"""Convert various I2P address formats to a 32-byte hash.

Ported from net.i2p.util.ConvertToHash.
"""

from __future__ import annotations

import base64


def convert_to_hash(input_str: str) -> bytes | None:
    """Convert a Base64 hash, .b32.i2p address, or full destination to a 32-byte hash.

    Returns None if the input is not a recognized format.
    """
    if not input_str:
        return None

    # 43 or 44-char Base64 → raw 32-byte hash
    # I2P uses modified Base64: -~ instead of +/
    # 32 bytes = 43 Base64 chars + 1 padding, or 44 chars if padding included
    if len(input_str) in (43, 44) and not input_str.endswith(".i2p"):
        try:
            std = input_str.replace("-", "+").replace("~", "/")
            # Pad to multiple of 4
            pad = (4 - len(std) % 4) % 4
            decoded = base64.b64decode(std + "=" * pad)
            if len(decoded) == 32:
                return decoded
        except Exception:
            pass
        return None

    # 52-char-prefix.b32.i2p → Base32 decode to 32 bytes
    if input_str.endswith(".b32.i2p"):
        b32_part = input_str[: -len(".b32.i2p")]
        if len(b32_part) == 52:
            try:
                decoded = base64.b32decode(b32_part.upper() + "====")
                if len(decoded) == 32:
                    return decoded
            except Exception:
                pass
        return None

    return None