from typing import *
import textwrap
import re
from agast import *

global i
i = 0

class TypecheckResult:
	def __init__(self, pd: str = "", ex: str = ""):
		self.parser_data = pd
		self.extra = ex

def typecheck(program: List[Decl]) -> TypecheckResult:
	res = TypecheckResult()
	def gen(prefix: str = "", suffix: str = "") -> str:
		global i
		presan = re.sub("[^0-9a-zA-Z]+", "_", prefix)
		sufsan = re.sub("[^0-9a-zA-Z]+", "_", suffix)
		i += 1
		return f"{presan}{i}{sufsan}"
	def v(name: str) -> str:
		return f"__ag_{name}"

	# collect a list of name -> iface declarations
	ifaces: Dict[str, Decl] = dict(
		map(lambda c: (c.name, c),
		filter(lambda c: isinstance(c, Iface),
			program)))
	print(ifaces)

	# a high-level dictionary of productions; this has sub-productions
	# that should be further expanded at a later step before converting
	# into lark code
	productions_hi: Dict[str, Union[str, List[str]]] = dict()

	for node in filter(lambda c: isinstance(c, Node), program):
		node = cast(Node, node)
		n_class_name = gen(node.name)
		class_decl = textwrap.dedent(f"""
			class {v(n_class_name)}: pass
		""")
		res.extra += class_decl

		print(node.name, node.ifaces)

		for variant in node.variants:
			v_class_name = gen(f"{n_class_name}_var")
			class_decl = textwrap.dedent(f"""
				class {v(v_class_name)}({v(n_class_name)}):
					''' '''
					pass
			""")
			res.extra += class_decl

			prod_name = gen(node.name)
			print(prod_name)

			for sym in variant.prod:
				print("sym", sym)
			
			# for each of the equations, find out what the equation is
			# trying to compute, and generate a thunk corresponding to
			# that value.
			for eq in variant.equations:
				print("--eq", eq)
				print(eq.lhs)
				eq_name = gen(f"eq_{node.name}")
				thunk_name = gen(f"thunk_{node.name}")

				func_impl = textwrap.dedent(f"""
					def {eq_name}() -> None:
						''' {repr(eq)} '''
						pass
					def {thunk_name}() -> Thunk[None]:
						return Thunk({eq_name})
				""")
				print(f"```py\n{func_impl}\n```")
				res.extra += func_impl

		# this is a "type alias" that connects it to one of the generated
		# names above
		res.extra += f"{node.name} = {v(n_class_name)}"

	return res