from lexer import TokenType

class Expr:

    def accept(self, visitor):
        raise Exception("needs to be implemented")

    class Literal:
        def __init__(self, value):
            self.value = value
        def accept(self, visitor):
            visitor.visitLiteral(self)
        def __str__(self):
            return f"{self.value}"

    class Type:
        def __init__(self, name):
            self.name = name
        def __str__(self):
            return self.name

    class Symbol:
        def __init__(self, name):
            self.name = name
        def accept(self, visitor):
            visitor.visitSymbol(self)
        def __str__(self):
            return f"'{self.name}"

    class List:
        def __init__(self, args):
            self.args = args
        def accept(self, visitor):
            visitor.visitNary(self)
        def __str__(self):
            return "(" +  " ".join(f"{arg}" for arg in self.args) + ")"

def parseExpression(token, prev, tokens):
    idx = 0
    args = []
    prev = token
    while tokens[idx].type_ != TokenType.CLOSE_PAREN:
        token = tokens[idx]
        inc = 1
        if token.type_ == TokenType.OPEN_PAREN:
            expr, inc = parseExpression(token, prev, tokens[idx+1:])
            args.append(expr)
        elif token.type_ in (TokenType.STRING, TokenType.TRUE, TokenType.FALSE, TokenType.INT, TokenType.FLOAT):
            expr, inc = parseLiteral(token, prev, tokens[idx+1:])
            args.append(expr)
        elif token.type_ in (TokenType.INT_TYPE, TokenType.FLOAT_TYPE, TokenType.STRING_TYPE, TokenType.ANY_TYPE):
            expr, inc = parseType(token, prev, tokens[idx+1:])
            args.append(expr)
        else:
            expr, inc = parseSymbol(token, prev, tokens[idx+1:])
            args.append(expr)
        idx += inc
        prev = token
    
    return Expr.List(args), idx + 2  # parens

def parseSymbol(token, prev, tokens):
    return Expr.Symbol(token.text), 1

def parseLiteral(token, prev, tokens):
    return Expr.Literal(token.value), 1

def parseType(token, prev, tokens):
    return Expr.Type(token.text), 1

def parse(tokens):
    idx = 0
    prev = None
    exprs = []
    while tokens[idx].type_ != TokenType.EOF:
        token = tokens[idx]
        counter = 1
        if token.type_ == TokenType.OPEN_PAREN:
            expr, counter = parseExpression(token, prev, tokens[idx+1:])
            exprs.append(expr)
        elif token.type_ in (TokenType.FALSE, TokenType.TRUE, TokenType.STRING, TokenType.INT, TokenType.FLOAT):
            lit, counter = parseLiteral(token, prev, tokens[idx+1:])
            exprs.append(lit)
        elif token.type_ in (TokenType.INT_TYPE, TokenType.FLOAT_TYPE, TokenType.STRING_TYPE, TokenType.ANY_TYPE):
            typ, counter = parseType(token, prev, tokens[idx+1:])
            exprs.append(typ)
        else:
            sym, counter = parseSymbol(token, prev, tokens[idx+1:])
            exprs.append(sym)
        
        idx += counter
        prev = token
    return exprs