using System;
using System.Collections.Generic;
using System.Linq;
using UnityEditor;
using UnityEngine;
using UnityEngine.TestTools;

namespace BracerLib.Editor.Utility
{
    /// <summary>
    /// A set-up for a component that can be a searchable list. Deprecated but fun to create.
    /// Doesn't work for entry adds.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    [ExcludeFromCoverage]
    [Obsolete]
    public class SearchableScrollView<T>
    {
        public delegate void DataDelegate(int index, string originalValue, string newValue);

        public delegate bool ValidationDelegate(string entry);

        private static class Styles
        {
            public static readonly GUIStyle SELECTED;

            static Styles()
            {
                var t = new Texture2D(1, 1);
                t.SetPixel(0, 0, new Color(0.4f, 0.4f, 0.4f));
                t.Apply();

                SELECTED = new GUIStyle(EditorStyles.label);
                SELECTED.normal.textColor = Color.white;
                SELECTED.normal.background = t;
            }
        }

        private static readonly string EDIT_FIELD = "selectedTextField";

        private readonly EditorSearchField searchField;
        private IList<T> data;
        private IList<string> dataLabels = new List<string>();
        private IList<string> searchResults;
        private readonly IDictionary<int, int> filteredLabelsToData = new Dictionary<int, int>();
        private EventType prevEventType;
        private int selectedIndex = -1;
        private bool isEditing;
        private bool isNewEntry;
        private bool cancelEdit;
        private bool editingFinished;
        private string originalEntryText;
        private string editedEntryText;
        private Vector2 scrollPosition;

        public float MaxWidth { get; set; }
        public IList<T> Data
        {
            set
            {
                if (value == null)
                    return;

                data = value;

                searchField.SearchString = string.Empty;

                dataLabels.Clear();
                dataLabels = data.Select(d => d.ToString()).ToList();

                filteredLabelsToData.Clear();
            }
        }
        /// <summary>
        /// The modified index of the selection in the list with the search results taken into account.
        /// </summary>
        public int SelectedIndex => filteredLabelsToData.ContainsKey(selectedIndex) ? filteredLabelsToData[selectedIndex] : selectedIndex;
        public ValidationDelegate ValidateEntry { get; set; }
        public DataDelegate DataEntryAdded { get; set; }
        public DataDelegate DataEntryEdited { get; set; }
        public DataDelegate DataEntryRemoved { get; set; }

        private IList<string> TargetData => (searchResults?.Count ?? 0) > 0 ? searchResults : dataLabels;

        public SearchableScrollView()
        {
            searchField = new EditorSearchField();
            searchField.OnInputChanged += SearchFieldInputChanged;
        }

        public void OnGUI()
        {
            HandleEditing();

            GUILayout.BeginVertical();
            GUILayout.BeginVertical(EditorStyles.helpBox);

            searchField.OnGUI();

            scrollPosition = GUILayout.BeginScrollView(scrollPosition, false, true, GUILayout.MaxWidth(MaxWidth));
            GUILayout.BeginVertical();

            // Output all keys in the list, with some being modified in style or interact-ability by way of flags
            var newEntryIndex = -1;
            var targetData = TargetData;
            for (var i = 0; i < (targetData?.Count ?? 0); i++)
            {
                var target = targetData![i];
                var selected = selectedIndex == i;

                if (isEditing && selected)
                {
                    if (originalEntryText == null)
                    {
                        originalEntryText = target;
                        editedEntryText = target;
                    }

                    GUI.SetNextControlName(EDIT_FIELD);
                    editedEntryText = GUILayout.TextField(editedEntryText, Styles.SELECTED);
                    GUI.FocusControl(EDIT_FIELD);
                }
                else if (cancelEdit && selected)
                {
                    cancelEdit = false;

                    if (isNewEntry)
                        newEntryIndex = i;
                    else
                        targetData[i] = originalEntryText;

                    originalEntryText = null;
                    editedEntryText = null;
                }
                else if (editingFinished && selected)
                {
                    editingFinished = false;
                    UpdateListValue(i, originalEntryText, editedEntryText);

                    originalEntryText = null;
                    editedEntryText = null;
                }
                else if (GUILayout.Button(target, selected ? Styles.SELECTED : EditorStyles.label) && !isEditing)
                    selectedIndex = selected ? -1 : i;
            }

            GUILayout.FlexibleSpace();

            GUILayout.EndVertical();
            GUILayout.EndScrollView();

            GUILayout.EndVertical();

            GUILayout.Label("F2 = Edit entry\nEnter = Accept and apply changes\nEscape = Cancel entry edit", EditorStyles.helpBox);

            GUILayout.EndVertical();
        }

        public void AddNewEntry()
        {
            searchField.SearchString = string.Empty;
            dataLabels.Add(string.Empty);

            selectedIndex = dataLabels.Count - 1;
            isEditing = true;
            isNewEntry = true;
        }

        public void DeleteEntry()
        {
            if (selectedIndex < 0)
                return;

            dataLabels.RemoveAt(SelectedIndex);

            DataEntryRemoved?.Invoke(SelectedIndex, null, null);

            searchField.SearchString = string.Empty;
        }

        private void FinalizeNewEntry()
        {
            if (!isEditing)
                return;

            isEditing = false;
            editingFinished = true;
        }

        private void HandleEditing()
        {
            var eventType = Event.current.type;
            var isKeyDown = eventType == EventType.KeyDown;
            if (selectedIndex < 0 || !isKeyDown || eventType == prevEventType)
            {
                if (!isKeyDown)
                    prevEventType = eventType;

                return;
            }

            prevEventType = eventType;

            var keyCode = Event.current.keyCode;
            switch (keyCode)
            {
                case KeyCode.Escape:
                    if (!isEditing)
                        return;

                    isEditing = false;
                    cancelEdit = true;

                    break;
                case KeyCode.Return:
                case KeyCode.KeypadEnter:
                    FinalizeNewEntry();

                    break;
                case KeyCode.F2:
                    isEditing = true;

                    break;
            }
        }

        private void UpdateListValue(int index, string origText, string editedText)
        {
            if (editedText == origText || (ValidateEntry != null && !ValidateEntry(editedText)))
            {
                if (isNewEntry)
                {
                    isNewEntry = false;

                    dataLabels.RemoveAt(dataLabels.Count - 1);
                }

                return;
            }

            if (filteredLabelsToData.TryGetValue(index, out var origIndex))
            {
                searchResults[index] = editedText;
                dataLabels[origIndex] = editedText;

                index = origIndex;
            }
            else
                dataLabels[index] = editedText;

            if (isNewEntry)
            {
                isNewEntry = false;
                DataEntryAdded?.Invoke(index, null, editedText);
            }
            else
                DataEntryEdited?.Invoke(index, origText, editedText);
        }

        private void SearchFieldInputChanged(string searchString)
        {
            searchResults ??= new List<string>();

            searchResults.Clear();
            filteredLabelsToData.Clear();

            if (searchString != null)
            {
                var newIndex = 0;
                searchResults = dataLabels.Where((label, index) =>
                {
                    var result = label.IndexOf(searchString, StringComparison.OrdinalIgnoreCase) >= 0;

                    if (result)
                        filteredLabelsToData.Add(newIndex++, index);

                    return result;
                }).ToList();
            }
            else
                searchResults = dataLabels;

            if (selectedIndex >= searchResults.Count)
                selectedIndex = -1;
        }
    }
}