"""placeholder module for compilation"""

from __future__ import annotations

import datetime
import hashlib
import struct
import time

import cython
import dopt_basics.datetime

# from cython.cimports.cpython.ref import Py_INCREF, PyObject

PyStringC = cython.struct(
    ptr=cython.p_char,
    length=cython.Py_ssize_t,
)


@cython.cfunc
def PyStringC_to_unicode(
    string: PyStringC,
) -> str:
    return string.ptr[: string.length].decode("UTF-8", "strict")


@cython.cfunc
def PyStringC_to_bytes(
    string: PyStringC,
) -> bytes:
    return cython.cast(bytes, string.ptr[: string.length])


@cython.cfunc
def timestamp_to_datetime(
    ts: cython.double,
) -> datetime.datetime:
    return datetime.datetime.fromtimestamp(ts, dopt_basics.datetime.TIMEZONE_UTC)


@cython.cclass
class StringHolder:
    c = cython.declare(PyStringC, visibility="readonly")
    _py_data = cython.declare(object, visibility="private")

    def __cinit__(self, data: str):
        """accepting Python str

        Parameters
        ----------
        data : str
            _description_
        """
        if not isinstance(data, str):
            raise TypeError("Data not 'str'")

        self._py_data = data.encode("UTF-8")
        self.c = PyStringC(self._py_data, len(self._py_data))

    @property
    def py_string(self):
        return PyStringC_to_unicode(self.c)

    @property
    def py_bytes(self):
        return PyStringC_to_bytes(self.c)


# BlockC = cython.struct(
#     index=cython.ulonglong,
#     timestamp=cython.double,
#     data=PyStringC,
#     previous_hash=PyStringC,
#     nonce=cython.ulonglong,
# )


@cython.cfunc
def float_to_bytes(num: cython.double):
    return struct.pack(">d", num)


@cython.cclass
class Block:
    _index = cython.declare(cython.ulong, visibility="private")
    _timestamp = cython.declare(cython.double, visibility="private")
    _data = cython.declare(StringHolder, visibility="private")
    _prev_hash = cython.declare(StringHolder, visibility="private")
    _nonce = cython.declare(cython.ulong, visibility="private")
    _hash = cython.declare(StringHolder, visibility="private")

    def __init__(
        self,
        index: int,
        data: str,
        previous_hash: str,
        nonce: int,
    ):
        self._index = index
        # self._timestamp = dopt_basics.datetime.current_time_tz().timestamp()
        self._timestamp = datetime.datetime(2025, 12, 1, 12, 0, 0).timestamp()
        self._data = StringHolder.__new__(StringHolder, data)
        self._prev_hash = StringHolder.__new__(StringHolder, previous_hash)
        self._nonce = nonce
        self._hash = StringHolder.__new__(StringHolder, "")

    @cython.ccall
    def _perform_hash(self):
        parts = bytearray()
        parts.extend(self._index.to_bytes(8, "big"))
        parts.extend(float_to_bytes(self._timestamp))
        parts.extend(self._data.py_bytes)
        parts.extend(self._prev_hash.py_bytes)
        parts.extend(self._nonce.to_bytes(8, "big"))

        return hashlib.sha256(parts)

    def compute_hash_bytes(self):
        return self._perform_hash().digest()

    def compute_hash(self):
        return self._perform_hash().hexdigest()

    # Python public API
    @property
    def index(self):
        return self._index

    @property
    def timestamp(self):
        return timestamp_to_datetime(self._timestamp)

    @property
    def data(self):
        return self._data.py_string

    @property
    def prev_hash(self):
        return self._prev_hash.py_string

    @property
    def nonce(self):
        return self._nonce

    @nonce.setter
    def nonce(self, value: int):
        self._nonce = value

    @property
    def hash(self):
        return self._hash.py_string

    @hash.setter
    def hash(self, value: str):
        if not isinstance(value, str):
            raise TypeError("No string")
        self._hash = StringHolder.__new__(StringHolder, value)


@cython.cclass
class Blockchain:
    _difficulty = cython.declare(cython.int, visibility="private")
    _index = cython.declare(cython.Py_ssize_t, visibility="private")
    chain = cython.declare(list[Block], visibility="public")

    def __cinit__(self):
        self._index = 0

    def __init__(
        self,
        difficulty: int = 1,
    ) -> None:
        self.chain: list[Block] = []
        # self.difficulty = difficulty.to_bytes(8, "big")
        self._difficulty = difficulty

    @property
    def index(self):
        return self._index

    @property
    def difficulty(self):
        return self._difficulty

    @cython.ccall
    def create_genesis_block(self):
        genesis = Block(
            index=0,
            data="Genesis Block",
            previous_hash="0",
            nonce=0,
        )
        genesis.hash = genesis.compute_hash()
        self.chain.append(genesis)

    @cython.ccall
    def proof_of_work(
        self,
        block: Block,
    ) -> str:
        prefix = "0" * self._difficulty
        while True:
            block_hash = block.compute_hash()
            if block_hash.startswith(prefix):
                return block_hash
            block._nonce += 1

    @cython.ccall
    def add_block(self, data: str) -> Block:
        prev_hash = self.chain[self._index].hash
        new_block = Block(
            index=(self._index + 1),
            data=data,
            previous_hash=prev_hash,
            nonce=0,
        )

        # start = time.perf_counter()
        new_block.hash = self.proof_of_work(new_block)
        # elapsed = time.perf_counter() - start

        self.chain.append(new_block)
        self._index += 1
        print(f"Mined block {new_block.index} with nonce={new_block.nonce}")
        # print(f"Mined block {new_block.index} in {elapsed:.3f}s with nonce={new_block.nonce}")

        return new_block