using UnityEngine;
using System.Collections.Generic;
using Lean.Common;

namespace Lean.Pool
{
    /// <summary>This class handles the association between a spawned prefab, and the LeanGameObjectPool component that manages it.</summary>
    public static class LeanPool
    {
        public const string HelpUrlPrefix = LeanHelper.HelpUrlPrefix + "LeanPool#";

        public const string ComponentPathPrefix = LeanHelper.ComponentPathPrefix + "Pool/Lean ";

        /// <summary>This stores all references between a spawned GameObject and its pool.</summary>
        public static Dictionary<GameObject, LeanGameObjectPool> Links = new Dictionary<GameObject, LeanGameObjectPool>();

        /// <summary>This allows you to spawn a prefab via Component.</summary>
        public static T Spawn<T>(T prefab, Transform parent, bool worldPositionStays = false)
            where T : Component
        {
            if (prefab == null) { Debug.LogError("Attempting to spawn a null prefab."); return null; }
            var clone = Spawn(prefab.gameObject, parent, worldPositionStays); return clone != null ? clone.GetComponent<T>() : null;
        }

        /// <summary>This allows you to spawn a prefab via Component.</summary>
        public static T Spawn<T>(T prefab, Vector3 position, Quaternion rotation, Transform parent = null)
            where T : Component
        {
            if (prefab == null) { Debug.LogError("Attempting to spawn a null prefab."); return null; }
            var clone = Spawn(prefab.gameObject, position, rotation, parent); return clone != null ? clone.GetComponent<T>() : null;
        }

        /// <summary>This allows you to spawn a prefab via Component.</summary>
        public static T Spawn<T>(T prefab)
            where T : Component
        {
            if (prefab == null) { Debug.LogError("Attempting to spawn a null prefab."); return null; }
            var clone = Spawn(prefab.gameObject); return clone != null ? clone.GetComponent<T>() : null;
        }

        /// <summary>This allows you to spawn a prefab via GameObject.</summary>
        public static GameObject Spawn(GameObject prefab, Transform parent, bool worldPositionStays = false)
        {
            if (prefab == null) { Debug.LogError("Attempting to spawn a null prefab."); return null; }
            var transform = prefab.transform;
            if (parent != null && worldPositionStays == true)
            {
                return Spawn(prefab, prefab.transform.position, Quaternion.identity, Vector3.one, parent, worldPositionStays);
            }
            return Spawn(prefab, transform.localPosition, transform.localRotation, transform.localScale, parent, false);
        }

        /// <summary>This allows you to spawn a prefab via GameObject.</summary>
        public static GameObject Spawn(GameObject prefab, Vector3 position, Quaternion rotation, Transform parent = null)
        {
            if (prefab == null) { Debug.LogError("Attempting to spawn a null prefab."); return null; }
            if (parent != null)
            {
                position = parent.InverseTransformPoint(position);
                rotation = Quaternion.Inverse(parent.rotation) * rotation;
            }
            return Spawn(prefab, position, rotation, prefab.transform.localScale, parent, false);
        }

        /// <summary>This allows you to spawn a prefab via GameObject.</summary>
        public static GameObject Spawn(GameObject prefab)
        {
            if (prefab == null) { Debug.LogError("Attempting to spawn a null prefab."); return null; }
            var transform = prefab.transform;
            return Spawn(prefab, transform.localPosition, transform.localRotation, transform.localScale, null, false);
        }

        /// <summary>This allows you to spawn a prefab via GameObject.</summary>
        private static GameObject Spawn(GameObject prefab, Vector3 localPosition, Quaternion localRotation, Vector3 localScale, Transform parent, bool worldPositionStays)
        {
            if (prefab != null)
            {
                // Find the pool that handles this prefab
                var pool = default(LeanGameObjectPool);

