//
// Copyright (c) 2010-2018 Antmicro
// Copyright (c) 2011-2015 Realtime Embedded
//
// This file is licensed under the MIT License.
// Full license text is available in 'licenses/MIT.txt'.
//
using System;
using Antmicro.Renode.Peripherals.Bus;
using Antmicro.Renode.Logging;
using Antmicro.Renode.Core.Structure;
using System.Collections.Generic;
using Antmicro.Renode.Core;
using Antmicro.Renode.Core.Structure.Registers;

namespace Antmicro.Renode.Peripherals.SPI
{
    public sealed class BSOCSPI : NullRegistrationPointPeripheralContainer<ISPIPeripheral>, IWordPeripheral, IDoubleWordPeripheral, IBytePeripheral, IKnownSize
    {
        public BSOCSPI(Machine machine) : base(machine)
        {
            // receiveBuffer = new Queue<byte>();
            // IRQ = new GPIO();
            SetupRegisters();
            Reset();
        }

        public byte ReadByte(long offset)
        {
            // byte interface is there for DMA
            if(offset % 4 == 0)
            {
                return (byte)ReadDoubleWord(offset);
            }
            this.LogUnhandledRead(offset);
            return 0;
        }

        public void WriteByte(long offset, byte value)
        {
            if(offset % 4 == 0)
            {
                WriteDoubleWord(offset, (uint)value);
            }
            else
            {
                this.LogUnhandledWrite(offset, value);
            }
        }

        public ushort ReadWord(long offset)
        {
            return (ushort)ReadDoubleWord(offset);
        }

        public void WriteWord(long offset, ushort value)
        {
            WriteDoubleWord(offset, (uint)value);
        }

        public uint ReadDoubleWord(long offset)
        {
            // switch((Registers)offset)
            // {
            // case Registers.Data:
            //     return HandleDataRead();
            // default:
                return registers.Read(offset);
            // }
        }

        public void WriteDoubleWord(long offset, uint value)
        {
            // switch((Registers)offset)
            // {
            // case Registers.Data:
            //     HandleDataWrite(value);
            //     break;
            // default:
                registers.Write(offset, value);
                // break;
            // }
        }

        public override void Reset()
        {
            // lock(receiveBuffer)
            // {
            //     receiveBuffer.Clear();
            // }
            registers.Reset();
        }

        public long Size
        {
            get
            {
                return 0x400;
            }
        }

        // public GPIO IRQ
        // {    
        //     get;
        //     private set;
        // }

        // private uint HandleDataRead()
        // {
        //     IRQ.Unset();
        //     lock(receiveBuffer)
        //     {
        //         if(receiveBuffer.Count > 0)
        //         {
        //             var value = receiveBuffer.Dequeue();
        //             return value; // TODO: verify if Update should be called
        //         }
        //         this.Log(LogLevel.Warning, "Trying to read data register while no data has been received.");
        //         return 0;
        //     }
        // }

        // private void HandleDataWrite(uint value)
        // {
        //     IRQ.Unset();
        //     lock(receiveBuffer)
        //     {
        //         var peripheral = RegisteredPeripheral;
        //         if(peripheral == null)
        //         {
        //             this.Log(LogLevel.Warning, "SPI transmission while no SPI peripheral is connected.");
        //             receiveBuffer.Enqueue(0x0);
        //             return;
        //         }
        //         receiveBuffer.Enqueue(peripheral.Transmit((byte)value)); // currently byte mode is the only one we support
        //         this.NoisyLog("Transmitted 0x{0:X}, received 0x{1:X}.", value, receiveBuffer.Peek());
        //     }
        //     Update();
        // }

        private void Update()
        {
            // TODO: verify this condition
            // IRQ.Set(txBufferEmptyInterruptEnable.Value || rxBufferNotEmptyInterruptEnable.Value || txDmaEnable.Value || rxDmaEnable.Value);
        }

        private void SetupRegisters()
        {
            var registerDictionary = new Dictionary<long, DoubleWordRegister>
            { 
                { (long)Registers.TX1, new DoubleWordRegister(this, 0).WithValueField(0, 8, name:"TX1")},
                { (long)Registers.TX0, new DoubleWordRegister(this, 0).WithValueField(0, 8, name:"TX0")},
                { (long)Registers.RX1, new DoubleWordRegister(this, 0).WithValueField(0, 8, name:"RX1")},
                { (long)Registers.RX0, new DoubleWordRegister(this, 0).WithValueField(0, 8, name:"RX0")},
                { (long)Registers.CONTROL, new DoubleWordRegister(this)
                    .WithFlag(0, FieldMode.Write, name:"CLR_DONE")
                    .WithFlag(1, FieldMode.Write, name:"GO", changeCallback: (oldValue, newValue) => {
                        // Execute operation here
                    })
                    .WithFlag(2, FieldMode.Write, name:"INTENA")
                },
                {(long)Registers.STATUS, new DoubleWordRegister(this, 2)
                    .WithFlag(0, FieldMode.Read, name:"TIP")
                    .WithFlag(1, FieldMode.Read, name: "DONE", valueProviderCallback: (_) => {doneBit = !doneBit; return doneBit; })
                },
            };
            registers = new DoubleWordRegisterCollection(this, registerDictionary);
        }

        private bool doneBit;

        private DoubleWordRegisterCollection registers;

        private enum Registers
        {
            TX1 = 0x00,
            TX0 = 0x04,
            RX1 = 0x08,
            RX0 = 0x0c,
            CONTROL = 0x10,
            STATUS = 0x14,
        }
    }
}