//------------------------------------------------------------------------------
// <copyright file="DbCommand.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
// <owner current="true" primary="false">Microsoft</owner>
//------------------------------------------------------------------------------
 
namespace System.Data.Common {
 
    using System;
    using System.ComponentModel;
    using System.Data;
    using System.Threading.Tasks;
    using System.Threading;
 
    public abstract class DbCommand : Component, IDbCommand { // V1.2.3300
        protected DbCommand() : base() {
        }
 
        [
        DefaultValue(""),
        RefreshProperties(RefreshProperties.All),
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_CommandText),
        ]
        abstract public string CommandText {
            get;
            set;
        }
 
        [
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_CommandTimeout),
        ]
        abstract public int CommandTimeout {
            get;
            set;
        }
 
        [
        DefaultValue(System.Data.CommandType.Text),
        RefreshProperties(RefreshProperties.All),
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_CommandType),
        ]
        abstract public CommandType CommandType {
            get;
            set;
        }
 
        [
        Browsable(false),
        DefaultValue(null),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_Connection),
        ]
        public DbConnection Connection {
            get {
                return DbConnection;
            }
            set {
                DbConnection = value;
            }
        }
 
        IDbConnection IDbCommand.Connection {
            get {
                return DbConnection;
            }
            set {
                DbConnection = (DbConnection)value;
            }
        }
 
        abstract protected DbConnection DbConnection { // V1.2.3300
            get;
            set;
        }
 
        abstract protected DbParameterCollection DbParameterCollection { // V1.2.3300
            get;
        }
 
        abstract protected DbTransaction DbTransaction { // V1.2.3300
            get;
            set;
        }
 
        // @devnote: By default, the cmd object is visible on the design surface (i.e. VS7 Server Tray)
        // to limit the number of components that clutter the design surface,
        // when the DataAdapter design wizard generates the insert/update/delete commands it will
        // set the DesignTimeVisible property to false so that cmds won't appear as individual objects
        [
        DefaultValue(true),
        DesignOnly(true),
        Browsable(false),
        EditorBrowsableAttribute(EditorBrowsableState.Never),
        ]
        public abstract bool DesignTimeVisible {
            get;
            set;
        }
 
        [
        Browsable(false),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_Parameters),
        ]
        public DbParameterCollection Parameters {
            get {
                return DbParameterCollection;
            }
        }
 
        IDataParameterCollection IDbCommand.Parameters {
            get {
                return (DbParameterCollection)DbParameterCollection;
            }
        }
 
        [
        Browsable(false),
        DefaultValue(null),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        ResDescriptionAttribute(Res.DbCommand_Transaction),
        ]
        public DbTransaction Transaction {
            get {
                return DbTransaction;
            }
            set {
                DbTransaction = value;
            }
        }
 
        IDbTransaction IDbCommand.Transaction {
            get {
                return DbTransaction;
            }
            set {
                DbTransaction = (DbTransaction)value;
            }
        }
 
        [
        DefaultValue(System.Data.UpdateRowSource.Both),
        ResCategoryAttribute(Res.DataCategory_Update),
        ResDescriptionAttribute(Res.DbCommand_UpdatedRowSource),
        ]
        abstract public UpdateRowSource UpdatedRowSource {
            get;
            set;
        }
 
        internal void CancelIgnoreFailure() {
            // This method is used to route CancellationTokens to the Cancel method.
            // Cancellation is a suggestion, and exceptions should be ignored
            // rather than allowed to be unhandled, as there is no way to route
            // them to the caller.  It would be expected that the error will be
            // observed anyway from the regular method.  An example is cancelling
            // an operation on a closed connection.
            try
            {
                Cancel();
            } catch(Exception) {
            }
        }
 
        abstract public void Cancel();
 
        public DbParameter CreateParameter(){ // V1.2.3300
            return CreateDbParameter();
        }
 
