import os
import time

from flask import request, jsonify, current_app
from flask_jwt_extended import jwt_required, get_jwt_identity

from app.constants import OperationType, UserRole
from app.decorators import login_required
from app.models import Operation, User
from app.routes import training_routes
from app.services import training_manager as tm
from app.utils import handle_operation_failure, handle_operation_success


def _jwt_user():
    uid = get_jwt_identity()
    try:
        pk = int(uid) if uid is not None else None
    except (TypeError, ValueError):
        pk = None
    return User.query.get(pk) if pk is not None else None


def _role_is_trainer(role) -> bool:
    if role is None:
        return False
    if isinstance(role, UserRole):
        return role in (UserRole.DEVELOPER, UserRole.ADMIN)
    name = str(getattr(role, 'name', role)).upper()
    value = str(getattr(role, 'value', role)).lower()
    return name in ('ADMIN', 'DEVELOPER') or value in ('admin', 'developer')


def _require_trainer(user):
    if not _role_is_trainer(getattr(user, 'role', None)):
        return jsonify({'message': '仅管理员或开发人员可访问模型训练功能'}), 403
    return None


@training_routes.route('/base-models', methods=['GET'])
@jwt_required()
@login_required
def base_models():
    user = _jwt_user()
    denied = _require_trainer(user)
    if denied:
        return denied
    return jsonify({'base_models': tm.list_base_models()}), 200


@training_routes.route('/datasets', methods=['GET'])
@jwt_required()
@login_required
def list_datasets():
    user = _jwt_user()
    denied = _require_trainer(user)
    if denied:
        return denied
    return jsonify({'datasets': tm.list_datasets(current_app)}), 200


@training_routes.route('/datasets/upload', methods=['POST'])
@jwt_required()
@login_required
def upload_dataset():
    start_time = time.time()
    current_user = _jwt_user()
    current_user_id = current_user.user_id if current_user else None

    denied = _require_trainer(current_user)
    if denied:
        return denied

    new_operation = Operation(
        operation_type=OperationType.CREATE,
        description='上传训练数据集',
        ip_address=request.remote_addr,
        device_info=request.user_agent.string,
    )

    zip_file = request.files.get('dataset_zip')
    display_name = (request.form.get('name') or '').strip()

    if not zip_file:
        msg = '【上传数据集失败】未选择 ZIP 文件'
        new_operation = handle_operation_failure(new_operation, start_time, msg, current_user_id)
        return jsonify({'operation': new_operation.to_dict(), 'message': msg}), 400

    max_size = current_app.config.get('MAX_DATASET_ZIP_SIZE', 500 * 1024 * 1024)
    zip_file.seek(0, os.SEEK_END)
    size = zip_file.tell()
    zip_file.seek(0)
    if size > max_size:
        msg = '【上传数据集失败】文件超过 500MB 限制'
        new_operation = handle_operation_failure(new_operation, start_time, msg, current_user_id)
        return jsonify({'operation': new_operation.to_dict(), 'message': msg}), 400

    try:
        item = tm.upload_dataset(
            current_app,
            zip_file,
            display_name,
            current_user_id,
            current_user.username,
        )
    except ValueError as exc:
        msg = f'【上传数据集失败】{exc}'
        new_operation = handle_operation_failure(new_operation, start_time, msg, current_user_id)
        return jsonify({'operation': new_operation.to_dict(), 'message': msg}), 400

    new_operation = handle_operation_success(new_operation, start_time, current_user_id)
    return jsonify({
        'operation': new_operation.to_dict(),
        'dataset': item,
    }), 201


@training_routes.route('/jobs', methods=['GET'])
@jwt_required()
@login_required
def list_jobs():
    user = _jwt_user()
    denied = _require_trainer(user)
    if denied:
        return denied
    return jsonify({'jobs': tm.list_jobs(current_app)}), 200


@training_routes.route('/jobs/<job_id>/resume', methods=['POST'])
@jwt_required()
@login_required
def resume_job_route(job_id):
    user = _jwt_user()
    denied = _require_trainer(user)
    if denied:
        return denied
    try:
        job = tm.resume_job(current_app, job_id)
    except ValueError as exc:
        return jsonify({'message': str(exc)}), 400
    return jsonify({'job': job}), 200


@training_routes.route('/jobs/<job_id>', methods=['GET'])
@jwt_required()
@login_required
def job_detail(job_id):
    user = _jwt_user()
    denied = _require_trainer(user)
    if denied:
        return denied
    job = tm.get_job(current_app, job_id)
    if not job:
        return jsonify({'message': '训练任务不存在'}), 404
    return jsonify({'job': job}), 200


@training_routes.route('/jobs', methods=['POST'])
@jwt_required()
@login_required
def start_job():
    start_time = time.time()
    current_user = _jwt_user()
    current_user_id = current_user.user_id if current_user else None

    denied = _require_trainer(current_user)
    if denied:
        return denied

    data = request.get_json() or {}
    new_operation = Operation(
        operation_type=OperationType.EXECUTE,
        description='启动 YOLO 模型训练',
        ip_address=request.remote_addr,
        device_info=request.user_agent.string,
    )

    try:
        job = tm.start_job(
            current_app,
            owner_id=current_user_id,
            owner_username=current_user.username,
            dataset_id=data.get('dataset_id'),
            base_model=data.get('base_model', 'yolov8n-seg.pt'),
            disease_category=data.get('disease_category', ''),
            output_model_name=data.get('output_model_name', ''),
            epochs=data.get('epochs', 50),
            imgsz=data.get('imgsz', 640),
            batch=data.get('batch', 8),
            augmentation=data.get('augmentation', '随机点+颜色扭曲+高斯模糊'),
            register_to_library=data.get('register_to_library', True),
        )
    except ValueError as exc:
        msg = f'【启动训练失败】{exc}'
        new_operation = handle_operation_failure(new_operation, start_time, msg, current_user_id)
        return jsonify({'operation': new_operation.to_dict(), 'message': msg}), 400

    new_operation = handle_operation_success(new_operation, start_time, current_user_id)
    return jsonify({
        'operation': new_operation.to_dict(),
        'job': job,
    }), 201