/*
 *                     GNU AFFERO GENERAL PUBLIC LICENSE
 *                       Version 3, 19 November 2007
 *  Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
 *  Everyone is permitted to copy and distribute verbatim copies
 *  of this license document, but changing it is not allowed.
 */

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Serialization;
using Emgu.CV;
using UVtools.Core.FileFormats;

namespace UVtools.Core.Operations
{
    [Serializable]
    public class OperationLayerArithmetic : Operation
    {
        #region Members
        private string _sentence;
        #endregion

        #region Enums
        public enum LayerArithmeticOperators : byte
        {
            None,
            Add,
            Subtract,
            Multiply,
            Divide,
            BitwiseAnd,
            BitwiseOr,
            BitwiseXor,
            AbsDiff
        }
        #endregion

        #region SubClasses
        public sealed class ArithmeticOperation
        {
            public uint LayerIndex { get; }
            public LayerArithmeticOperators Operator { get; }

            public ArithmeticOperation(uint layerIndex, LayerArithmeticOperators layerArithmeticOperator)
            {
                LayerIndex = layerIndex;
                Operator = layerArithmeticOperator;
            }
        }
        #endregion

        #region Overrides

        public override Enumerations.LayerRangeSelection StartLayerRangeSelection => Enumerations.LayerRangeSelection.None;
        public override string Title => "Layer arithmetic";
        public override string Description =>
            "Perform arithmetic operations over the layers\n" +
            "Available operators:\n" +
            " +  -  *  /  = Add, Subtract, Multiply, Divide\n" +
            " &  |  ^  = Bitwise AND, OR, XOR\n" +
            " $ = Absolute difference\n\n" +
            "Syntax: <set_to_layer_indexes> = <layer_index> <operator> <layer_index>\n" +
            "When: \"<set_to_layer_indexes> =\" is omitted, the result will assign to the first layer on the sentence.\n\n" +
            "Example 1: 10+11\n" +
            "Example 2: 10,11,12 = 11+12-10*5   Same as: 10:12 = 11+12-10*5\n" +
            "On example 1 the layer 10 will be set with the result of layer 10 plus layer 11.\n" +
            "On example 2 the layers 10,11,12 will be set with the result of layer 11 plus 12 minus 10 all multiplied by layer 5.\n\n" +
            "Note: Calculation are made sequential, math order rules wont apply here.";

        public override string ConfirmationText =>
            $"perform this arithmetic operation";

        public override string ProgressTitle =>
            $"performing the arithmetic operations";

        public override string ProgressAction => "Calculated layers";

        public override string ValidateInternally()
        {
            var sb = new StringBuilder();
            if (string.IsNullOrWhiteSpace(_sentence))
                sb.AppendLine("The sentence is empty.");
            else if(!Parse())
                sb.AppendLine("Unable to parse the sentence, malformed or incomplete.");
            else if (SetLayers.Count == 0)
                sb.AppendLine("No layers to assign.");
            else if (Operations.Count == 0)
                sb.AppendLine("No operations to perform.");
            else if (!IsValid)
                sb.AppendLine("The operation will have no impact and will not be performed.");

            return sb.ToString();
        }

        public override string ToString()
        {
            var result = $"{_sentence}";
            if (!string.IsNullOrEmpty(ProfileName)) result = $"{ProfileName}: {result}";
            return result;
        }
        #endregion

        #region Properties
        public string Sentence
        {
            get => _sentence;
            set => RaiseAndSetIfChanged(ref _sentence, value);
        }
        [XmlIgnore]
        public List<ArithmeticOperation> Operations { get; private set; } = new();

        [XmlIgnore]
        public List<uint> SetLayers { get; private set; } = new();

        public bool IsValid => SetLayers.Count > 0 && Operations.Count > 0 && 
                               !(SetLayers.Count == 1 && Operations.Count == 1 && SetLayers[0] == Operations[0].LayerIndex);
        #endregion

        #region Constructor

        public OperationLayerArithmetic() { }

        public OperationLayerArithmetic(FileFormat slicerFile) : base(slicerFile) { }

        #endregion

        #region Methods

        public bool Parse()
        {
            if (string.IsNullOrEmpty(_sentence)) return false;
            SetLayers.Clear();
            Operations.Clear();

            var splitSentence = _sentence.Split('=');
            var operations = splitSentence[0];
            if (splitSentence.Length >= 2)
            {
                operations = splitSentence[1];
                var setLayers = splitSentence[0].Replace(" ", string.Empty).Split(',', StringSplitOptions.TrimEntries);
                foreach (var layer in setLayers)
                {
                    var rangeSplit = layer.Split(':', StringSplitOptions.TrimEntries);
                    if (rangeSplit.Length > 1)
                    {
                        uint.TryParse(rangeSplit[0].Trim(), out var startLayer);
                        if (!uint.TryParse(rangeSplit[1].Trim(), out var endLayer)) endLayer = SlicerFile.LastLayerIndex;
                        for (var index = startLayer; index <= endLayer; index++)
                        {
                            if (SetLayers.Contains(index)) continue;
                            SetLayers.Add(index);
                        }
                        continue;
                    }

                    if (!uint.TryParse(layer.Trim(), out var layerIndex)) continue;
                    if (SetLayers.Contains(layerIndex)) continue;
                    SetLayers.Add(layerIndex);
                }
            }