        IDbDataParameter IDbCommand.CreateParameter() { // V1.2.3300
            return CreateDbParameter();
        }
 
        abstract protected DbParameter CreateDbParameter();
 
        abstract protected DbDataReader ExecuteDbDataReader(CommandBehavior behavior);
 
        abstract public int ExecuteNonQuery();
 
        public DbDataReader ExecuteReader() {
            return (DbDataReader)ExecuteDbDataReader(CommandBehavior.Default);
        }
 
        IDataReader IDbCommand.ExecuteReader() {
            return (DbDataReader)ExecuteDbDataReader(CommandBehavior.Default);
        }
 
        public DbDataReader ExecuteReader(CommandBehavior behavior){
            return (DbDataReader)ExecuteDbDataReader(behavior);
        }
 
        IDataReader IDbCommand.ExecuteReader(CommandBehavior behavior) {
            return (DbDataReader)ExecuteDbDataReader(behavior);
        }
 
        public Task<int> ExecuteNonQueryAsync() {
            return ExecuteNonQueryAsync(CancellationToken.None);
        }
 
        public virtual Task<int> ExecuteNonQueryAsync(CancellationToken cancellationToken) {
            if (cancellationToken.IsCancellationRequested) {
                return ADP.CreatedTaskWithCancellation<int>();
            }
            else {
                CancellationTokenRegistration registration = new CancellationTokenRegistration();
                if (cancellationToken.CanBeCanceled) {
                    registration = cancellationToken.Register(CancelIgnoreFailure);
                }
 
                try {
                    return Task.FromResult<int>(ExecuteNonQuery());
                }
                catch (Exception e) {
                    registration.Dispose();
                    return ADP.CreatedTaskWithException<int>(e);
                }
            }
        }
 
        public Task<DbDataReader> ExecuteReaderAsync() {
            return ExecuteReaderAsync(CommandBehavior.Default, CancellationToken.None);
        }
 
        public Task<DbDataReader> ExecuteReaderAsync(CancellationToken cancellationToken) {
            return ExecuteReaderAsync(CommandBehavior.Default, cancellationToken);
        }
 
        public Task<DbDataReader> ExecuteReaderAsync(CommandBehavior behavior) {
            return ExecuteReaderAsync(behavior, CancellationToken.None);
        }
 
        public Task<DbDataReader> ExecuteReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken) {
            return ExecuteDbDataReaderAsync(behavior, cancellationToken);
        }
 
        protected virtual Task<DbDataReader> ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken) {
            if (cancellationToken.IsCancellationRequested) {
                return ADP.CreatedTaskWithCancellation<DbDataReader>();
            }
            else {
                CancellationTokenRegistration registration = new CancellationTokenRegistration();
                if (cancellationToken.CanBeCanceled) {
                    registration = cancellationToken.Register(CancelIgnoreFailure);
                }
 
                try {
                    return Task.FromResult<DbDataReader>(ExecuteReader(behavior));
                }
                catch (Exception e) {
                    registration.Dispose();
                    return ADP.CreatedTaskWithException<DbDataReader>(e);
                }
            }
        }
 
        public Task<object> ExecuteScalarAsync() {
            return ExecuteScalarAsync(CancellationToken.None);
        }
 
        public virtual Task<object> ExecuteScalarAsync(CancellationToken cancellationToken) {
            if (cancellationToken.IsCancellationRequested) {
                return ADP.CreatedTaskWithCancellation<object>();
            }
            else {
                CancellationTokenRegistration registration = new CancellationTokenRegistration();
                if (cancellationToken.CanBeCanceled) {
                    registration = cancellationToken.Register(CancelIgnoreFailure);
                }
 
                try {
                    return Task.FromResult<object>(ExecuteScalar());
                }
                catch (Exception e) {
                    registration.Dispose();
                    return ADP.CreatedTaskWithException<object>(e);
                }
            }
        }
 
        abstract public object ExecuteScalar();
 
        abstract public void Prepare();
    }
}