using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Facepunch.Steamworks.Data;

namespace Facepunch.Steamworks
{
	public struct InventoryItem : IEquatable<InventoryItem>
	{
		internal InventoryItemId _id;
		internal InventoryDefId _def;
		internal SteamItemFlags _flags;
		internal ushort _quantity;
		internal Dictionary<string, string> _properties;

		public InventoryItemId Id => _id;

		public InventoryDefId DefId => _def;

		public int Quantity => _quantity;

		public InventoryDef Def => SteamInventory.FindDefinition( DefId );


		/// <summary>
		/// Only available if the result set was created with the getproperties
		/// </summary>
		public Dictionary<string, string> Properties => _properties;

		/// <summary>
		/// This item is account-locked and cannot be traded or given away. 
		/// This is an item status flag which is permanently attached to specific item instances
		/// </summary>
		public bool IsNoTrade => _flags.HasFlag( SteamItemFlags.NoTrade );

		/// <summary>
		/// The item has been destroyed, traded away, expired, or otherwise invalidated. 
		/// This is an action confirmation flag which is only set one time, as part of a result set.
		/// </summary>
		public bool IsRemoved => _flags.HasFlag( SteamItemFlags.Removed );

		/// <summary>
		/// The item quantity has been decreased by 1 via ConsumeItem API. 
		/// This is an action confirmation flag which is only set one time, as part of a result set.
		/// </summary>
		public bool IsConsumed => _flags.HasFlag( SteamItemFlags.Consumed );

		/// <summary>
		/// Consumes items from a user's inventory. If the quantity of the given item goes to zero, it is permanently removed.
		/// Once an item is removed it cannot be recovered.This is not for the faint of heart - if your game implements item removal at all, 
		/// a high-friction UI confirmation process is highly recommended.ConsumeItem can be restricted to certain item definitions or fully
		/// blocked via the Steamworks website to minimize support/abuse issues such as the classic "my brother borrowed my laptop and deleted all of my rare items".
		/// </summary>
		public async Task<InventoryResult?> ConsumeAsync( int amount = 1 )
		{
			var sresult = Defines.k_SteamInventoryResultInvalid;
			if ( !SteamInventory.Internal.ConsumeItem( ref sresult, Id, (uint)amount ) )
				return null;

			return await InventoryResult.GetAsync( sresult );
		}

		/// <summary>
		/// Split stack into two items
		/// </summary>
		public async Task<InventoryResult?> SplitStackAsync( int quantity = 1 )
		{
			var sresult = Defines.k_SteamInventoryResultInvalid;
			if ( !SteamInventory.Internal.TransferItemQuantity( ref sresult, Id, (uint)quantity, ulong.MaxValue ) )
				return null;

			return await InventoryResult.GetAsync( sresult );
		}

		/// <summary>
		/// Add x units of the target item to this item
		/// </summary>
		public async Task<InventoryResult?> AddAsync( InventoryItem add, int quantity = 1 )
		{
			var sresult = Defines.k_SteamInventoryResultInvalid;
			if ( !SteamInventory.Internal.TransferItemQuantity( ref sresult, add.Id, (uint)quantity, Id ) )
				return null;

			return await InventoryResult.GetAsync( sresult );
		}


		internal static InventoryItem From( SteamItemDetails_t details )
		{
			var i = new InventoryItem
			{
				_id = details.ItemId,
				_def = details.Definition,
				_flags = (SteamItemFlags) details.Flags,
				_quantity = details.Quantity
			};

			return i;
		}

		internal static Dictionary<string, string> GetProperties( SteamInventoryResult_t result, int index )
		{
			var strlen = (uint) Helpers.MemoryBufferSize;

			if ( !SteamInventory.Internal.GetResultItemProperty( result, (uint)index, null, out var propNames, ref strlen ) )
				return null;

			var props = new Dictionary<string, string>();

			foreach ( var propertyName in propNames.Split( ',' ) )
			{
				strlen = (uint)Helpers.MemoryBufferSize;

				if ( SteamInventory.Internal.GetResultItemProperty( result, (uint)index, propertyName, out var strVal, ref strlen ) )
				{
					props.Add( propertyName, strVal );
				}
			}

			return props;
		}

		/// <summary>
		/// Will try to return the date that this item was aquired. You need to have for the items
		/// with their properties for this to work.
		/// </summary>
		public DateTime Acquired
		{
			get
			{
				if ( Properties == null ) return DateTime.UtcNow;

				if ( Properties.TryGetValue( "acquired", out var str ) )
				{
					var y = int.Parse( str.Substring( 0, 4 ) );
					var m = int.Parse( str.Substring( 4, 2 ) );
					var d = int.Parse( str.Substring( 6, 2 ) );

					var h = int.Parse( str.Substring( 9, 2 ) );
					var mn = int.Parse( str.Substring( 11, 2 ) );
					var s = int.Parse( str.Substring( 13, 2 ) );

					return new DateTime( y, m, d, h, mn, s, DateTimeKind.Utc );
				}

				return DateTime.UtcNow;
			}
		}

		/// <summary>
		/// Tries to get the origin property. Need properties for this to work.
		/// Will return a string like "market"
		/// </summary>
		public string Origin
		{
			get
			{
				if ( Properties == null ) return null;
				
				if ( Properties.TryGetValue( "origin", out var str ) )
					return str;

				return null;
			}
		}

		/// <summary>
		/// Small utility class to describe an item with a quantity
		/// </summary>
		public struct Amount
		{
			public InventoryItem Item;
			public int Quantity;
		}

		public static bool operator ==( InventoryItem a, InventoryItem b ) => a._id == b._id;
		public static bool operator !=( InventoryItem a, InventoryItem b ) => a._id != b._id;
		public override bool Equals( object p ) => this.Equals( (InventoryItem)p );
		public override int GetHashCode() => _id.GetHashCode();
		public bool Equals( InventoryItem p ) => p._id == _id;
	}
}