"""Message encoding/decoding utilities for hbd protocol.

Message Types:
    HTB: Heartbeat message (client -> server)
    ACK: Acknowledgment (server -> client)
    CMD: Command message (server -> client)
    UPD: Update message (server -> client)
    PLG: Plugin data message (client -> server)
"""

from typing import Dict, Any, Union
import json
import zlib


def encode_value(v: Any) -> str:
    """Encode a value for protocol transmission.
    
    Args:
        v: Value to encode (int, float, str, bool, list, dict, etc.)
        
    Returns:
        String representation suitable for protocol
    """
    if isinstance(v, float):
        return f"{v:0.5f}"
    elif isinstance(v, (list, dict)):
        # Use JSON encoding for complex types, prefixed with @
        return "@" + json.dumps(v)
    elif isinstance(v, bool):
        return str(int(v))  # True->1, False->0
    else:
        return str(v)


def decode_value(val: str) -> Any:
    """Decode a value from protocol format.
    
    Args:
        val: String value from protocol
        
    Returns:
        Decoded Python object
    """
    if not val:
        return val
    
    # Check for JSON-encoded complex types
    if val.startswith("@"):
        try:
            return json.loads(val[1:])
        except Exception:
            return val[1:]  # Return as string without @
    
    # Try numeric conversion (avoid eval to prevent SyntaxWarnings on version strings)
    if val[0].isdigit() or (val[0] == '-' and len(val) > 1 and val[1].isdigit()):
        try:
            return int(val)
        except ValueError:
            pass
        try:
            return float(val)
        except ValueError:
            pass
        return val
    
    return val


def dicttos(ID: str, d: Dict[str, Any]):
    """Serialize a dict to protocol message bytes.

    If compress is True, the payload is zlib-compressed and the message is
    prefixed with `!ID:` as the original script did. Otherwise the format is
    `ID:key=value;...` (bytes).
    """
    s = []
    for k in d:
        v = d[k]
        encoded_val = encode_value(v)
        s.append(f"{k}={encoded_val}")
    pk = ";".join(s)
    zpk = zlib.compress(pk.encode(), 6)
    hdr = ("!" + ID + ":").encode()
    return hdr + zpk


def stodict(msg: bytes):
    """Deserialize a protocol message into a dict.

    Mirrors original behaviour: detects compressed messages starting with
    '!' and decodes accordingly. Returns a dict with key 'ID' set to the
    message ID and the parsed key/value pairs.
    """
    d = {}
    if len(msg) > 0 and chr(msg[0]) == "!":
        # message is: b'!ID:' + compressed_payload
        # original code used msg[1:4].decode() for ID (3 bytes including colon)
        try:
            pk = zlib.decompress(msg[5:]).decode()
        except Exception:
            # malformed compressed payload
            return {}
        d["ID"] = msg[1:4].decode()
    else:
        try:
            r0 = msg.split(b":", 1)
            pk = r0[1].decode()
            d["ID"] = r0[0].decode()
        except Exception:
            return {}
    if not pk:
        return d
    parts = pk.split(";")
    for v in parts:
        if not v:
            continue
        vr = v.split("=", 1)
        k = vr[0].strip()
        if len(vr) == 1:
            d[k] = None
        else:
            val = vr[1].strip()
            d[k] = decode_value(val)
    return d


def oldmtodict(msg: bytes):
    """Compatibility wrapper for old-style messages (no ID prefix).

    The original implementation prefixed with 'HTB:' and called stodict.
    """
    return stodict(b"HTB:" + msg)


def encode_plugin_data(plugin_name: str, data: Dict[str, Any]) -> bytes:
    """Encode plugin data into a PLG message.
    
    Args:
        plugin_name: Name of the plugin (e.g., "os_info", "cpu_monitor")
        data: Plugin data dictionary
        compress: Whether to compress the payload
        
    Returns:
        Encoded message bytes
    """
    # Add plugin name to data
    full_data = {"plugin": plugin_name, **data}
    return dicttos("PLG", full_data)


def decode_plugin_data(msg: bytes) -> Dict[str, Any]:
    """Decode a PLG message into plugin data.
    
    Args:
        msg: Raw message bytes
        
    Returns:
        Dictionary with 'ID', 'plugin', and plugin data fields
    """
    return stodict(msg)