from typing import *
from lark import Transformer, Tree, Token
import re
from re import Pattern

def unescape(s: str) -> str:
    q = s[0]
    t = ""
    i = 1
    escaped = False
    while i < len(s):
        c = s[i]
        if escaped:
            if c == q: t += q
            elif c == 'n': t += '\n'
            elif c == 't': t += '\t'
        if c == q: break
        if c == '\\':
            escaped = True
            i += 1
            continue
        t += c
        i += 1
    return t

T = TypeVar("T")

class Ast:
    # def __new__(cls: Type[Ast], name: str, bases: Tuple[type], namespace: Dict[str, Any]) -> Ast:
    #   x = super().__new__(cls, name, bases, namespace)
    #   x.id = cls.__gen()
    #   return x
    id: str
    n = 0
    @classmethod
    def __gen(cls, name: str = "") -> str:
        newid = cls.n
        cls.n += 1
        return f"_a{newid}{name}"
    def __init__(self) -> None:
        self.id = self.__gen()

class Decl:
    name: str

class IfaceRef(str): pass
class IfaceField:
    def __init__(self, name: str, ty: str):
        self.name = name
        self.ty = ty
class Iface(Decl):
    def __init__(self, name: str, fields: List[IfaceField]):
        self.name = name
        self.fields = fields

class Expr(Ast):
    def __init__(self) -> None:
        super().__init__()

class NodeRef: pass
class NodeRefByName(NodeRef, str):
    def __init__(self, name: str):
        self.name = name
    def __repr__(self) -> str: return f"NodeRefByName({self.name})"
class NodeRegex(NodeRef):
    def __init__(self, pat: str):
        self.pat = re.compile(unescape(pat))
    def __repr__(self) -> str: return f"NodeRegex({self.pat.pattern})"

class Sym: pass
class SymLit(Sym):
    def __init__(self, s: str):
        self.lit = unescape(s)
    def __repr__(self) -> str: return f"SymLit({repr(self.lit)})"
class SymRename(Sym):
    def __init__(self, name: str, ty: NodeRef):
        self.name = name
        self.ty = ty
    def __repr__(self) -> str: return f"SymRename({self.name} : {self.ty})"
class Equation:
    def __init__(self, lhs: Expr, rhs: Expr):
        self.lhs = lhs
        self.rhs = rhs
    def __repr__(self) -> str: return f"{self.lhs} = {self.rhs}"

class Variant:
    def __init__(self, prod: List[Sym], equations: List[Equation]):
        self.prod = prod
        self.equations = equations
    def __repr__(self) -> str: return f"Variant({self.prod}, {self.equations})"

class Node(Decl):
    def __init__(self, name: str, ifaces: List[IfaceRef], variants: List[Variant]):
        self.name = name
        self.ifaces = ifaces
        self.variants = variants

class ExprDot(Expr):
    def __init__(self, left: Expr, right: str):
        super().__init__()
        self.left = left
        self.right = right
    def __repr__(self) -> str: return f"{self.left}.{self.right}"
class ExprAdd(Expr):
    def __init__(self, left: Expr, right: Expr):
        super().__init__()
        self.left = left
        self.right = right
    def __repr__(self) -> str: return f"{self.left} + {self.right}"
class ExprMul(Expr):
    def __init__(self, left: Expr, right: Expr):
        super().__init__()
        self.left = left
        self.right = right
    def __repr__(self) -> str: return f"{self.left} * {self.right}"
class ExprCall(Expr):
    def __init__(self, func: Expr, args: List[Expr]):
        super().__init__()
        self.func = func
        self.args = args
    def __repr__(self) -> str: return f"{self.func}({self.args})"
class ExprName(Expr):
    def __init__(self, name: str):
        super().__init__()
        self.name = name
    def __repr__(self) -> str: return f"{self.name}"

class Parser(Transformer[List[Decl]]):
    def program(self, items: List[Decl]) -> List[Decl]: return items

    # interfaces
    def iface(self, items: List[Any]) -> Iface:
        [name, fields] = items
        return Iface(name, fields)
    def iface_field(self, items: List[str]) -> IfaceField:
        [name, ty] = items
        return IfaceField(name, ty)
    def iface_ref(self, items: List[str]) -> str: return items[0]
    def iface_refs(self, items: List[IfaceRef]) -> List[IfaceRef]: return items

    # nodes
    def node(self, items: List[Any]) -> Node:
        [name, ifaces, variants] = items
        return Node(name, ifaces, variants)
    def node_ref_name(self, items: List[str]) -> NodeRefByName: return NodeRefByName(items[0])
    def node_regex(self, items: List[str]) -> NodeRegex: return NodeRegex(items[0])

    # variants
    def variants(self, items: List[Variant]) -> List[Variant]: return items
    def variant(self, items: List[Any]) -> Variant:
        [prod, equations] = items
        return Variant(prod, equations)
    def prod(self, items: List[Sym]) -> List[Sym]: return items

    # symbols in productions
    def sym_lit(self, items: List[str]) -> Sym: return SymLit(items[0])
    def sym_rename(self, items: List[Any]) -> Sym: return SymRename(items[0], items[1])

    # equations
    def equations(self, items: List[Equation]) -> List[Equation]: return items
    def equation_semi(self, items: List[Equation]) -> Equation: return items[0]
    def equation(self, items: List[Expr]) -> Equation: return Equation(items[0], items[1])

    # expr
    def expr_dot(self, items: List[Any]) -> Expr:
        [left, right] = items
        return ExprDot(left, right)
    def expr_add(self, items: List[Expr]) -> Expr:
        [left, right] = items
        return ExprAdd(left, right)
    def expr_mul(self, items: List[Expr]) -> Expr:
        [left, right] = items
        return ExprMul(left, right)
    def expr_call(self, items: List[Expr]) -> Expr:
        [func, args] = items
        # TODO: args should be a list of exprs -_ -
        return ExprCall(func, [args])
    def expr_name(self, items: List[str]) -> Expr:
        return ExprName(items[0])

    def sep_trail(self, items: List[Tree]) -> List[T]:
        return list(map(lambda it: cast(T, it), items))

    def ident(self, items: List[Token]) -> str: return cast(str, items[0].value)