using System;

namespace TINK.Model.State
{
    /// <summary>
    /// Types of rent states
    /// </summary>
    public enum InUseStateEnum
    {
        /// <summary>
        /// Bike is not in use. Corresponding COPRI state is "available".
        /// </summary>
        Disposable,

        /// <summary>
        /// Bike is reserved. Corresponding COPRI state is "requested".
        /// </summary>
        Reserved,

        /// <summary>
        /// Bike is booked. Corresponding COPRI statie is "occupied".
        /// </summary>
        Booked
    }

    /// <summary>
    /// Manages the state of a bike.
    /// </summary>
    public class StateInfo : IStateInfo
    {
        // Holds the current disposable state value.
        private readonly BaseState m_oInUseState;

        /// <summary>
        /// Constructs a state info object when state is available.
        /// </summary>
        /// <param name="p_oDateTimeNowProvider">Provider for current date time to calculate remainig time on demand for state of type reserved.</param>
        public StateInfo()
        {
            m_oInUseState = new StateAvailableInfo();
        }

        /// <summary>
        /// Constructs a state info object when state is requested.
        /// </summary>
        /// <param name="p_oRequestedAt">Date time when bike was requested</param>
        /// <param name="p_strMailAddress">Mail address of user which requested bike.</param>
        /// <param name="p_strCode">Booking code.</param>
        /// <param name="p_oDateTimeNowProvider">Date time provider to calculate reaining time.</param>
        public StateInfo(
            Func<DateTime> p_oDateTimeNowProvider,
            DateTime p_oRequestedAt,
            string p_strMailAddress,
            string p_strCode)
        {
            // Todo: Handle p_oFrom == null here.
            // Todo: Handle p_oDuration == null here.
            m_oInUseState = new StateRequestedInfo(
                p_oDateTimeNowProvider ?? (() => DateTime.Now),
                p_oRequestedAt,
                p_strMailAddress,
                p_strCode);
        }

        /// <summary>
        /// Constructs a state info object when state is booked.
        /// </summary>
        /// <param name="p_oBookedAt">Date time when bike was booked</param>
        /// <param name="p_strMailAddress">Mail address of user which booked bike.</param>
        /// <param name="p_strCode">Booking code.</param>
        public StateInfo(
            DateTime p_oBookedAt,
            string p_strMailAddress,
            string p_strCode)
        {
            // Todo: Handle p_oFrom == null here.
            // Todo: Clearify question: What to do if code changes form one value to another? This should never happen.
            // Todo: Clearify question: What to do if from time changes form one value to another? This should never happen.
            m_oInUseState = new StateOccupiedInfo(
                p_oBookedAt,
                p_strMailAddress,
                p_strCode);
        }

        /// <summary>
        /// Gets the state value of object.
        /// </summary>
        public InUseStateEnum Value
        {
            get { return m_oInUseState.Value; }
        }

        /// <summary>
        /// Member for serialization purposes.
        /// </summary>
        internal BaseState StateInfoObject
        {
            get { return m_oInUseState; }
        }
        /// Transforms object to string.
        /// </summary>
        /// <returns></returns>
        public new string ToString()
        {
            return m_oInUseState.Value.ToString("g");
        }

        /// <summary>
        /// Date of request/ bookeing action.
        /// </summary>
        public DateTime? From
        {
            get
            {
                var l_oNotDisposableInfo = m_oInUseState as INotAvailableState;
                return l_oNotDisposableInfo != null ? l_oNotDisposableInfo.From : (DateTime?)null;
            }
        }

        /// <summary>
        /// Mail address.
        /// </summary>
        public string MailAddress
        {
            get
            {
                var l_oNotDisposableInfo = m_oInUseState as INotAvailableState;
                return l_oNotDisposableInfo?.MailAddress;
            }
        }

        /// <summary>
        /// Reservation code.
        /// </summary>
        public string Code
        {
            get
            {
                var l_oNotDisposableInfo = m_oInUseState as INotAvailableState;
                return l_oNotDisposableInfo?.Code;
            }
        }

        /// <summary>
        /// Tries update 
        /// </summary>
        /// <returns>True if reservation span has not exeeded and state remains reserved, false otherwise.</returns>
        /// <todo>Implement logging of time stamps.</todo>
        public bool GetIsStillReserved(out TimeSpan? p_oRemainingTime)
        {
            var l_oReservedInfo = m_oInUseState as StateRequestedInfo;
            if (l_oReservedInfo == null)
            {
                p_oRemainingTime = null;
                return false;
            }

            return l_oReservedInfo.GetIsStillReserved(out p_oRemainingTime);
        }
    }
}