CalculatorViewModel.cs

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using NeuroAccessMaui.Resources.Languages;
using NeuroAccessMaui.Services;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Globalization;
using System.Text;
using Waher.Script;
using Waher.Script.Operators.Vectors;
 
namespace NeuroAccessMaui.UI.Pages.Main.Calculator
{
    public partial class CalculatorViewModel : XmppViewModel
    {
        public CalculatorViewModel(CalculatorNavigationArgs? Args)
            : base()
        {
            this.Stack = [];
            this.MemoryItems = [];
 
            if (Args is not null)
            {
                this.Entry = Args.Entry;
                this.ViewModel = Args.ViewModel;
                this.Property = Args.Property;
 
                if (this.Entry is not null)
                    this.Value = this.Entry.Text;
                else if (this.ViewModel is not null && this.Property is not null)
                    this.Value = this.ViewModel.GetValue(this.Property)?.ToString() ?? string.Empty;
                else
                    this.Value = string.Empty;
            }
 
            this.DecimalSeparator = NumberFormatInfo.CurrentInfo.NumberDecimalSeparator;
            this.DisplayMain = true;
            this.DisplayFunctions = false;
            this.DisplayHyperbolic = false;
            this.DisplayInverse = false;
            this.DisplayEndParenthesis = false;
            this.DisplayEquals = true;
            this.Status = string.Empty;
            this.Memory = null;
            this.Entering = false;
            this.NrParentheses = 0;
            this.HasValue = !string.IsNullOrEmpty(this.Value);
            this.HasStatistics = false;
        }
 
        protected override async Task OnDispose()
        {
            await this.EvaluateStack(true);
 
            await base.OnDispose();
        }
 
        #region Properties
 
        protected override void OnPropertyChanged(PropertyChangedEventArgs e)
        {
            base.OnPropertyChanged(e);
 
            switch (e.PropertyName)
            {
                case nameof(this.Value):
                    this.HasValue = !string.IsNullOrEmpty(this.Value);
 
                    if (this.Entry is not null)
                        this.Entry.Text = this.Value;
 
                    if (this.ViewModel is not null && this.Property is not null)
                        this.ViewModel.SetValue(this.Property, this.Value);
                    break;
 
                case nameof(this.NrParentheses):
                case nameof(this.DisplayFunctions):
                case nameof(this.DisplayHyperbolic):
                case nameof(this.DisplayInverse):
                    this.CalcDisplay();
                    break;
            }
        }
 
        [ObservableProperty]
        private string? value;
 
        [ObservableProperty]
        private string? status;
 
        [ObservableProperty]
        private bool entering;
 
        [ObservableProperty]
        private bool hasValue;
 
        [ObservableProperty]
        private bool hasStatistics;
 
        [ObservableProperty]
        private int nrParentheses;
 
        [ObservableProperty]
        private object? memory;
 
        [ObservableProperty]
        private Entry? entry;
 
        [ObservableProperty]
        private BaseViewModel? viewModel;
 
        [ObservableProperty]
        private string? property;
 
        [ObservableProperty]
        private string? decimalSeparator;
 
        [ObservableProperty]
        private bool displayMain;
 
        [ObservableProperty]
        private bool displayFunctions;
 
        [ObservableProperty]
        private bool displayHyperbolic;
 
        [ObservableProperty]
        private bool displayInverse;
 
        [ObservableProperty]
        private bool displayNotHyperbolicNotInverse;
 
        [ObservableProperty]
        private bool displayHyperbolicNotInverse;
 
        [ObservableProperty]
        private bool displayNotHyperbolicInverse;
 
        [ObservableProperty]
        private bool displayHyperbolicInverse;
 
        [ObservableProperty]
        private bool displayEquals;
 
