import os
from pathlib import Path

import FreeCAD as App
import FreeCADGui as Gui


DEVICE_GROUP_PREFIX = "QETDevice_"
PREVIEW_DOC_PREFIX = "QETPreview_"
ROOT_GROUP_NAME = "QETExchangeDevices"


def _debug_log_path():
    local_app_data = os.environ.get("LOCALAPPDATA", "").strip()
    if local_app_data:
        return os.path.join(local_app_data, "QETDeps", "freecad_exchange_bootstrap.log")
    return os.path.join(str(Path.home()), "AppData", "Local", "QETDeps", "freecad_exchange_bootstrap.log")


def _append_debug_log(message):
    try:
        log_path = _debug_log_path()
        os.makedirs(os.path.dirname(log_path), exist_ok=True)
        with open(log_path, "a", encoding="utf-8") as handle:
            handle.write(message + "\n")
    except Exception:
        pass


def _safe_token(value):
    text = (value or "").strip()
    if not text:
        return "unknown"

    chars = []
    for ch in text:
        if ch.isalnum():
            chars.append(ch)
        else:
            chars.append("_")
    return "".join(chars)


def is_preview_document_name(doc_name):
    return str(doc_name or "").startswith(PREVIEW_DOC_PREFIX)


def _get_document_if_exists(doc_name):
    try:
        return App.getDocument(doc_name)
    except Exception:
        return None


def find_main_exchange_document(preferred_name=""):
    preferred_name = (preferred_name or "").strip()
    if preferred_name:
        preferred_doc = _get_document_if_exists(preferred_name)
        if preferred_doc is not None and not is_preview_document_name(preferred_doc.Name):
            return preferred_doc

    active_doc = App.ActiveDocument
    if (
        active_doc is not None
        and not is_preview_document_name(active_doc.Name)
        and active_doc.getObject(ROOT_GROUP_NAME) is not None
    ):
        return active_doc

    for candidate in App.listDocuments().values():
        if (
            candidate is not None
            and not is_preview_document_name(candidate.Name)
            and candidate.getObject(ROOT_GROUP_NAME) is not None
        ):
            return candidate

    if active_doc is not None and not is_preview_document_name(active_doc.Name):
        return active_doc

    return None


def is_qet_device_object(obj):
    if obj is None:
        return False
    if getattr(obj, "TypeId", "") != "App::Part":
        return False
    if not getattr(obj, "Name", "").startswith(DEVICE_GROUP_PREFIX):
        return False
    return "QetElementUuid" in getattr(obj, "PropertiesList", [])


def find_parent_qet_device_object(obj):
    """
    从当前选中对象向上查找所属的 QETDevice_xxx 设备组。

    作用：
    1. 双击 QETDevice_xxx 本身，可以预览；
    2. 双击 QETDevice_xxx 下面的子实体，也可以自动找到父设备并预览。
    """
    if obj is None:
        _append_debug_log("DevicePreview resolve parent: selected object is None")
        return None

    if is_qet_device_object(obj):
        _append_debug_log(
            "DevicePreview resolve parent: selected object is direct device {0}".format(
                getattr(obj, "Name", "")
            )
        )
        return obj

    visited = set()
    stack = list(getattr(obj, "InList", []) or [])

    while stack:
        parent = stack.pop()
        if parent is None:
            continue

        parent_name = getattr(parent, "Name", "")
        if parent_name in visited:
            continue

        visited.add(parent_name)

        if is_qet_device_object(parent):
            _append_debug_log(
                "DevicePreview resolve parent: found parent device {0} from child {1}".format(
                    getattr(parent, "Name", ""),
                    getattr(obj, "Name", ""),
                )
            )
            return parent

        stack.extend(list(getattr(parent, "InList", []) or []))

    _append_debug_log(
        "DevicePreview resolve parent: no device parent found for {0}".format(
            getattr(obj, "Name", "")
        )
    )
    return None


def _preview_document_name(device_group):
    display_tag = getattr(device_group, "QetDisplayTag", "")
    element_uuid = getattr(device_group, "QetElementUuid", "")
    display_token = _safe_token(display_tag)[:24]
    uuid_token = _safe_token(element_uuid)[:8] or _safe_token(device_group.Name)[-8:]
    if display_token:
        return "{0}{1}_{2}".format(PREVIEW_DOC_PREFIX, display_token, uuid_token)
    return "{0}{1}".format(PREVIEW_DOC_PREFIX, uuid_token)


def _clear_document_objects(doc):
    while getattr(doc, "Objects", []):
        doc.removeObject(doc.Objects[-1].Name)


def _activate_document(doc):
    App.setActiveDocument(doc.Name)
    App.ActiveDocument = doc
    try:
        Gui.ActiveDocument = Gui.getDocument(doc.Name)
    except Exception:
        pass


def _fit_active_view():
    try:
        active_view = Gui.activeDocument().activeView()
        active_view.viewIsometric()
        Gui.SendMsgToActiveView("ViewFit")
    except Exception:
        pass


def _set_visibility_recursive(obj, visible):
    if obj is None:
        return

    try:
        view_object = getattr(obj, "ViewObject", None)
        if view_object is not None and hasattr(view_object, "Visibility"):
            view_object.Visibility = bool(visible)
    except Exception:
        pass

    for child in list(getattr(obj, "Group", []) or []):
        _set_visibility_recursive(child, visible)


def _open_device_preview(device_group):
    doc_name = _preview_document_name(device_group)
    _append_debug_log(
        "DevicePreview opening preview doc={0} for device={1}".format(
            doc_name,
            getattr(device_group, "Name", ""),
        )
    )
    preview_doc = _get_document_if_exists(doc_name)
    if preview_doc is None:
        preview_doc = App.newDocument(doc_name)
        _append_debug_log("DevicePreview created new preview document")
    else:
        _append_debug_log("DevicePreview reusing existing preview document")

    _clear_document_objects(preview_doc)
    copied_device = preview_doc.copyObject(device_group, True)
    copied_device.Label = device_group.Label
    if hasattr(copied_device, "Placement"):
        copied_device.Placement = App.Placement()
    _set_visibility_recursive(copied_device, True)

    preview_doc.recompute()
    _activate_document(preview_doc)
    _fit_active_view()
    _append_debug_log(
        "DevicePreview preview ready: doc={0}, copied_name={1}, copied_label={2}".format(
            preview_doc.Name,
            getattr(copied_device, "Name", ""),
            getattr(copied_device, "Label", ""),
        )
    )
    return preview_doc


def open_preview_for_device_object(obj):
    if not is_qet_device_object(obj):
        return None
    if is_preview_document_name(getattr(getattr(obj, "Document", None), "Name", "")):
        return None
    _append_debug_log(
        "DevicePreview open requested element_uuid={0}, label={1}".format(
            getattr(obj, "QetElementUuid", ""),
            getattr(obj, "Label", ""),
        )
    )
    return _open_device_preview(obj)