using System.Text.Json;
using System.Text.Json.Serialization;
using Microsoft.Extensions.Logging;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Hosting;

namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus;

/// <summary>
///     Static factory registration helper for <see cref="ModbusDriver"/>. Server's Program.cs
///     calls <see cref="Register"/> once at startup; the bootstrapper then
///     materialises Modbus DriverInstance rows from the central config DB into live driver
///     instances. Mirrors <c>GalaxyProxyDriverFactoryExtensions</c> / <c>FocasDriverFactoryExtensions</c>.
/// </summary>
public static class ModbusDriverFactoryExtensions
{
    public const string DriverTypeName = "Modbus";

    /// <summary>
    ///     Register the Modbus factory with the driver registry. The optional
    ///     <paramref name="loggerFactory"/> is captured at registration time and used to
    ///     construct an <see cref="ILogger{ModbusDriver}"/> per driver instance — without it,
    ///     the driver runs with the null logger (existing tests and standalone callers stay
    ///     unchanged).
    /// </summary>
    /// <param name="registry">The driver factory registry to register with.</param>
    /// <param name="loggerFactory">Optional logger factory for creating loggers per driver instance.</param>
    public static void Register(DriverFactoryRegistry registry, ILoggerFactory? loggerFactory = null)
    {
        ArgumentNullException.ThrowIfNull(registry);
        registry.Register(DriverTypeName, (id, json) => CreateInstance(id, json, loggerFactory));
    }

    /// <summary>Public for the Server-side bootstrapper + test consumers (Admin.Tests, etc.).</summary>
    /// <param name="driverInstanceId">The unique identifier for the driver instance.</param>
    /// <param name="driverConfigJson">The JSON configuration string for the driver.</param>
    /// <returns>The constructed <see cref="ModbusDriver"/> instance.</returns>
    public static ModbusDriver CreateInstance(string driverInstanceId, string driverConfigJson)
        => CreateInstance(driverInstanceId, driverConfigJson, loggerFactory: null);

    /// <summary>Logger-aware overload — used by <see cref="Register"/>'s closure when wired through DI.</summary>
    /// <param name="driverInstanceId">The unique identifier for the driver instance.</param>
    /// <param name="driverConfigJson">The JSON configuration string for the driver.</param>
    /// <param name="loggerFactory">Optional logger factory for creating loggers per driver instance.</param>
    /// <returns>The constructed <see cref="ModbusDriver"/> instance.</returns>
    public static ModbusDriver CreateInstance(string driverInstanceId, string driverConfigJson, ILoggerFactory? loggerFactory)
    {
        return new ModbusDriver(
            ParseOptions(driverInstanceId, driverConfigJson), driverInstanceId,
            transportFactory: null,
            logger: loggerFactory?.CreateLogger<ModbusDriver>());
    }

    /// <summary>
    ///     Parses a Modbus <c>DriverConfig</c> JSON document into typed options. Extracted from
    ///     <see cref="CreateInstance(string,string,ILoggerFactory?)"/> so <see cref="ModbusDriver.InitializeAsync"/>
    ///     can re-parse a CHANGED config on reinitialize (Gitea #516) rather than serving the options it was
    ///     constructed with — which silently discarded every edit while the deployment still sealed green.
    /// </summary>
    /// <param name="driverInstanceId">The unique identifier for the driver instance.</param>
    /// <param name="driverConfigJson">The JSON configuration string for the driver.</param>
    /// <returns>The parsed <see cref="ModbusDriverOptions"/>.</returns>
    internal static ModbusDriverOptions ParseOptions(string driverInstanceId, string driverConfigJson)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(driverInstanceId);
        ArgumentException.ThrowIfNullOrWhiteSpace(driverConfigJson);

        var dto = JsonSerializer.Deserialize<ModbusDriverConfigDto>(driverConfigJson, JsonOptions)
            ?? throw new InvalidOperationException(
                $"Modbus driver config for '{driverInstanceId}' deserialised to null");

        if (string.IsNullOrWhiteSpace(dto.Host))
            throw new InvalidOperationException(
                $"Modbus driver config for '{driverInstanceId}' missing required Host");

