"""
Email and PDF Processing Module for Bank Statement Analysis
"""
import imaplib
from email.message import Message
import os
import io
import re
import pandas as pd
from typing import List, Dict, Optional, Tuple
from dataclasses import dataclass
from datetime import datetime, timedelta
import PyPDF2
import fitz  # PyMuPDF
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
import logging

@dataclass
class BankTransaction:
    date: datetime
    description: str
    amount: float
    category: str = "Unknown"
    account: str = ""
    balance: Optional[float] = None

@dataclass
class StatementInfo:
    bank_name: str
    account_number: str
    statement_period: str
    transactions: List[BankTransaction]
    opening_balance: float
    closing_balance: float

class EmailProcessor:
    def __init__(self, email_config: Dict):
        self.email_config = email_config
        self.logger = logging.getLogger(__name__)
        self.bank_patterns = {
            'chase': r'chase\.com|jpmorgan',
            'bofa': r'bankofamerica\.com|bofa',
            'wells': r'wellsfargo\.com',
            'citi': r'citi\.com|citibank',
            'amex': r'americanexpress\.com|amex',
            'hdfc': r'hdfcbank\.com',
            'icici': r'icicibank\.com',
            'sbi': r'sbi\.co\.in',
            'axis': r'axisbank\.com',
        }

    async def connect_to_email(self) -> imaplib.IMAP4_SSL:
        """Connect to email server"""
        try:
            mail = imaplib.IMAP4_SSL(self.email_config['imap_server'])
            mail.login(self.email_config['email'], self.email_config['password'])
            return mail
        except Exception as e:
            self.logger.error(f"Failed to connect to email: {e}")
            raise

    async def fetch_bank_emails(self, days_back: int = 30) -> List[Message]:
        """Fetch emails from banks containing statements"""
        mail = await self.connect_to_email()
        mail.select('inbox')

        # Calculate date range
        end_date = datetime.now()
        start_date = end_date - timedelta(days=days_back)

        # Search for bank emails
        bank_domains = '|'.join(self.bank_patterns.values())
        search_criteria = f'(FROM "{bank_domains}" SINCE "{start_date.strftime("%d-%b-%Y")}")'

        try:
            status, messages = mail.search(None, search_criteria)
            email_ids = messages[0].split()

            emails = []
            for email_id in email_ids[-50:]:  # Limit to recent 50 emails
                status, msg_data = mail.fetch(email_id, '(RFC822)')
                msg = Message.from_bytes(msg_data[0][1])
                emails.append(msg)

            return emails
        finally:
            mail.close()
            mail.logout()

    def identify_bank(self, sender_email: str) -> str:
        """Identify bank from sender email"""
        sender_lower = sender_email.lower()
        for bank, pattern in self.bank_patterns.items():
            if re.search(pattern, sender_lower):
                return bank
        return "unknown"

    async def extract_attachments(self, msg: Message) -> List[Tuple[str, bytes, str]]:
        """Extract PDF attachments from email"""
        attachments = []
        self.logger.debug(f"Processing message with type: {type(msg)}")

        for part in msg.walk():
            self.logger.debug(f"Processing part with type: {type(part)}")
            try:
                if part.get_content_disposition() == 'attachment':
                    filename = part.get_filename()
                    if filename and filename.lower().endswith('.pdf'):
                        content = part.get_payload(decode=True)
                        attachments.append((filename, content, 'pdf'))
            except Exception as e:
                self.logger.error(f"Error processing part: {e}, Part type: {type(part)}")
                continue

        return attachments

class PDFProcessor:
    def __init__(self):
        self.logger = logging.getLogger(__name__)
        self.transaction_patterns = {
            'date': r'(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})',
            'amount': r'([\$\-]?[\d,]+\.?\d{0,2})',
            'description': r'([A-Za-z0-9\s\*\#\-_]+)'
        }

    async def process_pdf(self, pdf_content: bytes, password: Optional[str] = None) -> StatementInfo:
        """Process PDF bank statement"""
        try:
            # Try PyMuPDF first
            doc = fitz.open(stream=pdf_content, filetype="pdf")

