namespace EC.Helper.RabbitFunc.Runtime;

public class RuntimeContext
{
    private readonly Dictionary<string, RuntimeVariable> variables = new Dictionary<string, RuntimeVariable>();
    private readonly RuntimeContext parent;

    public RuntimeContext()
    { }

    internal RuntimeContext(RuntimeContext parent)
    {
        if (parent == null)
            throw new ArgumentNullException(nameof(parent));

        this.parent = parent;
        this.Domain = parent.Domain;
    }

    public object this[string name]
    {
        set
        {
            if (name == null)
                throw new ArgumentNullException(nameof(name));

            variables[name] = new RuntimeVariable(value);
        }
    }

    internal RabbitDomain Domain { get; set; }

    private RuntimeContext FindCurrentOrParent(string name)
    {
        return variables.ContainsKey(name) ? this : parent?.FindCurrentOrParent(name);
    }

    public void Variable(string name, object value)
    {
        if (name == null)
            throw new ArgumentNullException(nameof(name));

        variables[name] = new RuntimeVariable(value);
    }

    public RuntimeVariable Assign(string name, object value)
    {
        if (name == null)
            throw new ArgumentNullException(nameof(name));

        var context = FindCurrentOrParent(name);
        if (context == null) return null;
        if (!context.variables.TryGetValue(name, out RuntimeVariable rv)) return null;

        rv.SetValue(value);
        return rv;
    }

    public RuntimeVariable Access(string name)
    {
        if (name == null)
            throw new ArgumentNullException(nameof(name));

        var context = FindCurrentOrParent(name);
        if (context == null) return null;
        if (!context.variables.TryGetValue(name, out RuntimeVariable rv)) return null;
        return rv;
    }

    public class RuntimeVariable
    {
        public RuntimeVariable()
        { }

        public RuntimeVariable(object value)
        {
            Value = value;
            IsAssigned = true;
        }

        public object Value { get; set; }

        public bool IsAssigned { get; set; }

        public void SetValue(object value)
        {
            Value = value;
            IsAssigned = true;
        }
    }
}