                // Create a new pool for this prefab?
                if (LeanGameObjectPool.TryFindPoolByPrefab(prefab, ref pool) == false)
                {
                    pool = new GameObject("LeanPool (" + prefab.name + ")").AddComponent<LeanGameObjectPool>();

                    pool.Prefab = prefab;
                }

                // Try and spawn a clone from this pool
                var clone = default(GameObject);

                if (pool.TrySpawn(ref clone, localPosition, localRotation, localScale, parent, worldPositionStays) == true)
                {
                    // Clone already registered?
                    if (Links.Remove(clone) == true)
                    {
                        // If this pool recycles clones, then this can be expected
                        if (pool.Recycle == true)
                        {

                        }
                        // This shouldn't happen
                        else
                        {
                            Debug.LogWarning("You're attempting to spawn a clone that hasn't been despawned. Make sure all your Spawn and Despawn calls match, you shouldn't be manually destroying them!", clone);
                        }
                    }

                    // Associate this clone with this pool
                    Links.Add(clone, pool);

                    return clone;
                }
            }
            else
            {
                Debug.LogError("Attempting to spawn a null prefab.");
            }

            return null;
        }

        /// <summary>This will despawn all pool clones.</summary>
        public static void DespawnAll()
        {
            foreach (var instance in LeanGameObjectPool.Instances)
            {
                instance.DespawnAll();
            }

            Links.Clear();
        }

        /// <summary>This allows you to despawn a clone via Component, with optional delay.</summary>
        public static void Despawn(Component clone, float delay = 0.0f)
        {
            if (clone != null) Despawn(clone.gameObject, delay);
        }

        /// <summary>This allows you to despawn a clone via GameObject, with optional delay.</summary>
        public static void Despawn(GameObject clone, float delay = 0.0f)
        {
            if (clone != null)
            {
                var pool = default(LeanGameObjectPool);

                // Try and find the pool associated with this clone
                if (Links.TryGetValue(clone, out pool) == true)
                {
                    // Remove the association
                    Links.Remove(clone);

                    pool.Despawn(clone, delay);
                }
                else
                {
                    if (LeanGameObjectPool.TryFindPoolByClone(clone, ref pool) == true)
                    {
                        pool.Despawn(clone, delay);
                    }
                    else
                    {
                        Debug.LogWarning("You're attempting to despawn a gameObject that wasn't spawned from this pool", clone);

                        // Fall back to normal destroying
#if UNITY_EDITOR
                        if (Application.isPlaying == false)
                        {
                            Object.DestroyImmediate(clone);

                            return;
                        }
#endif
                        Object.Destroy(clone);
                    }
                }
            }
            else
            {
                Debug.LogWarning("You're attempting to despawn a null gameObject", clone);
            }
        }

        /// <summary>This allows you to detach a clone via Component, with optional delay.
        /// A detached clone will act as a normal GameObject, requiring you to manually destroy or otherwise manage it.
        /// NOTE: If this clone has been despawned then it will still be parented to the pool.</summary>
        public static void Detach(Component clone)
        {
            if (clone != null) Detach(clone.gameObject);
        }

        /// <summary>This allows you to detach a clone via GameObject, with optional delay.
        /// A detached clone will act as a normal GameObject, requiring you to manually destroy or otherwise manage it.
        /// NOTE: If this clone has been despawned then it will still be parented to the pool.</summary>
        public static void Detach(GameObject clone)
        {
            if (clone != null)
            {
                var pool = default(LeanGameObjectPool);

                // Try and find the pool associated with this clone
                if (Links.TryGetValue(clone, out pool) == true)
                {
                    // Remove the association
                    Links.Remove(clone);

                    pool.Detach(clone);
                }
                else
                {
                    if (LeanGameObjectPool.TryFindPoolByClone(clone, ref pool) == true)
                    {
                        pool.Detach(clone);
                    }
                    else
                    {
                        Debug.LogWarning("You're attempting to detach a gameObject that wasn't spawned from this pool", clone);
                    }
                }
            }
            else
            {
                Debug.LogWarning("You're attempting to detach a null gameObject", clone);
            }
        }
    }
}