namespace Campaign_Tracker.Server.LegacyData.Schema;

/// <summary>
/// Categorisation of a structural delta detected by the compatibility check
/// (Story 1.7 AC #2). Used in <see cref="LegacySchemaDrift"/> entries.
/// </summary>
public enum LegacySchemaChangeType
{
    TableMissing,
    TableAdded,
    ColumnMissing,
    ColumnAdded,
    ColumnTypeChanged,
    ColumnSizeChanged,
    ColumnNullabilityChanged,
    ColumnConstraintsChanged,
}

/// <summary>
/// One structural delta entry between baseline and live schema.
/// <see cref="ColumnName"/> is null for table-level drift entries.
/// </summary>
public sealed record LegacySchemaDrift(
    string TableName,
    string? ColumnName,
    LegacySchemaChangeType ChangeType,
    string Detail);

/// <summary>
/// Outcome of a compatibility check run.
/// AC #2: failure includes structured drift list identifying table, column, and change type.
/// AC #3: pass returns timestamp, count of tables verified, and zero drift count.
/// </summary>
public sealed record LegacySchemaCheckResult(
    bool Passed,
    int TablesVerified,
    int DriftCount,
    DateTimeOffset CheckedAt,
    IReadOnlyList<LegacySchemaDrift> Drifts,
    string BaselineSource);