using System;
using System.Collections;
using NUnit.Framework;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.TestTools;

namespace Tests
{
    public class ShopUnitTests
    {
        private ShopView shopView; //This is the grid buy view we want to test
        private SellViewGrid sellView;
        private ShopView upgradeView;

        //Setup the test scene
        [OneTimeSetUp]
        public void LoadShopScene()
        {
            // Load the Scene to do unit test. In the scope of this project, this is fine. In a more complicated project, a game scene could take
            // a long time to load, in which case it's better to create test scenes to do unit tests
            SceneManager.LoadScene(0);
        }

        //Setup the unit tests here
        [UnitySetUp]
        public IEnumerator SetupTests()
        {
            yield return
                null; //yield return null skips one frame, this is to make sure that this happens after the scene is loaded

            //The shop scene only contains one grid buy view, we use Resources.FindObjectsOfTypeAll to get the reference to it,
            //Resources.FFindObjectsOfTypeAll is used instead of GameObject.Find because the later can't find disabled objects
            var shops = Resources.FindObjectsOfTypeAll<ShopViewGrid>();
            shopView = shops[2];    // For some reason this reverses it. We just want to hardcode it for this scene, no annoying for loops to compare
            upgradeView = shops[1];
            
            sellView = Resources.FindObjectsOfTypeAll<SellViewGrid>()[0];
            
            // Turn on all views so they function correctly. We do not care for the looks during unit tests, obviously.
            sellView.gameObject.SetActive(true);
            upgradeView.gameObject.SetActive(true);
            //Active the gridBuyView game object to initialize the class, if we don't do this 'void Start()' won't be called
            //You should active all the game objects that are involved in the test before testing the functions from their components
            shopView.gameObject.SetActive(true);
        }

        // Use meaningful name for your test cases, this case tests if the ShopGridBuyView component has initialized its ShopModel property 
        [UnityTest]
        public IEnumerator ShopGridBuyViewInitializedShopModel()
        {
            yield return null; //yield return null skips one frame, waits for the Unity scene to load

            //now test if a ShopModel is assigned to gridBuyView
            Assert.IsNotNull(shopView.ShopModel, "No Model is assigned in ShopView");
        }

        //This case tests if the grid buy view displays the correct amount of Items
        [UnityTest,Order(1)]    // Run this one first to see if we populated everything correctly
        public IEnumerator ShopGridBuyViewDisplaysCorrectAmountOfItems()
        {
            yield return null; //yield return null skips one frame, waits for the Unity scene to load

            //Now that the scene is loaded and the gridBuyView game object was activated in SetupTests(), we can use GameObject.Find
            //to find the game object we want to test
            GameObject gridItemsPanel = GameObject.Find("GridItemsPanel");

            yield return
                new WaitForEndOfFrame(); //Since we are testing how many items are displayed, we should use WaitForEndOfFrame to wait until the end of the frame,
            //so that the view finished updating and rendering everything 

            yield return null;
            int itemCount = gridItemsPanel.transform.childCount;
            Assert.AreEqual(shopView.ShopModel.inventory.GetItemCount(), itemCount,
                "The generated item count is not equal to shopModel's itemCount");
        }
        
        // This case tests if the shop model gets populated with items
        [UnityTest,Order(0)]    // Run this one before the view tests to see if the factory works
        public IEnumerator ShopFactoryPopulatesShop()
        {
            yield return null; //yield return null skips one frame, waits for the Unity scene to load

            //Now that the scene is loaded and the gridBuyView game object was activated in SetupTests(), we can use GameObject.Find
            //to find the game object we want to test
            var count = 0;
            Assert.DoesNotThrow(delegate
            {
                count = shopView.ShopModel.inventory.GetItemCount();
            });
            Assert.Greater(count,1);    // Having just one item probably means something went wrong and crashed

        }

        //This case tests if the buyModel can throw an ArgumentOutOfRangeException when it's asked to select an item by a negative
        //index. Incorrect indexes can be generated from bugs in views or controllers, throwing the correct type of exceptions is
        //better than failing silently for debugging. Your unit tests should cover exception handlings
        [UnityTest]
        public IEnumerator ShopModelThrowsExceptionsWhenSelectingNegativeIndex()
        {
            //yield return null skips one frame, waits for the Unity scene to load and buyModel to be assigned
            yield return null;

            //Creates a delegate that call gridBuyView.ShopModel.SelectItemByIndex(-1), the test runner will run the function, and
            //check if an ArgumentOutOfRangeException is thrown, the unit test would fail if no ArgumentOutOfRangeException
            //was thrown
            Assert.Throws<System.ArgumentOutOfRangeException>(delegate
            {
                shopView.ShopModel.SelectItemByIndex(-1);
            });
        }

