"""
Email Service
處理所有郵件相關功能，包括通知、提醒和摘要郵件
"""

import os
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.application import MIMEApplication
from datetime import datetime, date
from flask import current_app
from jinja2 import Environment, FileSystemLoader, select_autoescape
from utils.logger import get_logger
from utils.ldap_utils import get_user_info

logger = get_logger(__name__)

class EmailService:
    """郵件服務類別"""
    
    def __init__(self):
        self.smtp_server = os.getenv('SMTP_SERVER')
        self.smtp_port = int(os.getenv('SMTP_PORT', 587))
        self.use_tls = os.getenv('SMTP_USE_TLS', 'false').lower() == 'true'
        self.use_ssl = os.getenv('SMTP_USE_SSL', 'false').lower() == 'true'
        self.auth_required = os.getenv('SMTP_AUTH_REQUIRED', 'false').lower() == 'true'
        self.sender_email = os.getenv('SMTP_SENDER_EMAIL')
        self.sender_password = os.getenv('SMTP_SENDER_PASSWORD', '')
        
        # 設定 Jinja2 模板環境
        template_dir = os.path.join(os.path.dirname(__file__), '..', 'templates', 'emails')
        self.jinja_env = Environment(
            loader=FileSystemLoader(template_dir),
            autoescape=select_autoescape(['html', 'xml'])
        )
    
    def _create_smtp_connection(self):
        """建立 SMTP 連線"""
        try:
            if self.use_ssl:
                server = smtplib.SMTP_SSL(self.smtp_server, self.smtp_port)
            else:
                server = smtplib.SMTP(self.smtp_server, self.smtp_port)
                if self.use_tls:
                    server.starttls()
            
            if self.auth_required and self.sender_password:
                server.login(self.sender_email, self.sender_password)
            
            return server
        except Exception as e:
            logger.error(f"SMTP connection failed: {str(e)}")
            return None
    
    def _send_email(self, to_email, subject, html_content, text_content=None):
        """發送郵件的基礎方法"""
        try:
            if not self.smtp_server or not self.sender_email:
                logger.error("SMTP configuration incomplete")
                return False
            
            # 建立郵件
            msg = MIMEMultipart('alternative')
            msg['From'] = self.sender_email
            msg['To'] = to_email
            msg['Subject'] = subject
            
            # 添加文本內容
            if text_content:
                text_part = MIMEText(text_content, 'plain', 'utf-8')
                msg.attach(text_part)
            
            # 添加 HTML 內容
            html_part = MIMEText(html_content, 'html', 'utf-8')
            msg.attach(html_part)
            
            # 發送郵件
            server = self._create_smtp_connection()
            if not server:
                return False
            
            server.send_message(msg)
            server.quit()
            
            logger.info(f"Email sent successfully to {to_email}")
            return True
            
        except Exception as e:
            logger.error(f"Failed to send email to {to_email}: {str(e)}")
            return False
    
    def _get_user_email(self, ad_account):
        """取得使用者郵件地址"""
        user_info = get_user_info(ad_account)
        if user_info and user_info.get('email'):
            return user_info['email']
        
        # 如果無法從 LDAP 取得，嘗試組合郵件地址
        domain = os.getenv('LDAP_DOMAIN', 'panjit.com.tw')
        return f"{ad_account}@{domain}"
    
    def send_fire_email(self, todo, recipient, sender, custom_message=''):
        """發送緊急通知郵件"""
        try:
            recipient_email = self._get_user_email(recipient)
            sender_info = get_user_info(sender)
            sender_name = sender_info.get('displayName', sender) if sender_info else sender
            
            # 準備模板資料
            template_data = {
                'todo': todo,
                'recipient': recipient,
                'sender': sender,
                'sender_name': sender_name,
                'custom_message': custom_message,
                'timestamp': datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
                'app_name': current_app.config.get('APP_NAME', 'PANJIT Todo List')
            }
            
            # 渲染模板
            template = self.jinja_env.get_template('fire_email.html')
            html_content = template.render(**template_data)
            
            # 主題
            subject = f"🚨 緊急通知 - {todo.title}"
            
            return self._send_email(recipient_email, subject, html_content)
            
        except Exception as e:
            logger.error(f"Fire email failed for {recipient}: {str(e)}")
            return False
    
    def send_reminder_email(self, todo, recipient, reminder_type):
        """發送提醒郵件"""
        try:
            recipient_email = self._get_user_email(recipient)
            
            # 根據提醒類型設定主題和模板
            if reminder_type == 'due_tomorrow':
                subject = f"📅 明日到期提醒 - {todo.title}"
                template_name = 'reminder_due_tomorrow.html'
            elif reminder_type == 'overdue':
                subject = f"⚠️ 逾期提醒 - {todo.title}"
                template_name = 'reminder_overdue.html'
            else:
                subject = f"📋 待辦提醒 - {todo.title}"
                template_name = 'reminder_general.html'
            
            # 準備模板資料
            template_data = {
                'todo': todo,
                'recipient': recipient,
                'reminder_type': reminder_type,
                'timestamp': datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
                'app_name': current_app.config.get('APP_NAME', 'PANJIT Todo List')
            }
            
            # 渲染模板
            template = self.jinja_env.get_template(template_name)
            html_content = template.render(**template_data)
            
            return self._send_email(recipient_email, subject, html_content)
            
        except Exception as e:
            logger.error(f"Reminder email failed for {recipient}: {str(e)}")
            return False
    
    def send_digest_email(self, recipient, digest_data):
        """發送摘要郵件"""
        try:
            recipient_email = self._get_user_email(recipient)
            
