from __future__ import annotations

from dataclasses import dataclass
from functools import reduce
from itertools import chain
from typing import Any, Callable, Generic, Self, TypeVar, overload
import unicodedata

from .result import Result

T = TypeVar('T')
T1 = TypeVar('T1')
T2 = TypeVar('T2')
T3 = TypeVar('T3')
T4 = TypeVar('T4')
T5 = TypeVar('T5')
TR = TypeVar('TR')


@dataclass(slots=True, frozen=True)
class ParserInput:
    input: str
    start: int

    def step(self, count: int = 1) -> tuple[Self, str]:
        assert count > 0
        if self.start + count > len(self.input):
            raise Exception("Not enough chars left in string")
        return ParserInput(self.input, self.start
                           + count), self.input[self.start:self.start + count]

    def is_eof(self) -> bool:
        return self.start >= len(self.input)

    def __repr__(self) -> str:
        if self.start == 0:
            return f'->[{self.input}]'
        if self.start >= len(self.input):
            return f'{self.input}'
        if self.start < 3:
            return f'{self.input[0:self.start-1]}->[{self.input[self.start:]}]'
        return f'{self.input[self.start-3:self.start-1]}->[{self.input[self.start:]}]'


ParserResult = Result[tuple[ParserInput, T]]
ParserFunc = Callable[[ParserInput], ParserResult[T]]


class P(Generic[T]):
    def __init__(self, func: ParserFunc[T]):
        self.func = func

    def parse(self, s: str, i: int = 0) -> Result[T]:
        result = self.func(ParserInput(s, i))
        return result.fmap(lambda pr: pr[1])

    @staticmethod
    def pure(value: T) -> P[T]:
        return P(lambda parserPos: Result.of((parserPos, value)))

    @staticmethod
    def fail(text: str) -> P[Any]:
        return P(lambda pp: Result.fail(f'@: {pp}\ntext: {text}'))

    @staticmethod
    def _fix(p1: Callable[[P[Any]], P[T]]) -> P[T]:
        """ Not really nice helper function, but it works"""
        return [p._forward(q.func) for p in [P(None)] for q in [p1(p)]][0]  # type: ignore

    def _forward(self, func: ParserFunc[T]) -> Self:
        self.func = func
        return self

    def bind(self, bind_func: Callable[[T], P[TR]]) -> P[TR]:
        def inner(x: tuple[ParserInput, T]):
            parserPos, v = x
            return bind_func(v).func(parserPos)

        return P(lambda parserPos: self.func(parserPos).bind(inner))

    def fmap(self, map_func: Callable[[T], TR]) -> P[TR]:
        def inner(x: tuple[ParserInput, T]):
            parserPos, v = x
            return (parserPos, map_func(v))
        return P(lambda parserPos: self.func(parserPos).fmap(inner))

    def safe_fmap(self, map_func: Callable[[T], TR]) -> P[TR]:
        def inner(value: T) -> P[TR]:
            try:
                return P.pure(map_func(value))
            except Exception as e:
                return P.fail(f'Failed with {e}')
        return self.bind(inner)

    def replace(self, value: TR) -> P[TR]:
        return self.fmap(lambda _: value)

    def unit(self) -> P[tuple[()]]:
        return self.fmap(lambda _: ())

    def apply(self, p2: P[Callable[[T], TR]]) -> P[TR]:
        return self.bind(lambda x: p2.bind(lambda y: P.pure(y(x))))

    def between(self, pre: P[Any], post: P[Any]) -> P[T]:
        return P.map3(pre, self, post, lambda _1, v, _2: v)

    def surround(self, other: P[Any]) -> P[T]:
        return P.map3(other, self, other, lambda _1, v, _2: v)

    def some(self) -> P[list[T]]:
        return P._fix(lambda p: self.bind(
            lambda x: P.either(p, P.pure([])).fmap(lambda ys: [x] + ys)))

    def many(self) -> P[list[T]]:
        return P.either(self.some(), P.pure([]))

    def satisfies(self, pred: Callable[[T], bool], failtext: str) -> P[T]:
        return self.bind(lambda v: P.pure(v) if pred(
            v) else P.fail(f'Does not satisfy: {failtext}'))

    def optional(self) -> P[T | None]:
        return P.either(self, P.pure(None))

    def sep_by(self, sep: P[Any]) -> P[list[T]]:
        return P.map2(self, P.snd(sep, self).many(), lambda f, r: [f] + r)

    @staticmethod
    def snd(p1: P[Any], p2: P[T2]) -> P[T2]:
        return p1.bind(lambda _: p2)

