using EC.Helper.RabbitFunc.Compiler;
using EC.Helper.RabbitFunc.Expressions;
using EC.Helper.RabbitFunc.Extern;
using System.Reflection;

namespace EC.Helper.RabbitFunc;

public class Rabbit
{
    private static readonly Dictionary<string, SystemLambdaExpression> systemFunctions = new Dictionary<string, SystemLambdaExpression>();

    static Rabbit()
    {
        var assembly = Assembly.GetExecutingAssembly();
        foreach (var type in assembly.GetTypes())
        {
            var attributes = type.GetCustomAttributes(typeof(ExternLambdaAttribute), false);
            if (attributes.Length > 0)
            {
                var constructor = type.GetConstructor(Type.EmptyTypes);
                if (constructor != null)
                    Register((SystemLambdaExpression)constructor.Invoke(null));
            }
        }
    }

    internal static void Register(SystemLambdaExpression lambda)
    {
        if (lambda == null)
            throw new ArgumentNullException(nameof(lambda));

        systemFunctions[lambda.Name] = lambda;
    }

    internal static bool TryGetSystemLambda(string name, out SystemLambdaExpression? lambda)
    {
        return systemFunctions.TryGetValue(name, out lambda);
    }

    internal static SystemLambdaExpression? GetSystemLambda(string name)
    {
        systemFunctions.TryGetValue(name, out SystemLambdaExpression? lambda);
        return lambda;
    }

    public static LambdaExpression CompileFromSource(string source)
    {
        if (source == null)
            throw new ArgumentNullException(nameof(source));

        LambdaExpression? lambda = null;
        using var reader = new StringReader(source);
        var tokenizer = new Tokenizer(reader);
        var parser = new Parser(tokenizer);
        while (!tokenizer.EndOfStream)
        {
            var expression = parser.Parse();
            if (expression == null) break;
            else lambda = expression;
        }

        return lambda ?? throw new CompilerException(tokenizer.Position, "The formula was not found");
    }

    public static LambdaExpression CompileFromFile(string path)
    {
        if (path == null)
            throw new ArgumentNullException(nameof(path));

        LambdaExpression? lambda = null;
        using var stream = new FileStream(path, FileMode.Open, FileAccess.Read);
        using var reader = new StreamReader(stream, System.Text.Encoding.UTF8);
        var tokenizer = new Tokenizer(reader);
        var parser = new Parser(tokenizer);
        while (!tokenizer.EndOfStream)
        {
            var expression = parser.Parse();
            if (expression == null) break;
            else lambda = expression;
        }

        return lambda ?? throw new CompilerException(tokenizer.Position, "The formula was not found");
    }
}