mapo-core/MP.Land/Components/DiffView.razor

@using MP.Land.Data
@using System.Text
@using DiffMatchPatch

<div class="row">
    <div class="col-6 table-success">
        <div class="row">
            <div class="col-4 text-success">
                <h4>Archivio</h4>
            </div>
            <div class="col-4">
            </div>
            <div class="col-4 text-end">
                <input @bind="@pHeight" class="text-end" width="20" inputmode="numeric" /> <i class="fas fa-arrows-alt-v"></i>
            </div>
        </div>
    </div>
    @if (numChanges > 0)
    {
        <div class="col-6 table-danger">
            <div class="row">
                <div class="col-4 text-danger">
                    <h4>Attuale</h4>
                </div>
                <div class="col-4">
                </div>
                <div class="col-4 text-end p-2">
                    <span class="border border-danger table-danger py-1 px-2"><b>@numChanges</b> modifiche</span>
                </div>
            </div>
        </div>
    }
</div>
<div class="row" style="height: @(pHeight)em; overflow-y: scroll;">
    <div class="col-6 table-success">
        <div class="border border-success p-2 bg-light">
            <p>@((MarkupString)oldResult)</p>
        </div>
    </div>
    @if (numChanges > 0)
    {
        <div class="col-6 table-danger">
            <div class="border border-danger p-2 bg-light">
                <p>@((MarkupString)newResult)</p>
            </div>
        </div>
    }
</div>

@code {

    string sepDest = "<br />";

    protected int pHeight = 25;

    protected string oldResult = "";
    protected string newResult = "";

    protected string _oldText = "";
    protected string _newText = "";

    [Parameter]
    public EventCallback<int> diffDone { get; set; }

    protected int numChanges { get; set; } = 0;

    [Parameter]
    public string oldText
    {
        get
        {
            return _oldText;
        }
        set
        {
            _oldText = value;
        }
    }

    protected string oldTextFix
    {
        get
        {
            return _oldText.Replace(Environment.NewLine, sepDest).Replace("\n", sepDest).Replace("\r", sepDest);
        }
    }

    protected string newTextFix
    {
        get
        {
            return _newText.Replace(Environment.NewLine, sepDest).Replace("\n", sepDest).Replace("\r", sepDest);
        }
    }
    [Parameter]
    public string newText
    {
        get
        {
            return _newText;
        }
        set
        {
            _newText = value;
            ReloadData();
        }
    }
    protected void ReloadData()
    {
        numChanges = 0;
        // calcolo diff
        diff_match_patch dmp = new diff_match_patch();
        List<Diff> diff = dmp.diff_main(oldTextFix, newTextFix);
        dmp.diff_cleanupSemantic(diff);

        // predispongo la stringa secondo l'elenco dei diff....
        StringBuilder sbNew = new StringBuilder();
        StringBuilder sbOld = new StringBuilder();
        foreach (var item in diff)
        {
            switch (item.operation)
            {
                case Operation.DELETE:
                    sbOld.Append($"<span class=\"border border-success table-success\">{item.text}</span>");
                    break;
                case Operation.INSERT:
                    sbNew.Append($"<span class=\"border border-danger table-danger\">{item.text}</span>");
                    numChanges++;
                    break;
                case Operation.EQUAL:
                    sbNew.Append($"<span class=\"text-dark\">{item.text}</span>");
                    sbOld.Append($"<span class=\"text-dark\">{item.text}</span>");
                    break;
                default:
                    break;
            }
        }

        newResult = sbNew.ToString().Trim();
        oldResult = sbOld.ToString().Trim();
        var pUpd = Task.Run(async () =>
        {
            await diffDone.InvokeAsync(numChanges);
        });
        pUpd.Wait();
    }

    protected override Task OnInitializedAsync()
    {
        ReloadData();
        return base.OnInitializedAsync();
    }

}