        //This case tests whether info panels and selection highlights work correctly when a specific item is selected, while disabling correctly when it is unselected
        [UnityTest]
        public IEnumerator UpdateViewItemInfoPanelAndSelection()
        {
            yield return null;

            var selectedItem = shopView.transform.Find("GridItemsPanel");
            var active = selectedItem.GetComponentInChildren<ViewItemInfoPanel>();    // In grid view, one item panel will be active. That's the selected item!
            shopView.ShopModel.SelectItemByIndex(shopView.ShopModel.GetSelectedItemIndex() + 1);
            var newActive = selectedItem.GetComponentInChildren<ViewItemInfoPanel>(); 

            Assert.AreNotSame(active, newActive,"Previous item is still selected!");
        }
        
        // This test case tests that either no item is selected, or exactly one item is selected
        [UnityTest]
        public IEnumerator NoMoreThanOneItemSelectedInView()
        {
            yield return null;

            var selectedItem = shopView.transform.Find("GridItemsPanel");
            var active = selectedItem.GetComponentsInChildren<ViewItemInfoPanel>();    // In grid view, one item panel will be active. That's the selected item!
            
            Assert.Greater(2,active.Length,"Too many items selected!");    // Depending on what's up, either we want none or just one selected now
            shopView.ShopModel.SelectItemByIndex(shopView.ShopModel.GetSelectedItemIndex() + 1);
            shopView.ShopModel.SelectItemByIndex(shopView.ShopModel.GetSelectedItemIndex() + 1);
            active = selectedItem.GetComponentsInChildren<ViewItemInfoPanel>();    // In grid view, one item panel will be active. That's the selected item!
            UnityEngine.Assertions.Assert.AreEqual(active.Length,1,"Too many items or no item selected!");    // Now we definitely need one to be selected!
        }
        
        // This test case tests if the currently selected item disappears from the view when the buy model confirms the selection
        [UnityTest]
        public IEnumerator ModelSelectionRemovesViewItem()
        {
            yield return null;
            var selectedItem = shopView.transform.Find("GridItemsPanel");
            shopView.ShopModel.SelectItemByIndex(shopView.ShopModel.GetSelectedItemIndex() + 1);

            yield return null;
            var active = selectedItem.GetComponentInChildren<ViewItemInfoPanel>();    // In grid view, one item panel will be active. That's the selected item!
            shopView.ShopModel.ConfirmSelectedItem();
            yield return null;
            UnityEngine.Assertions.Assert.IsTrue(active == null,"Selected item view was not destroyed when bought!");    // Now we definitely need one to be selected!
        }
        
        // Tests if the player inventory doesn't allow to overdraw money. We test on shop inventory even though that one's money's technically irrelevant, but works the same on all
        [UnityTest]
        public IEnumerator InventoryDoesNotAllowExceedingTransactions()
        {
            yield return null;
            // So if we pay too much, we expect an exception
            Assert.Throws<InsufficientMoneyException>(delegate
            {
                shopView.ShopModel.inventory.ChangeBalance(-shopView.ShopModel.inventory.Money -
                                                           1); // Pay one money more than it's got!
            });
        }
        
        // Tests if transaction changes actually change an inventory's balance
        [UnityTest]
        public IEnumerator InventoryCorrectlyHandlesBalanceChange()
        {
            yield return null;

            var moneyBefore = shopView.ShopModel.inventory.Money;
            shopView.ShopModel.inventory.ChangeBalance(-shopView.ShopModel.inventory.Money); // Spend all our money!
            
            Assert.AreNotEqual(moneyBefore,shopView.ShopModel.inventory.Money);
            Assert.Zero(shopView.ShopModel.inventory.Money);
            shopView.ShopModel.inventory.ChangeBalance(moneyBefore + 1);    // For good measure, re-add all money plus a one money bonus
            
            Assert.AreEqual(moneyBefore + 1,shopView.ShopModel.inventory.Money);
        }
        
        // Tests if a model throws an error when trying to select an item directly that isn't part of it
        [UnityTest]
        public IEnumerator ModelSelectionErrorIfInvalid()
        {
            yield return null;

            Assert.Throws<ArgumentException>(delegate
            {
                shopView.ShopModel.SelectItem(new ItemPotion("some name","invalidIcon",5,2,PotionType.Healing));
            });
        }
        
