using EC.Helper.RabbitFunc.Runtime;
using System.Collections.ObjectModel;
using System.Text;
using MissingMethodException = EC.Helper.RabbitFunc.Runtime.MissingMethodException;

namespace EC.Helper.RabbitFunc.Expressions;

public class MethodCallExpression : Expression
{
    internal MethodCallExpression(Expression instance, string methodName, IList<Expression> arguments)
        : base(ExpressionType.MethodCall)
    {
        Instance = instance;
        MethodName = methodName;
        Arguments = new ReadOnlyCollection<Expression>(arguments);
    }

    public Expression Instance { get; }

    public string MethodName { get; }

    public ReadOnlyCollection<Expression> Arguments { get; }

    internal LambdaExpression GetLambda(RabbitDomain domain)
    {
        LambdaExpression lambda;
        if (domain != null)
        {
            lambda = domain.GetLambda(MethodName);
        }
        else
        {
            lambda = Rabbit.GetSystemLambda(MethodName);
        }

        return lambda;
    }

    public override object Eval(RuntimeContext context)
    {
        if (context == null)
            throw new ArgumentNullException(nameof(context));

        if (Instance == null)
        {
            var lambdaExpression = GetLambda(context.Domain);
            if (lambdaExpression == null)
                throw new MissingMethodException(string.Format("missing method:{0}", MethodName));
            if (Arguments.Count != lambdaExpression.Parameters.Count)
                throw new RuntimeException(string.Format("method:{0}. parame count error!", MethodName));

            var lambdaContext = new RuntimeContext(context);
            for (int i = 0; i < Arguments.Count; i++)
            {
                var parameter = lambdaExpression.Parameters[i];
                var argument = Arguments[i];
                var value = argument.Eval(context);
                lambdaContext.Variable(parameter.Name, value);
            }

            return lambdaExpression.Body.Eval(lambdaContext);
        }
        else
        {
            throw new NotSupportedException();
        }
    }

    public override string ToString()
    {
        var sb = new StringBuilder();
        sb.Append(MethodName).Append('(');
        using (var e = Arguments.GetEnumerator())
        {
            if (e.MoveNext())
            {
                sb.Append(e.Current.ToString());
                while (e.MoveNext())
                {
                    sb.Append(',');
                    sb.Append(e.Current.ToString());
                }
            }
        }
        sb.Append(')');
        return sb.ToString();
    }
}