using System.Collections.Immutable;
using System.Linq;
using Upsilon.BaseTypes;
using Upsilon.Binder;
using Upsilon.Evaluator;

namespace Upsilon.StandardLibraries
{
    public static class StaticScope
    {
        private static EvaluationScope _staticScope;
        private static BoundScope _staticBoundScope;

        public static EvaluationScope Scope
        {
            get
            {
                if (_staticScope != null)
                    return _staticScope;

                var (evaluationScope, boundScope) = CreateStandardLibrary();
                _staticScope                      = evaluationScope;
                _staticBoundScope                 = boundScope;
                return _staticScope;
            }
        }

        public static BoundScope BoundScope
        {
            get
            {
                if (_staticBoundScope != null)
                    return _staticBoundScope;

                var (evaluationScope, boundScope) = CreateStandardLibrary();
                _staticScope                      = evaluationScope;
                _staticBoundScope                 = boundScope;
                return _staticBoundScope;
            }
        }

        public static (EvaluationScope, BoundScope) CreateStandardLibrary()
        {
            var basicFunctions = new BasicFunctions().LoadMethods();
            var scope = new EvaluationScope(basicFunctions.ToDictionary(x => x.Key, x => (ScriptType)x.Value));
            var boundScope =
                new BoundScope(
                    scope.Variables.ToDictionary(x => x.Key,
                        x => (VariableSymbol) new FunctionVariableSymbol(x.Key, false,
                            ImmutableArray<VariableSymbol>.Empty, x.Value.Type) {IsBound = true}),
                    null);
            return (scope, boundScope);
        }

        public static void RegisterStaticVariable(string name, object value)
        {
            var luaVariable = value.ToScriptType();
            var varSymbol = new VariableSymbol(name, luaVariable.Type, false);
            BoundScope.AssignToNearest(varSymbol);
            Scope.AssignToNearest(varSymbol, luaVariable);
        }
    }
}