using static System.Console;

using Env = System.Collections.Generic.Dictionary<string, Value>;

interface Value {
    string to_string();
    bool as_bool() => throw new Exception("bool expected");
    int as_int() => throw new Exception("int expected");
}

record Bool(bool b) : Value {
    public bool as_bool() => b;
    public string to_string() => b.ToString();
}

record Int(int i) : Value {
    public int as_int() => i;
    public string to_string() => i.ToString();
}

interface Expr {
    Value eval(Env env);
}

record Const(Value v) : Expr {
    public Value eval(Env env) => v;
}

record Var(string s) : Expr {
    public Value eval(Env env) => env[s];
}

record BinOp(Expr e, string op, Expr f) : Expr {
    public Value eval(Env env) {
        Value x = e.eval(env), y = f.eval(env);
        return op switch {
            "+" => new Int(x.as_int() + y.as_int()),
            "-" => new Int(x.as_int() - y.as_int()),
            "*" => new Int(x.as_int() * y.as_int()),
            "/" => new Int(x.as_int() / y.as_int()),
            "%" => new Int(x.as_int() % y.as_int()),
            "==" => new Bool(x.Equals(y)),
            "!=" => new Bool(!x.Equals(y)),
            "<" => new Bool(x.as_int() < y.as_int()),
            "<=" => new Bool(x.as_int() <= y.as_int()),
            ">" => new Bool(x.as_int() > y.as_int()),
            ">=" => new Bool(x.as_int() >= y.as_int()),
            _ => throw new Exception("bad operation")
        };
    }
}

interface Stmt {
    void run(Env env);
}

record Block(List<Stmt> stmts) : Stmt {
    public void run(Env env) {
        foreach (Stmt stmt in stmts)
            stmt.run(env);
    }
}

record Print(Expr e) : Stmt {
    public void run(Env env) {
        WriteLine(e.eval(env).to_string());
    }
}

record Assign(string id, Expr e) : Stmt {
    public void run(Env env) {
        env[id] = e.eval(env);
    }
}

class Top {
    static void Main(string[] args) {
        if (args.Length < 1) {
            WriteLine("usage: p2 <file.p2>");
            return;
        }
        Parser p = new(File.ReadAllText(args[0]));
        p.parse_program().run([]);
    }
}