using System;

using Gamecraft.Wires;
using Svelto.ECS;
using Svelto.ECS.Experimental;

using TechbloxModdingAPI.Blocks.Engines;
using TechbloxModdingAPI.Utility;

namespace TechbloxModdingAPI.Blocks
{
    public class Wire : EcsObjectBase
    {
        internal static SignalEngine signalEngine;

        protected EGID startPortEGID;

        protected EGID endPortEGID;

        protected EGID startBlockEGID;

        protected EGID endBlockEGID;

        protected EGID wireEGID;

        protected bool inputToOutput;
        
        protected byte startPort;

        protected byte endPort;

        public static Wire Connect(SignalingBlock start, byte startPort, SignalingBlock end, byte endPort)
        {
            var (wire, id) = signalEngine.CreateNewWire(start.Id, startPort, end.Id, endPort);
            return new Wire(wire, start, end, id);
        }

        /// <summary>
        /// An existing wire connection ending at the specified input.
        /// If multiple exist, this will return the first one found.
        /// </summary>
        /// <param name="end">Destination block.</param>
        /// <param name="endPort">Port number.</param>
        /// <returns>The wire, where the end of the wire is the block port specified, or null if does not exist.</returns>
        public static Wire ConnectedToInputPort(SignalingBlock end, byte endPort)
        {
            var port = signalEngine.MatchBlockIOToPort(end, endPort, false);
            if (!port) return null;
            var wire = signalEngine.MatchPortToWire(port, end.Id, out var egid);
            return wire
                ? new Wire(wire.Get().sourceBlockEGID, end.Id, wire.Get().sourcePortUsage, endPort, egid, false)
                : null;
        }

        /// <summary>
        /// An existing wire connection starting at the specified output.
        /// If multiple exist, this will return the first one found.
        /// </summary>
        /// <param name="start">Source block entity ID.</param>
        /// <param name="startPort">Port number.</param>
        /// <returns>The wire, where the start of the wire is the block port specified, or null if does not exist.</returns>
        public static Wire ConnectedToOutputPort(SignalingBlock start, byte startPort)
        {
            var port = signalEngine.MatchBlockIOToPort(start, startPort, true);
            if (!port) return null;
            var wire = signalEngine.MatchPortToWire(port, start.Id, out var egid);
            return wire
                ? new Wire(start.Id, wire.Get().destinationBlockEGID, startPort, wire.Get().destinationPortUsage, egid, false)
                : null;
        }

        /// <summary>
        /// Construct a wire object froam n existing connection.
        /// </summary>
        /// <param name="start">Starting block ID.</param>
        /// <param name="end">Ending block ID.</param>
        /// <param name="startPort">Starting port number, or guess if omitted.</param>
        /// <param name="endPort">Ending port number, or guess if omitted.</param>
        /// <exception cref="WireInvalidException">Guessing failed or wire does not exist.</exception>
        public Wire(Block start, Block end, byte startPort = Byte.MaxValue, byte endPort = Byte.MaxValue) : base(ecs =>
        {
            var th = (Wire)ecs;
            th.startBlockEGID = start.Id;
            th.endBlockEGID = end.Id;
            bool flipped = false;
            // find block ports
            EGID wire = signalEngine.MatchBlocksToWire(start.Id, end.Id, startPort, endPort);
            if (wire == default)
            {
                // flip I/O around and try again
                wire = signalEngine.MatchBlocksToWire(end.Id, start.Id, endPort, startPort);
                flipped = true;
                // NB: start and end are handled exactly as they're received as params.
                // This makes wire traversal easier, but makes logic in this class a bit more complex
            }

            if (wire != default)
            {
                th.Construct(start.Id, end.Id, startPort, endPort, wire, flipped);
            }
            else
            {
                throw new WireInvalidException("Wire not found");
            }

            return th.wireEGID;
        })
        {
        }

        /// <summary>
        /// Construct a wire object from an existing wire connection.
        /// </summary>
        /// <param name="start">Starting block ID.</param>
        /// <param name="end">Ending block ID.</param>
        /// <param name="startPort">Starting port number.</param>
        /// <param name="endPort">Ending port number.</param>
        /// <param name="wire">The wire ID.</param>
        /// <param name="inputToOutput">Whether the wire direction goes input -> output (true) or output -> input (false, preferred).</param>
        public Wire(Block start, Block end, byte startPort, byte endPort, EGID wire, bool inputToOutput)
            : this(start.Id, end.Id, startPort, endPort, wire, inputToOutput)
        {
        }

        private Wire(EGID startBlock, EGID endBlock, byte startPort, byte endPort, EGID wire, bool inputToOutput) : base(wire)
        {
            Construct(startBlock, endBlock, startPort, endPort, wire, inputToOutput);
        }

        private void Construct(EGID startBlock, EGID endBlock, byte startPort, byte endPort, EGID wire, bool inputToOutput)
        {
            this.startBlockEGID = startBlock;
            this.endBlockEGID = endBlock;
            this.inputToOutput = inputToOutput;
            this.wireEGID = wire;
            endPortEGID = signalEngine.MatchBlockIOToPort(startBlock, startPort, inputToOutput).EGID; 
            if (endPortEGID == default) throw new WireInvalidException("Wire end port not found");
            startPortEGID = signalEngine.MatchBlockIOToPort(endBlock, endPort, !inputToOutput).EGID;
            if (startPortEGID == default) throw new WireInvalidException("Wire start port not found");
            this.startPort = startPort;
            this.endPort = endPort;
        }

