@using TuringMachine.Core

<div class="tape-wrapper">
    <button class="scroll-btn" @onclick="ScrollLeft" disabled="@(ScrollOffset <= 0)">◀</button>
    
    <div class="tape-container" @ref="tapeContainer">
        @for (int i = StartIndex; i <= EndIndex; i++)
        {
            var isHead = i == HeadPosition;
            <div class="tape-cell @(isHead ? "head" : "")" id="@($"cell-{i}")">
                <span class="cell-index">@i</span>
                <span class="cell-value">@Tape[i]</span>
            </div>
        }
    </div>
    
    <button class="scroll-btn" @onclick="ScrollRight" disabled="@(ScrollOffset >= MaxScrollOffset)">▶</button>
</div>

<style>
    .tape-wrapper {
        display: flex;
        align-items: center;
        gap: 10px;
        padding: 20px;
        background-color: var(--tape-bg);
        border-radius: 8px;
        overflow: hidden;
    }

    .scroll-btn {
        background-color: var(--button-bg);
        color: var(--button-text);
        border: none;
        padding: 10px 15px;
        cursor: pointer;
        border-radius: 4px;
        font-size: 18px;
        transition: background-color 0.2s;
    }

    .scroll-btn:hover:not(:disabled) {
        background-color: var(--button-hover-bg);
    }

    .scroll-btn:disabled {
        opacity: 0.3;
        cursor: not-allowed;
    }

    .tape-container {
        display: flex;
        gap: 5px;
        overflow-x: scroll;
        flex: 1;
        padding: 10px 0;
        scrollbar-width: thin;
        scrollbar-color: var(--border-color) var(--tape-bg);
    }

    .tape-container::-webkit-scrollbar {
        height: 8px;
    }

    .tape-container::-webkit-scrollbar-track {
        background: var(--tape-bg);
    }

    .tape-container::-webkit-scrollbar-thumb {
        background: var(--border-color);
        border-radius: 4px;
    }

    .tape-cell {
        min-width: 60px;
        height: 80px;
        border: 2px solid var(--tape-cell-border);
        background-color: var(--tape-cell-bg);
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        border-radius: 4px;
        transition: all 0.3s ease;
    }

    .tape-cell.head {
        background-color: var(--tape-head-bg);
        border-color: var(--tape-head-border);
        border-width: 3px;
        transform: scale(1.1);
        box-shadow: 0 4px 8px rgba(0, 123, 255, 0.3);
    }

    .cell-index {
        font-size: 10px;
        color: var(--text-secondary);
        margin-bottom: 4px;
    }

    .cell-value {
        font-size: 24px;
        font-weight: bold;
        font-family: 'Courier New', monospace;
        color: var(--text-primary);
    }
</style>

@code {
    [Parameter] public Tape Tape { get; set; } = new();
    [Parameter] public int HeadPosition { get; set; }

    private ElementReference tapeContainer;
    private int ScrollOffset = 0;
    private const int CellsPerPage = 15;
    private const int Padding = 5;

    private int TapeStart => Tape.MinIndex - Padding;
    private int TapeEnd => Tape.MaxIndex + Padding;
    private int StartIndex => TapeStart + ScrollOffset;
    private int EndIndex => Math.Min(StartIndex + CellsPerPage - 1, TapeEnd);
    private int MaxScrollOffset => Math.Max(0, TapeEnd - TapeStart - CellsPerPage + 1);

    private void ScrollLeft()
    {
        ScrollOffset = Math.Max(0, ScrollOffset - CellsPerPage / 2);
    }

    private void ScrollRight()
    {
        ScrollOffset = Math.Min(MaxScrollOffset, ScrollOffset + CellsPerPage / 2);
    }

    protected override void OnParametersSet()
    {
        // Auto-center on head if it's outside visible range
        if (HeadPosition < StartIndex || HeadPosition > EndIndex)
        {
            ScrollOffset = Math.Max(0, HeadPosition - TapeStart - CellsPerPage / 2);
        }
    }
}