            # 根據摘要類型設定主題
            digest_type = digest_data.get('type', 'weekly')
            type_names = {
                'daily': '每日',
                'weekly': '每週',
                'monthly': '每月'
            }
            subject = f"📊 {type_names.get(digest_type, '定期')}摘要報告"
            
            # 準備模板資料
            template_data = {
                'recipient': recipient,
                'digest_data': digest_data,
                'timestamp': datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
                'app_name': current_app.config.get('APP_NAME', 'PANJIT Todo List')
            }
            
            # 渲染模板
            template = self.jinja_env.get_template('digest.html')
            html_content = template.render(**template_data)
            
            return self._send_email(recipient_email, subject, html_content)
            
        except Exception as e:
            logger.error(f"Digest email failed for {recipient}: {str(e)}")
            return False
    
    def send_todo_notification(self, todo, recipients, action, actor):
        """發送待辦事項變更通知"""
        try:
            success_count = 0
            
            for recipient in recipients:
                try:
                    recipient_email = self._get_user_email(recipient)
                    actor_info = get_user_info(actor)
                    actor_name = actor_info.get('displayName', actor) if actor_info else actor
                    
                    # 根據動作類型設定主題和模板
                    action_names = {
                        'CREATE': '建立',
                        'UPDATE': '更新',
                        'DELETE': '刪除',
                        'ASSIGN': '指派',
                        'COMPLETE': '完成'
                    }
                    
                    action_name = action_names.get(action, action)
                    subject = f"📋 待辦事項{action_name} - {todo.title}"
                    
                    # 準備模板資料
                    template_data = {
                        'todo': todo,
                        'recipient': recipient,
                        'action': action,
                        'action_name': action_name,
                        'actor': actor,
                        'actor_name': actor_name,
                        'timestamp': datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
                        'app_name': current_app.config.get('APP_NAME', 'PANJIT Todo List')
                    }
                    
                    # 渲染模板
                    template = self.jinja_env.get_template('todo_notification.html')
                    html_content = template.render(**template_data)
                    
                    if self._send_email(recipient_email, subject, html_content):
                        success_count += 1
                        
                except Exception as e:
                    logger.error(f"Todo notification failed for {recipient}: {str(e)}")
            
            return success_count
            
        except Exception as e:
            logger.error(f"Todo notification batch failed: {str(e)}")
            return 0
    
    def send_test_email(self, recipient):
        """發送測試郵件"""
        try:
            recipient_email = self._get_user_email(recipient)
            
            subject = "✅ 郵件服務測試"
            html_content = f"""
            <html>
            <body>
                <h2>郵件服務測試</h2>
                <p>您好 {recipient}，</p>
                <p>這是一封測試郵件，用於驗證 PANJIT Todo List 系統的郵件功能是否正常運作。</p>
                <p>如果您收到這封郵件，表示郵件服務配置正確。</p>
                <br>
                <p>測試時間: {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}</p>
                <p>此郵件由系統自動發送，請勿回覆。</p>
            </body>
            </html>
            """
            
            return self._send_email(recipient_email, subject, html_content)
            
        except Exception as e:
            logger.error(f"Test email failed for {recipient}: {str(e)}")
            return False
    
    def send_test_email_direct(self, recipient_email):
        """直接發送測試郵件到指定郵件地址"""
        try:
            subject = "✅ PANJIT Todo List 郵件服務測試"
            html_content = f"""
            <html>
            <body style="font-family: Arial, sans-serif; line-height: 1.6; color: #333;">
                <div style="max-width: 600px; margin: 0 auto; padding: 20px;">
                    <h2 style="color: #2563eb; border-bottom: 2px solid #e5e7eb; padding-bottom: 10px;">📧 郵件服務測試</h2>
                    <p>您好！</p>
                    <p>這是一封來自 <strong>PANJIT Todo List 系統</strong> 的測試郵件，用於驗證郵件服務功能是否正常運作。</p>
                    
                    <div style="background-color: #f0f9ff; border-left: 4px solid #2563eb; padding: 15px; margin: 20px 0;">
                        <p style="margin: 0;"><strong>✅ 如果您收到這封郵件，表示：</strong></p>
                        <ul style="margin: 10px 0; padding-left: 20px;">
                            <li>SMTP 服務器連線正常</li>
                            <li>郵件發送功能運作良好</li>
                            <li>您的郵件地址設定正確</li>
                        </ul>
                    </div>
                    
                    <hr style="border: none; border-top: 1px solid #e5e7eb; margin: 30px 0;">
                    <p style="font-size: 14px; color: #6b7280;">
                        <strong>測試詳細資訊：</strong><br>
                        📅 測試時間: {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}<br>
                        📧 收件人: {recipient_email}<br>
                        🏢 發件人: PANJIT Todo List 系統
                    </p>
                    
                    <p style="font-size: 12px; color: #9ca3af; margin-top: 30px;">
                        此郵件由系統自動發送，請勿回覆。如有任何問題，請聯繫系統管理員。
                    </p>
                </div>
            </body>
            </html>
            """
            
            return self._send_email(recipient_email, subject, html_content)
            
        except Exception as e:
            logger.error(f"Direct test email failed for {recipient_email}: {str(e)}")
            return False