import os
#Flask的基础库
from flask import Flask, abort, request, jsonify, g, url_for
#Flaks的数据库操作的库
from flask.ext.sqlalchemy import SQLAlchemy
#Flask登录注册的库
from flask.ext.httpauth import HTTPBasicAuth
#加密解密密码的库
from passlib.apps import custom_app_context as pwd_context
#URL安全序列化工具
from itsdangerous import (TimedJSONWebSignatureSerializer
             as Serializer, BadSignature, SignatureExpired)

app = Flask(__name__)
# 设置密钥
app.config['SECRET_KEY'] = 'the quick brown fox jumps over the lazy dog'
# 数据库的配置
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///db.sqlite'
app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True

#数据库初始化
db = SQLAlchemy(app)
# 验证的初始化
auth = HTTPBasicAuth()

class User(db.Model):
  __tablename__ = 'users'
  id = db.Column(db.Integer, primary_key=True)
  username = db.Column(db.String(32), index=True)
  password_hash = db.Column(db.String(64))
  # 加密密码
  def hash_password(self, password):
    self.password_hash = pwd_context.encrypt(password)
  # 验证密码
  def verify_password(self, password):
    return pwd_context.verify(password, self.password_hash)
  # 生成token，并设置过期时间
  def generate_auth_token(self, expiration=600):
    s = Serializer(app.config['SECRET_KEY'], expires_in=expiration)
    return s.dumps({'id': self.id})
  # 静态的验证token的方法
  @staticmethod
  def verify_auth_token(token):
    s = Serializer(app.config['SECRET_KEY'])
    try:
      data = s.loads(token)
    except SignatureExpired:
      return None  # token过期
    except BadSignature:
      return None  # token无效
    user = User.query.get(data['id'])
    return user

@app.route('/api/users', methods=['POST'])
def new_user():
  username = request.json.get('username')
  password = request.json.get('password')
  if username is None or password is None:
    abort(400)  # 用户名或者密码为空
  if User.query.filter_by(username=username).first() is not None:
    abort(400)  # 用户已存在
  user = User(username=username)
  # 加密密码
  user.hash_password(password)
  # 保存进数据库
  db.session.add(user)
  db.session.commit()
  # 成功注册后返回用户名，Location后面接着的是跳转的地址
  return (jsonify({'username': user.username}), 201,
      {'Location': url_for('get_user', id=user.id, _external=True)})

# 登录后获取token
@app.route('/api/token')
@auth.login_required
def get_auth_token():
  # 设置token过期时间
  token = g.user.generate_auth_token(600)
  return jsonify({'token': token.decode('ascii'), 'duration': 600})

# 可以通过token或者账号密码登录
@app.route('/api/resource')
@auth.login_required
def get_resource():
  # 如果token有效的话就返回username
  return jsonify({'data': 'Hello, %s!' % g.user.username})

# 有@auth.login_required标志的都要调用这个方法,传token或者传账号和密码
@auth.verify_password
def verify_password(username_or_token, password):
  # 首先验证token
  user = User.verify_auth_token(username_or_token)
  if not user:
    # 然后再验证用户名和密码
    user = User.query.filter_by(username=username_or_token).first()
    if not user or not user.verify_password(password):
      return False
  g.user = user
  return True

if __name__ == '__main__':
  # 如果这个数据库不存在就创建
  if not os.path.exists('db.sqlite'):
    db.create_all()
  app.run(debug=True)