using ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common;
using System.Collections.Frozen;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
using ZB.MOM.WW.OtOpcUa.Runtime.Historian;

namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb;

/// <summary>
///     <see cref="IHistorianBackendProvider"/> for the QuestDB historian. Supports every
///     <see cref="HistorianValueKind"/> and HistoryUpdate (soft delete). All seams share ONE connection helper, ONE
///     schema bootstrapper, ONE tag catalog (R7: the only "known tag" authority) and ONE WAL visibility wait, so the
///     schema is ensured once and known tags are cached once.
/// </summary>
/// <remarks>
///     The shared state is built on the first <c>Create*</c> call, not in the constructor: the constructor does no
///     validation and no I/O, so resolving the provider for a backend nobody consumes never fails on its options
///     (they are validated, consumer-gated, by the host's <c>ServerHistorianOptionsValidator</c>). The first
///     <c>Create*</c> call's service provider supplies the logger factory the shared pieces log through.
///     <para>The provider owns the shared connection pool and disposes it (IAsyncDisposable/IDisposable); the host
///     registers the provider through a DI factory so the container disposes it at shutdown.</para>
/// </remarks>
public sealed class QuestDbHistorianProvider : IHistorianBackendProvider, IAsyncDisposable, IDisposable
{
    private static readonly FrozenSet<HistorianValueKind> Kinds =
        Enum.GetValues<HistorianValueKind>().ToFrozenSet();

    private readonly QuestDbHistorianOptions _options;
    private readonly object _initLock = new();
    private Shared? _shared;
    private bool _disposed;

    /// <summary>Creates the provider over the <c>ServerHistorian:QuestDb</c> options (validated elsewhere).</summary>
    /// <param name="options">The <c>ServerHistorian:QuestDb</c> options.</param>
    /// <param name="maxTimeWeightedRawRows">The shared <c>ServerHistorian:MaxTimeWeightedRawRows</c> cap (&lt;= 0 = unbounded).</param>
    public QuestDbHistorianProvider(QuestDbHistorianOptions options,
        int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows)
    {
        _options = options ?? throw new ArgumentNullException(nameof(options));
        _maxTimeWeightedRawRows = maxTimeWeightedRawRows;
    }

    private readonly int _maxTimeWeightedRawRows;

    /// <inheritdoc />
    public string Name => "QuestDb";

    /// <inheritdoc />
    public IReadOnlySet<HistorianValueKind> SupportedKinds => Kinds;

    private static ILoggerFactory Loggers(IServiceProvider sp) =>
        (sp.GetService(typeof(ILoggerFactory)) as ILoggerFactory) ?? NullLoggerFactory.Instance;

    private Shared Get(IServiceProvider sp)
    {
        if (Volatile.Read(ref _shared) is { } built) return built;
        lock (_initLock)
        {
            if (_shared is { } raced) return raced;
            var loggers = Loggers(sp);
            ObjectDisposedException.ThrowIf(_disposed, this);
            var conn = new QuestDbConnection(_options, loggers.CreateLogger<QuestDbConnection>());
            var bootstrap = new QuestDbSchemaBootstrapper(conn, _options, loggers.CreateLogger<QuestDbSchemaBootstrapper>());
            var wal = new QuestDbWalVisibility(conn, _options.VisibilityTimeout, loggers.CreateLogger<QuestDbWalVisibility>());
            var shared = new Shared(conn, bootstrap, new QuestDbTagCatalog(conn, bootstrap, wal), wal);
            Volatile.Write(ref _shared, shared);
            return shared;
        }
    }

    /// <inheritdoc />
    public IHistorianDataSource CreateDataSource(IServiceProvider sp)
    {
        var s = Get(sp);
        return new QuestDbHistorianDataSource(s.Conn, s.Bootstrap, s.Catalog,
            Loggers(sp).CreateLogger<QuestDbHistorianDataSource>(), maxTimeWeightedRawRows: _maxTimeWeightedRawRows);
    }

    /// <inheritdoc />
    public IHistorianValueWriter CreateValueWriter(IServiceProvider sp)
    {
        var s = Get(sp);
        return new QuestDbHistorianValueWriter(s.Conn, s.Catalog, s.Wal,
            Loggers(sp).CreateLogger<QuestDbHistorianValueWriter>());
    }

    /// <inheritdoc />
    public IAlarmHistorianWriter CreateAlarmWriter(IServiceProvider sp)
    {
        var s = Get(sp);
        return new QuestDbAlarmHistorianWriter(s.Conn, s.Bootstrap, s.Wal,
            Loggers(sp).CreateLogger<QuestDbAlarmHistorianWriter>());
    }

    /// <inheritdoc />
    public IHistorianProvisioning CreateProvisioning(IServiceProvider sp)
    {
        var s = Get(sp);
        return new QuestDbTagProvisioner(s.Conn, s.Bootstrap, s.Catalog, s.Wal,
            Loggers(sp).CreateLogger<QuestDbTagProvisioner>());
    }

    /// <inheritdoc />
    /// <remarks>The soft-delete updater: deletes write tombstones (INSERT only, never QuestDB UPDATE/DELETE).</remarks>
    public IHistorianDataUpdater? CreateUpdater(IServiceProvider sp)
    {
        var s = Get(sp);
        return new QuestDbHistorianDataUpdater(s.Conn, s.Catalog, s.Wal,
            Loggers(sp).CreateLogger<QuestDbHistorianDataUpdater>());
    }

    /// <summary>Disposes the shared connection pool, when one was built. Idempotent.</summary>
    /// <returns>A task completing when the pool is disposed.</returns>
    public async ValueTask DisposeAsync()
    {
        if (TakeForDispose() is { } conn) await conn.DisposeAsync().ConfigureAwait(false);
    }

    /// <summary>Disposes the shared connection pool, when one was built. Idempotent.</summary>
    public void Dispose() => TakeForDispose()?.Dispose();

    private QuestDbConnection? TakeForDispose()
    {
        lock (_initLock)
        {
            if (_disposed) return null;
            _disposed = true;
            var conn = _shared?.Conn;
            _shared = null;
            return conn;
        }
    }

    private sealed record Shared(
        QuestDbConnection Conn, QuestDbSchemaBootstrapper Bootstrap, QuestDbTagCatalog Catalog, QuestDbWalVisibility Wal);
}