        /// <summary>
        /// Construct a wire object from an existing wire connection.
        /// </summary>
        /// <param name="wireEgid">The wire ID.</param>
        public Wire(EGID wireEgid) : base(wireEgid)
        {
            WireEntityStruct wire = signalEngine.GetWire(wireEGID);
            Construct(wire.sourceBlockEGID, wire.destinationBlockEGID, wire.sourcePortUsage, wire.destinationPortUsage,
                wireEgid, false);
        }

        private Wire(WireEntityStruct wire, SignalingBlock src, SignalingBlock dest, EGID wireEgid)
            : this(src, dest, wire.sourcePortUsage, wire.destinationPortUsage, wireEgid, false)
        {
        }

        /// <summary>
        /// The wire's signal value, as a float.
        /// </summary>
        public float Float
        {
            get
            {
                return signalEngine.GetChannelDataStruct(startPortEGID).Get().valueAsFloat;
            }

            set
            {
                signalEngine.GetChannelDataStruct(startPortEGID).Get().valueAsFloat = value;
            }
        }

        /// <summary>
        /// The wire's string signal.
        /// </summary>
        public string String
        {
            get
            {
                return signalEngine.GetChannelDataStruct(startPortEGID).Get().valueAsEcsString;
            }

            set
            {
                signalEngine.GetChannelDataStruct(startPortEGID).Get().valueAsEcsString.Set(value);
            }
        }
        
        /// <summary>
        /// The wire's raw string signal.
        /// </summary>
        public ECSString ECSString
        {
            get
            {
                return signalEngine.GetChannelDataStruct(startPortEGID).Get().valueAsEcsString;
            }

            set
            {
                signalEngine.GetChannelDataStruct(startPortEGID).Get().valueAsEcsString = value;
            }
        }

        /// <summary>
        /// The wire's signal id.
        /// I'm 50% sure this is useless.
        /// </summary>
        public uint SignalId
        {
            get
            {
                return signalEngine.GetChannelDataStruct(startPortEGID).Get().valueAsID;
            }

            set
            {
                signalEngine.GetChannelDataStruct(startPortEGID).Get().valueAsID = value;
            }
        }

        /// <summary>
        /// The block at the beginning of the wire.
        /// </summary>
        public SignalingBlock Start
        {
            get => (SignalingBlock)Block.New(startBlockEGID);
        }

        /// <summary>
        /// The port number that the beginning of the wire connects to.
        /// </summary>
        public byte StartPort
        {
            get => startPort;
        }

        /// <summary>
        /// The display name of the start port.
        /// </summary>
        public string StartPortName
        {
            get => signalEngine.GetPort(startPortEGID).portNameLocalised;
        }
        
        /// <summary>
        /// The block at the end of the wire.
        /// </summary>
        public SignalingBlock End
        {
            get => (SignalingBlock)Block.New(endBlockEGID);
        }
        
        /// <summary>
        /// The port number that the end of the wire connects to.
        /// </summary>
        public byte EndPort
        {
            get => endPort;
        }

        /// <summary>
        /// The display name of the end port.
        /// </summary>
        public string EndPortName
        {
            get => signalEngine.GetPort(endPortEGID).portNameLocalised;
        }

        /// <summary>
        /// Create a copy of the wire object where the direction of the wire is guaranteed to be from a block output to a block input.
        /// This is simply a different memory configuration and does not affect the in-game wire (which is always output -> input).
        /// </summary>
        /// <returns>A copy of the wire object.</returns>
        public Wire OutputToInputCopy()
        {
            return GetInstance(wireEGID, egid => new Wire(egid));
        }
        
        /// <summary>
        /// Convert the wire object to the direction the signal flows.
        /// Signals on wires always flow from a block output port to a block input port.
        /// This is simply a different memory configuration and does not affect the in-game wire (which is always output -> input).
        /// </summary>
        public void OutputToInputInPlace()
        {
            if (inputToOutput)
            {
                inputToOutput = false;
                // swap inputs and outputs
                (endBlockEGID, startBlockEGID) = (startBlockEGID, endBlockEGID);
                var tempPort = endPortEGID;
                endPortEGID = startPortEGID;
                startPortEGID = tempPort;
                (endPort, startPort) = (startPort, endPort);
            }
        }

        public override string ToString()
        {
            if (signalEngine.Exists<WireEntityStruct>(wireEGID))
            {
                return $"{nameof(Id)}: {Id}, Start{nameof(Start.Id)}: {Start.Id}, End{nameof(End.Id)}: {End.Id}, ({Start.Type}::{StartPort} aka {(StartPort != byte.MaxValue ? Start.PortName(StartPort, inputToOutput) : "")}) -> ({End.Type}::{EndPort} aka {(EndPort != byte.MaxValue ? End.PortName(EndPort, !inputToOutput) : "")})";
            }
            return $"{nameof(Id)}: {Id}, Start{nameof(Start.Id)}: {Start.Id}, End{nameof(End.Id)}: {End.Id}, ({Start.Type}::{StartPort} -> {End.Type}::{EndPort})";
        }

        internal static void Init() { }
    }
}