            if doc.needs_pass and password:
                if not doc.authenticate(password):
                    raise ValueError("Invalid PDF password")
            elif doc.needs_pass and not password:
                raise ValueError("PDF requires password")

            text = ""
            for page in doc:
                text += page.get_text()

            doc.close()

            return await self.parse_statement_text(text)

        except Exception as e:
            self.logger.error(f"Error processing PDF: {e}")
            # Fallback to PyPDF2
            return await self.process_pdf_fallback(pdf_content, password)

    async def process_pdf_fallback(self, pdf_content: bytes, password: Optional[str] = None) -> StatementInfo:
        """Fallback PDF processing with PyPDF2"""
        try:
            pdf_reader = PyPDF2.PdfReader(io.BytesIO(pdf_content))

            if pdf_reader.is_encrypted:
                if password:
                    pdf_reader.decrypt(password)
                else:
                    raise ValueError("PDF requires password")

            text = ""
            for page in pdf_reader.pages:
                text += page.extract_text()

            return await self.parse_statement_text(text)

        except Exception as e:
            self.logger.error(f"Fallback PDF processing failed: {e}")
            raise

    async def parse_statement_text(self, text: str) -> StatementInfo:
        """Parse bank statement text to extract transactions"""
        lines = text.split('\n')
        transactions = []

        # Bank-specific parsing logic
        bank_name = self.detect_bank_from_text(text)
        account_number = self.extract_account_number(text)
        statement_period = self.extract_statement_period(text)

        # Extract transactions based on patterns
        for line in lines:
            transaction = self.parse_transaction_line(line)
            if transaction:
                transactions.append(transaction)

        # Extract balances
        opening_balance = self.extract_opening_balance(text)
        closing_balance = self.extract_closing_balance(text)

        return StatementInfo(
            bank_name=bank_name,
            account_number=account_number,
            statement_period=statement_period,
            transactions=transactions,
            opening_balance=opening_balance,
            closing_balance=closing_balance
        )

    def detect_bank_from_text(self, text: str) -> str:
        """Detect bank from statement text"""
        text_lower = text.lower()
        if 'chase' in text_lower or 'jpmorgan' in text_lower:
            return 'Chase'
        elif 'bank of america' in text_lower or 'bofa' in text_lower:
            return 'Bank of America'
        elif 'wells fargo' in text_lower:
            return 'Wells Fargo'
        elif 'citibank' in text_lower or 'citi' in text_lower:
            return 'Citibank'
        elif 'american express' in text_lower or 'amex' in text_lower:
            return 'American Express'
        return 'Unknown Bank'

    def extract_account_number(self, text: str) -> str:
        """Extract account number from statement"""
        # Look for account number patterns
        patterns = [
            r'Account\s+(?:Number|#)?\s*:\s*(\*\+\d{4})',
            r'Account\s+(\d{4,})',
            r'(\*\+\d{4})'
        ]

        for pattern in patterns:
            match = re.search(pattern, text, re.IGNORECASE)
            if match:
                return match.group(1)
        return "Unknown"

    def extract_statement_period(self, text: str) -> str:
        """Extract statement period"""
        # Look for date ranges
        pattern = r'(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})\s*(?:to|through|-)\s*(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})'
        match = re.search(pattern, text, re.IGNORECASE)

        if match:
            return f"{match.group(1)} to {match.group(2)}"
        return "Unknown Period"

    def parse_transaction_line(self, line: str) -> Optional[BankTransaction]:
        """Parse individual transaction line"""
        # Common transaction line patterns
        patterns = [
            # Date, Description, Amount
            r'(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})\s+(.+?)\s+([\$\-]?[\d,]+\.?\d{0,2})$',
            # Date, Amount, Description
            r'(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})\s+([\$\-]?[\d,]+\.?\d{0,2})\s+(.+)$'
        ]

        for pattern in patterns:
            match = re.search(pattern, line.strip())
            if match:
                try:
                    date_str = match.group(1)
                    if len(match.groups()) == 3:
                        if '$' in match.group(2) or match.group(2).replace('-', '').replace('.', '').replace(',', '').isdigit():
                            # Pattern: Date, Amount, Description
                            amount_str = match.group(2)
                            description = match.group(3)
                        else:
                            # Pattern: Date, Description, Amount
                            description = match.group(2)
                            amount_str = match.group(3)

