from __future__ import annotations

from dataclasses import dataclass
from typing import Iterable, Tuple

from app.core._utils.hash import blake3_hex


BLAKE3_DIGEST_SIZE = 32


def _ensure_bytes(data: Iterable[int] | bytes | bytearray) -> bytes:
    if isinstance(data, (bytes, bytearray)):
        return bytes(data)
    if isinstance(data, str):
        return data.encode()
    return bytes(data)


def digest_hex(data: Iterable[int] | bytes | bytearray | str) -> str:
    return blake3_hex(_ensure_bytes(data))


def compute_node_id(public_key: bytes) -> str:
    """NodeID = blake3(pubkey)."""

    if not isinstance(public_key, (bytes, bytearray)):
        raise TypeError("public_key must be bytes")
    return digest_hex(public_key)


def compute_content_id(encrypted_blob: bytes) -> str:
    """ContentID = blake3(encrypted_blob)."""

    return digest_hex(encrypted_blob)


def compute_view_id(content_id: str, viewer_salt: bytes) -> str:
    """ViewID = blake3(ContentID||viewer_salt)."""

    if not viewer_salt:
        raise ValueError("viewer_salt must not be empty")
    return digest_hex(content_id.encode() + viewer_salt)


def bits_from_hex(hex_digest: str, prefix_bits: int) -> Tuple[int, int]:
    """Extract first prefix_bits from a hex digest. Returns (prefix, total_bits)."""

    if prefix_bits < 0:
        raise ValueError("prefix_bits must be >= 0")
    bitstring = bin(int(hex_digest, 16))[2:].zfill(len(hex_digest) * 4)
    if prefix_bits == 0:
        return 0, len(bitstring)
    return int(bitstring[:prefix_bits], 2), len(bitstring)


def rendezvous_score(content_id: str, node_id: str) -> int:
    """Return rendezvous score via blake3(ContentID||NodeID)."""
    return int(blake3_hex(f"{content_id}:{node_id}".encode()), 16)


@dataclass(frozen=True)
class ContentFingerprint:
    content_id: str
    node_id_prefix: int
    prefix_bits: int

    def matches(self, node_id: str) -> bool:
        prefix, total = bits_from_hex(node_id, self.prefix_bits)
        return prefix == self.node_id_prefix and total >= self.prefix_bits