/******************************************************************************
 * Copyright (C) Ultraleap, Inc. 2011-2021.                                   *
 *                                                                            *
 * Use subject to the terms of the Apache License 2.0 available at            *
 * http://www.apache.org/licenses/LICENSE-2.0, or another agreement           *
 * between Ultraleap and you, your company or other organization.             *
 ******************************************************************************/

using System;
using UnityEditor;
using UnityEngine;

namespace Leap.Unity.Interaction.Internal
{

    using Query;
    using UnityObject = UnityEngine.Object;

    public static class InteractionChecks
    {
        public const float MAX_GRAVITY_MAGNITUDE = 4.905f;
        public const float MAX_TIMESTEP = 1.0f / 90.0f;

        private const string IGNORE_GRAVITY_CHECK_KEY = "LeapIEIgnoreGravityCheck";
        private const string IGNORE_TIMESTEP_CHECK_KEY = "LeapIEIgnoreTimestepCheck";
        private const string IGNORE_RIGID_HANDS_CHECK_KEY = "LeapIEIgnoreRigidHandsCheck";

        private const string SHOULD_LAUNCH_FOR_IE = "LeapWindowPanelShouldLaunchForIE";

        [InitializeOnLoadMethod]
        private static void init()
        {
            EditorApplication.delayCall += () =>
            {
                if (EditorPrefs.GetBool(SHOULD_LAUNCH_FOR_IE, defaultValue: true))
                {
                    EditorPrefs.SetBool(SHOULD_LAUNCH_FOR_IE, false);
                    LeapUnityWindow.Init();
                }
            };

            EditorApplication.playModeStateChanged -= onPlayModeStateChanged;
            EditorApplication.playModeStateChanged += onPlayModeStateChanged;
        }

        private static void onPlayModeStateChanged(PlayModeStateChange stateChange)
        {
            if (stateChange == PlayModeStateChange.EnteredPlayMode)
            {
                bool allChecksPassed = runAllChecks_NoGUI();

                if (!allChecksPassed && EditorPrefs.GetBool(SHOULD_LAUNCH_FOR_IE))
                {
                    EditorApplication.delayCall += LeapUnityWindow.Init;
                }
            }
        }

        [LeapProjectCheck("Interaction Engine", 10)]
        public static bool CheckInteractionSettings()
        {
            EditorGUILayout.LabelField("Interaction Engine", EditorStyles.boldLabel);

            bool allChecksPassed = runAllChecks_WithGUI();

            EditorGUILayout.Space();

            if (allChecksPassed)
            {
                EditorGUILayout.HelpBox("All settings are good for the Interaction Engine!",
                  MessageType.Info);
            }

            return true;
        }

        #region Run All Checks

        private static bool runAllChecks_NoGUI()
        {
            bool allChecksPassed = true;

            allChecksPassed &= checkGravity();

            allChecksPassed &= checkTimeStep();

            allChecksPassed &= checkRigidHands();

            return allChecksPassed;
        }

        private static bool runAllChecks_WithGUI()
        {
            bool allChecksPassed = true;

            allChecksPassed &= checkGravityAndDrawGUI();

            allChecksPassed &= checkTimeStepAndDrawGUI();

            allChecksPassed &= checkRigidHandsAndDrawGUI();

            if (!allChecksPassed && Application.isPlaying)
            {
                EditorGUILayout.Space();

                EditorGUILayout.HelpBox("Editor is currently in play-mode, so any project setting "
                  + "changes will be reverted upon returning to edit-mode. You should return to "
                  + "edit-mode if you want auto-fixes to stick.", MessageType.Warning);
            }

            return allChecksPassed;
        }

        #endregion

        #region Check Gravity

        private static bool checkGravity()
        {
            if (LeapProjectChecks.CheckIgnoredKey(IGNORE_GRAVITY_CHECK_KEY))
            {
                return true;
            }

            if (Mathf.Abs(Physics.gravity.y) > MAX_GRAVITY_MAGNITUDE)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        private static bool checkGravityAndDrawGUI()
        {
            var gravityOK = checkGravity();

            if (!gravityOK)
            {

                EditorGUILayout.Space();

