using System;
using System.Collections.Generic;
using System.Reflection;

namespace RocketUtils
{
    public static class AssemblyCache
    {
        private static readonly Dictionary<string, Assembly> Assemblies = new Dictionary<string, Assembly>(StringComparer.OrdinalIgnoreCase);

        public static bool TryGetAssembly(string assemblyName, out Assembly assembly)
        {
            WarmupAssembliesIfRequired();
            
            return Assemblies.TryGetValue(assemblyName, out assembly);
        }

        public static bool TryGetAssemblyWithAttribute<T>(out Assembly assembly) where T : Attribute
        {
            WarmupAssembliesIfRequired();
            
            foreach (var asm in Assemblies.Values)
            {
                if (asm.GetCustomAttributes(typeof(T), false).Length > 0)
                {
                    assembly = asm;
                    return true;
                }
            }

            assembly = null;
            return false;
        }
        
        public static IEnumerable<Assembly> GetAssembliesWithAttribute<T>() where T : Attribute
        {
            WarmupAssembliesIfRequired();
            
            foreach (var asm in Assemblies.Values)
            {
                if (asm.GetCustomAttributes(typeof(T), false).Length > 0)
                {
                    yield return asm;
                }
            }
        }
        
        private static void WarmupAssembliesIfRequired()
        {
            if (Assemblies.Count > 0)
                return;

            var assemblies = AppDomain.CurrentDomain.GetAssemblies();
            foreach (var assembly in assemblies)
            {
                Assemblies[assembly.FullName] = assembly;
            }
        }
    }
}