using System.Data;
using Microsoft.Data.SqlClient.Server;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common;

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

/// <summary>
///     The <c>SqlDataRecord</c> TVP builders. The HistorianValue ⇄ column mapping itself is
///     <see cref="SampleColumnMapper"/> (shared with the other SQL backends).
/// </summary>
internal static class SampleRowMapper
{
    private static readonly SqlMetaData[] SampleMeta =
    [
        new("SourceTimeUtc", SqlDbType.DateTime2, 0, 7),
        new("ValueKind", SqlDbType.TinyInt),
        new("NumValue", SqlDbType.Float),
        new("IntValue", SqlDbType.BigInt),
        new("StrValue", SqlDbType.NVarChar, SqlMetaData.Max),
        new("StatusCode", SqlDbType.Int),
    ];

    private static readonly SqlMetaData[] TimeMeta = [new("T", SqlDbType.DateTime2, 0, 7)];

    /// <summary>Builds <c>SampleRow</c> TVP records (datetime2(7); never a DataTable). Lazy; enumerate once.</summary>
    /// <param name="rows">Samples; must be time-unique (the TVP has a PK on time) and non-empty when bound.</param>
    /// <returns>Records for <see cref="SqlHistorianConnection.AddStructured"/>.</returns>
    public static IEnumerable<SqlDataRecord> ToSampleRecords(IEnumerable<HistorianSampleRow> rows)
    {
        foreach (var r in rows)
        {
            var c = SampleColumnMapper.ToColumns(r.Value);
            var rec = new SqlDataRecord(SampleMeta);
            rec.SetDateTime(0, DateTime.SpecifyKind(r.TimeUtc, DateTimeKind.Utc));
            rec.SetByte(1, c.ValueKind);
            if (c.NumValue is { } n) rec.SetDouble(2, n); else rec.SetDBNull(2);
            if (c.IntValue is { } i) rec.SetInt64(3, i); else rec.SetDBNull(3);
            if (c.StrValue is { } s) rec.SetString(4, s); else rec.SetDBNull(4);
            rec.SetInt32(5, SampleColumnMapper.ToDbStatus(r.StatusCode));
            yield return rec;
        }
    }

    /// <summary>Builds <c>TimeRow</c> TVP records (datetime2(7)). Lazy; enumerate once.</summary>
    /// <param name="timesUtc">Distinct UTC times; non-empty when bound.</param>
    /// <returns>Records for <see cref="SqlHistorianConnection.AddStructured"/>.</returns>
    public static IEnumerable<SqlDataRecord> ToTimeRecords(IEnumerable<DateTime> timesUtc)
    {
        foreach (var t in timesUtc)
        {
            var rec = new SqlDataRecord(TimeMeta);
            rec.SetDateTime(0, DateTime.SpecifyKind(t, DateTimeKind.Utc));
            yield return rec;
        }
    }
}