        var options = new ModbusDriverOptions
        {
            Host = dto.Host!,
            Port = dto.Port ?? 502,
            UnitId = dto.UnitId ?? 1,
            Timeout = TimeSpan.FromMilliseconds(dto.TimeoutMs ?? 2_000),
            MaxRegistersPerRead = dto.MaxRegistersPerRead ?? 125,
            MaxRegistersPerWrite = dto.MaxRegistersPerWrite ?? 123,
            MaxCoilsPerRead = dto.MaxCoilsPerRead ?? 2000,
            UseFC15ForSingleCoilWrites = dto.UseFC15ForSingleCoilWrites ?? false,
            UseFC16ForSingleRegisterWrites = dto.UseFC16ForSingleRegisterWrites ?? false,
            DisableFC23 = dto.DisableFC23 ?? false,
            WriteOnChangeOnly = dto.WriteOnChangeOnly ?? false,
            MaxReadGap = dto.MaxReadGap ?? 0,
            Family = dto.Family is null ? ModbusFamily.Generic
                : ParseEnum<ModbusFamily>(dto.Family, "<driver-level>", driverInstanceId, "Family"),
            MelsecSubFamily = dto.MelsecSubFamily is null ? MelsecFamily.Q_L_iQR
                : ParseEnum<MelsecFamily>(dto.MelsecSubFamily, "<driver-level>", driverInstanceId, "MelsecSubFamily"),
            Transport = dto.Transport is null ? ModbusTransportMode.Tcp
                : ParseEnum<ModbusTransportMode>(dto.Transport, "<driver-level>", driverInstanceId, "Transport"),
            AutoProhibitReprobeInterval = dto.AutoProhibitReprobeMs is { } reprobeMs ? TimeSpan.FromMilliseconds(reprobeMs) : null,
            AutoReconnect = dto.AutoReconnect ?? true,
            // v3: the deploy artifact (Wave C) populates rawTags with the cluster's authored raw Modbus
            // tags. The driver maps each RawTagEntry's TagConfig blob through ModbusTagDefinitionFactory
            // at Initialize; the legacy pre-declared DTO tag path (structured/AddressString → BuildTag)
            // is retired.
            RawTags = dto.RawTags is { Count: > 0 } ? [.. dto.RawTags] : [],
            Probe = new ModbusProbeOptions
            {
                Enabled = dto.Probe?.Enabled ?? true,
                Interval = TimeSpan.FromMilliseconds(dto.Probe?.IntervalMs ?? 5_000),
                Timeout = TimeSpan.FromMilliseconds(dto.Probe?.TimeoutMs ?? 2_000),
                ProbeAddress = dto.Probe?.ProbeAddress ?? 0,
            },
            KeepAlive = dto.KeepAlive is null ? new ModbusKeepAliveOptions() : new ModbusKeepAliveOptions
            {
                Enabled = dto.KeepAlive.Enabled ?? true,
                Time = TimeSpan.FromMilliseconds(dto.KeepAlive.TimeMs ?? 30_000),
                Interval = TimeSpan.FromMilliseconds(dto.KeepAlive.IntervalMs ?? 10_000),
                RetryCount = dto.KeepAlive.RetryCount ?? 3,
            },
            IdleDisconnectTimeout = dto.IdleDisconnectMs is { } ms ? TimeSpan.FromMilliseconds(ms) : null,
            Reconnect = dto.Reconnect is null ? new ModbusReconnectOptions() : new ModbusReconnectOptions
            {
                InitialDelay = TimeSpan.FromMilliseconds(dto.Reconnect.InitialDelayMs ?? 0),
                MaxDelay = TimeSpan.FromMilliseconds(dto.Reconnect.MaxDelayMs ?? 30_000),
                BackoffMultiplier = dto.Reconnect.BackoffMultiplier ?? 2.0,
            },
        };

        return options;
    }

    private static T ParseEnum<T>(string? raw, string? tagName, string driverInstanceId, string field) where T : struct, Enum
    {
        if (string.IsNullOrWhiteSpace(raw))
            throw new InvalidOperationException(
                $"Modbus tag '{tagName ?? "<unnamed>"}' in '{driverInstanceId}' missing {field}");
        return Enum.TryParse<T>(raw, ignoreCase: true, out var v)
            ? v
            : throw new InvalidOperationException(
                $"Modbus tag '{tagName}' has unknown {field} '{raw}'. " +
                $"Expected one of {string.Join(", ", Enum.GetNames<T>())}");
    }

