using System;

using System.Collections.Generic;

using System.Dynamic;

using System.Linq;

using System.Linq.Expressions;

using System.Runtime.CompilerServices;

using Microsoft.CSharp.RuntimeBinder;

namespace Python.Runtime;

class DynamicObjectMemberAccessor

{

const int MaxCacheEntries = 1000;

readonly ConcurrentLruCache<MemberKey, Func<object, object>> getters = new(MaxCacheEntries);

readonly ConcurrentLruCache<MemberKey, Action<object, object?>> setters = new(MaxCacheEntries);

readonly ConcurrentLruCache<MemberKey, Func<object, bool>> deleters = new(MaxCacheEntries);

static readonly CSharpArgumentInfo[] getArgumentInfo =

{

CSharpArgumentInfo.Create(CSharpArgumentInfoFlags.None, null),

};

static readonly CSharpArgumentInfo[] setArgumentInfo =

{

CSharpArgumentInfo.Create(CSharpArgumentInfoFlags.None, null),

CSharpArgumentInfo.Create(CSharpArgumentInfoFlags.None, null),

};

public bool TryGetMember(IDynamicMetaObjectProvider obj, string memberName, out object? value)

{

if (obj is null)

throw new ArgumentNullException(nameof(obj));

if (memberName is null)

throw new ArgumentNullException(nameof(memberName));

var getter = getters.GetOrAdd(new MemberKey(obj.GetType(), memberName), static key =>

{

if (typeof(DynamicObject).IsAssignableFrom(key.Type))

{

var getBinder = new GetMemberNameBinder(key.MemberName);

return obj =>

{

if (((DynamicObject)obj).TryGetMember(getBinder, out object? result))

{

return result;

}

throw new RuntimeBinderException($"Could not get member '{key.MemberName}'");

};

}

var binder = Binder.GetMember(CSharpBinderFlags.None, key.MemberName, key.Type, getArgumentInfo);

var callSite = CallSite<Func<CallSite, IDynamicMetaObjectProvider, object>>.Create(binder);

return obj => callSite.Target(callSite, (IDynamicMetaObjectProvider)obj);

});

try

{

value = getter(obj);

return true;

}

catch (RuntimeBinderException)

{

value = null;

return false;

}

}

public bool TrySetMember(IDynamicMetaObjectProvider obj, string memberName, object? value)

{

if (obj is null)

throw new ArgumentNullException(nameof(obj));

if (memberName is null)

throw new ArgumentNullException(nameof(memberName));

var setter = setters.GetOrAdd(new MemberKey(obj.GetType(), memberName), static key =>

{

if (typeof(DynamicObject).IsAssignableFrom(key.Type))

{

var setBinder = new SetMemberNameBinder(key.MemberName);

return (obj, value) =>

{

if (!((DynamicObject)obj).TrySetMember(setBinder, value))

{

throw new RuntimeBinderException($"Could not set member '{key.MemberName}'");

}

};

}

var binder = Binder.SetMember(CSharpBinderFlags.None, key.MemberName, key.Type, setArgumentInfo);

var callSite = CallSite<Action<CallSite, IDynamicMetaObjectProvider, object?>>.Create(binder);

return (obj, value) => callSite.Target(callSite, (IDynamicMetaObjectProvider)obj, value);

});

try

{

setter(obj, value);

return true;

}

catch (RuntimeBinderException)

{

return false;

}

}

public bool TryDeleteMember(IDynamicMetaObjectProvider obj, string memberName)

{

if (obj is null)

throw new ArgumentNullException(nameof(obj));

if (memberName is null)

throw new ArgumentNullException(nameof(memberName));

var deleter = deleters.GetOrAdd(new MemberKey(obj.GetType(), memberName), static key =>

{

if (typeof(DynamicObject).IsAssignableFrom(key.Type))

{

var binder = new DeleteMemberNameBinder(key.MemberName);

return obj => ((DynamicObject)obj).TryDeleteMember(binder);

}

if (typeof(ExpandoObject).IsAssignableFrom(key.Type))

{

return obj => ((IDictionary<string, object>)(ExpandoObject)obj).Remove(key.MemberName);

}

return _ => false;

});

try

{

return deleter(obj);

}

catch (RuntimeBinderException)

{

return false;

}

}

public IReadOnlyCollection<string> GetDynamicMemberNames(IDynamicMetaObjectProvider obj)

{

if (obj is null)

throw new ArgumentNullException(nameof(obj));

if (obj is ExpandoObject expandoObject)

{

return ((IDictionary<string, object>)expandoObject).Keys.ToArray();

}

if (obj is DynamicObject dynamicObject)

{

return dynamicObject.GetDynamicMemberNames().ToArray();

}

var metaObject = obj.GetMetaObject(Expression.Constant(obj));

return metaObject.GetDynamicMemberNames().ToArray();

}

readonly record struct MemberKey(Type Type, string MemberName);

sealed class DeleteMemberNameBinder : DeleteMemberBinder

{

public DeleteMemberNameBinder(string name)

: base(name, ignoreCase: false)

{

}

public override DynamicMetaObject FallbackDeleteMember(DynamicMetaObject target, DynamicMetaObject? errorSuggestion)

=> errorSuggestion ?? throw new RuntimeBinderException($"Could not delete member '{Name}'");

}

sealed class GetMemberNameBinder : GetMemberBinder

{

public GetMemberNameBinder(string name)

: base(name, ignoreCase: false)

{

}

public override DynamicMetaObject FallbackGetMember(DynamicMetaObject target, DynamicMetaObject? errorSuggestion)

=> errorSuggestion ?? throw new RuntimeBinderException($"Could not get member '{Name}'");

}

sealed class SetMemberNameBinder : SetMemberBinder

{

public SetMemberNameBinder(string name)

: base(name, ignoreCase: false)

{

}

public override DynamicMetaObject FallbackSetMember(

DynamicMetaObject target,

DynamicMetaObject value,

DynamicMetaObject? errorSuggestion)

=> errorSuggestion ?? throw new RuntimeBinderException($"Could not set member '{Name}'");

}

public void Clear()

{

getters.Clear();

setters.Clear();

deleters.Clear();

}

}