using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using Uniject;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.Purchasing;
using UnityEngine.Purchasing.Extension;
using UnityEngine.UI;

namespace UnityEngine.Purchasing
{
    /// <summary>
    /// User interface fake store.
    /// </summary>
    internal class UIFakeStore : FakeStore
    {
        const string EnvironmentDescriptionPostfix = "\n\n[Environment: FakeStore]";
        const string SuccessString = "Success";
        const int RetrieveProductsDescriptionCount = 2;

        DialogRequest m_CurrentDialog;
        int m_LastSelectedDropdownIndex;

        GameObject m_UIFakeStoreWindowObject;

        GameObject m_EventSystem; // Dynamically created. Auto-null'd by UI system.

#pragma warning disable 0414
        readonly IUtil m_Util;
#pragma warning restore 0414

        public UIFakeStore()
        {
        }

        public UIFakeStore(IUtil util)
        {
            m_Util = util;
        }

        /// <summary>
        /// Creates and displays a modal dialog UI. Note pointer events can "drill through" the
        /// UI activating underlying interface elements. Consider using techniques mentioned in
        /// http://forum.unity3d.com/threads/frequently-asked-ui-questions.264479/ in apps
        /// to mitigate this. Shows only one at a time.
        /// </summary>
        /// <returns><c>true</c>, if UI was started, <c>false</c> otherwise.</returns>
        /// <param name="model">Store model being shown; uses dialogType to decode.</param>
        /// <param name="dialogType">Dialog type.</param>
        /// <param name="callback">Callback called when dialog dismissed.</param>
        /// <typeparam name="T">The 1st type parameter.</typeparam>
        protected override bool StartUI<T>(object model, DialogType dialogType, Action<bool, T> callback)
        {
            var options = new List<string>
            {
                // Add a default option for "Success"
                SuccessString
            };

            foreach (T code in Enum.GetValues(typeof(T)))
            {
                options.Add(code.ToString());
            }

            var callbackWrapper = new Action<bool, int>((bool result, int codeValue) =>
            {
                // TRICKY: Would prefer to use .NET 4+'s dynamic keyword over double-casting to what I know is an enum type.
                var value = (T)(object)codeValue;
                callback(result, value);
            });

            string title = null, okayButton = null, cancelButton = null;
            if (dialogType == DialogType.Purchase)
            {
                title = CreatePurchaseQuestion((ProductDefinition)model);
                if (UIMode == FakeStoreUIMode.DeveloperUser)
                {
                    // Developer UIMode is one button, one option menu, so the button must support both pass and fail
                    okayButton = "OK";
                }
                else
                {
                    okayButton = "Buy";
                }
            }
            else if (dialogType == DialogType.RetrieveProducts)
            {
                title = CreateRetrieveProductsQuestion((ReadOnlyCollection<ProductDefinition>)model);
                okayButton = "OK";
            }
            else
            {
                Debug.LogError("Unrecognized DialogType " + dialogType);
            }
            cancelButton = "Cancel";

            return StartUI(title, okayButton, cancelButton, options, callbackWrapper);
        }

        /// <summary>
        /// Helper
        /// </summary>
        bool StartUI(string queryText, string okayButtonText, string cancelButtonText,
            List<string> options, Action<bool, int> callback)
        {
            // One dialog at a time please
            if (IsShowingDialog())
            {
                return false;
            }

            // Wrap this dialog request for later use
            var dr = new DialogRequest
            {
                QueryText = queryText,
                OkayButtonText = okayButtonText,
                CancelButtonText = cancelButtonText,
                Options = options,
                Callback = callback
            };

            m_CurrentDialog = dr;

            InstantiateDialog();

            return true;
        }

        private void InstantiateDialog()
        {
            if (m_CurrentDialog != null)
            {
                var runtimeCanvas = GetOrCreateFakeStoreWindow();

