using System.Text.Json;
using System.Text.Json.Serialization;
using ZB.MOM.WW.OtOpcUa.Core.Hosting;

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

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

    /// <summary>
    /// Registers the AB CIP driver factory with the driver registry.
    /// </summary>
    /// <param name="registry">The driver factory registry to register with.</param>
    public static void Register(DriverFactoryRegistry registry)
    {
        ArgumentNullException.ThrowIfNull(registry);
        registry.Register(DriverTypeName, CreateInstance);
    }

    /// <summary>
    /// Creates an instance of the AB CIP driver from configuration.
    /// </summary>
    /// <param name="driverInstanceId">The unique identifier for this driver instance.</param>
    /// <param name="driverConfigJson">The driver configuration as a JSON string.</param>
    /// <returns>A configured <see cref="AbCipDriver"/> instance.</returns>
    internal static AbCipDriver CreateInstance(string driverInstanceId, string driverConfigJson)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(driverInstanceId);
        var options = ParseOptions(driverInstanceId, driverConfigJson);
        return new AbCipDriver(options, driverInstanceId);
    }

    /// <summary>
    ///     Deserialise an AB CIP driver-config JSON document into <see cref="AbCipDriverOptions"/>.
    ///     Shared by <see cref="CreateInstance"/> (first construction) and
    ///     <see cref="AbCipDriver.InitializeAsync"/> / <see cref="AbCipDriver.ReinitializeAsync"/>
    ///     so a reinitialize with a changed config JSON (new device, new tag, changed timeout)
    ///     actually takes effect rather than being silently discarded.
    /// </summary>
    /// <param name="driverInstanceId">The unique identifier for this driver instance.</param>
    /// <param name="driverConfigJson">The driver configuration as a JSON string.</param>
    /// <returns>Parsed driver options.</returns>
    internal static AbCipDriverOptions ParseOptions(string driverInstanceId, string driverConfigJson)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(driverInstanceId);
        ArgumentException.ThrowIfNullOrWhiteSpace(driverConfigJson);

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

        return new AbCipDriverOptions
        {
            Devices = dto.Devices is { Count: > 0 }
                ? [.. dto.Devices.Select(d => new AbCipDeviceOptions(
                    HostAddress: d.HostAddress ?? throw new InvalidOperationException(
                        $"AB CIP config for '{driverInstanceId}' has a device missing HostAddress"),
                    PlcFamily: ParseEnum<AbCipPlcFamily>(d.PlcFamily, "device", driverInstanceId, "PlcFamily",
                        fallback: AbCipPlcFamily.ControlLogix),
                    DeviceName: d.DeviceName,
                    AllowPacking: d.AllowPacking,
                    ConnectionSize: d.ConnectionSize))]
                : [],
            Tags = dto.Tags is { Count: > 0 }
                ? [.. dto.Tags.Select(t => BuildTag(t, driverInstanceId))]
                : [],
            Probe = new AbCipProbeOptions
            {
                Enabled = dto.Probe?.Enabled ?? true,
                Interval = TimeSpan.FromMilliseconds(dto.Probe?.IntervalMs ?? 5_000),
                Timeout = TimeSpan.FromMilliseconds(dto.Probe?.TimeoutMs ?? 2_000),
                ProbeTagPath = dto.Probe?.ProbeTagPath,
            },
            Timeout = TimeSpan.FromMilliseconds(dto.TimeoutMs ?? 2_000),
            EnableControllerBrowse = dto.EnableControllerBrowse ?? false,
            EnableAlarmProjection = dto.EnableAlarmProjection ?? false,
            AlarmPollInterval = TimeSpan.FromMilliseconds(dto.AlarmPollIntervalMs ?? 1_000),
            EnableDeclarationOnlyUdtGrouping = dto.EnableDeclarationOnlyUdtGrouping ?? false,
        };
    }

    private static AbCipTagDefinition BuildTag(AbCipTagDto t, string driverInstanceId) =>
        new(
            Name: t.Name ?? throw new InvalidOperationException(
                $"AB CIP config for '{driverInstanceId}' has a tag missing Name"),
            DeviceHostAddress: t.DeviceHostAddress ?? throw new InvalidOperationException(
                $"AB CIP tag '{t.Name}' in '{driverInstanceId}' missing DeviceHostAddress"),
            TagPath: t.TagPath ?? throw new InvalidOperationException(
                $"AB CIP tag '{t.Name}' in '{driverInstanceId}' missing TagPath"),
            DataType: ParseEnum<AbCipDataType>(t.DataType, t.Name, driverInstanceId, "DataType"),
            Writable: t.Writable ?? true,
            WriteIdempotent: t.WriteIdempotent ?? false,
            Members: t.Members is { Count: > 0 }
                ? [.. t.Members.Select(m => new AbCipStructureMember(
                    Name: m.Name ?? throw new InvalidOperationException(
                        $"AB CIP tag '{t.Name}' in '{driverInstanceId}' has a member missing Name"),
                    DataType: ParseEnum<AbCipDataType>(m.DataType, t.Name, driverInstanceId,
                        $"Members[{m.Name}].DataType"),
                    Writable: m.Writable ?? true,
                    WriteIdempotent: m.WriteIdempotent ?? false,
                    ElementCount: m.ElementCount is > 0 ? m.ElementCount.Value : 1,
                    IsArray: m.IsArray))]
                : null,
            SafetyTag: t.SafetyTag ?? false,
            ElementCount: t.ElementCount is > 0 ? t.ElementCount.Value : 1,
            IsArray: t.IsArray);

    private static T ParseEnum<T>(string? raw, string? tagName, string driverInstanceId, string field,
        T? fallback = null) where T : struct, Enum
    {
        if (string.IsNullOrWhiteSpace(raw))
        {
            if (fallback.HasValue) return fallback.Value;
            throw new InvalidOperationException(
                $"AB CIP tag '{tagName ?? "<unnamed>"}' in '{driverInstanceId}' missing {field}");
        }
        return Enum.TryParse<T>(raw, ignoreCase: true, out var v)
            ? v
            : throw new InvalidOperationException(
                $"AB CIP 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 AbCipDriverConfigDto
    {
        /// <summary>
        /// Gets or sets the timeout in milliseconds for operations.
        /// </summary>
        public int? TimeoutMs { get; init; }

