@using Microsoft.AspNetCore.Components.Forms
@using NexusReader.Application.Abstractions.Services
@using NexusReader.Application.Queries.Reader
@using NexusReader.Application.Commands.Library
@using NexusReader.UI.Shared.Services
@using System.Net.Http.Json
@inject IEpubMetadataExtractor MetadataExtractor
@inject ILogger<BookIngestionModal> Logger
@inject HttpClient Http
@inject IReaderNavigationService ReaderNavigation
@inject IJSRuntime JSRuntime
@inject ISyncService SyncService
@implements IAsyncDisposable

@if (IsOpen)
{
    <div class="modal-backdrop" @onclick="CloseModal">
        <div class="modal-content glass-panel" @onclick:stopPropagation>
            <div class="modal-header">
                <h2>Add New Book</h2>
                @if (!IsIngesting && !IsIndexing)
                {
                    <button class="close-btn" @onclick="CloseModal">
                        <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><line x1="18" y1="6" x2="6" y2="18"></line><line x1="6" y1="6" x2="18" y2="18"></line></svg>
                    </button>
                }
            </div>

            <div class="modal-body">
                <div class="parsing-state shimmer" style="@(IsParsing ? "display:flex;" : "display:none;")">
                    <div class="shimmer-content">
                        <div class="spinner"></div>
                        <p>Scanning metadata...</p>
                    </div>
                </div>

                <div class="ingesting-state shimmer" style="@(IsIngesting ? "display:flex;" : "display:none;")">
                    <div class="shimmer-content">
                        <div class="spinner"></div>
                        <p>Saving book to library...</p>
                    </div>
                </div>
                
                <div class="verification-state" style="@((IsVerifying && !IsIngesting) ? "display:flex;" : "display:none;")">
                    @if (Metadata != null)
                    {
                        <div class="verification-layout">
                            <div class="cover-preview">
                                @if (Metadata.CoverImage != null)
                                {
                                    <img src="data:image/jpeg;base64,@Convert.ToBase64String(Metadata.CoverImage)" alt="Cover Preview" />
                                }
                                else
                                {
                                    <div class="glowing-placeholder">
                                        <svg xmlns="http://www.w3.org/2000/svg" width="48" height="48" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M4 19.5A2.5 2.5 0 0 1 6.5 17H20"></path><path d="M6.5 2H20v20H6.5A2.5 2.5 0 0 1 4 19.5v-15A2.5 2.5 0 0 1 6.5 2z"></path></svg>
                                    </div>
                                }
                            </div>
                            
                            <div class="verification-form">
                                <div class="form-group">
                                    <label>Title</label>
                                    <input type="text" class="form-input" @bind="Metadata.Title" placeholder="Enter book title" />
                                </div>
                                <div class="form-group">
                                    <label>Author</label>
                                    <input type="text" class="form-input" @bind="Metadata.Author" placeholder="Enter author name" />
                                </div>
                                <div class="form-group">
                                    <label>Description</label>
                                    <textarea class="form-input" @bind="Metadata.Description" placeholder="Book description" rows="3"></textarea>
                                </div>
                            </div>
                        </div>

                        <div class="actions">
                            <NexusButton Class="btn-secondary" OnClick="Reset" Disabled="IsIngesting">Back</NexusButton>
                            <NexusButton Class="@($"btn-primary {(IsIngesting ? "btn-loading" : "")}")" 
                                          OnClick="SaveToLibrary" 
                                          Disabled="IsIngesting">
                                @(IsIngesting ? "" : "Save to Library")
                            </NexusButton>
                        </div>
                    }
                </div>
                
                <div class="upload-state @(_isDragging ? "drag-over" : "")" 
                      style="@(IsUploadActive ? "display:flex;" : "display:none;")"
                      @ondragenter="OnDragEnter" 
                      @ondragleave="OnDragLeave">
                    <div class="drop-zone">
                        <InputFile id="epub-upload" OnChange="HandleFileSelected" accept=".epub" class="file-input-cover" />
                        <div class="drop-zone-content">
                            <svg xmlns="http://www.w3.org/2000/svg" width="48" height="48" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M21 15v4a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2v-4"></path><polyline points="17 8 12 3 7 8"></polyline><line x1="12" y1="3" x2="12" y2="15"></line></svg>
                            <p>Drag and drop your .epub file here</p>
                            <span>or click to browse</span>
                        </div>
                    </div>
                </div>

                <div class="indexing-state" style="@(IsIndexing ? "display:flex;" : "display:none;")">
                    <div class="indexing-content">
                        <div class="spinner"></div>
                        <h3>Nexus AI Indexing</h3>
                        <p class="status-msg">@IngestionStatusMessage</p>
                        <div class="progress-bar-container">
                            <div class="progress-bar-fill" style="width: @((IngestionProgressPercent * 100).ToString("F0"))%"></div>
                        </div>
                        <span class="percent">@((IngestionProgressPercent * 100).ToString("F0"))%</span>
                    </div>
                </div>

                
                @if (!string.IsNullOrEmpty(ErrorMessage))
                {
                    <div class="error-message">
                        @ErrorMessage
                    </div>
                }
            </div>
        </div>
    </div>
}



@code {
    /// <summary>
    /// Gets or sets a value indicating whether the modal is open.
    /// </summary>
    [Parameter]
    public bool IsOpen { get; set; }

