import logging
import os
import re
import uuid
from datetime import datetime
from pathlib import Path

logger = logging.getLogger(__name__)


def get_unique_filename(original_path, check_exists_func=None):
    """
    Generates a unique filename by appending a timestamp or counter when a collision occurs.

    Args:
        original_path (str): The original file path
        check_exists_func (callable): Function that checks if file exists in target system.
                                     Takes a path string and returns True if exists, False otherwise.
                                     If None, will use local filesystem check.

    Returns:
        str: A unique filename that doesn't collide with existing files
    """
    if check_exists_func is None:
        check_exists_func = os.path.exists

    path = Path(original_path)
    directory = str(path.parent)
    filename = path.name
    name, ext = os.path.splitext(filename)

    # If file doesn't exist, return the original
    if not check_exists_func(original_path):
        return original_path

    # Try timestamp-based suffix first (more user-friendly)
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
    new_filename = f"{name}_{timestamp}{ext}"
    new_path = os.path.join(directory, new_filename)

    if not check_exists_func(new_path):
        logger.info(f"Renamed '{filename}' to '{new_filename}' to avoid collision")
        return new_path

    # If timestamp-based name also exists, try random UUID
    uuid_str = str(uuid.uuid4())[:8]  # Use first 8 chars of UUID for brevity
    new_filename = f"{name}_{uuid_str}{ext}"
    new_path = os.path.join(directory, new_filename)

    if not check_exists_func(new_path):
        logger.info(f"Renamed '{filename}' to '{new_filename}' using UUID to avoid collision")
        return new_path

    # If that still exists (very unlikely), use incremental numbering
    counter = 1
    while counter < 1000:  # Limit to avoid infinite loop
        new_filename = f"{name}_{counter}{ext}"
        new_path = os.path.join(directory, new_filename)
        if not check_exists_func(new_path):
            logger.info(f"Renamed '{filename}' to '{new_filename}' using counter to avoid collision")
            return new_path
        counter += 1

    # If we got here, something is weird - just use a full UUID
    new_filename = f"{name}_{str(uuid.uuid4())}{ext}"
    new_path = os.path.join(directory, new_filename)
    logger.warning(f"Had to use full UUID to rename '{filename}' to '{new_filename}'")

    return new_path


def sanitize_filename(filename):
    """
    Sanitize a filename to ensure it's valid across different file systems.

    Args:
        filename (str): The filename to sanitize

    Returns:
        str: A sanitized filename
    """
    # Replace characters that are problematic in various filesystems
    # Keep only alphanumeric, dash, underscore, period, and space
    sanitized = re.sub(r"[^\w\-\. ]", "_", filename)

    # Replace multiple spaces/underscores with single ones
    sanitized = re.sub(r"__+", "_", sanitized)
    sanitized = re.sub(r"  +", " ", sanitized)

    # Trim leading/trailing spaces and periods which cause issues in Windows
    sanitized = sanitized.strip(". ")

    # Ensure the filename isn't empty after sanitization
    if not sanitized or sanitized == ".":
        sanitized = f"document_{datetime.now().strftime('%Y%m%d_%H%M%S')}"

    return sanitized


def extract_remote_path(file_path, base_dir, remote_base=""):
    """
    Extract a remote path for a file by preserving its directory structure
    relative to the base directory, but with a new remote base path.

    Modified to skip 'processed' directory in the remote path.
    """
    # Normalize paths for consistent handling across platforms
    file_path = os.path.normpath(file_path)
    base_dir = os.path.normpath(base_dir)

    # Get relative path from base directory
    if file_path.startswith(base_dir):
        rel_path = os.path.relpath(file_path, base_dir)
    else:
        # If not a subdirectory of base_dir, just use the filename
        rel_path = os.path.basename(file_path)

    # Skip 'processed' directory if it's in the path
    path_parts = rel_path.split(os.sep)
    if "processed" in path_parts:
        # Remove 'processed' from the path
        path_parts.remove("processed")
        rel_path = os.path.join(*path_parts)

    # Combine with remote base path
    if remote_base:
        if remote_base.startswith("/"):
            # Handle absolute path for services like Dropbox
            remote_path = os.path.join(remote_base[1:], rel_path)
        else:
            remote_path = os.path.join(remote_base, rel_path)
    else:
        remote_path = rel_path

    # Convert to forward slashes for compatibility with most cloud services
    remote_path = remote_path.replace(os.sep, "/")

    return remote_path