                using (new EditorGUILayout.HorizontalScope())
                {
                    EditorGUILayout.HelpBox("Your gravity magnitude is " + Physics.gravity.y
                                        + " which is stronger than the recommended value "
                                        + "of -4.905!\n\nGo to Edit/Project Settings/Physics "
                                        + "to change the magnitude.", MessageType.Warning);

                    if (GUILayout.Button("Auto-fix"))
                    {
                        Physics.gravity = Vector3.down * MAX_GRAVITY_MAGNITUDE;
                    }

                    if (GUILayout.Button("Ignore"))
                    {
                        LeapProjectChecks.SetIgnoredKey(IGNORE_GRAVITY_CHECK_KEY, ignore: true);
                    }
                }
            }

            return gravityOK;
        }

        #endregion

        #region Check Timestep

        private static bool checkTimeStep()
        {
            if (LeapProjectChecks.CheckIgnoredKey(IGNORE_TIMESTEP_CHECK_KEY))
            {
                return true;
            }

            if (Time.fixedDeltaTime > MAX_TIMESTEP + Mathf.Epsilon)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        private static bool checkTimeStepAndDrawGUI()
        {
            var timeStepOK = checkTimeStep();

            if (!timeStepOK)
            {
                float roundedTimestep = (float)Math.Round(MAX_TIMESTEP, 4);

                EditorGUILayout.Space();

                using (new EditorGUILayout.HorizontalScope())
                {
                    EditorGUILayout.HelpBox(
                      "Your fixed timestep is " + Time.fixedDeltaTime +
                      ", which is slower than the recommended value " +
                      "of " + roundedTimestep + ".\n\nGo to Edit/Project Settings/Time " +
                      "to change the fixed timestep.", MessageType.Warning);

                    if (GUILayout.Button("Auto-fix"))
                    {
                        Time.fixedDeltaTime = roundedTimestep;
                    }

                    if (GUILayout.Button("Ignore"))
                    {
                        LeapProjectChecks.SetIgnoredKey(IGNORE_TIMESTEP_CHECK_KEY, ignore: true);
                    }
                }
            }

            return timeStepOK;
        }

        #endregion

        #region Check Rigid Hands

        private static bool checkRigidHands()
        {
            var unusedRigidHandObjects = (GameObject[])null;
            return checkRigidHands(out unusedRigidHandObjects);
        }

        private static bool checkRigidHands(out GameObject[] rigidHandObjects)
        {
            if (LeapProjectChecks.CheckIgnoredKey(IGNORE_RIGID_HANDS_CHECK_KEY))
            {
                rigidHandObjects = null;
                return true;
            }

            rigidHandObjects = UnityObject.FindObjectsOfType<RigidHand>().Query()
              .Select(x => x.gameObject).ToArray();
            if (rigidHandObjects.Length != 0
                  && UnityObject.FindObjectOfType<InteractionManager>() != null)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        private static bool checkRigidHandsAndDrawGUI()
        {
            var rigidHandObjects = (GameObject[])null;
            var rigidHandsOK = checkRigidHands(out rigidHandObjects);

            if (!rigidHandsOK)
            {

                EditorGUILayout.Space();

                using (new EditorGUILayout.HorizontalScope())
                {
                    EditorGUILayout.HelpBox(
                      "Rigid Hands AND an Interaction Manager are present in your scene. " +
                      "Rigid Hands are not compatible with the Interaction Engine and should " +
                       "never be used in tandem with it. You should remove them " +
                       "from your scene.", MessageType.Warning);

                    if (GUILayout.Button(new GUIContent("Select Rigid Hands",
                          "Select RigidHand objects in the current scene."),
                          GUILayout.ExpandHeight(true), GUILayout.MaxHeight(40F)))
                    {
                        Selection.objects = rigidHandObjects;
                    }

                    if (GUILayout.Button("Ignore"))
                    {
                        LeapProjectChecks.SetIgnoredKey(IGNORE_RIGID_HANDS_CHECK_KEY, ignore: true);
                    }
                }
            }

            return rigidHandsOK;
        }

        #endregion

    }
}