using FluentTerminal.Models;
using FluentTerminal.Models.Enums;
using FluentTerminal.Models.Responses;
using System;
using System.Threading.Tasks;

namespace FluentTerminal.App.Services
{
    public class Terminal
    {
        private readonly ITrayProcessCommunicationService _trayProcessCommunicationService;
        private Func<Task<string>> _selectedTextCallback;

        public Terminal(ITrayProcessCommunicationService trayProcessCommunicationService)
        {
            _trayProcessCommunicationService = trayProcessCommunicationService;
            _trayProcessCommunicationService.TerminalExited += OnTerminalExited;
            Id = _trayProcessCommunicationService.GetNextTerminalId();
        }

        private void OnTerminalExited(object sender, int e)
        {
            if (e == Id)
            {
                Closed?.Invoke(this, System.EventArgs.Empty);
            }
        }

        /// <summary>
        /// To be observed by both view and viewmodel
        /// </summary>
        public event EventHandler Closed;

        /// <summary>
        /// to be observed by viewmodel
        /// </summary>
        public event EventHandler<string> KeyboardCommandReceived;

        /// <summary>
        /// to be observed by view
        /// </summary>
        public event EventHandler<byte[]> OutputReceived;

        /// <summary>
        /// to be observed by viewmodel
        /// </summary>
        public event EventHandler<TerminalSize> SizeChanged;

        /// <summary>
        /// to be observed by viewmodel
        /// </summary>
        public event EventHandler<string> TitleChanged;

        public string FallbackTitle { get; private set; }

        public int Id { get; }

        /// <summary>
        /// To be called by either view or viewmodel
        /// </summary>
        public async Task Close()
        {
            await _trayProcessCommunicationService.CloseTerminal(Id).ConfigureAwait(true);
        }

        /// <summary>
        /// to be called by viewmodel
        /// </summary>
        /// <returns></returns>
        public Task<string> GetSelectedText()
        {
            return _selectedTextCallback();
        }

        /// <summary>
        /// to be called by view
        /// </summary>
        public void ProcessKeyboardCommand(string command)
        {
            KeyboardCommandReceived?.Invoke(this, command);
        }

        /// <summary>
        /// To be set by view
        /// </summary>
        public void RegisterSelectedTextCallback(Func<Task<string>> selectedTextCallback)
        {
            _selectedTextCallback = selectedTextCallback;
        }

        /// <summary>
        /// To be called by view
        /// </summary>
        public async Task SetSize(TerminalSize size)
        {
            await _trayProcessCommunicationService.ResizeTerminal(Id, size);
            SizeChanged?.Invoke(this, size);
        }

        /// <summary>
        /// to be called by view
        /// </summary>
        public void SetTitle(string title)
        {
            if (string.IsNullOrWhiteSpace(title))
            {
                title = FallbackTitle;
            }
            TitleChanged?.Invoke(this, title);
        }

        /// <summary>
        /// to be called by view when ready
        /// </summary>
        /// <param name="shellProfile"></param>
        /// <param name="size"></param>
        /// <param name="sessionType"></param>
        public async Task<CreateTerminalResponse> StartShellProcess(ShellProfile shellProfile, TerminalSize size, SessionType sessionType)
        {
            _trayProcessCommunicationService.SubscribeForTerminalOutput(Id, t => OutputReceived?.Invoke(this, t));
            var response = await _trayProcessCommunicationService.CreateTerminal(Id, size, shellProfile, sessionType).ConfigureAwait(true);

            if (response.Success)
            {
                FallbackTitle = response.ShellExecutableName;
                SetTitle(FallbackTitle);
            }
            return response;
        }

        public Task Write(byte[] data)
        {
            return _trayProcessCommunicationService.Write(Id, data);
        }

        /// <summary>
        /// Tells the ViewModel that this view failed to launch and can be closed.
        /// </summary>
        public void ReportLauchFailed()
        {
            Closed?.Invoke(this, System.EventArgs.Empty);
        }
    }
}