import secrets
from fastapi import BackgroundTasks
from typing import Optional
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from jinja2 import Template
import aiosmtplib
from ..config import settings
import os
import string

class EmailService:
    def __init__(self):
        self.smtp_host = settings.SMTP_HOST
        self.smtp_port = settings.SMTP_PORT
        self.smtp_user = settings.SMTP_USER
        self.smtp_password = settings.SMTP_PASSWORD
        self.from_email = settings.EMAILS_FROM_EMAIL
        self.from_name = settings.EMAILS_FROM_NAME
        
    async def send_email_async(
        self,
        email_to: str,
        subject: str,
        html_content: str,
        text_content: Optional[str] = None
    ) -> bool:
        """异步发送邮件"""
        message = MIMEMultipart("alternative")
        message["Subject"] = subject
        message["From"] = f"{self.from_name} <{self.from_email}>"
        message["To"] = email_to
        
        # 添加纯文本版本
        if text_content:
            part1 = MIMEText(text_content, "plain")
            message.attach(part1)
        
        # 添加HTML版本
        part2 = MIMEText(html_content, "html")
        message.attach(part2)
        
        try:
            await aiosmtplib.send(
                message,
                hostname=self.smtp_host,
                port=self.smtp_port,
                username=self.smtp_user,
                password=self.smtp_password,
                use_tls=True,
            )
            return True
        except Exception as e:
            print(f"Error sending email: {e}")
            return False
    
    def send_email_sync(
        self,
        email_to: str,
        subject: str,
        html_content: str,
        text_content: Optional[str] = None
    ) -> bool:
        """同步发送邮件"""
        message = MIMEMultipart("alternative")
        message["Subject"] = subject
        message["From"] = f"{self.from_name} <{self.from_email}>"
        message["To"] = email_to
        
        if text_content:
            part1 = MIMEText(text_content, "plain")
            message.attach(part1)
        
        part2 = MIMEText(html_content, "html")
        message.attach(part2)
        
        try:
            with smtplib.SMTP(self.smtp_host, self.smtp_port) as server:
                server.starttls()
                server.login(self.smtp_user, self.smtp_password)
                server.send_message(message)
            return True
        except Exception as e:
            print(f"Error sending email: {e}")
            return False
    
    async def send_verification_email(
        self,
        email_to: str,
        username: str,
        verification_url: str,
        verification_code: Optional[str] = None
    ) -> bool:
        """发送验证邮件"""
        # 加载模板
        template_path = os.path.join("templates", "email", "verify_email.html")
        with open(template_path, "r") as f:
            template_str = f.read()
        
        template = Template(template_str)
        html_content = template.render(
            username=username,
            verification_url=verification_url,
            verification_code=verification_code,
            frontend_url=settings.FRONTEND_URL
        )
        
        subject = "Verify Your Email Address"
        text_content = f"Hello {username},\n\nPlease verify your email by clicking: {verification_url}"
        
        if verification_code:
            text_content += f"\n\nOr use this verification code: {verification_code}"
        
        return await self.send_email_async(email_to, subject, html_content, text_content)
    
    async def send_password_reset_email(
        self,
        email_to: str,
        username: str,
        reset_url: str
    ) -> bool:
        """发送密码重置邮件"""
        template_path = os.path.join("templates", "email", "reset_password.html")
        with open(template_path, "r") as f:
            template_str = f.read()
        
        template = Template(template_str)
        html_content = template.render(
            username=username,
            reset_url=reset_url,
            frontend_url=settings.FRONTEND_URL
        )
        
        subject = "Password Reset Request"
        text_content = f"Hello {username},\n\nClick here to reset your password: {reset_url}"
        
        return await self.send_email_async(email_to, subject, html_content, text_content)
    
    async def send_welcome_email(
        self,
        email_to: str,
        username: str
    ) -> bool:
        """发送欢迎邮件"""
        template_path = os.path.join("templates", "email", "welcome.html")
        with open(template_path, "r") as f:
            template_str = f.read()
        
        template = Template(template_str)
        html_content = template.render(
            username=username,
            frontend_url=settings.FRONTEND_URL
        )
        
        subject = "Welcome to Our Platform!"
        text_content = f"Welcome {username}! We're glad to have you on board."
        
        return await self.send_email_async(email_to, subject, html_content, text_content)
    
    def generate_random_string(self, length: int = 6) -> str:
        """生成随机数字加字母字符串"""
        name = string.digits + string.ascii_letters
        return ''.join(secrets.choice(name) for _ in range(length))

email_service = EmailService()