inabox/InABox.Avalonia/DataModels/Shell.cs

using System.ComponentModel;
using System.Runtime.CompilerServices;
using DynamicData.Binding;
using InABox.Clients;
using InABox.Core;

namespace InABox.Avalonia;

public abstract class Shell<TParent,TEntity> : INotifyPropertyChanged, IShell, IShell<TEntity>
    where TParent : ICoreRepository
    where TEntity : Entity, IPersistent, IRemotable, new()
{
    private object? _tag;
    public object? Tag
    {
        get => _tag;
        set => SetProperty(ref _tag, value);
    }

    private bool _isSelected;
    public bool IsSelected
    {
        get => _isSelected;
        set
        {
            if(_isSelected != value)
            {
                _isSelected = value;
                DoPropertyChanged(nameof(IsSelected));
            }
        }
    }
    
    #region INotifyPropertyChanged
    
    public event PropertyChangedEventHandler? PropertyChanged;
    
    protected void DoPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
    
    protected bool SetProperty<T>(ref T field, T value, [CallerMemberName] string propertyName = "")
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        DoPropertyChanged(propertyName);
        return true;
    }

    
    #endregion

    private TEntity? _entity;
    
    private TEntity CheckEntity()
    {
        _entity ??= Row.ToObject<TEntity>();
        _entity.PropertyCascaded -= _entity_PropertyChanged;
        _entity.PropertyCascaded += _entity_PropertyChanged;
        return _entity;
    }

    private void _entity_PropertyChanged(object? sender, PropertyChangedEventArgs e)
    {
        if(e.PropertyName is not null && Columns.FindShellProperty(e.PropertyName) is string property)
        {
            DoPropertyChanged(property);
        }
    }

    public TEntity Entity => CheckEntity();
    
    protected virtual void RowChanged()
    {
    }

    public bool IsChanged() => _entity?.IsChanged() ?? false;

    public void SyncRow()
    {
        Row.Table.FillRow(Row, Entity);
    }
    
    public virtual void Save(string auditmessage)
    {
        new Client<TEntity>().Save(Entity, auditmessage);
        Entity.CommitChanges();
        SyncRow();
        if (!Parent.HasItem(this))
        {
            Parent.CommitItem(this);
        }
    }

    public Task SaveAsync(string auditMessage)
    {
        return Task.Run(() => Save(auditMessage));
    }

    public void Cancel()
    {
        _entity?.CancelChanges();
    }
    
    private CoreRow _row = null!;
    public CoreRow Row
    {
        get => _row;
        set
        {
            _row = value;
            RowChanged();
        }
    }
    
    public TParent Parent { get; set; }

    ICoreRepository IShell.Parent => this.Parent;

    public Guid ID => Get<Guid>();

    public virtual string[] TextSearchValues() => [];
    
    public bool Match(string? text)
    {
        if (string.IsNullOrWhiteSpace(text))
            return true;
        foreach (var value in TextSearchValues())
        {
            if (value.Contains(text, StringComparison.InvariantCultureIgnoreCase))
                return true;
        }
        return false;
    }
    
    #region Row Get/Set Caching
    
    // We do this for three reasons:
    // 1. Rather than define properties in once class and columns in another,
    // we can define and link properties and columns in the one class,
    // using a _static_ constructor, which reduces complexity
    // 2. By caching based on the property name, we eliminate the need to convert
    // expressions to strings (expensive), while still retaining type-safety
    // 3. Using the Get/Set helper functions reduces code complexity when defining 
    // shell properties, and distinguishes between data and calculated properties

    private static ShellColumns<TParent, TEntity>? _columns;
    
    public ShellColumns<TParent, TEntity> Columns
    {
        get
        {
            if (_columns == null)
            {
                _columns = new ShellColumns<TParent, TEntity>();
                _columns.Map(nameof(ID), x => x.ID);
                ConfigureColumns(_columns);
            }
            return _columns;
        }
    }

    protected abstract void ConfigureColumns(ShellColumns<TParent, TEntity> columns);
    
    /// <summary>
    /// Get the property on the entity, coercing <see langword="default"/>(<typeparamref name="T"/>) into <see langword="null"/>.
    /// </summary>
    protected T? GetNullable<T>([CallerMemberName] string property = null)
        where T : struct
    {
        var value = Get<T>(property);
        if(Equals(value, default(T)))
        {
            return null;
        }
        else
        {
            return value;
        }
    }

    /// <summary>
    /// Set the property on the entity, coercing <see langword="null"/> into <see langword="default"/>(<typeparamref name="T"/>).
    /// </summary>
    protected void SetNullable<T>(T? value, bool donotify = true, [CallerMemberName] string property = null, params string[] notify)
        where T : struct
    {
        if(value is null)
        {
            Set(default(T), donotify, property, notify);
        }
        else
        {
            Set(value.Value, donotify, property, notify);
        }
    }

    protected virtual T Get<T>([CallerMemberName] string property = null)
    {
        if (_entity != null)
        {
            return (T)CoreUtils.GetPropertyValue(
                _entity,
                Columns[property]
            );
        }

        if (_row != null)
        {
            var col = _columns?.IndexOf(property);
            if (col != null)
                return Row.Get<T>(col.Value); //() Row.Values[];
        }

        return CoreUtils.GetDefault<T>();

        //return value != null ? (T)CoreUtils.ChangeType(value, typeof(T)) : CoreUtils.GetDefault<T>();        
    }
    
    protected virtual void Set<T>(T value, bool donotify = true, [CallerMemberName] string property = null, params string[] notify)
    {
        CheckEntity();
        CoreUtils.SetPropertyValue(_entity, Columns[property], value);
        //Row.Values[Columns.IndexOf(property)] = value;
        // if (donotify)
        // {
        //     DoPropertyChanged(property);
        //     foreach (var _property in notify)
        //         DoPropertyChanged(_property);
        // }
    }
    

    #endregion
    
}