QueryContext.Objects.cs

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using System;

using Deveel.Data.Security;
using Deveel.Data.Sql.Cursors;
using Deveel.Data.Sql.Variables;
using Deveel.Data.Transactions;

namespace Deveel.Data.Sql {
    public static class QueryContextExtensions {
        public static bool ObjectExists(this IQueryContext context, ObjectName objectName) {
            // Special types for these database objects that can be 
            // declared in a limited context
            if (context.CursorExists(objectName.Name))
                return true;
            if (context.VariableExists(objectName.Name))
                return true;

            // We haven't found it neither in this context nor in the parent: 
            //   fallback to the transaction scope
            return context.Session().ObjectExists(objectName);
        }

        public static bool ObjectExists(this IQueryContext context, DbObjectType objectType, ObjectName objectName) {
            // Special types for these database objects that can be 
            // declared in a limited context
            if (objectType == DbObjectType.Cursor &&
                context.CursorExists(objectName.Name))
                return true;

            if (objectType == DbObjectType.Variable &&
                context.VariableExists(objectName.Name))
                return true;

            // We haven't found it neither in this context nor in the parent: 
            //   fallback to the transaction scope
            return context.Session().ObjectExists(objectType, objectName);
        }

        public static IDbObject GetObject(this IQueryContext context, DbObjectType objType, ObjectName objName) {
            return GetObject(context, objType, objName, AccessType.ReadWrite);
        }

        public static IDbObject GetObject(this IQueryContext context, DbObjectType objType, ObjectName objName, AccessType accessType) {
            // First handle the special cases of cursors and variable, that can be declared
            //  in a query context
            // If they are declared in the context, the user owns them and we don't need
            //  to verify the ownership
            if (objType == DbObjectType.Cursor) {
                var obj = context.FindCursor(objName.Name);
                if (obj != null)
                    return obj;
            } else if (objType == DbObjectType.Variable) {
                var obj = context.FindVariable(objName.Name);
                if (obj != null)
                    return obj;
            }

            // TODO: throw a specialized exception
            if (!context.UserCanAccessObject(objType, objName))
                throw new InvalidOperationException();

            return context.Session().GetObject(objType, objName, accessType);
        }

        internal static void CreateObject(this IQueryContext context, IObjectInfo objectInfo) {
            // TODO: throw a specialized exception
            if (!context.UserCanCreateObject(objectInfo.ObjectType, objectInfo.FullName))
                throw new InvalidOperationException();

            context.Session().CreateObject(objectInfo);
        }

        public static bool DropObject(this IQueryContext context, DbObjectType objectType, ObjectName objectName) {
            if (objectType == DbObjectType.Variable &&
                context.DropVariable(objectName.Name)) {
                return true;
            }
            if (objectType == DbObjectType.Cursor &&
                context.DropCursor(objectName.Name)) {
                return true;
            }

            if (!context.UserCanDropObject(objectType, objectName))
                throw new MissingPrivilegesException(context.UserName(), objectName, Privileges.Drop);

            context.Session().DropObject(objectType, objectName);
            return true;
        }

        public static void AlterObject(this IQueryContext context, IObjectInfo objectInfo) {
            if (objectInfo == null)
                throw new ArgumentNullException("objectInfo");

            if (!context.UserCanAlterObject(objectInfo.ObjectType, objectInfo.FullName))
                throw new MissingPrivilegesException(context.UserName(), objectInfo.FullName, Privileges.Alter);

            context.Session().AlterObject(objectInfo);
        }

        public static ObjectName ResolveObjectName(this IQueryContext context, string name) {
            if (context.VariableExists(name) ||
                context.CursorExists(name))
                return new ObjectName(name);

            return context.Session().ResolveObjectName(name);
        }

        public static ObjectName ResolveObjectName(this IQueryContext context, DbObjectType objectType, ObjectName objectName) {
            if (objectType == DbObjectType.Variable &&
                context.VariableExists(objectName.Name))
                return new ObjectName(objectName.Name);
            if (objectType == DbObjectType.Cursor &&
                context.CursorExists(objectName.Name))
                return new ObjectName(objectName.Name);

            return context.Session().ResolveObjectName(objectType, objectName);
        }

        public static IDbObject FindObject(this IQueryContext context, ObjectName objectName) {
            return context.Session().FindObject(objectName);
        }
    }
}