    @staticmethod
    def fst(p1: P[T1], p2: P[Any]) -> P[T1]:
        return P.map2(p1, p2, lambda v1, _: v1)

    @staticmethod
    def no_match(p: P[Any], failtext: str) -> P[tuple[()]]:
        def inner(pp: ParserInput) -> ParserResult[tuple[()]]:
            result = p.func(pp)
            if result.is_fail():
                return Result.of((pp, ()))
            else:
                return Result.fail(failtext)
        return P(inner)

    @ staticmethod
    def map2(p1: P[T1], p2: P[T2], func: Callable[[T1, T2], TR]) -> P[TR]:
        return p1.bind(lambda v1: p2.fmap(lambda v2: func(v1, v2)))

    @ staticmethod
    def map3(p1: P[T1], p2: P[T2], p3: P[T3], func: Callable[[T1, T2, T3], TR]) -> P[TR]:
        return p1.bind(
            lambda v1: p2.bind(
                lambda v2: p3.fmap(
                    lambda v3: func(v1, v2, v3))))

    @ staticmethod
    def map4(p1: P[T1], p2: P[T2], p3: P[T3], p4: P[T4],
             func: Callable[[T1, T2, T3, T4], TR]) -> P[TR]:
        return p1.bind(
            lambda v1: p2.bind(
                lambda v2: p3.bind(
                    lambda v3: p4.fmap(
                        lambda v4: func(v1, v2, v3, v4)))))

    @ staticmethod
    def map5(p1: P[T1], p2: P[T2], p3: P[T3], p4: P[T4], p5: P[T5],
             func: Callable[[T1, T2, T3, T4, T5], TR]) -> P[TR]:
        return p1.bind(
            lambda v1: p2.bind(
                lambda v2: p3.bind(
                    lambda v3: p4.bind(
                        lambda v4: p5.fmap(
                            lambda v5: func(v1, v2, v3, v4, v5))))))

    @ staticmethod
    @ overload
    def seq(p1: P[T1], p2: P[T2], /) -> P[tuple[T1, T2]]:
        ...

    @ staticmethod
    @ overload
    def seq(p1: P[T1], p2: P[T2], p3: P[T3], /) -> P[tuple[T1, T2, T3]]:
        ...

    @ staticmethod
    @ overload
    def seq(p1: P[T1], p2: P[T2], p3: P[T3], p4: P[T4], /) -> P[tuple[T1, T2, T3, T4]]:
        ...

    @ staticmethod
    @ overload
    def seq(p1: P[T1], p2: P[T2], p3: P[T3], p4: P[T4],
            p5: P[T5], /) -> P[tuple[T1, T2, T3, T4, T5]]:
        ...

    @ staticmethod
    def seq(*ps: P[Any]) -> P[tuple[Any, ...]]:
        return reduce(lambda p, x: x.bind(
            lambda a: p.fmap(lambda b: chain([a], b))),
            list(ps)[::-1], P.pure(iter([]))).fmap(tuple)

    @ staticmethod
    @ overload
    def sep_seq(p1: P[T1], p2: P[T2], /, *, sep: P[Any]) -> P[tuple[T1, T2]]:
        ...

    @ staticmethod
    @ overload
    def sep_seq(p1: P[T1], p2: P[T2], p3: P[T3], /, *, sep: P[Any]) -> P[tuple[T1, T2, T3]]:
        ...

    @ staticmethod
    @ overload
    def sep_seq(p1: P[T1], p2: P[T2], p3: P[T3], p4: P[T4], /,
                *, sep: P[Any]) -> P[tuple[T1, T2, T3, T4]]:
        ...

    @ staticmethod
    @ overload
    def sep_seq(p1: P[T1], p2: P[T2], p3: P[T3], p4: P[T4],
                p5: P[T5], /, *, sep: P[Any]) -> P[tuple[T1, T2, T3, T4, T5]]:
        ...

    @ staticmethod
    def sep_seq(*ps: P[Any], sep: P[Any]) -> P[tuple[Any, ...]]:
        first, *rest = list(ps)
        return P.map2(first,
                      reduce(lambda p, x: P.snd(sep, x.bind(
                          lambda a: p.fmap(lambda b: chain([a], b)))),
                          rest[::-1], P.pure(iter([]))),
                      lambda f, r: (f,) + tuple(r))

    @ staticmethod
    def either(p1: P[T1], p2: P[T2], /) -> P[T1 | T2]:
        def inner(parserPos: ParserInput):
            result = p1.func(parserPos)
            return result if result.is_ok() else p2.func(parserPos)

        return P(inner)

    @ staticmethod
    @ overload
    def choice(p1: P[T1], p2: P[T2], p3: P[T3], /) -> P[T1 | T2 | T3]:
        ...

