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.SqlServer;

/// <summary>
///     <see cref="IHistorianBackendProvider"/> for the SQL Server historian. Supports every
///     <see cref="HistorianValueKind"/> and HistoryUpdate. All seams share ONE connection helper, ONE schema
///     bootstrapper and ONE tag catalog, so the schema is ensured once and tag ids 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 bootstrapper logs through.
/// </remarks>
public sealed class SqlServerHistorianProvider : IHistorianBackendProvider
{
    private static readonly FrozenSet<HistorianValueKind> Kinds =
        Enum.GetValues<HistorianValueKind>().ToFrozenSet();

    private readonly SqlServerHistorianOptions _options;
    private readonly object _initLock = new();
    private Shared? _shared;

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

    private readonly int _maxTimeWeightedRawRows;

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

    /// <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 conn = new SqlHistorianConnection(_options);
            var bootstrap = new SqlServerSchemaBootstrapper(conn, _options,
                Loggers(sp).CreateLogger<SqlServerSchemaBootstrapper>());
            var shared = new Shared(conn, bootstrap, new SqlServerTagCatalog(conn, bootstrap));
            Volatile.Write(ref _shared, shared);
            return shared;
        }
    }

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

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

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

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

    /// <inheritdoc />
    public IHistorianDataUpdater? CreateUpdater(IServiceProvider sp)
    {
        var s = Get(sp);
        return new SqlServerHistorianDataUpdater(s.Conn, s.Bootstrap, s.Catalog);
    }

    /// <inheritdoc />
    public IHistorianRetention? CreateRetention(IServiceProvider sp)
    {
        if (_options.RetentionDays is not { } days) return null;
        var s = Get(sp);
        return new SqlServerHistorianRetention(s.Conn, s.Bootstrap, _options.PurgeInterval, days,
            _options.PurgeBatchSize, Loggers(sp).CreateLogger<SqlServerHistorianRetention>());
    }

    private sealed record Shared(SqlHistorianConnection Conn, SqlServerSchemaBootstrapper Bootstrap, SqlServerTagCatalog Catalog);
}