using System;
using System.Collections.Generic;

namespace Chernobyl.Threading
{
    /// <summary>
    /// A DataAccessor for strings - used to access strings
    /// from a <see cref="DataSafe"/>.
    /// </summary>
    public class StringAccessor : DataAccessor<String>
    {
        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="attachTo">The <see cref="DataSafe"/> to attach to.</param>
        /// <param name="accessRights">The rights granted to this accessor.</param>
        public StringAccessor(DataSafe<String> attachTo, AccessRights accessRights)
            : base(attachTo, accessRights)
        {
            _theString = String.Empty;
        }

        /// <summary>
        /// Returns the current value of the string.
        /// </summary>
        public string Read()
        {
            return _theString;
        }

        /// <summary>
        /// Changes the value of the string to the 
        /// string passed in. Only call this method
        /// when you have to. Fewer calls to this
        /// method will help performance.
        /// </summary>
        /// <param name="newValue">The new value of the string.</param>
        public void Write(string newValue)
        {
            _theString = newValue;
            MyDataSafe.RecordChange(this, (ref string oldString) => oldString = String.Copy(newValue));
        }

        /// <summary>
        /// This method is called when the DataSafe is synchronized.
        /// The passed in changeRecords are to be run on the accessors
        /// data so that it can have it's data synchronized with the other
        /// accessors.
        /// </summary>
        /// <param name="changeRecords">The change records to run on the internal
        /// data.</param>
        public override void Synchronize(Queue<DataSafe<string>.ChangeRecord> changeRecords)
        {
            foreach(DataSafe<String>.ChangeRecord cr in changeRecords)
            {
                cr(ref _theString);
            }
        }

        String _theString;
    }
}