        [ObservableProperty]
        private bool displayEndParenthesis;
 
        private void CalcDisplay()
        {
            this.DisplayHyperbolicInverse = this.DisplayFunctions && this.DisplayHyperbolic && this.DisplayInverse;
            this.DisplayNotHyperbolicInverse = this.DisplayFunctions && !this.DisplayHyperbolic && this.DisplayInverse;
            this.DisplayHyperbolicNotInverse = this.DisplayFunctions && this.DisplayHyperbolic && !this.DisplayInverse;
            this.DisplayNotHyperbolicNotInverse = this.DisplayFunctions && !this.DisplayHyperbolic && !this.DisplayInverse;
            this.DisplayEquals = this.DisplayMain && this.NrParentheses == 0;
            this.DisplayEndParenthesis = this.DisplayMain && this.NrParentheses > 0;
        }
 
        public ObservableCollection<StackItem> Stack { get; }
 
        public ObservableCollection<object> MemoryItems { get; }
 
        #endregion
 
        #region Commands
 
        [RelayCommand]
        private void Toggle()
        {
            this.DisplayMain = !this.DisplayMain;
            this.DisplayFunctions = !this.DisplayFunctions;
        }
 
        [RelayCommand]
        private void ToggleHyperbolic()
        {
            this.DisplayHyperbolic = !this.DisplayHyperbolic;
        }
 
        [RelayCommand]
        private void ToggleInverse()
        {
            this.DisplayInverse = !this.DisplayInverse;
        }
 
        [RelayCommand]
        private async Task KeyPress(object P)
        {
            try
            {
                string Key = P?.ToString() ?? string.Empty;
 
                switch (Key)
                {
                    // Key entry
 
                    case "0":
                        if (!this.Entering)
                            break;
 
                        this.Value += Key;
                        break;
 
                    case "1":
                    case "2":
                    case "3":
                    case "4":
                    case "5":
                    case "6":
                    case "7":
                    case "8":
                    case "9":
                        if (!this.Entering)
                        {
                            this.Value = string.Empty;
                            this.Entering = true;
                        }
 
                        this.Value += Key;
                        break;
 
                    case ".":
                        Key = NumberFormatInfo.CurrentInfo.NumberDecimalSeparator;
                        this.Value += Key;
                        this.Entering = true;
                        break;
 
                    // Results
 
                    case "C":
                        this.Value = string.Empty;
                        this.Entering = false;
                        break;
 
                    case "CE":
                        this.Value = string.Empty;
                        this.Memory = null;
                        this.Stack.Clear();
                        this.MemoryItems.Clear();
                        this.Entering = false;
                        this.HasStatistics = false;
 
                        this.OnPropertyChanged(nameof(this.StackString));
                        this.OnPropertyChanged(nameof(this.MemoryString));
                        break;
 
                    case "=":
                        await this.EvaluateStack();
                        break;
 
                    // Unary operators
 
                    case "+-":
                        await this.Evaluate("-x");
                        break;
 
                    case "1/x":
                        await this.Evaluate("1/x");
                        break;
 
                    case "%":
                        await this.Evaluate("x%");
                        break;
 
                    case "%0":
                        await this.Evaluate("x‰");
                        break;
 
                    case "°":
                        await this.Evaluate("x°");
                        break;
 
                    case "x2":
                        await this.Evaluate("x^2");
                        break;
 
                    case "sqrt":
                        await this.Evaluate("sqrt(x)");
                        break;
 
                    case "10^x":
                        await this.Evaluate("10^x");
                        break;
 
                    case "2^x":
                        await this.Evaluate("2^x");
                        break;
 
                    case "rad":
                        await this.Evaluate("x*180/pi");
                        break;
 
                    // Binary operators
 
                    case "+":
                        await this.Evaluate("x+y", "+", OperatorPriority.Terms, false);
                        break;
 
                    case "-":
                        await this.Evaluate("x-y", "−", OperatorPriority.Terms, false);
                        break;
 
                    case "*":
                        await this.Evaluate("x*y", "⨉", OperatorPriority.Factors, false);
                        break;
 
                    case "/":
                        await this.Evaluate("x/y", "÷", OperatorPriority.Factors, false);
                        break;
 
                    case "^":
                        await this.Evaluate("x^y", "^", OperatorPriority.Powers, false);
                        break;
 
                    case "yrt":
                        await this.Evaluate("x^(1/y)", "ʸ√", OperatorPriority.Powers, false);
                        break;
 
                    // Order
 
                    case "(":
 
                        if (this.Entering)
                        {
                            await this.Evaluate("x*y", "⨉", OperatorPriority.Factors, true);
                            break;
                        }
 