                    # Parse date
                    transaction_date = self.parse_date(date_str)

                    # Parse amount
                    amount = self.parse_amount(amount_str)

                    # Categorize transaction
                    category = self.categorize_transaction(description)

                    return BankTransaction(
                        date=transaction_date,
                        description=description.strip(),
                        amount=amount,
                        category=category
                    )

                except Exception as e:
                    self.logger.debug(f"Failed to parse transaction line: {line}, Error: {e}")
                    continue
        return None

    def parse_date(self, date_str: str) -> datetime:
        """Parse date string to datetime object"""
        # Try different date formats
        formats = ['%m/%d/%Y', '%m-%d-%Y', '%m/%d/%y', '%m-%d-%y']

        for fmt in formats:
            try:
                return datetime.strptime(date_str, fmt)
            except ValueError:
                continue
        # If all fails, return current date
        return datetime.now()

    def parse_amount(self, amount_str: str) -> float:
        """Parse amount string to float"""
        # Clean amount string
        clean_amount = amount_str.replace('$', '').replace(',', '').strip()

        # Handle negative amounts
        is_negative = clean_amount.startswith('-') or clean_amount.startswith('(')
        clean_amount = clean_amount.replace('-', '').replace('(', '').replace(')', '')

        try:
            amount = float(clean_amount)
            return -amount if is_negative else amount
        except ValueError:
            return 0.0

    def categorize_transaction(self, description: str) -> str:
        """Categorize transaction based on description"""
        desc_lower = description.lower()

        categories = {
            'Food & Dining': ['restaurant', 'mcdonalds', 'starbucks', 'food', 'dining', 'cafe', 'pizza'],
            'Shopping': ['amazon', 'walmart', 'target', 'shopping', 'store', 'retail'],
            'Gas & Transport': ['shell', 'exxon', 'gas', 'fuel', 'uber', 'lyft', 'taxi'],
            'Utilities': ['electric', 'water', 'gas bill', 'internet', 'phone', 'utility'],
            'Entertainment': ['netflix', 'spotify', 'movie', 'entertainment', 'gaming'],
            'Healthcare': ['pharmacy', 'doctor', 'hospital', 'medical', 'health'],
            'Banking': ['atm', 'fee', 'interest', 'transfer', 'deposit']
        }

        for category, keywords in categories.items():
            if any(keyword in desc_lower for keyword in keywords):
                return category
        return 'Other'

    def extract_opening_balance(self, text: str) -> float:
        """Extract opening balance from statement"""
        patterns = [
            r'Beginning\s+Balance\s*:\s*\$?([\d,]+\.?\d{0,2})',
            r'Opening\s+Balance\s*:\s*\$?([\d,]+\.?\d{0,2})',
            r'Previous\s+Balance\s*:\s*\$?([\d,]+\.?\d{0,2})'
        ]

        for pattern in patterns:
            match = re.search(pattern, text, re.IGNORECASE)
            if match:
                return float(match.group(1).replace(',', ''))
        return 0.0

    def extract_closing_balance(self, text: str) -> float:
        """Extract closing balance from statement"""
        patterns = [
            r'Ending\s+Balance\s*:\s*\$?([\d,]+\.?\d{0,2})',
            r'Closing\s+Balance\s*:\s*\$?([\d,]+\.?\d{0,2})',
            r'Current\s+Balance\s*:\s*\$?([\d,]+\.?\d{0,2})'
        ]

        for pattern in patterns:
            match = re.search(pattern, text, re.IGNORECASE)
            if match:
                return float(match.group(1).replace(',', ''))
        return 0.0

# Example usage
if __name__ == "__main__":
    # Test PDF processing
    pdf_processor = PDFProcessor()

    # Example test with sample PDF content
    print("PDF Processor initialized successfully")