import ctypes
from pathlib import Path

_suffixtool = ctypes.CDLL("./suffixtool.so")

_suffixtool.csa_build.argtypes = [ctypes.c_char_p, ctypes.c_char_p]
_suffixtool.csa_build.restype = ctypes.c_int

_suffixtool.csa_load.argtypes = [ctypes.c_char_p]
_suffixtool.csa_load.restype = ctypes.c_void_p

_suffixtool.csa_free.argtypes = [ctypes.c_void_p]
_suffixtool.csa_free.restype = None

_suffixtool.csa_count.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
_suffixtool.csa_count.restype = ctypes.c_ssize_t

def _path_to_bytes(x):
    if isinstance(x, Path):
        return bytes(x)
    if isinstance(x, str):
        return x.encode('utf-8')
    if isinstance(x, bytes):
        return x
    raise RuntimeError(f'Expected path-like object but got {x}')

class CSA:
    def __init__(self, ptr):
        self.ptr = ptr

    @staticmethod
    def build(input_file, output_file):
        res = _suffixtool.csa_build(_path_to_bytes(input_file), _path_to_bytes(output_file))
        if not res:
            raise RuntimeError('Failed to build CSA')

    @classmethod
    def load(cls, input_file):
        res = _suffixtool.csa_load(_path_to_bytes(input_file))
        if res is None:
            raise RuntimeError('Failed to load CSA')
        return cls(res)

    def count(self, byte_seq):
        if self.ptr is None:
            raise RuntimeError('Called CSA.count() but CSA was already deleted')
        res = _suffixtool.csa_count(self.ptr, byte_seq)
        if res == -1:
            raise RuntimeError('Failed to count CSA byte sequence occurrences')
        return res

    def delete_now(self):
        if self.ptr is not None:
            _suffixtool.csa_free(self.ptr)
            self.ptr = None

    def __del__(self):
        self.delete_now()