using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using HC_APTBS.Services;

namespace HC_APTBS.ViewModels.Dialogs
{
    /// <summary>
    /// ViewModel for the WReport dialog.
    ///
    /// <para>
    /// Lets the operator fill in client and company information before generating
    /// the PDF report.  The client list is backed by the
    /// <see cref="IConfigurationService"/> and persisted when the dialog is accepted.
    /// </para>
    /// </summary>
    public sealed partial class ReportViewModel : ObservableObject
    {
        // ── Services ──────────────────────────────────────────────────────────────

        private readonly IConfigurationService _config;

        // ── Constructor ───────────────────────────────────────────────────────────

        /// <summary>Initialises and populates the dialog from configuration.</summary>
        public ReportViewModel(IConfigurationService configService)
        {
            _config = configService;

            CompanyName = _config.Settings.CompanyName;
            CompanyInfo = _config.Settings.CompanyInfo;

            foreach (var name in _config.Clients.Keys)
                ClientNames.Add(name);
        }

        // ── Company ───────────────────────────────────────────────────────────────

        /// <summary>Company name shown in the report header.</summary>
        [ObservableProperty] private string _companyName = string.Empty;

        /// <summary>Company address / contact info shown in the report header.</summary>
        [ObservableProperty] private string _companyInfo = string.Empty;

        // ── Client ────────────────────────────────────────────────────────────────

        /// <summary>List of known client names for the autocomplete combo box.</summary>
        public ObservableCollection<string> ClientNames { get; } = new();

        /// <summary>Currently selected or typed client name.</summary>
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(SaveClientCommand))]
        [NotifyCanExecuteChangedFor(nameof(DeleteClientCommand))]
        private string _selectedClientName = string.Empty;

        /// <summary>Free-text notes for the selected client.</summary>
        [ObservableProperty] private string _clientInfo = string.Empty;

        /// <summary>Operator name.</summary>
        [ObservableProperty] private string _operatorName = string.Empty;

        /// <summary>Free-text observations appended to the report.</summary>
        [ObservableProperty] private string _observations = string.Empty;

        // ── Dialog result ─────────────────────────────────────────────────────────

        /// <summary>True after the user clicks Accept; false if they cancel.</summary>
        public bool Accepted { get; private set; }

        // ── Commands ──────────────────────────────────────────────────────────────

        /// <summary>Saves the current client entry, closes the dialog with Accepted=true.</summary>
        [RelayCommand]
        private void Accept()
        {
            SaveCurrentClient();

            _config.Settings.CompanyName = CompanyName;
            _config.Settings.CompanyInfo = CompanyInfo;
            _config.SaveClients();
            _config.SaveSettings();

            Accepted = true;
            RequestClose?.Invoke();
        }

        /// <summary>Closes the dialog without saving.</summary>
        [RelayCommand]
        private void Cancel()
        {
            Accepted = false;
            RequestClose?.Invoke();
        }

        /// <summary>Persists the current client entry and refreshes the client list.</summary>
        [RelayCommand(CanExecute = nameof(HasClientName))]
        private void SaveClient()
        {
            SaveCurrentClient();
            RefreshClientList();
        }

        /// <summary>Deletes the currently selected client from the list.</summary>
        [RelayCommand(CanExecute = nameof(HasClientName))]
        private void DeleteClient()
        {
            string name = SelectedClientName.Trim();
            if (string.IsNullOrEmpty(name)) return;

            if (_config.Clients.ContainsKey(name))
                _config.Clients.Remove(name);

            SelectedClientName = string.Empty;
            ClientInfo         = string.Empty;
            RefreshClientList();
        }

        /// <summary>
        /// Called when the user picks a client name from the combo box.
        /// Loads the associated info text.
        /// </summary>
        public void SelectClient(string name)
        {
            SelectedClientName = name ?? string.Empty;
            if (!string.IsNullOrEmpty(name) && _config.Clients.TryGetValue(name, out var info))
                ClientInfo = info;
        }

        // ── Events ────────────────────────────────────────────────────────────────

        /// <summary>Raised when the dialog should close itself.</summary>
        public event System.Action? RequestClose;

        // ── Helpers ───────────────────────────────────────────────────────────────

        private bool HasClientName() => !string.IsNullOrWhiteSpace(SelectedClientName);

        private void SaveCurrentClient()
        {
            string name = SelectedClientName.Trim();
            if (string.IsNullOrEmpty(name)) return;

            if (_config.Clients.ContainsKey(name))
                _config.Clients[name] = ClientInfo;
            else
                _config.Clients.Add(name, ClientInfo);
        }

        private void RefreshClientList()
        {
            ClientNames.Clear();
            foreach (var name in _config.Clients.Keys)
                ClientNames.Add(name);
        }
    }
}