import requests
import base64
from datetime import datetime
from django.conf import settings
from django.utils import timezone
import json
import logging

logger = logging.getLogger(__name__)

class MpesaAPI:
    def __init__(self):
        self.consumer_key = getattr(settings, 'MPESA_CONSUMER_KEY', '')
        self.consumer_secret = getattr(settings, 'MPESA_CONSUMER_SECRET', '')
        self.business_short_code = getattr(settings, 'MPESA_BUSINESS_SHORT_CODE', '')
        self.passkey = getattr(settings, 'MPESA_PASSKEY', '')
        self.environment = getattr(settings, 'MPESA_ENVIRONMENT', 'sandbox')
        
        if self.environment == 'production':
            self.base_url = 'https://api.safaricom.co.ke'
        else:
            self.base_url = 'https://sandbox.safaricom.co.ke'

    def get_access_token(self):
        """Get M-Pesa access token"""
        try:
            url = f"{self.base_url}/oauth/v1/generate?grant_type=client_credentials"
            
            # Create basic auth header
            credentials = f"{self.consumer_key}:{self.consumer_secret}"
            encoded_credentials = base64.b64encode(credentials.encode()).decode()
            
            headers = {
                'Authorization': f'Basic {encoded_credentials}',
                'Content-Type': 'application/json'
            }
            
            response = requests.get(url, headers=headers)
            response.raise_for_status()
            
            return response.json().get('access_token')
        
        except Exception as e:
            logger.error(f"Error getting M-Pesa access token: {e}")
            return None

    def generate_password(self):
        """Generate M-Pesa password"""
        timestamp = datetime.now().strftime('%Y%m%d%H%M%S')
        password_string = f"{self.business_short_code}{self.passkey}{timestamp}"
        password = base64.b64encode(password_string.encode()).decode()
        return password, timestamp

    def stk_push(self, phone_number, amount, account_reference, transaction_desc, callback_url):
        """Initiate STK Push payment"""
        try:
            access_token = self.get_access_token()
            if not access_token:
                return {'success': False, 'message': 'Failed to get access token'}

            password, timestamp = self.generate_password()
            
            # Format phone number
            if phone_number.startswith('0'):
                phone_number = '254' + phone_number[1:]
            elif phone_number.startswith('+254'):
                phone_number = phone_number[1:]
            elif not phone_number.startswith('254'):
                phone_number = '254' + phone_number

            url = f"{self.base_url}/mpesa/stkpush/v1/processrequest"
            
            headers = {
                'Authorization': f'Bearer {access_token}',
                'Content-Type': 'application/json'
            }
            
            payload = {
                'BusinessShortCode': self.business_short_code,
                'Password': password,
                'Timestamp': timestamp,
                'TransactionType': 'CustomerPayBillOnline',
                'Amount': int(amount),
                'PartyA': phone_number,
                'PartyB': self.business_short_code,
                'PhoneNumber': phone_number,
                'CallBackURL': callback_url,
                'AccountReference': account_reference,
                'TransactionDesc': transaction_desc
            }
            
            response = requests.post(url, json=payload, headers=headers)
            result = response.json()
            
            if response.status_code == 200 and result.get('ResponseCode') == '0':
                return {
                    'success': True,
                    'merchant_request_id': result.get('MerchantRequestID'),
                    'checkout_request_id': result.get('CheckoutRequestID'),
                    'response_description': result.get('ResponseDescription')
                }
            else:
                return {
                    'success': False,
                    'message': result.get('ResponseDescription', 'Payment failed')
                }
                
        except Exception as e:
            logger.error(f"STK Push error: {e}")
            return {'success': False, 'message': str(e)}

    def query_transaction(self, checkout_request_id):
        """Query transaction status"""
        try:
            access_token = self.get_access_token()
            if not access_token:
                return {'success': False, 'message': 'Failed to get access token'}

            password, timestamp = self.generate_password()
            
            url = f"{self.base_url}/mpesa/stkpushquery/v1/query"
            
            headers = {
                'Authorization': f'Bearer {access_token}',
                'Content-Type': 'application/json'
            }
            
            payload = {
                'BusinessShortCode': self.business_short_code,
                'Password': password,
                'Timestamp': timestamp,
                'CheckoutRequestID': checkout_request_id
            }
            
            response = requests.post(url, json=payload, headers=headers)
            return response.json()
            
        except Exception as e:
            logger.error(f"Transaction query error: {e}")
            return {'success': False, 'message': str(e)}