    /// <summary>
    /// Event triggered when the IsOpen state changes.
    /// </summary>
    [Parameter]
    public EventCallback<bool> IsOpenChanged { get; set; }

    private bool _isDragging;
    private bool IsParsing { get; set; }
    private bool IsVerifying { get; set; }
    private bool IsIngesting { get; set; }
    private bool IsIndexing { get; set; }
    private string IngestionStatusMessage { get; set; } = "Initializing...";
    private double IngestionProgressPercent { get; set; }
    private Guid IngestedBookId { get; set; } = Guid.Empty;
    private LocalEpubMetadata? Metadata { get; set; }
    private string? ErrorMessage { get; set; }
    private byte[]? _epubBytes;
    private bool _disposed;
    private bool IsUploadActive => !IsParsing && !IsVerifying && !IsIngesting && !IsIndexing;
    
    // Allow up to 50 MB
    private const long MaxFileSize = 50 * 1024 * 1024;

    protected override async Task OnInitializedAsync()
    {
        await SyncService.InitializeAsync();
        SyncService.OnIngestionProgressReceived += HandleIngestionProgress;
    }

    private async Task HandleIngestionProgress(string message, double progress)
    {
        if (_disposed) return;
        if (!IsIndexing) return;

        IngestionStatusMessage = message;
        IngestionProgressPercent = progress;
        
        if (!_disposed)
        {
            // Dispatch the state change to the Blazor synchronization context
            // because this event is triggered asynchronously from a SignalR / WebSocket background thread.
            await InvokeAsync(StateHasChanged);
        }

        if (progress >= 1.0)
        {
            // Give the user a moment to see the completion message
            await Task.Delay(2500);
            
            if (_disposed) return;

            // Now close the modal and navigate to the book
            if (IngestedBookId != Guid.Empty)
            {
                var bookId = IngestedBookId;
                // Dispatch UI updates and navigation back to the Blazor thread
                // to avoid thread affinity issues and potential UI lockups in MAUI/Web applications.
                await InvokeAsync(async () => {
                    if (_disposed) return;
                    await CloseModal();
                    ReaderNavigation.NavigateToBook(bookId);
                });
            }
        }
    }

    private async Task CloseModal()
    {
        if (IsIngesting || IsIndexing) return;

        IsOpen = false;
        Reset();
        await IsOpenChanged.InvokeAsync(false);
    }

    private void Reset()
    {
        IsParsing = false;
        IsVerifying = false;
        IsIngesting = false;
        IsIndexing = false;
        IngestionStatusMessage = "Initializing...";
        IngestionProgressPercent = 0.0;
        IngestedBookId = Guid.Empty;
        Metadata = null;
        ErrorMessage = null;
        _isDragging = false;
        _epubBytes = null;
    }

    private void OnDragEnter() => _isDragging = true;
    private void OnDragLeave() => _isDragging = false;

    private async Task HandleFileSelected(InputFileChangeEventArgs e)
    {
        _isDragging = false;
        var file = e.File;
        
        if (file == null) return;
        
        if (!file.Name.EndsWith(".epub", StringComparison.OrdinalIgnoreCase))
        {
            ErrorMessage = "Only .epub files are supported.";
            return;
        }

        ErrorMessage = null;
        IsParsing = true;
        StateHasChanged();

        try
        {
            using var stream = file.OpenReadStream(MaxFileSize);
            using var memoryStream = new MemoryStream();
            await stream.CopyToAsync(memoryStream);
            if (_disposed) return;
            _epubBytes = memoryStream.ToArray();
            
            memoryStream.Position = 0;
            var result = await MetadataExtractor.ExtractMetadataAsync(memoryStream);
            if (_disposed) return;

            if (result.IsSuccess)
            {
                Metadata = result.Value;
                IsVerifying = true;
            }
            else
            {
                ErrorMessage = result.Errors.FirstOrDefault()?.Message ?? "Failed to parse EPUB.";
            }
        }
        catch (Exception ex)
        {
            Logger.LogError(ex, "Error uploading EPUB");
            if (!_disposed)
            {
                ErrorMessage = $"An unexpected error occurred: {ex.Message}";
            }
        }
        finally
        {
            if (!_disposed)
            {
                IsParsing = false;
                StateHasChanged();
            }
        }
    }

    private async Task SaveToLibrary()
    {
        if (Metadata == null || _epubBytes == null) return;

        IsIngesting = true;
        ErrorMessage = null;
        StateHasChanged();

        try
        {
            var request = new IngestEbookRequest(
                Metadata.Title,
                Metadata.Author,
                Metadata.CoverImage != null ? Convert.ToBase64String(Metadata.CoverImage) : null,
                Convert.ToBase64String(_epubBytes),
                Metadata.Description
            );

            var response = await Http.PostAsJsonAsync("api/library/ingest", request);
            if (_disposed) return;

            if (response.IsSuccessStatusCode)
            {
                var result = await response.Content.ReadFromJsonAsync<IngestResult>();
                if (_disposed) return;
                if (result != null)
                {
                    IngestedBookId = result.Id;
                    IsVerifying = false;
                    IsIngesting = false;
                    IsIndexing = true;
                    IngestionStatusMessage = "Book saved! Starting background indexing...";
                    IngestionProgressPercent = 0.0;
                    StateHasChanged();
                }
            }
            else
            {
                ErrorMessage = await response.Content.ReadAsStringAsync();
                IsIngesting = false;
            }
        }
        catch (Exception ex)
        {
            Logger.LogError(ex, "Error during ingestion");
            if (!_disposed)
            {
                ErrorMessage = "Failed to save book to library. Please try again.";
                IsIngesting = false;
            }
        }
        finally
        {
            if (!_disposed)
            {
                StateHasChanged();
            }
        }
    }

    private record IngestResult(Guid Id);

    public async ValueTask DisposeAsync()
    {
        _disposed = true;
        SyncService.OnIngestionProgressReceived -= HandleIngestionProgress;
        // Clear the large byte array so it is eligible for GC even if the component is cached.
        _epubBytes = null;
        await ValueTask.CompletedTask;
    }
}