"""
╔══════════════════════════════════════════════════════════════════╗
║        VTPRestAPI  —  Python Client                               ║
║  Install:  pip install requests                                   ║
╚══════════════════════════════════════════════════════════════════╝

FLOW:
  1. api = VTPApiClient('http://vivekamih.gotdns.com:8033/api/')
  2. api.login('username', 'password')    # get API Key
  3. api.get('vtp/valid-trading-date')    # use API Key
  4. Session expires → auto re-login on next call
"""

import requests
import json
from datetime import datetime, timezone

class VTPApiClient:

    # ── Server endpoints ──────────────────────────────────────────────
    LOCAL = 'http://localhost:51631/api/'
    TEST  = 'http://vivekamih.gotdns.com:8033/api/'
    PROD  = 'http://vtpapi.vivekam.com/api/'

    def __init__(self, base_url=None):
        self.base_url      = (base_url or self.TEST).rstrip('/') + '/'
        self.session_token = None
        self.expires_at    = None
        self.current_user  = None
        self.current_role  = None
        self._saved_user   = None
        self._saved_pass   = None
        self._session      = requests.Session()
        self._session.headers.update({
            'Content-Type': 'application/json',
            'Accept':       'application/json'
        })

    @property
    def is_logged_in(self):
        if not self.session_token or not self.expires_at:
            return False
        return datetime.now(timezone.utc) < self.expires_at

    # ══════════════════════════════════════════════════════════════════
    #  AUTH
    # ══════════════════════════════════════════════════════════════════

    def login(self, username: str, password: str) -> dict:
        """Login and get session API Key. Call once before any API."""
        res  = self._session.post(
                   self.base_url + 'auth/login',
                   json={'username': username, 'password': password})
        data = res.json()

        if not res.ok or not data.get('success'):
            raise Exception(f"Login failed: {data.get('message')}")

        self.session_token = data['sessionToken']
        self.expires_at    = datetime.fromisoformat(
                                 data['expiresAt'].replace('Z', '+00:00'))
        self.current_user  = data['username']
        self.current_role  = data['role']
        self._saved_user   = username
        self._saved_pass   = password

        # Attach token to all future requests
        self._session.headers.update({'X-Session-Token': self.session_token})

        print(f"[VTPApi] ✅ Logged in as [{data['role']}] {data['username']}")
        print(f"[VTPApi] 🔑 API Key: {self.session_token}")
        print(f"[VTPApi] ⏰ Expires: {self.expires_at.astimezone().strftime('%H:%M:%S')}")
        return data

    def logout(self):
        """Logout and clear session."""
        try:
            self._session.post(self.base_url + 'auth/logout')
        except Exception:
            pass
        self.session_token = None
        self._session.headers.pop('X-Session-Token', None)
        print('[VTPApi] Logged out.')

    # ══════════════════════════════════════════════════════════════════
    #  HTTP METHODS — auto refresh session on 401
    # ══════════════════════════════════════════════════════════════════

    def get(self, endpoint: str, params: dict = None):
        return self._call('GET', endpoint, params=params)

    def post(self, endpoint: str, body: dict = None):
        return self._call('POST', endpoint, body=body)

    def put(self, endpoint: str, body: dict = None):
        return self._call('PUT', endpoint, body=body)

    def delete(self, endpoint: str):
        return self._call('DELETE', endpoint)

    # ══════════════════════════════════════════════════════════════════
    #  INTERNALS
    # ══════════════════════════════════════════════════════════════════

    def _call(self, method: str, endpoint: str,
              params=None, body=None, is_retry=False):
        self._ensure_session()

        url = self.base_url + endpoint
        res = self._session.request(
                  method, url, params=params,
                  json=body if body else None)

        # Session expired → re-login and retry ONCE
        if res.status_code == 401 and not is_retry:
            print('[VTPApi] ⚠️  Session expired. Re-logging in…')
            self.login(self._saved_user, self._saved_pass)
            return self._call(method, endpoint, params, body, True)

        try:
            data = res.json()
        except Exception:
            data = res.text

        if not res.ok:
            msg = data.get('message', str(data)) if isinstance(data, dict) else data
            raise Exception(f'[VTPApi] {res.status_code}: {msg}')

        return data

    def _ensure_session(self):
        if self.is_logged_in:
            return
        if self._saved_user:
            print('[VTPApi] Session expired. Auto re-login…')
            self.login(self._saved_user, self._saved_pass)
        else:
            raise Exception(
                'Not logged in. Call api.login(username, password) first.')

    def __enter__(self):
        return self

    def __exit__(self, *args):
        self.logout()


# ══════════════════════════════════════════════════════════════════════
#  QUICK-START DEMO
# ══════════════════════════════════════════════════════════════════════
if __name__ == '__main__':

    # ── 1. Create client ──────────────────────────────────────────────
    with VTPApiClient(VTPApiClient.TEST) as api:

        # ── 2. Login → get API Key ────────────────────────────────────
        api.login('admin', 'Admin@123')

        # ── 3. Call APIs — token sent automatically ───────────────────

        # GET (no params)
        trading_date = api.get('vtp/valid-trading-date')
        print('Valid Trading Date:', json.dumps(trading_date, indent=2))

        # GET with query params
        clients = api.get('vtp/clients-by-product', params={'productId': 116})
        print('Clients:', json.dumps(clients, indent=2))

        # GET with multiple params
        ledger = api.get('vtp/member-ledger',
                         params={'memberId': 135, 'partnerId': 1})
        print('Member Ledger:', json.dumps(ledger, indent=2))

        # POST with body
        bill = api.post('vtp/bill-summary', {
            'MpcId':    1234,
            'Date':     datetime.today().strftime('%Y-%m-%d'),
            'BillType': 'Q'
        })
        print('Bill Summary:', json.dumps(bill, indent=2))

        # ── 4. Logout handled automatically by 'with' block ──────────