        // Tests if a model selects an item correctly when it's valid
        [UnityTest]
        public IEnumerator ModelSelectionIndexCorrectIfValid()
        {
            yield return null;

            var item = shopView.ShopModel.GetSelectedItem();
            shopView.ShopModel.SelectItemByIndex(shopView.ShopModel.GetSelectedItemIndex() + 1);
            
            Assert.AreNotSame(item,shopView.ShopModel.GetSelectedItem());
            
            Assert.DoesNotThrow(delegate
            {
                shopView.ShopModel.SelectItem(item);
            });
            
            Assert.AreSame(item,shopView.ShopModel.GetSelectedItem());
        }
        
        // Tests if a buy model removes an item on confirmation, and then selects another one
        [UnityTest]
        public IEnumerator BuyModelConfirmationRemovesItemAndSelectsNew()
        {
            yield return null;

            var item = shopView.ShopModel.GetSelectedItem();
            shopView.ShopModel.ConfirmSelectedItem();
            
            Assert.AreNotSame(item,shopView.ShopModel.GetSelectedItem());
            
            Assert.Throws<ArgumentException>(delegate
            {
                shopView.ShopModel.SelectItem(item);
            });
            
            Assert.AreNotSame(item,shopView.ShopModel.GetSelectedItem());
        }
        
        // Tests if a buy model removes money from an inventory it buys from
        [UnityTest]
        public IEnumerator BuyingItemCostsMoney()
        {
            yield return null;

            var money = sellView.ShopModel.inventory.Money;    // In the scene setup, sellView happens to reference the player inventory the shop trades with
            Assert.DoesNotThrow(delegate
            {
                shopView.ShopModel.ConfirmSelectedItem();
            });
            
            Assert.Less(sellView.ShopModel.inventory.Money,money);
        }
        
        // Tests if a sell model gains money from selling
        [UnityTest]
        public IEnumerator SellingItemGivesMoney()
        {
            yield return null;

            var money = sellView.ShopModel.inventory.Money;    // In the scene setup, sellView happens to reference the player inventory the shop trades with
            Assert.DoesNotThrow(delegate
            {
                sellView.ShopModel.ConfirmSelectedItem();
            });
            
            Assert.Greater(sellView.ShopModel.inventory.Money,money);
        }
        
        // Tests if selling removes the item from the sell inventory
        [UnityTest]
        public IEnumerator SellingItemRemovesFromInventory()
        {
            yield return null;

            var item = sellView.ShopModel.GetSelectedItem();
            sellView.ShopModel.ConfirmSelectedItem();
            
            Assert.AreNotSame(item,sellView.ShopModel.GetSelectedItem());
            
            Assert.Throws<ArgumentException>(delegate
            {
                sellView.ShopModel.SelectItem(item);
            });
            
            Assert.AreNotSame(item,sellView.ShopModel.GetSelectedItem());
        }
        
        // Tests if upgrading an item does not remove it
        [UnityTest]
        public IEnumerator UpgradingKeepsInInventory()
        {
            yield return null;

            var item = upgradeView.ShopModel.GetSelectedItem();
            upgradeView.ShopModel.ConfirmSelectedItem();
            
            Assert.AreSame(item,upgradeView.ShopModel.GetSelectedItem());
            
            Assert.DoesNotThrow(delegate
            {
                upgradeView.ShopModel.SelectItem(item);
            });
            
            Assert.AreSame(item,upgradeView.ShopModel.GetSelectedItem());
        }
        
        // Tests if upgrading costs money
        [UnityTest]
        public IEnumerator UpgradingCostsMoney()
        {
            yield return null;

            var money = upgradeView.ShopModel.inventory.Money;    // In the scene setup, sellView happens to reference the player inventory the shop trades with
            Assert.DoesNotThrow(delegate
            {
                upgradeView.ShopModel.ConfirmSelectedItem();
            });
            
            Assert.Less(upgradeView.ShopModel.inventory.Money,money);
        }
        
        // Tests if upgrading improves an item's stats
        [UnityTest]
        public IEnumerator UpgradingImprovesStats()
        {
            yield return null;

            var item = upgradeView.ShopModel.GetSelectedItem();    // In the scene setup, sellView happens to reference the player inventory the shop trades with
            var stats = item.GetStats();        // Stats right now are turned into a generic string type. If we get a different one post-upgrade, it should've worked
            Assert.DoesNotThrow(delegate
            {
                upgradeView.ShopModel.ConfirmSelectedItem();
            });
            
            Assert.AreNotEqual(stats,upgradeView.ShopModel.GetSelectedItem().GetStats());
        }
    }
}