using UnityEngine;

namespace AssetManagement
{
    public class BundleLoader : AsyncLoadUnit
    {
        public AssetBundle bundle { get; private set; }
        private AssetBundleCreateRequest _bundleRequest;
        
        public override float GetProgress()
        {
            // ReSharper disable once SwitchStatementMissingSomeCases
            switch (state)
            {
                case AsyncLoadUnitState.Done:
                    return 1f;
                case AsyncLoadUnitState.Loading:
                    return _bundleRequest == null ? 0f : _bundleRequest.progress;
                default:
                    return 0f;
            }
        }

        protected override AsyncOperation StartOperation(out string startError)
        {
            var path = pathHub.GetPath(name);
            if (string.IsNullOrEmpty(path))
            {
                startError = "Path Error: cannot get load path for asset " + name;
                return null;
            }
            else
            {
                startError = string.Empty;
                _bundleRequest = AssetBundle.LoadFromFileAsync(path + AssetConst.bundleVariant);
                return _bundleRequest;
            }
        }

        protected override string HandleOperation(AsyncOperation operation)
        {
            if (operation == _bundleRequest)
            {
                bundle = _bundleRequest.assetBundle;
                return bundle == null ? "Load Error: cannot load asset bundle from path " + name : string.Empty;
            }
            else
                return "Process Error: completed operation is not the original one!";
        }
    }
}