from datetime import datetime, timedelta
import json
import os
import socket


class InMemoryTokenStore:
    def __init__(self, refresh_skew_seconds=120):
        self.refresh_skew_seconds = int(refresh_skew_seconds)
        self._session = None

    def save(self, token, expire_time):
        self._session = {
            'token': token,
            'expire_time': expire_time,
        }
        return self._session

    def get(self):
        return self._session

    def clear(self):
        self._session = None

    def is_expiring(self):
        if not self._session:
            return True
        expire_time = self._session.get('expire_time')
        if not expire_time:
            return True
        if isinstance(expire_time, str) and expire_time.endswith('Z'):
            expire_time = expire_time[:-1] + '+00:00'
        expires_at = datetime.fromisoformat(str(expire_time))
        return expires_at <= datetime.now(expires_at.tzinfo) + timedelta(seconds=self.refresh_skew_seconds)

    def require_token(self):
        if not self._session or not self._session.get('token'):
            raise RuntimeError('mcp token missing')
        return self._session['token']


class FileTokenStore(InMemoryTokenStore):
    def __init__(self, path, refresh_skew_seconds=120):
        super().__init__(refresh_skew_seconds=refresh_skew_seconds)
        self.path = path
        self._session = self._read_session()

    def save(self, token, expire_time):
        session = super().save(token, expire_time)
        directory = os.path.dirname(self.path)
        if directory:
            os.makedirs(directory, exist_ok=True)
        with open(self.path, 'w', encoding='utf-8') as handle:
            json.dump(session, handle, ensure_ascii=False)
        return session

    def get(self):
        if self._session is None and os.path.exists(self.path):
            self._session = self._read_session()
        return self._session

    def clear(self):
        super().clear()
        if os.path.exists(self.path):
            os.remove(self.path)

    def _read_session(self):
        if not os.path.exists(self.path):
            return None
        with open(self.path, 'r', encoding='utf-8') as handle:
            return json.load(handle)


class RedisTokenStore(InMemoryTokenStore):
    def __init__(self, client, prefix='fms:mcp:workbuddy:', session_key='', refresh_skew_seconds=120):
        super().__init__(refresh_skew_seconds=refresh_skew_seconds)
        session_key = str(session_key or '').strip()
        if not session_key:
            raise ValueError('session_key is required for RedisTokenStore')
        self.client = client
        self.prefix = str(prefix or 'fms:mcp:workbuddy:')
        self.session_key = session_key
        self.key = self.prefix + self.session_key

    def save(self, token, expire_time):
        session = super().save(token, expire_time)
        payload = json.dumps(session, ensure_ascii=False)
        ttl = self._ttl_seconds(expire_time)
        self.client.set(self.key, payload, ex=ttl if ttl and ttl > 0 else None)
        return session

    def get(self):
        raw = self.client.get(self.key)
        if raw is None or raw == '':
            self._session = None
            return None
        if isinstance(raw, bytes):
            raw = raw.decode('utf-8')
        self._session = json.loads(raw)
        return self._session

    def clear(self):
        super().clear()
        self.client.delete(self.key)

    def is_expiring(self):
        self.get()
        return super().is_expiring()

    @staticmethod
    def _ttl_seconds(expire_time):
        if not expire_time:
            return None
        value = expire_time[:-1] + '+00:00' if isinstance(expire_time, str) and expire_time.endswith('Z') else expire_time
        expires_at = datetime.fromisoformat(str(value))
        now = datetime.now(expires_at.tzinfo) if expires_at.tzinfo else datetime.now()
        return max(1, int((expires_at - now).total_seconds()))


class RedisSocketClient:
    def __init__(self, host='127.0.0.1', port=6379, db=0, password='', timeout=5):
        self.host = host
        self.port = int(port)
        self.db = int(db)
        self.password = password or ''
        self.timeout = int(timeout)

    def set(self, key, value, ex=None):
        command = ['SET', key, value]
        if ex is not None:
            command.extend(['EX', int(ex)])
        return self._execute(*command) == 'OK'

    def get(self, key):
        return self._execute('GET', key)

    def delete(self, key):
        return self._execute('DEL', key)

    def _execute(self, *parts):
        with socket.create_connection((self.host, self.port), timeout=self.timeout) as sock:
            stream = sock.makefile('rb')
            if self.password:
                self._send(sock, 'AUTH', self.password)
                self._read_response(stream)
            if self.db:
                self._send(sock, 'SELECT', self.db)
                self._read_response(stream)
            self._send(sock, *parts)
            return self._read_response(stream)

    @staticmethod
    def _send(sock, *parts):
        payload = ['*{0}\r\n'.format(len(parts)).encode('utf-8')]
        for part in parts:
            if isinstance(part, bytes):
                data = part
            else:
                data = str(part).encode('utf-8')
            payload.append('${0}\r\n'.format(len(data)).encode('utf-8'))
            payload.append(data + b'\r\n')
        sock.sendall(b''.join(payload))

    def _read_response(self, stream):
        prefix = stream.read(1)
        if not prefix:
            raise RuntimeError('empty redis response')
        if prefix == b'+':
            return self._read_line(stream).decode('utf-8')
        if prefix == b'-':
            raise RuntimeError(self._read_line(stream).decode('utf-8'))
        if prefix == b':':
            return int(self._read_line(stream))
        if prefix == b'$':
            length = int(self._read_line(stream))
            if length == -1:
                return None
            data = stream.read(length)
            stream.read(2)
            return data.decode('utf-8')
        if prefix == b'*':
            length = int(self._read_line(stream))
            return [self._read_response(stream) for _ in range(length)]
        raise RuntimeError('unsupported redis response: {0}'.format(prefix))

    @staticmethod
    def _read_line(stream):
        line = stream.readline()
        if not line.endswith(b'\r\n'):
            raise RuntimeError('invalid redis line')
        return line[:-2]