                        if (this.Stack.Count > 0)
                        {
                            this.Stack[^1].StartParenthesis = true;
                            this.OnPropertyChanged(nameof(this.StackString));
                        }
 
                        break;
 
                    case ")":
                        await this.Evaluate(string.Empty, "=", OperatorPriority.Parenthesis, false);
                        if (this.Stack.Count > 0)
                        {
                            this.Stack[^1].StartParenthesis = false;
                            this.OnPropertyChanged(nameof(this.StackString));
                        }
                        break;
 
                    // Analytical Funcions
 
                    case "exp":
                    case "lg":
                    case "log2":
                    case "ln":
                    case "sin":
                    case "sinh":
                    case "asin":
                    case "asinh":
                    case "cos":
                    case "cosh":
                    case "acos":
                    case "acosh":
                    case "tan":
                    case "tanh":
                    case "atan":
                    case "atanh":
                    case "sec":
                    case "sech":
                    case "asec":
                    case "asech":
                    case "csc":
                    case "csch":
                    case "acsc":
                    case "acsch":
                    case "cot":
                    case "coth":
                    case "acot":
                    case "acoth":
                        await this.Evaluate(Key + "(x)");
                        break;
 
                    // Other scalar functions
 
                    case "abs":
                    case "sign":
                    case "round":
                    case "ceil":
                    case "floor":
                        await this.Evaluate(Key + "(x)");
                        break;
 
                    case "frac":
                        await this.Evaluate("x-floor(x)");
                        break;
 
                    // Statistics
 
                    case "M+":
                        await this.AddToMemory();
                        break;
 
                    case "M-":
                        await this.SubtractFromMemory();
                        break;
 
                    case "MR":
                        this.Value = Expression.ToString(this.Memory);
                        this.Entering = false;
                        break;
 
                    case "avg":
                    case "stddev":
                    case "sum":
                    case "prod":
                    case "min":
                    case "max":
                        await this.EvaluateStatistics(Key + "(x)");
                        break;
                }
            }
            catch (Exception ex)
            {
                this.Status = ex.Message;
            }
        }
 
        private async Task<object> Evaluate()
        {
            if (string.IsNullOrEmpty(this.Value))
                throw new Exception(ServiceRef.Localizer[nameof(AppResources.EnterValue)]);
 
            try
            {
                return await Expression.EvalAsync(this.Value);
            }
            catch (Exception)
            {
                throw new Exception(ServiceRef.Localizer[nameof(AppResources.EnterValidValue)]);
            }
        }
 
        private async Task Evaluate(string Script)
        {
            object x = await this.Evaluate();
 
            try
            {
                Variables v = [];
 
                v["x"] = x;
 
                object y = await Expression.EvalAsync(Script, v);
 
                this.Value = Expression.ToString(y);
                this.Entering = false;
            }
            catch (Exception)
            {
                throw new Exception(ServiceRef.Localizer[nameof(AppResources.CalculationError)]);
            }
        }
 
        private async Task Evaluate(string Script, string Operator, OperatorPriority Priority, bool StartParenthesis)
        {
            object x = await this.Evaluate();
            StackItem Item;
            int c = this.Stack.Count;
 
            // if (c > 0 && (Item = this.Stack[c - 1]).StartParenthesis)
            //  Priority = OperatorPriority.Parenthesis;
 
            while (c > 0 && (Item = this.Stack[c - 1]).Priority >= Priority && !Item.StartParenthesis)
            {
                object y = x;
 
                this.Value = Item.Entry ?? string.Empty;
                x = await this.Evaluate();
 
                try
                {
                    Variables v = [];
 
                    v["x"] = x;
                    v["y"] = y;
 
                    x = await Expression.EvalAsync(Item.Script, v);
 
                    this.Value = Expression.ToString(x);
                    this.Entering = false;
                }
                catch (Exception)
                {
                    throw new Exception(ServiceRef.Localizer[nameof(AppResources.CalculationError)]);
                }
 
                c--;
                this.Stack.RemoveAt(c);
            }
 
            if (!string.IsNullOrEmpty(Script))
            {
                this.Stack.Add(new StackItem()
                {
                    Entry = this.Value,
                    Script = Script,
                    Operator = Operator,
                    Priority = Priority,
                    StartParenthesis = StartParenthesis
                });
 
