import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

from flask import current_app as app

import requests

from nyaa import models


class EmailHolder(object):
    ''' Holds email subject, recipient and content, so we have a general class for
        all mail backends. '''

    def __init__(self, subject=None, recipient=None, text=None, html=None):
        self.subject = subject
        self.recipient = recipient  # models.User or string
        self.text = text
        self.html = html

    def format_recipient(self):
        if isinstance(self.recipient, models.User):
            return '{} <{}>'.format(self.recipient.username, self.recipient.email)
        else:
            return self.recipient

    def recipient_email(self):
        if isinstance(self.recipient, models.User):
            return self.recipient.email
        else:
            return self.recipient.email

    def as_mimemultipart(self):
        msg = MIMEMultipart()
        msg['Subject'] = self.subject
        msg['From'] = app.config['MAIL_FROM_ADDRESS']
        msg['To'] = self.format_recipient()

        msg.attach(MIMEText(self.text, 'plain'))
        if self.html:
            msg.attach(MIMEText(self.html, 'html'))

        return msg


def send_email(email_holder):
    """Send an email using the configured mail backend."""
    mail_backend = app.config.get('MAIL_BACKEND')
    
    if not mail_backend:
        app.logger.warning('No mail backend configured, skipping email send')
        return False
        
    try:
        if mail_backend == 'mailgun':
            success = _send_mailgun(email_holder)
        elif mail_backend == 'smtp':
            success = _send_smtp(email_holder)
        else:
            app.logger.error(f'Unknown mail backend: {mail_backend}')
            return False
            
        if not success:
            app.logger.error(f'Failed to send email using {mail_backend} backend')
            return False
            
        app.logger.info(f'Email successfully sent using {mail_backend} backend')
        return True
        
    except Exception as e:
        app.logger.error(f'Error sending email: {str(e)}')
        return False


def _send_mailgun(email_holder):
    """Send an email using Mailgun API with proper error handling."""
    try:
        mailgun_endpoint = app.config['MAILGUN_API_BASE'] + '/messages'
        auth = ('api', app.config['MAILGUN_API_KEY'])
        data = {
            'from': app.config['MAIL_FROM_ADDRESS'],
            'to': email_holder.format_recipient(),
            'subject': email_holder.subject,
            'text': email_holder.text,
            'html': email_holder.html
        }
        
        r = requests.post(mailgun_endpoint, data=data, auth=auth)
        
        if r.status_code != 200:
            app.logger.error(f'Mailgun API error: {r.status_code} - {r.text}')
            return False
            
        return True
        
    except Exception as e:
        app.logger.error(f'Error sending email via Mailgun: {str(e)}')
        return False


def _send_smtp(email_holder):
    # NOTE: Unused, most likely untested! Should work, however.
    msg = email_holder.as_mimemultipart()

    server = smtplib.SMTP(app.config['SMTP_SERVER'], app.config['SMTP_PORT'])
    server.set_debuglevel(1)
    server.ehlo()
    server.starttls()
    server.ehlo()
    server.login(app.config['SMTP_USERNAME'], app.config['SMTP_PASSWORD'])
    server.sendmail(app.config['SMTP_USERNAME'], email_holder.recipient_email(), msg.as_string())
    server.quit()