@inject Services.BlazorTimer Timer

<div class="row">
    <div class="col-6 col-lg-10 text-left">
        <div class="row">
            <div class="col-9 small">
                @if (totalCount > 0)
                {
                    <Pagination>
                        <PaginationItem>
                            <PaginationLink Clicked="@HandlePaginationItemClick" Page="1">
                                <i class="fas fa-angle-double-left"></i>
                            </PaginationLink>
                        </PaginationItem>
                        <PaginationItem>
                            <PaginationLink Clicked="@HandlePaginationItemClick" Page="@prevBlock.ToString()">
                                <span aria-hidden="true"><i class="fas fa-angle-left"></i></span>
                            </PaginationLink>
                        </PaginationItem>
                        @for (int i = @startPage; i <= endPage; ++i)
                        {
                            var pageNum = i;
                            <PaginationItem Active="@(currPage.Equals(pageNum))">
                                <PaginationLink Clicked="@HandlePaginationItemClick" Page="@pageNum.ToString()">
                                    @pageNum
                                </PaginationLink>
                            </PaginationItem>
                        }
                        <PaginationItem>
                            <PaginationLink Clicked="@HandlePaginationItemClick" Page="@nextBlock.ToString()">
                                <i class="fas fa-angle-right"></i>
                            </PaginationLink>
                        </PaginationItem>
                        <PaginationItem>
                            <PaginationLink Clicked="@HandlePaginationItemClick" Page="@LastPage.ToString()">
                                <i class="fas fa-angle-double-right"></i>
                            </PaginationLink>
                        </PaginationItem>
                    </Pagination>
                }
            </div>
            <div class="col-3">
                @if (!showLoading)
                {
                    <span>@totalCount records</span>
                }
            </div>
        </div>
        <div class="row">
            <div class="col-12 small">
                @if (showLoading)
                {
                    <Progress>
                        <ProgressBar Value="@percLoading" Striped="true" Animated="true" />
                    </Progress>
                }
            </div>
        </div>
    </div>
    <div class="col-6 col-lg-2 text-right">
        @if (totalCount > 0)
        {
            <div class="input-group input-group-sm">
                row/pag:&nbsp;
                <select @bind="@PageSize" class="form-control form-control-sm">
                    <option value="5">5</option>
                    <option value="10">10</option>
                    <option value="25">25</option>
                    <option value="50">50</option>
                    <option value="100">100</option>
                </select>
            </div>
        }
    </div>
</div>

@code {

    void HandlePaginationItemClick(string page)
    {
        currPage = int.Parse(page);
        reportChangePage();
    }

    private int numPages { get; set; } = 10;

    // calcola un set 1..numPOages centrato sulla pagina corrente...
    private int startPage
    {
        get
        {
            int answ = (int)(currPage / numPages) * numPages;
            answ = answ > 0 ? answ : 1;
            return answ;
        }
    }
    private int endPage
    {
        get
        {
            int answ = (int)(currPage / numPages) * numPages + numPages;
            answ = answ < LastPage ? answ : LastPage;
            return answ;
        }
    }

    private int prevBlock
    {
        get
        {
            int answ = currPage - numPages;
            answ = answ > 0 ? answ : 1;
            return answ;
        }
    }
    private int nextBlock
    {
        get
        {
            int answ = currPage + numPages;
            answ = answ < LastPage ? answ : LastPage;
            return answ;
        }
    }

    private int LastPage
    {
        get
        {
            return Math.Max((int)Math.Ceiling(totalCount / (double)PageSize), 1);
        }
    }

    protected override Task OnInitializedAsync()
    {
        showLoading = false;
        return base.OnInitializedAsync();
    }

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

    protected bool _showLoading = false;

    [Parameter]
    public bool showLoading
    {
        get
        {
            return _showLoading;
        }
        set
        {
            if (value)
            {
                Random random = new Random();
                percLoading = random.Next(30, 90);
            }
            else
            {
                percLoading = 5;
            }
            _showLoading = value;
        }
    }

    [Parameter]
    public int totalCount { get; set; } = 0;

    protected int _numRecord { get; set; } = 10;
    protected int _numPage { get; set; } = 1;

    [Parameter]
    public int PageSize
    {
        get
        {
            return _numRecord;
        }
        set
        {
            bool doReport = !_numRecord.Equals(value);
            if (doReport)
            {
                _numRecord = value;
                reportChange();
            }
        }
    }

    [Parameter]
    public int currPage
    {
        get
        {
            return _numPage;
        }
        set
        {
            bool doReport = !_numPage.Equals(value);
            if (doReport)
            {
                _numPage = value;
                reportChangePage();
            }
        }
    }

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

    private void reportChange()
    {
        numRecordChanged.InvokeAsync(PageSize);
    }
    private void reportChangePage()
    {
        numPageChanged.InvokeAsync(currPage);
    }

}