                this.Value = string.Empty;
            }
 
            this.Entering = false;
            this.OnPropertyChanged(nameof(this.StackString));
        }
 
        private async Task EvaluateStatistics(string Script)
        {
            List<Waher.Script.Abstraction.Elements.IElement> Elements = [];
 
            foreach (object Item in this.MemoryItems)
                Elements.Add(Expression.Encapsulate(Item));
 
            try
            {
                Variables v = [];
 
                v["x"] = VectorDefinition.Encapsulate(Elements, false, null);
 
                object y = await Expression.EvalAsync(Script, v);
 
                this.Value = Expression.ToString(y);
                this.Entering = false;
            }
            catch (Exception)
            {
                throw new Exception(ServiceRef.Localizer[nameof(AppResources.CalculationError)]);
            }
        }
 
        public string StackString
        {
            get
            {
                StringBuilder sb = new();
                bool First = true;
                int NrParantheses = 0;
                OperatorPriority PrevPriority = OperatorPriority.Equals;
                bool StartParenthesis = false;
 
                foreach (StackItem Item in this.Stack)
                {
                    if (First)
                        First = false;
                    else
                        sb.Append(' ');
 
                    if (Item.Priority < PrevPriority || StartParenthesis)
                    {
                        NrParantheses++;
                        sb.Append(" ( ");
                    }
 
                    PrevPriority = Item.Priority;
                    StartParenthesis = Item.StartParenthesis;
 
                    sb.Append(Item.Entry);
                    sb.Append(' ');
                    sb.Append(Item.Operator);
                }
 
                if (StartParenthesis)
                {
                    sb.Append(" (");
                    NrParantheses++;
                }
 
                this.NrParentheses = NrParantheses;
 
                while (NrParantheses > 0)
                {
                    sb.Append(" )");
                    NrParantheses--;
                }
 
                return sb.ToString();
            }
        }
 
        public Task EvaluateStack()
        {
            return this.EvaluateStack(false);
        }
 
        public async Task EvaluateStack(bool IgnoreError)
        {
            if (this.Stack.Count == 0 && string.IsNullOrEmpty(this.Value))
                return;
 
            if (IgnoreError)
            {
                try
                {
                    await this.Evaluate(string.Empty, "=", OperatorPriority.Equals, false);
                }
                catch (Exception)
                {
                    // Ignore
                }
            }
            else
                await this.Evaluate(string.Empty, "=", OperatorPriority.Equals, false);
        }
 
        public string MemoryString
        {
            get
            {
                if (this.Memory is null)
                    return string.Empty;
 
                StringBuilder sb = new();
 
                sb.Append("M: ");
                sb.Append(Expression.ToString(this.Memory));
                sb.Append(" (");
                sb.Append(this.MemoryItems.Count.ToString(CultureInfo.InvariantCulture));
                sb.Append(')');
 
                return sb.ToString();
            }
        }
 
        private async Task AddToMemory()
        {
            await this.EvaluateStack();
 
            object x = await this.Evaluate();
 
            this.MemoryItems.Add(x);
 
            if (this.Memory is null)
                this.Memory = x;
            else
            {
                Variables v = [];
 
                v["M"] = this.Memory;
                v["x"] = x;
 
                this.Memory = await Expression.EvalAsync("M+x", v);
            }
 
            this.HasStatistics = true;
            this.OnPropertyChanged(nameof(this.MemoryString));
        }
 
        private async Task SubtractFromMemory()
        {
            await this.EvaluateStack();
 
            object x = await this.Evaluate();
 
            this.MemoryItems.Add(x);
 
            if (this.Memory is null)
            {
                Variables v = [];
 
                v["x"] = x;
 
                this.Memory = await Expression.EvalAsync("-x", v);
            }
            else
            {
                Variables v = [];
 
                v["M"] = this.Memory;
                v["x"] = x;
 
                this.Memory = await Expression.EvalAsync("M+x", v);
            }
 
            this.HasStatistics = true;
            this.OnPropertyChanged(nameof(this.MemoryString));
        }
 
        #endregion
    }
}