using Jint.Collections;
using Jint.Native.Function;
using Jint.Native.Object;
using Jint.Native.Symbol;
using Jint.Runtime;
using Jint.Runtime.Descriptors;
using Jint.Runtime.Interop;

namespace Jint.Native.Set
{
    public sealed class SetConstructor : FunctionInstance, IConstructor
    {
        private static readonly JsString _functionName = new JsString("Set");

        private SetConstructor(Engine engine)
            : base(engine, _functionName, FunctionThisMode.Global)
        {
        }

        public SetPrototype PrototypeObject { get; private set; }

        public static SetConstructor CreateSetConstructor(Engine engine)
        {
            var obj = new SetConstructor(engine)
            {
                _prototype = engine.Function.PrototypeObject
            };

            // The value of the [[Prototype]] internal property of the Set constructor is the Function prototype object
            obj.PrototypeObject = SetPrototype.CreatePrototypeObject(engine, obj);

            obj._length = new PropertyDescriptor(0, PropertyFlag.Configurable);

            // The initial value of Set.prototype is the Set prototype object
            obj._prototypeDescriptor = new PropertyDescriptor(obj.PrototypeObject, PropertyFlag.AllForbidden);

            return obj;
        }

        protected override void Initialize()
        {
            var symbols = new SymbolDictionary(1)
            {
                [GlobalSymbolRegistry.Species] = new GetSetPropertyDescriptor(get: new ClrFunctionInstance(_engine, "get [Symbol.species]", Species, 0, PropertyFlag.Configurable), set: Undefined, PropertyFlag.Configurable)
            };

            SetSymbols(symbols);
        }

        private static JsValue Species(JsValue thisObject, JsValue[] arguments)
        {
            return thisObject;
        }

        public override JsValue Call(JsValue thisObject, JsValue[] arguments)
        {
            ExceptionHelper.ThrowTypeError(_engine, "Constructor Set requires 'new'");
            return null;
        }

        /// <summary>
        /// https://tc39.es/ecma262/#sec-set-iterable
        /// </summary>
        public ObjectInstance Construct(JsValue[] arguments, JsValue newTarget)
        {
            if (newTarget.IsUndefined())
            {
                ExceptionHelper.ThrowTypeError(_engine);
            }

            var set = OrdinaryCreateFromConstructor(newTarget, PrototypeObject, static (engine, _) => new SetInstance(engine));
            if (arguments.Length > 0 && !arguments[0].IsNullOrUndefined())
            {
                var adderValue = set.Get("add");
                if (!(adderValue is ICallable adder))
                {
                    return ExceptionHelper.ThrowTypeError<ObjectInstance>(_engine, "add must be callable");
                }

                var iterable = arguments.At(0).GetIterator(_engine);

                try
                {
                    var args = new JsValue[1];
                    do
                    {
                        if (!iterable.TryIteratorStep(out var next))
                        {
                            return set;
                        }

                        next.TryGetValue(CommonProperties.Value, out var nextValue);
                        args[0] = nextValue;
                        adder.Call(set, args);
                    } while (true);
                }
                catch
                {
                    iterable.Close(CompletionType.Throw);
                    throw;
                }
            }

            return set;
        }
    }
}