            SetLayers = SetLayers.Where(layerIndex => layerIndex <= SlicerFile.LastLayerIndex).ToList();
            SetLayers.Sort();

            operations = operations.Replace(" ", string.Empty);
            if (string.IsNullOrWhiteSpace(operations)) return false;

            string layerIndexStr = string.Empty;
            foreach (char c in operations)
            {
                if (c >= '0' && c <= '9')
                {
                    layerIndexStr += c;
                    continue;
                }

                LayerArithmeticOperators op = LayerArithmeticOperators.None;
                switch (c)
                {
                    case '+':
                        op = LayerArithmeticOperators.Add;
                        break;
                    case '-':
                        op = LayerArithmeticOperators.Subtract;
                        break;
                    case '*':
                        op = LayerArithmeticOperators.Multiply;
                        break;
                    case '/':
                        op = LayerArithmeticOperators.Divide;
                        break;
                    case '&':
                        op = LayerArithmeticOperators.BitwiseAnd;
                        break;
                    case '|':
                        op = LayerArithmeticOperators.BitwiseOr;
                        break;
                    case '^':
                        op = LayerArithmeticOperators.BitwiseXor;
                        break;
                    case '$':
                        op = LayerArithmeticOperators.AbsDiff;
                        break;
                }

                if (op == LayerArithmeticOperators.None  // No valid operator
                    || string.IsNullOrWhiteSpace(layerIndexStr) // Started with a operator instead of layer
                    ) continue; 


                if (uint.TryParse(layerIndexStr, out var layerIndex))
                {
                    Operations.Add(new ArithmeticOperation(layerIndex, op));
                }

                // Reset layer string
                layerIndexStr = string.Empty;
            }

            // Append the left over
            if (!string.IsNullOrWhiteSpace(layerIndexStr))
            {
                if (uint.TryParse(layerIndexStr, out var layerIndex))
                {
                    Operations.Add(new ArithmeticOperation(layerIndex, LayerArithmeticOperators.None));
                }
            }

            Operations = Operations.Where(op => op.LayerIndex <= SlicerFile.LastLayerIndex).ToList();

            //if (Operations.Count == 0) return false;
            if (SetLayers.Count == 0 && Operations.Count > 0)
            {
                SetLayers.Add(Operations[0].LayerIndex);
            }

            return true;
        }

        protected override bool ExecuteInternally(OperationProgress progress)
        {
            if (!IsValid) return false;

            using var result = SlicerFile[Operations[0].LayerIndex].LayerMat;
            using var resultRoi = GetRoiOrDefault(result);
            using var imageMask = GetMask(resultRoi);

            progress.ItemCount = (uint) Operations.Count;
            for (int i = 1; i < Operations.Count; i++)
            {
                progress.Token.ThrowIfCancellationRequested();
                using var image = SlicerFile[Operations[i].LayerIndex].LayerMat;
                var imageRoi = GetRoiOrDefault(image);
                
                switch (Operations[i - 1].Operator)
                {
                    case LayerArithmeticOperators.Add:
                        CvInvoke.Add(resultRoi, imageRoi, resultRoi, imageMask);
                        break;
                    case LayerArithmeticOperators.Subtract:
                        CvInvoke.Subtract(resultRoi, imageRoi, resultRoi, imageMask);
                        break;
                    case LayerArithmeticOperators.Multiply:
                        CvInvoke.Multiply(resultRoi, imageRoi, resultRoi);
                        break;
                    case LayerArithmeticOperators.Divide:
                        CvInvoke.Divide(resultRoi, imageRoi, resultRoi);
                        break;
                    case LayerArithmeticOperators.BitwiseAnd:
                        CvInvoke.BitwiseAnd(resultRoi, imageRoi, resultRoi, imageMask);
                        break;
                    case LayerArithmeticOperators.BitwiseOr:
                        CvInvoke.BitwiseOr(resultRoi, imageRoi, resultRoi, imageMask);
                        break;
                    case LayerArithmeticOperators.BitwiseXor:
                        CvInvoke.BitwiseXor(resultRoi, imageRoi, resultRoi, imageMask);
                        break;
                    case LayerArithmeticOperators.AbsDiff:
                        CvInvoke.AbsDiff(resultRoi, imageRoi, resultRoi);
                        break;
                }

                progress++;
            }

            progress.Reset("Applied layers", (uint) SetLayers.Count);
            Parallel.ForEach(SetLayers, layerIndex =>
            {
                if (progress.Token.IsCancellationRequested) return;
                progress.LockAndIncrement();
                if (Operations.Count == 1 || HaveROIorMask)
                {
                    using var mat = SlicerFile[layerIndex].LayerMat;
                    var matRoi = GetRoiOrDefault(mat);
                    resultRoi.CopyTo(matRoi, imageMask);
                    SlicerFile[layerIndex].LayerMat = mat;
                    return;
                }

                //ApplyMask(mat, resultRoi, imageMask);

                SlicerFile[layerIndex].LayerMat = result;
            });

            return !progress.Token.IsCancellationRequested;
        }

        #endregion

        #region Equality
        protected bool Equals(OperationLayerArithmetic other)
        {
            return _sentence == other._sentence;
        }

        public override bool Equals(object obj)
        {
            if (obj is null) return false;
            if (ReferenceEquals(this, obj)) return true;
            if (obj.GetType() != GetType()) return false;
            return Equals((OperationLayerArithmetic) obj);
        }

        public override int GetHashCode()
        {
            return (_sentence != null ? _sentence.GetHashCode() : 0);
        }
        #endregion
    }
}