from flask import Blueprint, jsonify, request, abort
from flask_login import login_required, current_user

from app.extensions import db
from app.models.folder import Folder
from app.utils.file_handler import delete_resource_file

folders_bp = Blueprint('folders', __name__)


# ── 递归删除辅助函数 ──────────────────────────────────────────────────────────

def _delete_folder_recursive(folder: Folder):
    """DFS 递归删除文件夹：先删子文件夹，再删资源（含磁盘文件），最后删自身"""
    for child in list(folder.children):
        _delete_folder_recursive(child)
    for res in folder.resources.all():
        delete_resource_file(res.file_path)
        db.session.delete(res)
    db.session.delete(folder)


# ── 路由 ──────────────────────────────────────────────────────────────────────

@folders_bp.route('/tree')
@login_required
def tree():
    """返回当前用户的完整文件夹树（JSON）"""
    return jsonify(Folder.get_user_tree(current_user.id))


@folders_bp.route('/create', methods=['POST'])
@login_required
def create():
    """创建文件夹"""
    name = request.form.get('name', '').strip()
    parent_id_raw = request.form.get('parent_id', '').strip()
    parent_id = int(parent_id_raw) if parent_id_raw.isdigit() else None

    if not name or len(name) > 128:
        return jsonify(ok=False, msg='文件夹名称无效（1-128位）'), 400

    # 验证父文件夹归属
    if parent_id is not None:
        parent = db.session.get(Folder, parent_id)
        if parent is None or parent.user_id != current_user.id:
            abort(403)

    # 同级重名校验（覆盖 NULL parent_id 场景）
    dup = Folder.query.filter_by(
        user_id=current_user.id,
        parent_id=parent_id,
        name=name
    ).first()
    if dup:
        return jsonify(ok=False, msg='该位置已存在同名文件夹'), 409

    folder = Folder(user_id=current_user.id, name=name, parent_id=parent_id)
    db.session.add(folder)
    db.session.commit()
    return jsonify(ok=True, folder={
        'id': folder.id, 'name': folder.name,
        'parent_id': folder.parent_id, 'resource_count': 0, 'children': []
    })


@folders_bp.route('/<int:folder_id>/rename', methods=['POST'])
@login_required
def rename(folder_id):
    """重命名文件夹"""
    folder = db.session.get(Folder, folder_id)
    if folder is None or folder.user_id != current_user.id:
        abort(403)

    name = request.form.get('name', '').strip()
    if not name or len(name) > 128:
        return jsonify(ok=False, msg='文件夹名称无效'), 400

    if name == folder.name:
        return jsonify(ok=True)

    # 同级重名校验
    dup = Folder.query.filter_by(
        user_id=current_user.id,
        parent_id=folder.parent_id,
        name=name
    ).filter(Folder.id != folder_id).first()
    if dup:
        return jsonify(ok=False, msg='该位置已存在同名文件夹'), 409

    folder.name = name
    db.session.commit()
    return jsonify(ok=True)


@folders_bp.route('/<int:folder_id>/delete', methods=['POST'])
@login_required
def delete(folder_id):
    """递归删除文件夹（含所有子文件夹和资源）"""
    folder = db.session.get(Folder, folder_id)
    if folder is None or folder.user_id != current_user.id:
        abort(403)

    _delete_folder_recursive(folder)
    db.session.commit()
    return jsonify(ok=True)


@folders_bp.route('/<int:folder_id>/move', methods=['POST'])
@login_required
def move(folder_id):
    """移动文件夹到新的父文件夹"""
    folder = db.session.get(Folder, folder_id)
    if folder is None or folder.user_id != current_user.id:
        abort(403)

    parent_id_raw = request.form.get('parent_id', '').strip()
    new_parent_id = int(parent_id_raw) if parent_id_raw.isdigit() else None

    if new_parent_id is not None:
        # 不能移动到自身
        if new_parent_id == folder_id:
            return jsonify(ok=False, msg='不能将文件夹移动到自身'), 400
        # 不能移动到自己的子孙节点
        if folder.is_ancestor_of(new_parent_id):
            return jsonify(ok=False, msg='不能将文件夹移动到其子文件夹中'), 400
        # 验证目标父文件夹归属
        new_parent = db.session.get(Folder, new_parent_id)
        if new_parent is None or new_parent.user_id != current_user.id:
            abort(403)

    # 同级重名校验
    dup = Folder.query.filter_by(
        user_id=current_user.id,
        parent_id=new_parent_id,
        name=folder.name
    ).filter(Folder.id != folder_id).first()
    if dup:
        return jsonify(ok=False, msg='目标位置已有同名文件夹'), 409

    folder.parent_id = new_parent_id
    db.session.commit()
    return jsonify(ok=True)