using System.IO;
using System.Text.Json;
using System.Text.Json.Serialization;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Hosting;
using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Import;
using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.PlcFamilies;

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

/// <summary>
///     Static factory registration helper for <see cref="AbLegacyDriver"/>. Server's Program.cs
///     calls <see cref="Register"/> once at startup; the bootstrapper (task #248) then
///     materialises AB Legacy DriverInstance rows from the central config DB into live
///     driver instances. Mirrors <c>GalaxyProxyDriverFactoryExtensions</c>.
/// </summary>
public static class AbLegacyDriverFactoryExtensions
{
    public const string DriverTypeName = "AbLegacy";

    public static void Register(DriverFactoryRegistry registry)
    {
        ArgumentNullException.ThrowIfNull(registry);
        registry.Register(DriverTypeName, CreateInstance);
    }

    internal static AbLegacyDriver CreateInstance(string driverInstanceId, string driverConfigJson)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(driverInstanceId);
        ArgumentException.ThrowIfNullOrWhiteSpace(driverConfigJson);

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

        var options = new AbLegacyDriverOptions
        {
            Devices = dto.Devices is { Count: > 0 }
                ? [.. dto.Devices.Select(d => new AbLegacyDeviceOptions(
                    HostAddress: d.HostAddress ?? throw new InvalidOperationException(
                        $"AB Legacy config for '{driverInstanceId}' has a device missing HostAddress"),
                    PlcFamily: ParseEnum<AbLegacyPlcFamily>(d.PlcFamily, driverInstanceId, "PlcFamily",
                        fallback: AbLegacyPlcFamily.Slc500),
                    DeviceName: d.DeviceName,
                    // PR 9 — per-device timeout / retry overrides. Device-level wins over driver-wide.
                    Timeout: d.TimeoutMs is int devMs ? TimeSpan.FromMilliseconds(devMs) : null,
                    Retries: d.Retries))]
                : [],
            Tags = dto.Tags is { Count: > 0 }
                ? [.. dto.Tags.Select(t => new AbLegacyTagDefinition(
                    Name: t.Name ?? throw new InvalidOperationException(
                        $"AB Legacy config for '{driverInstanceId}' has a tag missing Name"),
                    DeviceHostAddress: t.DeviceHostAddress ?? throw new InvalidOperationException(
                        $"AB Legacy tag '{t.Name}' in '{driverInstanceId}' missing DeviceHostAddress"),
                    Address: t.Address ?? throw new InvalidOperationException(
                        $"AB Legacy tag '{t.Name}' in '{driverInstanceId}' missing Address"),
                    DataType: ParseEnum<AbLegacyDataType>(t.DataType, driverInstanceId, "DataType",
                        tagName: t.Name),
                    Writable: t.Writable ?? true,
                    WriteIdempotent: t.WriteIdempotent ?? false,
                    ArrayLength: t.ArrayLength,
                    AbsoluteDeadband: t.AbsoluteDeadband,
                    PercentDeadband: t.PercentDeadband))]
                : [],
            Probe = new AbLegacyProbeOptions
            {
                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 ?? "S:0",
            },
            Timeout = TimeSpan.FromMilliseconds(dto.TimeoutMs ?? 2_000),
            // PR 9 — driver-wide retry default. null ≡ 0 retries (single attempt). Per-device
            // Retries on AbLegacyDeviceOptions still wins.
            Retries = dto.Retries,
        };

        return new AbLegacyDriver(options, driverInstanceId);
    }

    /// <summary>
    ///     ablegacy-11 / #254 — append RSLogix CSV symbol-export rows to
    ///     <paramref name="options"/> as <see cref="AbLegacyTagDefinition"/> entries bound to
    ///     <paramref name="deviceHostAddress"/>. Returns a new <see cref="AbLegacyDriverOptions"/>
    ///     with the imported tags concatenated onto the existing <c>Tags</c> list — useful both
    ///     at startup-time (server-side bootstrap that wants to seed a device's address space
    ///     from a customer-supplied CSV) and from the CLI (<c>import-rslogix</c> emits the
    ///     resulting JSON fragment for hand-merging into an appsettings file).
    /// </summary>
    /// <remarks>
    ///     <para>
    ///         The importer is permissive by default — malformed rows are logged and skipped;
    ///         the resulting <see cref="RsLogixImportResult"/> counts surface on
    ///         <paramref name="result"/> for callers that want to assert "we got the row count
    ///         we expected".
    ///     </para>
    ///     <para>
    ///         RSLogix 500's <c>.RSS</c> + RSLogix 5's <c>.RSP</c> binary project files are
    ///         out of scope for v1 — the binary format is proprietary and undocumented; no
    ///         libplctag or community parser exists. Customers must export to text/CSV via
    ///         RSLogix's "Tools → Database → Save" or "Database Export" before pointing the
    ///         importer at the file. See <c>docs/drivers/AbLegacy-RSLogix-Import.md</c>.
    ///     </para>
    /// </remarks>
    public static AbLegacyDriverOptions AddRsLogixImport(
        this AbLegacyDriverOptions options,
        string path,
        string deviceHostAddress,
        out RsLogixImportResult result,
        ImportOptions? importOptions = null,
        ILogger<RsLogixSymbolImport>? logger = null)
    {
        ArgumentNullException.ThrowIfNull(options);
        ArgumentException.ThrowIfNullOrWhiteSpace(path);
        ArgumentException.ThrowIfNullOrWhiteSpace(deviceHostAddress);

        using var stream = File.OpenRead(path);
        var importer = new RsLogixSymbolImport(logger ?? NullLogger<RsLogixSymbolImport>.Instance);
        result = importer.Parse(stream, deviceHostAddress, importOptions);

