using System.Data;
using Model;
using System;
using System.Collections.Generic;
using System.ComponentModel.Design;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp.Menu
{
    internal abstract class Menu<T> : IMenu
        where T : notnull
    {
        protected StringBuilder _screenDisplay;

        protected List<Selector<T>> _allSelectors = new List<Selector<T>>();
        protected List<Selector<T>> _selectList = new List<Selector<T>>();

        public string Title { get; private set; }
        public StringBuilder InputStr { get; set; }

        private int _currentLine;
        public int CurrentLine
        {
            get
            {
                if (_currentLine >= _selectList.Count) _currentLine = _selectList.Count - 1;
                return _currentLine;
            }
            protected set
            {
                _currentLine = value;
                if (_currentLine <= 0) _currentLine = 0;
                else if (_currentLine >= _selectList.Count) _currentLine = _selectList.Count-1;
            }
        }

        public T? CurrentSelected { get; protected set; }
        public bool WriteMode { get; set; }

        protected Menu(string title)
        {
            Title = title;
            CurrentLine = 0;
            WriteMode = false;
            _screenDisplay = new StringBuilder();
            InputStr = new StringBuilder();
        }

        protected Menu(string title, params Selector<T>[] selections ) : this(title)
        {
            if (selections == null || selections.Length == 0)
            {
                Console.WriteLine("Empty menu...");
                return;
            }

            _allSelectors = selections.ToList();
            _selectList = _allSelectors;
            CurrentSelected = _allSelectors[0].Item;
        }

        public abstract IMenu? Return();

        protected virtual List<Selector<T>> SearchInSelection()
        {
            if (_allSelectors is null)
                throw new Exception("Error: _allSelector is null.");

            return _allSelectors.FindAll(x =>
                x.Line.ToLower().Contains(InputStr.ToString().ToLower()));
        }

        public virtual void WriteMenuMode(ConsoleKeyInfo cki)
        {
            if (!WriteMode && cki.Key == ConsoleKey.R)
            {
                EnableWriteMode();
                return;
            }

            if (WriteMode)
            {
                if (cki.Key == ConsoleKey.Escape)
                {
                    DisableWriteMode();
                    InputStr.Clear();
                    return;
                }

                if (cki.Key == ConsoleKey.Backspace && InputStr.Length > 0)
                {
                    InputStr.Remove(InputStr.Length - 1, 1);
                    return;
                }

                InputStr.Append(cki.KeyChar);
            }
        }

        public virtual void Update()
        {
            _selectList = SearchInSelection();

            if (_selectList == null || _selectList.Count == 0)
            {
                CurrentSelected = default;
                return;
            }
            CurrentSelected = _selectList[CurrentLine].Item;
        }

        public virtual void Display()
        {
            _screenDisplay.Clear();
            Console.Clear();

            _screenDisplay.AppendLine($"[ {Title} ]");
            _screenDisplay.AppendLine("-------------------------------------------");

            if (WriteMode)
            {
                _screenDisplay.Append("Search: ");
                _screenDisplay.AppendLine(InputStr.ToString());
            }

            for (int i = 0; i < _selectList.Count; i++)
            {
                if (CurrentLine == i)
                    _screenDisplay.Append($">  ");
                else
                    _screenDisplay.Append($"   ");

                _screenDisplay.AppendLine($"{_selectList[i].Line}");
            }

            if (_selectList == null || _selectList.Count == 0)
                _screenDisplay.AppendLine("Empty...");

            _screenDisplay.AppendLine(
                "\n\nHint:\n^:previous, v:next, <:ret, -enter-:select, r:search, -escape-:exit search mode");
            Console.WriteLine(_screenDisplay);
        }

        public void SelectNext() => ++CurrentLine;

        public void SelectPrevious() => --CurrentLine;

        public void EnableWriteMode() => WriteMode = true;

        public void DisableWriteMode() => WriteMode = false;

        public void ToggleWriteMode()
        {
            if (WriteMode)
                DisableWriteMode();
            else
                EnableWriteMode();
        }
    }
}