using Microsoft.Data.SqlClient;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common;

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

/// <summary>
///     <see cref="IHistorianValueWriter"/> over the SQL <c>Sample</c> table. Redelivery-idempotent: rows are
///     inserted only where <c>(TagId, SourceTimeUtc)</c> is absent, so the recorder's at-least-once redelivery
///     leaves the first-stored sample untouched. Never throws; returns false on any failure so the recorder keeps
///     the entries and its #538 per-tag quarantine keeps working.
/// </summary>
/// <remarks>
///     <b>Non-finite doubles.</b> NaN / ±Infinity cannot live in a SQL <c>float</c> (the TVP throws). They are stored
///     as <see cref="HistorianValueKind.Empty"/> so the sample's presence survives and the tag is not quarantined
///     for one bad reading. <b>An Empty sample is always Bad</b> (the quality contract: a stored sample is never
///     served better than "no value"): a non-finite Double whose status is not already Bad is stored with
///     <c>BadOutOfRange</c>; any other Empty with a non-Bad status is stored with <c>BadNoData</c>. An existing
///     Bad code (e.g. the comms-loss <c>BadNoCommunication</c> marker) is kept as it is.
///     <b>Tag names over <see cref="SqlServerTagCatalog.MaxNameLength"/> characters</b> are refused (the write
///     returns false, a per-tag failure for the recorder's #538 quarantine), never truncated onto another tag.
///     <b>Duplicate timestamps within a batch</b> collapse to the first (matching insert-if-absent across batches).
///     The batch normalisation itself is <see cref="LiveWritePreparer.Prepare"/>.
/// </remarks>
internal sealed class SqlServerHistorianValueWriter : IHistorianValueWriter
{
    private readonly SqlHistorianConnection _conn;
    private readonly SqlServerSchemaBootstrapper _bootstrap;
    private readonly SqlServerTagCatalog _catalog;
    private readonly ILogger _log;
    private readonly Func<DateTime> _utcNow;

    /// <summary>Creates the writer.</summary>
    /// <param name="conn">Connection helper.</param>
    /// <param name="bootstrap">Schema bootstrapper.</param>
    /// <param name="catalog">Tag catalog.</param>
    /// <param name="log">Optional logger.</param>
    /// <param name="utcNow">Clock for null timestamps (tests).</param>
    public SqlServerHistorianValueWriter(SqlHistorianConnection conn, SqlServerSchemaBootstrapper bootstrap,
        SqlServerTagCatalog catalog, ILogger? log = null, Func<DateTime>? utcNow = null)
    {
        _conn = conn;
        _bootstrap = bootstrap;
        _catalog = catalog;
        _log = log ?? NullLogger.Instance;
        _utcNow = utcNow ?? (() => DateTime.UtcNow);
    }

    /// <inheritdoc/>
    public async Task<bool> WriteLiveValuesAsync(string tag, IReadOnlyList<HistorizationValue> values, CancellationToken ct)
    {
        try
        {
            if (!HistorianTagNames.IsValid(tag))
            {
                _log.LogWarning("SQL historian live-value write refused: tag name is missing or longer than {Max} characters.",
                    SqlServerTagCatalog.MaxNameLength);
                return false;
            }
            await _bootstrap.EnsureAsync(ct).ConfigureAwait(false);
            if (values is null || values.Count == 0) return true;

            var rows = LiveWritePreparer.Prepare(values, _utcNow);
            var dataType = HistorianDataTypes.FromKind(rows.Select(r => r.Value.Kind).FirstOrDefault(k => k != HistorianValueKind.Empty));
            var tagId = await _catalog.GetOrCreateTagIdAsync(tag, dataType, ct).ConfigureAwait(false);

            var sql =
                $"INSERT INTO {_conn.Q("Sample")} (TagId, SourceTimeUtc, ValueKind, NumValue, IntValue, StrValue, StatusCode, ServerTimeUtc) " +
                "SELECT @tagId, r.SourceTimeUtc, r.ValueKind, r.NumValue, r.IntValue, r.StrValue, r.StatusCode, SYSUTCDATETIME() " +
                "FROM @rows r WHERE NOT EXISTS (SELECT 1 FROM " + _conn.Q("Sample") +
                " s WITH (UPDLOCK, HOLDLOCK) WHERE s.TagId = @tagId AND s.SourceTimeUtc = r.SourceTimeUtc)";

            // A duplicate-key error rolls the WHOLE statement back, so "someone else wrote a row" is NOT proof our rows are
            // present. The retry re-evaluates NOT EXISTS against what is now there; only its success counts.
            for (var attempt = 0; ; attempt++)
            {
                try
                {
                    await using var conn = await _conn.OpenAsync(ct).ConfigureAwait(false);
                    await using var cmd = _conn.CreateCommand(conn, sql);
                    cmd.Parameters.Add(new SqlParameter("@tagId", System.Data.SqlDbType.Int) { Value = tagId });
                    _conn.AddStructured(cmd, "@rows", "SampleRow", SampleRowMapper.ToSampleRecords(rows));
                    await cmd.ExecuteNonQueryAsync(ct).ConfigureAwait(false);
                    return true;
                }
                catch (SqlException ex) when (attempt < 2 && SqlHistorianConnection.IsDuplicateKey(ex))
                {
                }
            }
        }
        catch (Exception ex)
        {
            _log.LogWarning("SQL historian live-value write failed ({Exception}); will retry.", ex.GetType().Name);
            return false;
        }
    }
}