using System.Text;
using Shouldly;
using Xunit;

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

[Collection(SqlHistorianCollection.Name)]
public sealed class EventReadTests(SqlHistorianFixture fx)
{
    private static readonly CancellationToken Ct = CancellationToken.None;
    private static DateTime At(double s) => ReadTestDb.At(s);

    private static async Task InsertEventAsync(ReadTestDb db, string id, string source, DateTime t, string? message, int severity)
    {
        await using var c = await db.Conn.OpenAsync(Ct);
        await using var cmd = db.Conn.CreateCommand(c,
            $"INSERT {db.Conn.Q("Event")} (EventId, SourceName, AlarmId, AlarmName, AlarmTypeName, Severity, EventKind, Message, " +
            "UserName, Comment, EventTimeUtc, ReceivedTimeUtc) VALUES (@id, @src, 'a', 'n', 'T', @sev, 'Activated', @msg, NULL, NULL, @t, @r)");
        cmd.Parameters.AddWithValue("@id", id);
        cmd.Parameters.AddWithValue("@src", source);
        cmd.Parameters.AddWithValue("@sev", severity);
        cmd.Parameters.AddWithValue("@msg", (object?)message ?? DBNull.Value);
        SqlHistorianConnection.AddDateTime2(cmd, "@t", t);
        SqlHistorianConnection.AddDateTime2(cmd, "@r", t.AddTicks(3));
        await cmd.ExecuteNonQueryAsync();
    }

    private static async Task<ReadTestDb> SeedAsync(SqlHistorianFixture fx)
    {
        var db = await ReadTestDb.CreateAsync(fx);
        await InsertEventAsync(db, "e1", "Eq/1", At(0), "first", 500);
        await InsertEventAsync(db, "e2", "Eq/2", At(1), null, 700);
        await InsertEventAsync(db, "e3", "Eq/1", At(2), "third", 900);
        await InsertEventAsync(db, "e4", "Eq/1", At(3), "at end", 100);
        return db;
    }

    [Fact]
    public async Task Source_filter_window_order_and_field_mapping()
    {
        var db = await SeedAsync(fx);
        var r = await db.Source().ReadEventsAsync("Eq/1", At(0), At(3), 0, Ct);
        r.Events.Select(e => e.EventId).ShouldBe(["e1", "e3"]); // e4 at end excluded, e2 other source
        var e = r.Events[0];
        e.SourceName.ShouldBe("Eq/1");
        e.EventTimeUtc.ShouldBe(At(0));
        e.EventTimeUtc.Kind.ShouldBe(DateTimeKind.Utc);
        e.ReceivedTimeUtc.ShouldBe(At(0).AddTicks(3));
        e.Message.ShouldBe("first");
        e.Severity.ShouldBe((ushort)500);
        r.ContinuationPoint.ShouldBeNull();
    }

    [Fact]
    public async Task Null_source_returns_every_source_and_null_messages()
    {
        var db = await SeedAsync(fx);
        var r = await db.Source().ReadEventsAsync(null, At(0), At(10), 0, Ct);
        r.Events.Select(e => e.EventId).ShouldBe(["e1", "e2", "e3", "e4"]);
        r.Events[1].Message.ShouldBeNull();
    }

    [Fact]
    public async Task Truncation_drops_the_extra_row_and_returns_a_continuation_point()
    {
        var db = await SeedAsync(fx);
        var r = await db.Source().ReadEventsAsync(null, At(0), At(3), 2, Ct); // 3 matching rows
        r.Events.Select(e => e.EventId).ShouldBe(["e1", "e2"]);
        r.ContinuationPoint.ShouldNotBeNull();
        Encoding.UTF8.GetString(r.ContinuationPoint!).ShouldBe($"{At(2).Ticks}|e3");
    }

    [Fact]
    public async Task An_exact_fit_or_an_unbounded_read_has_no_continuation_point()
    {
        var db = await SeedAsync(fx);
        var src = db.Source();
        var exact = await src.ReadEventsAsync(null, At(0), At(3), 3, Ct);
        exact.Events.Count.ShouldBe(3);
        exact.ContinuationPoint.ShouldBeNull();
        (await src.ReadEventsAsync(null, At(0), At(10), int.MaxValue, Ct)).Events.Count.ShouldBe(4); // node manager's "no limit"
        (await src.ReadEventsAsync(null, At(0), At(10), -1, Ct)).ContinuationPoint.ShouldBeNull();
    }

    [Fact]
    public async Task A_reversed_window_is_swapped()
    {
        var db = await SeedAsync(fx);
        (await db.Source().ReadEventsAsync(null, At(3), At(0), 0, Ct)).Events.Select(e => e.EventId)
            .ShouldBe(["e1", "e2", "e3"]);
    }
}