using System;

namespace Cosmos.HAL.BlockDevice
{
    /// <summary>
    /// Partition class. Used to read and write blocks of data.
    /// </summary>
    public class Partition : BlockDevice
    {
        /// <summary>
        /// Hosting device.
        /// </summary>
        private readonly BlockDevice mHost;
        /// <summary>
        /// Starting sector.
        /// </summary>
        private readonly UInt64 mStartingSector;

        /// <summary>
        /// Create new instance of the <see cref="Partition"/> class.
        /// </summary>
        /// <param name="aHost">A hosting device.</param>
        /// <param name="aStartingSector">A starting sector.</param>
        /// <param name="aSectorCount">A sector count.</param>
		public Partition(BlockDevice aHost, UInt64 aStartingSector, UInt64 aSectorCount)
		{
			mHost = aHost;
			mStartingSector = aStartingSector;
			mBlockCount = aSectorCount;
			mBlockSize = aHost.BlockSize;
		}

        /// <summary>
        /// Read block from partition.
        /// </summary>
        /// <param name="aBlockNo">A block to read from.</param>
        /// <param name="aBlockCount">A number of blocks in the partition.</param>
        /// <param name="aData">A data that been read.</param>
        /// <exception cref="OverflowException">Thrown when data lenght is greater then Int32.MaxValue.</exception>
        /// <exception cref="Exception">Thrown when data size invalid.</exception>
        public override void ReadBlock(UInt64 aBlockNo, UInt64 aBlockCount, ref byte[] aData)
        {
            CheckDataSize(aData, aBlockCount);
            UInt64 xHostBlockNo = mStartingSector + aBlockNo;
            CheckBlockNo(xHostBlockNo, aBlockCount);
            mHost.ReadBlock(xHostBlockNo, aBlockCount, ref aData);
        }

        /// <summary>
        /// Write block to partition.
        /// </summary>
        /// <param name="aBlockNo">A block number to write to.</param>
        /// <param name="aBlockCount">A number of blocks in the partition.</param>
        /// <param name="aData">A data to write.</param>
        /// <exception cref="OverflowException">Thrown when data lenght is greater then Int32.MaxValue.</exception>
        /// <exception cref="Exception">Thrown when data size invalid.</exception>
        public override void WriteBlock(UInt64 aBlockNo, UInt64 aBlockCount,ref  byte[] aData)
        {
            CheckDataSize(aData, aBlockCount);
            UInt64 xHostBlockNo = mStartingSector + aBlockNo;
            CheckBlockNo(xHostBlockNo, aBlockCount);
            mHost.WriteBlock(xHostBlockNo, aBlockCount, ref aData);
        }

        /// <summary>
        /// To string.
        /// </summary>
        /// <returns>string value.</returns>
        public override string ToString()
        {
            return "Partition";
        }
    }
}