@page "/visualise"
@page "/visualise/{View}"

@using RackPeek.Domain.Graph.Serialisers
@using RackPeek.Domain.Graph.UseCases
@using Shared.Rcl.Components.Graphs

@inject BuildPhysicalTopologyUseCase TopologyUseCase
@inject BuildLogicalGraphUseCase LogicalUseCase
@inject NavigationManager Nav
@inject IJSRuntime JS

<PageTitle>Visualise</PageTitle>

<div class="min-h-screen bg-zinc-950 text-zinc-200 font-mono p-6"
     data-testid="visualise-page-root">

    <div class="flex items-center justify-between mb-4">
        <div class="space-y-1">
            <div class="text-xs text-zinc-500 uppercase tracking-wider">Knowledge Base</div>
            <h1 class="text-lg text-zinc-100">
                Visualise
                <span class="text-zinc-500">:</span>
                <span class="text-emerald-400">@ActiveTitle</span>
            </h1>
        </div>

        <div class="flex items-center gap-4">
            <nav class="flex items-center gap-1 text-sm">
                <button class="@TabClass("topology")"
                        data-testid="visualise-tab-topology"
                        @onclick="@(() => SelectView("topology"))">
                    Physical
                </button>
                <button class="@TabClass("logical")"
                        data-testid="visualise-tab-logical"
                        @onclick="@(() => SelectView("logical"))">
                    Logical
                </button>
            </nav>

            <div class="flex items-center gap-1 text-sm">
                <button class="@ExportButtonClass"
                        disabled="@CannotExport"
                        data-testid="visualise-export-png"
                        @onclick="ExportPngAsync">
                    Save PNG
                </button>
                <button class="@ExportButtonClass"
                        disabled="@CannotExport"
                        data-testid="visualise-export-source"
                        @onclick="ExportSourceAsync">
                    Save Mermaid
                </button>
            </div>
        </div>
    </div>

    @if (_loading)
    {
        <div class="text-zinc-500 text-sm">loading inventory…</div>
    }
    else if (_error is not null)
    {
        <div class="text-red-400 text-sm">@_error</div>
    }
    else
    {
        <div class="border border-zinc-800 rounded-md bg-zinc-900/30" style="height: 75vh;">
            <GraphView Source="@_source"
                       Id="@HostId"
                       TestId="@($"visualise-graph-{ActiveView}")" />
        </div>
    }
</div>

@code {
    [Parameter] public string? View { get; set; }

    private string ActiveView => string.Equals(View, "logical", StringComparison.OrdinalIgnoreCase)
        ? "logical"
        : "topology";

    private string ActiveTitle => ActiveView switch
    {
        "logical" => "Logical — services & systems",
        _ => "Physical — hardware topology"
    };

    private string? _source;
    private bool _loading = true;
    private string? _error;
    private string? _lastLoadedView;

    private readonly MermaidSerialiser _serialiser = new();

    protected override async Task OnParametersSetAsync()
    {
        if (_lastLoadedView == ActiveView) return;
        _lastLoadedView = ActiveView;

        await LoadAsync();
    }

    private async Task LoadAsync()
    {
        _loading = true;
        _error = null;
        StateHasChanged();

        try
        {
            RackPeek.Domain.Graph.Graph graph = ActiveView switch
            {
                "logical" => await LogicalUseCase.ExecuteAsync(),
                _ => await TopologyUseCase.ExecuteAsync()
            };

            _source = _serialiser.Serialise(graph);
        }
        catch (Exception ex)
        {
            _error = $"Failed to build graph: {ex.Message}";
            _source = null;
        }
        finally
        {
            _loading = false;
            StateHasChanged();
        }
    }

    private void SelectView(string view)
    {
        Nav.NavigateTo($"visualise/{view}");
    }

    private const string HostId = "visualise-graph-host";

    private bool CannotExport => _loading || _source is null;

    private string ExportButtonClass =>
        "px-3 py-1 rounded border border-zinc-800 text-zinc-400 " +
        "hover:text-emerald-400 hover:border-zinc-700 disabled:opacity-40 disabled:hover:text-zinc-400";

    private string ExportFilenameBase =>
        ActiveView == "logical" ? "rackpeek-logical" : "rackpeek-topology";

    private async Task ExportPngAsync()
    {
        if (CannotExport) return;
        await JS.InvokeVoidAsync(
            "rackpeekGraph.downloadPng", HostId, $"{ExportFilenameBase}.png", ExportBackground, 2);
    }

    private const string ExportBackground = "#09090b";

    private async Task ExportSourceAsync()
    {
        if (CannotExport || _source is null) return;
        await JS.InvokeVoidAsync(
            "rackpeekGraph.downloadText", _source, $"{ExportFilenameBase}.mmd", "text/plain");
    }

    private string TabClass(string view) =>
        ActiveView == view
            ? "px-3 py-1 rounded border border-emerald-500/40 bg-emerald-500/10 text-emerald-400"
            : "px-3 py-1 rounded border border-zinc-800 text-zinc-400 hover:text-emerald-400 hover:border-zinc-700";
}