using System;
using System.Collections.Generic;

namespace AlicizaX.UI
{
    public class MixedViewProvider : ViewProvider
    {
        private readonly MixedObjectPool<ViewHolder> objectPool;
        private readonly Dictionary<string, ViewHolder> templatesByName = new(StringComparer.Ordinal);

        public override string PoolStats =>
            $"hits={objectPool.HitCount}, misses={objectPool.MissCount}, destroys={objectPool.DestroyCount}";

        public MixedViewProvider(RecyclerView recyclerView, ViewHolder[] templates) : base(recyclerView, templates)
        {
            for (int i = 0; i < templates.Length; i++)
            {
                ViewHolder template = templates[i];
                if (template == null)
                {
                    continue;
                }

                templatesByName[template.GetType().Name] = template;
            }

            UnityMixedComponentFactory<ViewHolder> factory = new(templatesByName, recyclerView.Content);
            objectPool = new MixedObjectPool<ViewHolder>(factory);
        }

        public override ViewHolder GetTemplate(string viewName)
        {
            if (templates == null || templates.Length == 0)
            {
                throw new NullReferenceException("ViewProvider templates can not null or empty.");
            }

            if (!templatesByName.TryGetValue(viewName, out ViewHolder template))
            {
                throw new KeyNotFoundException($"ViewProvider template '{viewName}' was not found.");
            }

            return template;
        }

        public override ViewHolder[] GetTemplates()
        {
            if (templates == null || templates.Length == 0)
            {
                throw new NullReferenceException("ViewProvider templates can not null or empty.");
            }

            ViewHolder[] values = new ViewHolder[templatesByName.Count];
            templatesByName.Values.CopyTo(values, 0);
            return values;
        }

        public override ViewHolder Allocate(string viewName)
        {
            var viewHolder = objectPool.Allocate(viewName);
            viewHolder.gameObject.SetActive(true);
            return viewHolder;
        }

        public override void Free(string viewName, ViewHolder viewHolder)
        {
            objectPool.Free(viewName, viewHolder);
        }

        public override void Reset()
        {
            Clear();
            (Adapter as IItemRenderCacheOwner)?.ReleaseAllItemRenders();
            objectPool.Dispose();
        }

        public override void PreparePool()
        {
            int warmCount = GetRecommendedWarmCount();
            if (warmCount <= 0)
            {
                return;
            }

            int itemCount = GetItemCount();
            int start = Math.Max(0, LayoutManager.GetStartIndex());
            int end = Math.Min(itemCount - 1, start + warmCount - 1);
            Dictionary<string, int> counts = new(StringComparer.Ordinal);

            for (int index = start; index <= end; index++)
            {
                string viewName = Adapter.GetViewName(index);
                if (string.IsNullOrEmpty(viewName))
                {
                    continue;
                }

                counts.TryGetValue(viewName, out int count);
                counts[viewName] = count + 1;
            }

            foreach (var pair in counts)
            {
                int targetCount = pair.Value + Math.Max(1, LayoutManager.Unit);
                objectPool.EnsureCapacity(pair.Key, targetCount);
                objectPool.Warm(pair.Key, targetCount);
            }
        }
    }
}