                AddLifeCycleNotifierAndSetDestroyCallback(runtimeCanvas.gameObject);
                EnsureEventSystemCreated(runtimeCanvas.transform);
                ConfigureDialogWindow(runtimeCanvas);
            }
            else
            {
                Debug.LogError(this + " requires m_CurrentDialog. Not showing dialog.");
            }
        }

        private UIFakeStoreWindow GetOrCreateFakeStoreWindow()
        {
            if (m_UIFakeStoreWindowObject == null)
            {
                m_UIFakeStoreWindowObject = new GameObject("UIFakeStoreWindow", typeof(Transform));
                m_UIFakeStoreWindowObject.AddComponent<UIFakeStoreWindow>();
            }

            return m_UIFakeStoreWindowObject.GetComponent<UIFakeStoreWindow>();
        }

        private void AddLifeCycleNotifierAndSetDestroyCallback(GameObject gameObject)
        {
            var notifier = gameObject.AddComponent<LifecycleNotifier>();
            notifier.OnDestroyCallback = () =>
            {
                m_CurrentDialog = null;
            };
        }

        private void EnsureEventSystemCreated(Transform rootTransform)
        {
            if (Object.FindObjectOfType<EventSystem>() == null)
            {
                CreateEventSystem(rootTransform);
            }
        }

        private void ConfigureDialogWindow(UIFakeStoreWindow dialogWindow)
        {
            var doCancel = UIMode != FakeStoreUIMode.DeveloperUser;
            var doDropDown = UIMode != FakeStoreUIMode.StandardUser;

            dialogWindow.ConfigureMainDialogText(m_CurrentDialog.QueryText, m_CurrentDialog.OkayButtonText, m_CurrentDialog.CancelButtonText);

            if (doDropDown)
            {
                dialogWindow.ConfigureDropdownOptions(m_CurrentDialog.Options);
            }

            ConfigureDialogWindowCallbacks(dialogWindow, doCancel, doDropDown);
        }

        void ConfigureDialogWindowCallbacks(UIFakeStoreWindow dialogWindow, bool assignCancelCallback, bool assignDropDownCallback)
        {
            Action cancelAction = null;
            Action<int> dropdownAction = null;

            if (assignCancelCallback)
            {
                cancelAction = CancelButtonClicked;
            }

            if (assignDropDownCallback)
            {
                dropdownAction = DropdownValueChanged;
            }

            dialogWindow.AssignCallbacks(OkayButtonClicked, cancelAction, dropdownAction);
        }

        private void CreateEventSystem(Transform rootTransform)
        {
            m_EventSystem = new GameObject("EventSystem", typeof(EventSystem));
            m_EventSystem.AddComponent<StandaloneInputModule>();
            m_EventSystem.transform.parent = rootTransform;
        }

        private string CreatePurchaseQuestion(ProductDefinition definition)
        {
            return "Do you want to Purchase " + definition.id + "?" + EnvironmentDescriptionPostfix;
        }

        private string CreateRetrieveProductsQuestion(ReadOnlyCollection<ProductDefinition> definitions)
        {
            var title = "Do you want to initialize purchasing for products {";
            title += string.Join(", ", definitions.Take(RetrieveProductsDescriptionCount).Select(pid => pid.id).ToArray());
            if (definitions.Count > RetrieveProductsDescriptionCount)
            {
                title += ", ...";
            }
            title += "}?" + EnvironmentDescriptionPostfix;

            return title;
        }

        /// <summary>
        /// Positive button clicked. For yes/no dialog will send true message. For
        /// multiselect (FakeStoreUIMode.DeveloperUser) dialog may send true or false
        /// message, along with chosen option.
        /// </summary>
        private void OkayButtonClicked()
        {
            var result = false;

            // Return false if the user chose something other than Success, and is in Development mode.
            // True if the "Success" option was chosen, or if this is non-Development mode.
            if (m_LastSelectedDropdownIndex == 0 || UIMode != FakeStoreUIMode.DeveloperUser)
            {
                // Ensure we return true
                result = true;
            }

            var codeValue = Math.Max(0, m_LastSelectedDropdownIndex - 1); // Pop SuccessString

            m_CurrentDialog.Callback(result, codeValue);
            CloseDialog();
        }

        /// <summary>
        /// Negative button clicked. Sends false message.
        /// </summary>
        private void CancelButtonClicked()
        {
            var codeValue = Math.Max(0, m_LastSelectedDropdownIndex - 1); // Pop SuccessString

            // ASSUME: This is FakeStoreUIMode.StandardUser
            m_CurrentDialog.Callback(false, codeValue);
            CloseDialog();
        }

        private void DropdownValueChanged(int selectedItem)
        {
            m_LastSelectedDropdownIndex = selectedItem;
        }

        private void CloseDialog()
        {
            m_CurrentDialog = null;

            if (m_UIFakeStoreWindowObject != null)
            {
                Object.Destroy(m_UIFakeStoreWindowObject);
            }
        }

        public bool IsShowingDialog()
        {
            return m_CurrentDialog != null;
        }
    }
}