using Xunit;

namespace ScadaLink.ConfigurationDatabase.Tests.Migrations;

/// <summary>
/// Audit Log #23 (ExecutionId Task 5) integration test for the
/// <c>AddNotificationOriginExecutionId</c> migration: applies the EF migrations
/// to a freshly-created MSSQL test database on the running infra/mssql container
/// and asserts that the <c>Notifications</c> table carries the new
/// <c>OriginExecutionId</c> column as a nullable <c>uniqueidentifier</c>.
/// </summary>
/// <remarks>
/// Unlike <c>AuditLog</c>, the <c>Notifications</c> table is not partitioned, so
/// the column is a plain metadata-only <c>ALTER TABLE … ADD</c> with no index.
/// Tests pair <see cref="SkippableFactAttribute"/> with <c>Skip.IfNot(...)</c> so
/// the runner reports them as Skipped (not Passed) when MSSQL is unreachable. The
/// fixture applies the migrations once at construction time.
/// </remarks>
public class AddNotificationOriginExecutionIdMigrationTests : IClassFixture<MsSqlMigrationFixture>
{
    private readonly MsSqlMigrationFixture _fixture;

    public AddNotificationOriginExecutionIdMigrationTests(MsSqlMigrationFixture fixture)
    {
        _fixture = fixture;
    }

    [SkippableFact]
    public async Task AppliesMigration_AddsOriginExecutionIdColumn_ToNotifications()
    {
        Skip.IfNot(_fixture.Available, _fixture.SkipReason);

        var present = await ScalarAsync<int>(
            "SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS " +
            "WHERE TABLE_NAME = 'Notifications' AND COLUMN_NAME = 'OriginExecutionId' " +
            "AND TABLE_SCHEMA = 'dbo';");
        Assert.Equal(1, present);
    }

    [SkippableFact]
    public async Task OriginExecutionIdColumn_IsNullableUniqueIdentifier()
    {
        Skip.IfNot(_fixture.Available, _fixture.SkipReason);

        var dataType = await ScalarAsync<string?>(
            "SELECT DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS " +
            "WHERE TABLE_NAME = 'Notifications' AND COLUMN_NAME = 'OriginExecutionId';");
        Assert.Equal("uniqueidentifier", dataType);

        var isNullable = await ScalarAsync<string?>(
            "SELECT IS_NULLABLE FROM INFORMATION_SCHEMA.COLUMNS " +
            "WHERE TABLE_NAME = 'Notifications' AND COLUMN_NAME = 'OriginExecutionId';");
        Assert.Equal("YES", isNullable);
    }

    // --- helpers ------------------------------------------------------------

    private async Task<T> ScalarAsync<T>(string sql)
    {
        await using var conn = _fixture.OpenConnection();
        await using var cmd = conn.CreateCommand();
        cmd.CommandText = sql;
        var result = await cmd.ExecuteScalarAsync();
        if (result is null || result is DBNull)
        {
            return default!;
        }
        return (T)Convert.ChangeType(result, typeof(T) == typeof(string) ? typeof(string) : Nullable.GetUnderlyingType(typeof(T)) ?? typeof(T))!;
    }
}