import logging
import sys
from pathlib import Path
from typing import List

logger = logging.getLogger(__name__)

SUPPORTED_IMAGE_EXTENSIONS = {".png", ".jpg", ".jpeg", ".webp"}


def is_supported_image(path):
    """Return True if path has a supported image extension (case-insensitive)."""
    return Path(path).suffix.lower() in SUPPORTED_IMAGE_EXTENSIONS


# ---------------------------------------------------------------------------
# Path helpers
# ---------------------------------------------------------------------------

def get_app_dir():
    """Return the application root directory as a Path.

    PyInstaller onedir: directory that contains the .exe.
    Development: project root (three levels above this file:
        src/services/file_service.py -> src/services -> src -> project root).
    """
    if getattr(sys, "frozen", False):
        return Path(sys.executable).resolve().parent
    return Path(__file__).resolve().parent.parent.parent


def get_resource_path(relative_path):
    """Return absolute Path for a resource file.

    Development resources live under src/resources/. In a PyInstaller onedir
    build, resources are copied next to the executable under resources/.
    """
    if getattr(sys, "frozen", False):
        return get_app_dir() / "resources" / relative_path
    return get_app_dir() / "src" / "resources" / relative_path


def get_config_path(relative_path):
    """Return absolute Path for a file under <app_dir>/config/."""
    return get_app_dir() / "config" / relative_path


def get_log_dir():
    """Return <app_dir>/logs/ as a Path, creating the directory if absent."""
    d = get_app_dir() / "logs"
    d.mkdir(exist_ok=True)
    return d


def get_output_dir():
    """Return <app_dir>/output/ as a Path, creating the directory if absent."""
    d = get_app_dir() / "output"
    d.mkdir(exist_ok=True)
    return d


# ---------------------------------------------------------------------------
# 文件夹扫描
# ---------------------------------------------------------------------------

def scan_image_folder(folder) -> List:
    """Recursively scan *folder* for supported images.

    Returns a list of ImageAsset objects (selected=True by default).
    Skips unsupported files and logs them at DEBUG level.
    Raises OSError if *folder* does not exist or is not a directory.
    """
    from core.models import ImageAsset

    folder = Path(folder)
    if not folder.exists():
        raise OSError("Folder not found: {}".format(folder))
    if not folder.is_dir():
        raise OSError("Path is not a directory: {}".format(folder))

    assets = []
    skipped_count = 0

    for entry in sorted(folder.rglob("*")):
        if not entry.is_file():
            continue
        if is_supported_image(entry):
            assets.append(ImageAsset(path=entry))
        else:
            skipped_count += 1
            logger.debug("Skipped unsupported file: %s", entry)

    if skipped_count:
        logger.info(
            "Skipped %d unsupported file(s) in %s", skipped_count, folder
        )
    logger.info("Found %d image(s) in %s", len(assets), folder)
    return assets


# ---------------------------------------------------------------------------
# 安全输出文件名
# ---------------------------------------------------------------------------

def make_safe_output_path(output_dir, garment_path, print_path, output_format="PNG"):
    """Return an output Path that will not overwrite an existing file.

    Filename pattern : <garment_stem>_<print_stem>.<ext>
    If that path exists, appends _1, _2, ... until a free slot is found.
    """
    output_dir = Path(output_dir)
    ext = ".png" if output_format.upper() == "PNG" else ".jpg"
    stem = "{}_{}".format(Path(garment_path).stem, Path(print_path).stem)

    candidate = output_dir / (stem + ext)
    counter = 1
    while candidate.exists():
        candidate = output_dir / ("{}_{}{}".format(stem, counter, ext))
        counter += 1

    return candidate