using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Windows;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using Microsoft.Extensions.Logging;
using Microsoft.Win32;
using SharepointToolbox.Core.Models;
using SharepointToolbox.Services;
using SharepointToolbox.Services.Export;

namespace SharepointToolbox.ViewModels.Tabs;

public partial class StorageViewModel : FeatureViewModelBase
{
    private readonly IStorageService _storageService;
    private readonly ISessionManager _sessionManager;
    private readonly StorageCsvExportService _csvExportService;
    private readonly StorageHtmlExportService _htmlExportService;
    private readonly ILogger<FeatureViewModelBase> _logger;
    private TenantProfile? _currentProfile;

    [ObservableProperty]
    private string _siteUrl = string.Empty;

    [ObservableProperty]
    private bool _perLibrary = true;

    [ObservableProperty]
    private bool _includeSubsites;

    [ObservableProperty]
    private int _folderDepth;

    public bool IsMaxDepth
    {
        get => FolderDepth >= 999;
        set
        {
            if (value) FolderDepth = 999;
            else if (FolderDepth >= 999) FolderDepth = 0;
            OnPropertyChanged();
        }
    }

    private ObservableCollection<StorageNode> _results = new();
    public ObservableCollection<StorageNode> Results
    {
        get => _results;
        private set
        {
            _results = value;
            OnPropertyChanged();
            ExportCsvCommand.NotifyCanExecuteChanged();
            ExportHtmlCommand.NotifyCanExecuteChanged();
        }
    }

    public IAsyncRelayCommand ExportCsvCommand { get; }
    public IAsyncRelayCommand ExportHtmlCommand { get; }

    public TenantProfile? CurrentProfile => _currentProfile;

    public StorageViewModel(
        IStorageService storageService,
        ISessionManager sessionManager,
        StorageCsvExportService csvExportService,
        StorageHtmlExportService htmlExportService,
        ILogger<FeatureViewModelBase> logger)
        : base(logger)
    {
        _storageService    = storageService;
        _sessionManager    = sessionManager;
        _csvExportService  = csvExportService;
        _htmlExportService = htmlExportService;
        _logger            = logger;

        ExportCsvCommand  = new AsyncRelayCommand(ExportCsvAsync,  CanExport);
        ExportHtmlCommand = new AsyncRelayCommand(ExportHtmlAsync, CanExport);
    }

    /// <summary>Test constructor — omits export services.</summary>
    internal StorageViewModel(
        IStorageService storageService,
        ISessionManager sessionManager,
        ILogger<FeatureViewModelBase> logger)
        : base(logger)
    {
        _storageService    = storageService;
        _sessionManager    = sessionManager;
        _csvExportService  = null!;
        _htmlExportService = null!;
        _logger            = logger;

        ExportCsvCommand  = new AsyncRelayCommand(ExportCsvAsync,  CanExport);
        ExportHtmlCommand = new AsyncRelayCommand(ExportHtmlAsync, CanExport);
    }

    protected override async Task RunOperationAsync(CancellationToken ct, IProgress<OperationProgress> progress)
    {
        if (_currentProfile == null)
        {
            StatusMessage = "No tenant selected. Please connect to a tenant first.";
            return;
        }
        if (string.IsNullOrWhiteSpace(SiteUrl))
        {
            StatusMessage = "Please enter a site URL.";
            return;
        }

        // Build a site-specific profile: same ClientId and Name, but TenantUrl points to the
        // site URL the user entered (may differ from the tenant root).
        var siteProfile = new TenantProfile
        {
            TenantUrl = SiteUrl.TrimEnd('/'),
            ClientId = _currentProfile.ClientId,
            Name = _currentProfile.Name
        };
        var ctx = await _sessionManager.GetOrCreateContextAsync(siteProfile, ct);

        var options = new StorageScanOptions(
            PerLibrary: PerLibrary,
            IncludeSubsites: IncludeSubsites,
            FolderDepth: FolderDepth);

        var nodes = await _storageService.CollectStorageAsync(ctx, options, progress, ct);

        // Flatten tree to one level for DataGrid display (assign IndentLevel during flatten)
        var flat = new List<StorageNode>();
        foreach (var node in nodes)
            FlattenNode(node, 0, flat);

        if (Application.Current?.Dispatcher is { } dispatcher)
        {
            await dispatcher.InvokeAsync(() =>
            {
                Results = new ObservableCollection<StorageNode>(flat);
            });
        }
        else
        {
            Results = new ObservableCollection<StorageNode>(flat);
        }
    }

    protected override void OnTenantSwitched(TenantProfile profile)
    {
        _currentProfile = profile;
        Results = new ObservableCollection<StorageNode>();
        SiteUrl = string.Empty;
        OnPropertyChanged(nameof(CurrentProfile));
        ExportCsvCommand.NotifyCanExecuteChanged();
        ExportHtmlCommand.NotifyCanExecuteChanged();
    }

    internal void SetCurrentProfile(TenantProfile profile) => _currentProfile = profile;

    internal Task TestRunOperationAsync(CancellationToken ct, IProgress<OperationProgress> progress)
        => RunOperationAsync(ct, progress);

    private bool CanExport() => Results.Count > 0;

    private async Task ExportCsvAsync()
    {
        if (Results.Count == 0) return;
        var dialog = new SaveFileDialog
        {
            Title = "Export storage metrics to CSV",
            Filter = "CSV files (*.csv)|*.csv|All files (*.*)|*.*",
            DefaultExt = "csv",
            FileName = "storage_metrics"
        };
        if (dialog.ShowDialog() != true) return;
        try
        {
            await _csvExportService.WriteAsync(Results, dialog.FileName, CancellationToken.None);
            OpenFile(dialog.FileName);
        }
        catch (Exception ex)
        {
            StatusMessage = $"Export failed: {ex.Message}";
            _logger.LogError(ex, "CSV export failed.");
        }
    }

    private async Task ExportHtmlAsync()
    {
        if (Results.Count == 0) return;
        var dialog = new SaveFileDialog
        {
            Title = "Export storage metrics to HTML",
            Filter = "HTML files (*.html)|*.html|All files (*.*)|*.*",
            DefaultExt = "html",
            FileName = "storage_metrics"
        };
        if (dialog.ShowDialog() != true) return;
        try
        {
            await _htmlExportService.WriteAsync(Results, dialog.FileName, CancellationToken.None);
            OpenFile(dialog.FileName);
        }
        catch (Exception ex)
        {
            StatusMessage = $"Export failed: {ex.Message}";
            _logger.LogError(ex, "HTML export failed.");
        }
    }

    private static void FlattenNode(StorageNode node, int level, List<StorageNode> result)
    {
        node.IndentLevel = level;
        result.Add(node);
        foreach (var child in node.Children)
            FlattenNode(child, level + 1, result);
    }

    private static void OpenFile(string filePath)
    {
        try { Process.Start(new ProcessStartInfo(filePath) { UseShellExecute = true }); }
        catch { /* ignore — file may open but this is best-effort */ }
    }
}