        // Concat onto whatever's already on the options — the importer is additive so
        // hand-edited Tags rows (e.g., system-status fields not surfaced by RSLogix) keep
        // sitting alongside the bulk-imported symbol rows. Use init-syntax with-expression
        // so the returned options keeps every other field (Devices, Probe, Timeout, …)
        // untouched.
        var merged = new List<AbLegacyTagDefinition>(options.Tags.Count + result.Tags.Count);
        merged.AddRange(options.Tags);
        merged.AddRange(result.Tags);
        return new AbLegacyDriverOptions
        {
            Devices = options.Devices,
            Tags = merged,
            Probe = options.Probe,
            Timeout = options.Timeout,
            Retries = options.Retries,
        };
    }

    /// <summary>
    ///     CLI-friendly overload that returns the <see cref="RsLogixImportResult"/> alongside
    ///     the modified options as a tuple. Mirrors <see cref="AddRsLogixImport"/> but avoids
    ///     the <c>out</c> parameter for call sites that prefer pattern-matched destructuring.
    /// </summary>
    public static (AbLegacyDriverOptions Options, RsLogixImportResult Result) AddRsLogixImportWithResult(
        this AbLegacyDriverOptions options,
        string path,
        string deviceHostAddress,
        ImportOptions? importOptions = null,
        ILogger<RsLogixSymbolImport>? logger = null)
    {
        var updated = options.AddRsLogixImport(path, deviceHostAddress, out var result, importOptions, logger);
        return (updated, result);
    }

    private static T ParseEnum<T>(string? raw, string driverInstanceId, string field,
        string? tagName = null, T? fallback = null) where T : struct, Enum
    {
        if (string.IsNullOrWhiteSpace(raw))
        {
            if (fallback.HasValue) return fallback.Value;
            throw new InvalidOperationException(
                $"AB Legacy {(tagName is null ? "config" : $"tag '{tagName}'")} in '{driverInstanceId}' missing {field}");
        }
        return Enum.TryParse<T>(raw, ignoreCase: true, out var v)
            ? v
            : throw new InvalidOperationException(
                $"AB Legacy {(tagName is null ? "config" : $"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 AbLegacyDriverConfigDto
    {
        public int? TimeoutMs { get; init; }
        /// <summary>
        ///     PR 9 — driver-wide retry count for transient <c>BadCommunicationError</c> reads.
        ///     <c>null</c> ≡ <c>0</c> (single attempt). A per-device override on
        ///     <see cref="AbLegacyDeviceDto.Retries"/> wins.
        /// </summary>
        public int? Retries { get; init; }
        public List<AbLegacyDeviceDto>? Devices { get; init; }
        public List<AbLegacyTagDto>? Tags { get; init; }
        public AbLegacyProbeDto? Probe { get; init; }
    }

    internal sealed class AbLegacyDeviceDto
    {
        public string? HostAddress { get; init; }
        public string? PlcFamily { get; init; }
        public string? DeviceName { get; init; }

        /// <summary>
        ///     PR 9 — optional per-device timeout in ms. Wins over the driver-wide
        ///     <see cref="AbLegacyDriverConfigDto.TimeoutMs"/>. Tune this per chassis: SLC 5/01
        ///     RS-232 ≈ 5000, SLC 5/05 ≈ 2000, MicroLogix 1100 ≈ 3000.
        /// </summary>
        public int? TimeoutMs { get; init; }

        /// <summary>
        ///     PR 9 — optional per-device retry count for transient <c>BadCommunicationError</c>
        ///     reads. Wins over the driver-wide <see cref="AbLegacyDriverConfigDto.Retries"/>.
        ///     <c>null</c> at both levels = single attempt.
        /// </summary>
        public int? Retries { get; init; }
    }

    internal sealed class AbLegacyTagDto
    {
        public string? Name { get; init; }
        public string? DeviceHostAddress { get; init; }
        public string? Address { get; init; }
        public string? DataType { get; init; }
        public bool? Writable { get; init; }
        public bool? WriteIdempotent { get; init; }
        /// <summary>
        ///     PR 7 — optional override for the parsed array suffix. When set and &gt; 1 the
        ///     driver issues a single contiguous PCCC block read for N elements.
        /// </summary>
        public int? ArrayLength { get; init; }

        /// <summary>
        ///     PR 8 — optional absolute change filter for numeric tags. <c>OnDataChange</c> is
        ///     suppressed unless <c>|new - prev| &gt;= AbsoluteDeadband</c>. Booleans bypass;
        ///     strings + status changes always publish.
        /// </summary>
        public double? AbsoluteDeadband { get; init; }

        /// <summary>
        ///     PR 8 — optional percent-of-previous change filter for numeric tags.
        ///     <c>OnDataChange</c> is suppressed unless <c>|new - prev| &gt;= |prev * Percent / 100|</c>.
        ///     <c>prev == 0</c> always publishes (avoids division-by-zero).
        /// </summary>
        public double? PercentDeadband { get; init; }
    }

    internal sealed class AbLegacyProbeDto
    {
        public bool? Enabled { get; init; }
        public int? IntervalMs { get; init; }
        public int? TimeoutMs { get; init; }
        public string? ProbeAddress { get; init; }
    }
}