"""Unified logging utility for automatic file and function name tracking."""

import sys
import inspect
import threading
from pathlib import Path

_DEBUG_ENABLED = False
_thread_local = threading.local()

def set_thread_stream(stream):
    """Set a custom output stream for the current thread."""
    _thread_local.stream = stream

def get_thread_stream():
    """Get the custom output stream for the current thread, if any."""
    return getattr(_thread_local, 'stream', None)

def set_debug(enabled: bool) -> None:
    """Enable or disable debug logging."""
    global _DEBUG_ENABLED
    _DEBUG_ENABLED = enabled

def is_debug_enabled() -> bool:
    """Check if debug logging is enabled."""
    return _DEBUG_ENABLED

def debug(*args, **kwargs) -> None:
    """Print debug message if debug logging is enabled.
    
    Automatically prepends [filename.function_name] to all output.
    """
    if not _DEBUG_ENABLED:
        return
    
    # Check if stderr has been redirected to /dev/null (quiet mode)
    # If so, skip output to avoid queuing in background worker's capture
    try:
        stderr_name = getattr(sys.stderr, 'name', '')
        if 'nul' in str(stderr_name).lower() or '/dev/null' in str(stderr_name):
            return
    except Exception:
        pass
        
    # Check for thread-local stream first
    stream = get_thread_stream()
    if stream:
        kwargs['file'] = stream
    # Set default to stderr for debug messages
    elif 'file' not in kwargs:
        kwargs['file'] = sys.stderr
        
    # Prepend DEBUG label
    args = ("DEBUG:", *args)
    
    # Use the same logic as log()
    log(*args, **kwargs)

def log(*args, **kwargs) -> None:
    """Print with automatic file.function prefix.
    
    Automatically prepends [filename.function_name] to all output.
    Defaults to stdout if not specified.
    
    Example:
        log("Upload started")  # Output: [add_file.run] Upload started
    """
    # When debug is disabled, suppress the automatic prefix for cleaner user-facing output.
    add_prefix = _DEBUG_ENABLED

    # Get the calling frame
    frame = inspect.currentframe()
    if frame is None:
        print(*args, **kwargs)
        return
    
    caller_frame = frame.f_back
    if caller_frame is None:
        print(*args, **kwargs)
        return
    
    try:
        # Get file name without extension
        file_name = Path(caller_frame.f_code.co_filename).stem
        
        # Get function name
        func_name = caller_frame.f_code.co_name
        
        # Check for thread-local stream first
        stream = get_thread_stream()
        if stream:
            kwargs['file'] = stream
        # Set default to stdout if not specified
        elif 'file' not in kwargs:
            kwargs['file'] = sys.stdout
        
        if add_prefix:
            prefix = f"[{file_name}.{func_name}]"
            print(prefix, *args, **kwargs)
        else:
            print(*args, **kwargs)
    finally:
        del frame
        del caller_frame