from core.parser.clean_string import cleanString
from core.parser.parse_token import parseToken
from core.parser.find_prefix import findPrefix

from core.primitives.list import (
    cons, 
    NIL
)
from core.exceptions import (
    syntaxError, 
    runtimeError
)

from core.tokens import SpecialForm

def parseExpression(s: str) -> tuple:
    s = cleanString(s)
    if not s:
        return NIL, s
    match s[0]:
        case '"':  # string
            matching = s.find('"', 1)
            if matching < 0:
                raise syntaxError(f'the closing " is missing: {s}')
            return s[1:matching], s[matching + 1:]
        case '(':  # list
            cache = s  # saving initial view for Error illustration
            s = s[1:]
            arr: list = []
            while s and s[0] != ')':
                elem, s = parseExpression(s)
                arr.append(elem)
                s = cleanString(s)
            if not s:
                raise syntaxError(f'the closing ) is missing: {cache}')
            result = NIL
            for elem in reversed(arr):
                result = cons(elem, result)
            return result, s[1:]
        case ')':
            raise syntaxError(f'extra closing bracket: {s}')  # TODO debug
        case "'":
            try:
                v, rem = parseExpression(s[1:])
            except Exception as e:
                raise runtimeError(f'invalid quote: {s}') from e
            if v is None:
                raise syntaxError(f'quote of nothing: {s}')
            return cons(SpecialForm.QUOTE, cons(v, NIL)), rem
        case _:  # maybe we can find token
            first = findPrefix(s)
            return parseToken(first) if first else NIL, s[len(first):]