    @ staticmethod
    @ overload
    def choice(p1: P[T1], p2: P[T2], p3: P[T3], p4: P[T4], /) -> P[T1 | T2 | T3 | T4]:
        ...

    @ staticmethod
    @ overload
    def choice(p1: P[T1], p2: P[T2], p3: P[T3], p4: P[T4],
               p5: P[T5], /) -> P[T1 | T2 | T3 | T4 | T5]:
        ...

    @ staticmethod
    def choice(*ps: P[Any]) -> P[Any]:
        return reduce(P.either, ps, P.fail('No Choice matched'))

    @ staticmethod
    def choice_same(*ps: P[T]) -> P[T]:
        return P.choice(*ps)

    @ staticmethod
    def any_char() -> P[str]:
        return P(lambda pp: Result.of(pp.step()) if not pp.is_eof()
                 else Result.fail('At EOF'))

    @ staticmethod
    def eof() -> P[tuple[()]]:
        return P.no_match(P.any_char(), 'Not at eof')

    @ staticmethod
    def is_char(cmp: str) -> P[str]:
        return P.any_char().satisfies(lambda c: c == cmp, f'match {cmp}')

    @staticmethod
    def is_not_char(s: str) -> P[tuple[()]]:
        return P.no_match(P.is_char(s), f'Did match {s}')

    @ staticmethod
    def char_by_func(cmp: Callable[[str], bool], failtext: str) -> P[str]:
        return P.any_char().satisfies(cmp, failtext)

    @ staticmethod
    def string(s: str) -> P[str]:
        return P.seq(*map(P.is_char, s)).replace(s)

    @ staticmethod
    def one_of(s: str) -> P[str]:
        return P.char_by_func(lambda c: c in s, f'one of {s}')

    @ staticmethod
    def any_decimal() -> P[str]:
        return P.char_by_func(lambda c: c.isdecimal(), 'decimal')

    @ staticmethod
    def is_decimal(num: int) -> P[str]:
        return P.any_decimal().bind(
            lambda c: P.pure(c) if unicodedata.decimal(c) == num else P.fail(f'Not {num}'))

    @ staticmethod
    def is_not_decimal(num: int) -> P[str]:
        return P.any_decimal().bind(
            lambda c: P.pure(c) if unicodedata.decimal(c) != num else P.fail(f'Is {num}'))

    @ staticmethod
    def lower() -> P[str]:
        return P.char_by_func(lambda c: c.islower(), 'lower')

    @ staticmethod
    def upper() -> P[str]:
        return P.char_by_func(lambda c: c.isupper(), 'upper')

    @ staticmethod
    def joined(p1: P[str]) -> P[str]:
        return p1.many().fmap(lambda cs: ''.join(cs))

    @ staticmethod
    def space() -> P[str]:
        return P.char_by_func(lambda c: c.isspace(), 'space')

    @ staticmethod
    def unsigned() -> P[int]:
        return P.either(P.fst(P.is_decimal(0), P.no_match(P.any_decimal(), 'starting Zero')),
                        P.map2(P.is_not_decimal(0), P.any_decimal().many(),
                               lambda f, s: f + ''.join(s))
                        ).fmap(int)

    @ staticmethod
    def signed() -> P[int]:
        return P.map2(P.one_of('+-').optional(), P.unsigned(),
                      lambda sign, num: num if sign != '-' else -num)

    def in_parens(self) -> P[T]:
        return self.between(P.is_char('('), P.is_char(')'))

    def in_angles(self) -> P[T]:
        return self.between(P.is_char('<'), P.is_char('>'))

    def in_brackets(self) -> P[T]:
        return self.between(P.is_char('['), P.is_char(']'))

    def in_curleys(self) -> P[T]:
        return self.between(P.is_char('{'), P.is_char('}'))

    def trim_left(self) -> P[T]:
        return P.snd(WHITE_SPACE, self)

    def trim_right(self) -> P[T]:
        return P.fst(self, WHITE_SPACE)

    def trim(self) -> P[T]:
        return self.surround(WHITE_SPACE)


WHITE_SPACE: P[tuple[()]] = P.space().many().unit()
SEP_SPACE: P[tuple[()]] = P.space().some().unit()