using Strata.SqlTools.SqlBreakdown.Extensions;

namespace Strata.SqlTools.SqlBreakdown.Utilities;

/// <summary>
/// SQL schema and table helper methods.
/// </summary>
public static partial class SqlUtils
{
    /// <summary>
    /// Returns SQL that will give you column information from a view or table.
    /// Uses Parameters @ObjectName and @SchemaName and returns columns: SQLColumnName (varchar), SQLDataType, ColumnID, SQLDataTypeName, IsIdentity.
    /// </summary>
    /// <returns>A SQL query string for retrieving table or view schema information.</returns>
    public static string GetTableOrViewSchema()
    {
        var sql = new StringBuilderEx();
        sql.Append("select C.name as SQLColumnName, C.system_type_id as SQLDataType, C.column_id as ColumnID, ST.name AS SQLDataTypeName, C.is_identity AS IsIdentity from sys.tables T ");
        sql.AppendLine("     inner join sys.columns C on C.object_id = T.object_id ");
        sql.AppendLine("     inner join sys.schemas S on S.schema_id = T.schema_id ");
        sql.AppendLine("     inner join sys.types st on st.user_type_id = c.user_type_id");
        sql.AppendLine("     where T.name = @ObjectName and S.name = @SchemaName ");

        sql.AppendLine("UNION ");

        sql.Append("select C.name as SQLColumnName, C.system_type_id as SQLDataType, C.column_id as ColumnID, ST.name AS SQLDataTypeName, C.is_identity AS IsIdentity from sys.views V ");
        sql.AppendLine("     inner join sys.columns C on C.object_id = V.object_id ");
        sql.AppendLine("     inner join sys.schemas S on S.schema_id = V.schema_id ");
        sql.AppendLine("     inner join sys.types st on st.user_type_id = c.user_type_id");
        sql.AppendLine("     where V.name = @ObjectName and S.name = @SchemaName ");
        sql.AppendLine("     order by ColumnID");

        return sql.ToString();
    }

    /// <summary>
    /// Gets a list of client-usable schemas (excluding system schemas).
    /// </summary>
    /// <returns>A list of schema names available to clients.</returns>
    public static List<string> GetClientUsableSchemas()
    {
        var list = new List<string>();

        try
        {
            // Would need to execute SQL here - skipping for this conversion

            // Remove system schemas
            return list.Except(GetSystemSchemas()).ToList();
        }
        catch
        {
            // Ignore error and return empty list
        }

        return list;
    }

    /// <summary>
    /// Gets a list of system schema names that should not be exposed to clients.
    /// </summary>
    /// <returns>A list of system schema names.</returns>
    public static List<string> GetSystemSchemas()
        => new List<string>
        {
            DEFAULT_SCHEMA,
            "int",      // integration
            "perf",
            "audit",
            "log",
            "sqlgen",
            "upgrade",
            "upg",
            "irc",      // irc chat rooms
            "migration"
        };
}