        /// <summary>
        /// Gets or sets whether controller browsing is enabled.
        /// </summary>
        public bool? EnableControllerBrowse { get; init; }

        /// <summary>
        /// Gets or sets whether alarm projection is enabled.
        /// </summary>
        public bool? EnableAlarmProjection { get; init; }

        /// <summary>
        /// Gets or sets whether declaration-only UDT grouping is enabled.
        /// </summary>
        public bool? EnableDeclarationOnlyUdtGrouping { get; init; }

        /// <summary>
        /// Gets or sets the alarm poll interval in milliseconds.
        /// </summary>
        public int? AlarmPollIntervalMs { get; init; }

        /// <summary>
        /// Gets or sets the list of devices to connect to.
        /// </summary>
        public List<AbCipDeviceDto>? Devices { get; init; }

        /// <summary>
        /// Gets or sets the list of tags to monitor.
        /// </summary>
        public List<AbCipTagDto>? Tags { get; init; }

        /// <summary>
        /// Gets or sets the probe configuration.
        /// </summary>
        public AbCipProbeDto? Probe { get; init; }
    }

    internal sealed class AbCipDeviceDto
    {
        /// <summary>
        /// Gets or sets the host address of the device.
        /// </summary>
        public string? HostAddress { get; init; }

        /// <summary>
        /// Gets or sets the PLC family.
        /// </summary>
        public string? PlcFamily { get; init; }

        /// <summary>
        /// Gets or sets the device name.
        /// </summary>
        public string? DeviceName { get; init; }

        /// <summary>
        /// Gets or sets whether packing is allowed.
        /// </summary>
        public bool? AllowPacking { get; init; }

        /// <summary>
        /// Gets or sets the connection size.
        /// </summary>
        public int? ConnectionSize { get; init; }
    }

    internal sealed class AbCipTagDto
    {
        /// <summary>
        /// Gets or sets the tag name.
        /// </summary>
        public string? Name { get; init; }

        /// <summary>
        /// Gets or sets the device host address.
        /// </summary>
        public string? DeviceHostAddress { get; init; }

        /// <summary>
        /// Gets or sets the tag path.
        /// </summary>
        public string? TagPath { get; init; }

        /// <summary>
        /// Gets or sets the data type.
        /// </summary>
        public string? DataType { get; init; }

        /// <summary>
        /// Gets or sets whether the tag is writable.
        /// </summary>
        public bool? Writable { get; init; }

        /// <summary>
        /// Gets or sets whether write is idempotent.
        /// </summary>
        public bool? WriteIdempotent { get; init; }

        /// <summary>
        /// Gets or sets the list of structure members.
        /// </summary>
        public List<AbCipMemberDto>? Members { get; init; }

        /// <summary>
        /// Gets or sets whether this is a safety tag.
        /// </summary>
        public bool? SafetyTag { get; init; }

        /// <summary>
        /// Gets or sets the explicit 1-D array signal — <c>true</c> ⟺ the tag is an array (even a
        /// 1-element one). Mirrors <c>AbCipTagDefinition.IsArray</c>; optional (absent ⇒ scalar).
        /// </summary>
        [JsonPropertyName("isArray")]
        public bool IsArray { get; init; }

        /// <summary>
        /// Gets or sets the number of elements for a 1-D array tag; <c>1</c> (or absent) for a scalar.
        /// Mirrors <c>AbCipTagDefinition.ElementCount</c>; only positive values are honoured.
        /// </summary>
        [JsonPropertyName("elementCount")]
        public int? ElementCount { get; init; }
    }

    internal sealed class AbCipMemberDto
    {
        /// <summary>
        /// Gets or sets the member name.
        /// </summary>
        public string? Name { get; init; }

        /// <summary>
        /// Gets or sets the data type.
        /// </summary>
        public string? DataType { get; init; }

        /// <summary>
        /// Gets or sets whether the member is writable.
        /// </summary>
        public bool? Writable { get; init; }

        /// <summary>
        /// Gets or sets whether write is idempotent.
        /// </summary>
        public bool? WriteIdempotent { get; init; }

        /// <summary>
        /// Gets or sets the explicit 1-D array signal for the member — <c>true</c> ⟺ the member is
        /// an array (even a 1-element one). Mirrors <c>AbCipStructureMember.IsArray</c>; optional.
        /// </summary>
        [JsonPropertyName("isArray")]
        public bool IsArray { get; init; }

        /// <summary>
        /// Gets or sets the number of elements for a 1-D array member; <c>1</c> (or absent) for a
        /// scalar. Mirrors <c>AbCipStructureMember.ElementCount</c>; only positive values are honoured.
        /// </summary>
        [JsonPropertyName("elementCount")]
        public int? ElementCount { get; init; }
    }

    internal sealed class AbCipProbeDto
    {
        /// <summary>
        /// Gets or sets 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 tag path.
        /// </summary>
        public string? ProbeTagPath { get; init; }
    }
}