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNameCaseInsensitive = true,
        ReadCommentHandling = JsonCommentHandling.Skip,
        AllowTrailingCommas = true,
    };

    internal sealed class ModbusDriverConfigDto
    {
        /// <summary>Gets or sets the host address.</summary>
        public string? Host { get; init; }
        /// <summary>Gets or sets the port number.</summary>
        public int? Port { get; init; }
        /// <summary>Gets or sets the unit identifier.</summary>
        public byte? UnitId { get; init; }
        /// <summary>Gets or sets the timeout in milliseconds.</summary>
        public int? TimeoutMs { get; init; }
        /// <summary>Gets or sets the maximum number of registers per read operation.</summary>
        public ushort? MaxRegistersPerRead { get; init; }
        /// <summary>Gets or sets the maximum number of registers per write operation.</summary>
        public ushort? MaxRegistersPerWrite { get; init; }
        /// <summary>Gets or sets the maximum number of coils per read operation.</summary>
        public ushort? MaxCoilsPerRead { get; init; }
        /// <summary>Gets or sets a value indicating whether to use function code 15 for single coil writes.</summary>
        public bool? UseFC15ForSingleCoilWrites { get; init; }
        /// <summary>Gets or sets a value indicating whether to use function code 16 for single register writes.</summary>
        public bool? UseFC16ForSingleRegisterWrites { get; init; }
        /// <summary>Gets or sets a value indicating whether to disable function code 23.</summary>
        public bool? DisableFC23 { get; init; }
        /// <summary>Gets or sets a value indicating whether to write only on change.</summary>
        public bool? WriteOnChangeOnly { get; init; }
        /// <summary>Gets or sets the maximum gap between register addresses for coalescing.</summary>
        public ushort? MaxReadGap { get; init; }
        /// <summary>Gets or sets the Modbus family type.</summary>
        public string? Family { get; init; }
        /// <summary>Gets or sets the Melsec subfamily.</summary>
        public string? MelsecSubFamily { get; init; }
        /// <summary>Gets or sets the wire transport mode (Tcp / RtuOverTcp). Null defaults to Tcp.</summary>
        public string? Transport { get; init; }
        /// <summary>Gets or sets the automatic prohibition reprobei interval in milliseconds.</summary>
        public int? AutoProhibitReprobeMs { get; init; }
        /// <summary>Gets or sets a value indicating whether automatic reconnection is enabled.</summary>
        public bool? AutoReconnect { get; init; }
        /// <summary>Gets or sets the authored raw tags (RawPath + TagConfig blob + WriteIdempotent) the
        /// deploy artifact delivers. The driver maps each through the tag-definition factory at Initialize.</summary>
        public List<RawTagEntry>? RawTags { get; init; }
        /// <summary>Gets or sets the probe configuration.</summary>
        public ModbusProbeDto? Probe { get; init; }

        /// <summary>Gets or sets the keep-alive configuration (connection-layer knob).</summary>
        public ModbusKeepAliveDto? KeepAlive { get; init; }
        /// <summary>Gets or sets the idle disconnect timeout in milliseconds.</summary>
        public int? IdleDisconnectMs { get; init; }
        /// <summary>Gets or sets the reconnect configuration.</summary>
        public ModbusReconnectDto? Reconnect { get; init; }
    }

    internal sealed class ModbusKeepAliveDto
    {
        /// <summary>Gets or sets a value indicating whether keep-alive is enabled.</summary>
        public bool? Enabled { get; init; }
        /// <summary>Gets or sets the keep-alive time in milliseconds.</summary>
        public int? TimeMs { get; init; }
        /// <summary>Gets or sets the keep-alive interval in milliseconds.</summary>
        public int? IntervalMs { get; init; }
        /// <summary>Gets or sets the retry count.</summary>
        public int? RetryCount { get; init; }
    }

    internal sealed class ModbusReconnectDto
    {
        /// <summary>Gets or sets the initial reconnect delay in milliseconds.</summary>
        public int? InitialDelayMs { get; init; }
        /// <summary>Gets or sets the maximum reconnect delay in milliseconds.</summary>
        public int? MaxDelayMs { get; init; }
        /// <summary>Gets or sets the backoff multiplier for exponential reconnect delays.</summary>
        public double? BackoffMultiplier { get; init; }
    }

    internal sealed class ModbusProbeDto
    {
        /// <summary>Gets or sets a value indicating whether probing is enabled.</summary>
        public bool? Enabled { get; init; }
        /// <summary>Gets or sets the probe interval in milliseconds.</summary>
        public int? IntervalMs { get; init; }
        /// <summary>Gets or sets the probe timeout in milliseconds.</summary>
        public int? TimeoutMs { get; init; }
        /// <summary>Gets or sets the probe register address.</summary>
        public ushort? ProbeAddress { get; init; }
    }
}
