnect so tests can assert the
        ///     picker's iteration order and failover sequence.
        /// </summary>
        public List<string> ConnectHistory { get; } = new List<string>();

        public HistorianAccess CreateAndConnect(HistorianConfiguration config, HistorianConnectionType type)
        {
            ConnectCallCount++;
            ConnectHistory.Add(config.ServerName);

            if (ServerBehaviors.TryGetValue(config.ServerName, out var serverException) && serverException != null)
                throw serverException;

            if (OnConnect != null)
            {
                OnConnect(ConnectCallCount);
            }
            else if (ConnectException != null)
            {
                throw ConnectException;
            }

            // Return a HistorianAccess that is not actually connected.
            // ReadRawAsync etc. will fail when they try to use it, which exercises
            // the HandleConnectionError → reconnect path.
            return new HistorianAccess();
        }
    }
}