"""Picdrop-Zugriff via SFTP: Galerien/Ordner listen, Bilder ziehen & hochladen."""
from __future__ import annotations

import posixpath
import stat
from contextlib import contextmanager
from typing import Iterator

import paramiko

from . import config

IMAGE_EXTS = {".jpg", ".jpeg", ".png", ".webp", ".tif", ".tiff", ".bmp"}


@contextmanager
def _sftp() -> Iterator[paramiko.SFTPClient]:
    transport = paramiko.Transport((config.PICDROP_HOST, config.PICDROP_PORT))
    transport.banner_timeout = 30
    transport.connect(username=config.PICDROP_USER, password=config.PICDROP_PASSWORD)
    try:
        sftp = paramiko.SFTPClient.from_transport(transport)
        sftp.get_channel().settimeout(60)
        yield sftp
    finally:
        transport.close()


def list_dir(path: str = "/") -> list[dict]:
    """Eintraege eines Verzeichnisses (Name, ob Ordner, Groesse)."""
    with _sftp() as sftp:
        out = []
        for attr in sftp.listdir_attr(path):
            is_dir = stat.S_ISDIR(attr.st_mode)
            out.append({
                "name": attr.filename,
                "is_dir": is_dir,
                "size": attr.st_size,
                "path": posixpath.join(path, attr.filename),
            })
        out.sort(key=lambda e: (not e["is_dir"], e["name"].lower()))
        return out


def list_images(path: str) -> list[dict]:
    return [
        e for e in list_dir(path)
        if not e["is_dir"] and posixpath.splitext(e["name"])[1].lower() in IMAGE_EXTS
    ]


def find_gallery(name_substr: str, root: str = "/", max_depth: int = 3) -> list[str]:
    """Sucht Ordner, deren Name den Teilstring enthaelt (case-insensitive)."""
    needle = name_substr.lower()
    matches: list[str] = []

    def walk(path: str, depth: int) -> None:
        if depth > max_depth:
            return
        try:
            entries = list_dir(path)
        except OSError:
            return
        for e in entries:
            if e["is_dir"]:
                if needle in e["name"].lower():
                    matches.append(e["path"])
                walk(e["path"], depth + 1)

    walk(root, 0)
    return matches


def download(remote_path: str) -> bytes:
    with _sftp() as sftp:
        with sftp.open(remote_path, "rb") as fh:
            fh.prefetch()
            return fh.read()


def upload(remote_path: str, data: bytes) -> None:
    with _sftp() as sftp:
        # Zielordner sicherstellen
        d = posixpath.dirname(remote_path)
        parts, cur = d.strip("/").split("/"), ""
        for p in parts:
            cur = cur + "/" + p
            try:
                sftp.stat(cur)
            except FileNotFoundError:
                sftp.mkdir(cur)
        with sftp.open(remote_path, "wb") as fh:
            fh.write(data)