"""
Subscription Billing Matrix Service

Generate a per-customer billing matrix showing:
- Rows: Products from e-conomic customer invoices
- Columns: Months
- Cells: Expected vs invoiced amounts, payment status, invoice references

Data source: e-conomic sales invoices only
"""

import logging
import json
from datetime import datetime, timedelta
from typing import Dict, List, Optional, Tuple
from collections import defaultdict
from app.services.economic_service import get_economic_service
from app.core.database import execute_query

logger = logging.getLogger(__name__)


class SubscriptionMatrixService:
    """Generate billing matrix for customer subscriptions"""
    
    def __init__(self):
        self.economic_service = get_economic_service()
    
    async def generate_billing_matrix(
        self, 
        customer_id: int, 
        months: int = 12
    ) -> Dict:
        """
        Generate subscription billing matrix for a customer
        
        Args:
            customer_id: BMC Hub customer ID (local database)
            months: Number of months to include (default 12)
            
        Returns:
            Dict with structure:
            {
                "customer_id": int,
                "generated_at": str (ISO datetime),
                "months_shown": int,
                "products": [
                    {
                        "product_number": str,
                        "product_name": str,
                        "rows": [
                            {
                                "year_month": "2025-01",
                                "amount": float,
                                "status": "paid|invoiced|missing",
                                "invoice_number": str (optional),
                                "period_label": str,
                                "period_from": str (ISO date),
                                "period_to": str (ISO date)
                            }
                        ],
                        "total_amount": float,
                        "total_paid": float
                    }
                ]
            }
        """
        try:
            # Get customer's e-conomic number from local database
            logger.info(f"🔍 [MATRIX] Starting matrix generation for customer {customer_id}")
            
            customer = execute_query(
                "SELECT economic_customer_number FROM customers WHERE id = %s",
                (customer_id,)
            )
            
            logger.info(f"🔍 [MATRIX] Query result: {customer}")
            
            if not customer or not customer[0].get('economic_customer_number'):
                logger.warning(f"⚠️ Customer {customer_id} has no e-conomic number")
                return {
                    "customer_id": customer_id,
                    "error": "No e-conomic customer number found",
                    "products": []
                }
            
            economic_customer_number = customer[0]['economic_customer_number']
            logger.info(f"📊 Generating matrix for e-conomic customer {economic_customer_number}")
            
            # Fetch invoices from e-conomic
            logger.info(f"🔍 [MATRIX] About to call get_customer_invoices with customer {economic_customer_number}")
            invoices = await self.economic_service.get_customer_invoices(
                economic_customer_number,
                include_lines=True
            )
            logger.info(f"🔍 [MATRIX] Returned {len(invoices)} invoices from e-conomic")
            
            if not invoices:
                logger.warning(f"⚠️ No invoices found for customer {economic_customer_number}")
                return {
                    "customer_id": customer_id,
                    "generated_at": datetime.now().isoformat(),
                    "months_shown": months,
                    "products": []
                }
            
            logger.info(f"📊 Processing {len(invoices)} invoices")
            
            # Debug: log first invoice structure
            if invoices:
                logger.debug(f"First invoice structure: {json.dumps(invoices[0], indent=2, default=str)[:500]}")
            
            # Group invoices by product number
            matrix_data = self._aggregate_by_product(invoices, months)
            
            return {
                "customer_id": customer_id,
                "economic_customer_number": economic_customer_number,
                "generated_at": datetime.now().isoformat(),
                "months_shown": months,
                "products": matrix_data
            }
            
        except Exception as e:
            logger.error(f"❌ Error generating billing matrix: {e}")
            import traceback
            logger.error(traceback.format_exc())
            return {
                "customer_id": customer_id,
                "error": str(e),
                "products": []
            }
    
    def _aggregate_by_product(self, invoices: List[Dict], months: int) -> List[Dict]:
        """
        Group invoice lines by product number and aggregate by month
        
        Args:
            invoices: List of e-conomic invoice objects
            months: Number of months to include
            
        Returns:
            List of product records with aggregated monthly data (including empty months)
        """
        # Generate list of all months to display (last N months from today)
        all_months = self._generate_month_range(months)
        
        # Structure: {product_number: {year_month: {amount, status, invoice_number, period_from, period_to}}}
        product_matrix = defaultdict(dict)
        product_names = {}  # Cache product names
        
        # Initialize products only if they have data within the selected month range
        try:
            # Fill in data from invoices, but only for months within range
            for invoice in invoices:
                invoice_number = invoice.get('bookedInvoiceNumber') or invoice.get('draftInvoiceNumber')
                # Determine status based on invoice type/endpoint it came from
                # Priority: use 'status' field, fallback to inferring from presence of certain fields
                invoice_status = invoice.get('status', 'unknown')
                if invoice_status == 'unknown':
                    # Infer status from invoice structure
                    if invoice.get('bookedInvoiceNumber'):
                        invoice_status = 'booked'
                    elif invoice.get('draftInvoiceNumber'):
                        invoice_status = 'draft'
                invoice_date = invoice.get('date')
                # Build invoice-level text (title/notes) for keyword matching
                invoice_text_parts = []
                notes = invoice.get('notes')
                if isinstance(notes, dict):
                    for key in ["heading", "textLine1", "textLine2", "textLine3", "textLine4", "textLine5"]:
                        val = notes.get(key)
                        if val:
                            invoice_text_parts.append(str(val))
                elif notes:
                    invoice_text_parts.append(str(notes))
                other_ref = invoice.get('otherReference') or invoice.get('orderNumberDb')
                if other_ref:
                    invoice_text_parts.append(str(other_ref))
                invoice_text = " ".join(invoice_text_parts).lower()
                
                # Process invoice lines
                lines = invoice.get('lines', [])
                for line in lines:
                    product_number = line.get('product', {}).get('productNumber')
                    product_name = line.get('product', {}).get('name') or line.get('description')
                    line_description = (line.get('description') or product_name or "").lower()
                    # Only include lines that indicate a period or subscription
                    if (
                        "periode" not in line_description
                        and "abonnement" not in line_description
                        and "periode" not in invoice_text
                        and "abonnement" not in invoice_text
                    ):
                        continue
                    
                    if not product_number:
                        logger.debug(f"Skipping line without product number: {line}")
                        continue
                    
                    # Cache product name
                    if product_number not in product_names:
                        product_names[product_number] = product_name or f"Product {product_number}"
                    
                    # Extract period from line
                    period_from_str = line.get('period', {}).get('from')
                    period_to_str = line.get('period', {}).get('to')
                    
                    # If no period on line, use invoice date as month
                    if not period_from_str:
                        if invoice_date:
                            period_from_str = invoice_date
                            # Assume monthly billing if no end date
                            period_from = datetime.fromisoformat(invoice_date.replace('Z', '+00:00'))
                            period_to = period_from + timedelta(days=31)
                            period_to_str = period_to.isoformat().split('T')[0]
                        else:
                            logger.warning(f"No period or date found for line in invoice {invoice_number}")
                            continue
                    
                    # Parse dates
                    try:
                        period_from = datetime.fromisoformat(period_from_str.replace('Z', '+00:00'))
                        period_to = datetime.fromisoformat(period_to_str.replace('Z', '+00:00'))
                    except (ValueError, AttributeError) as e:
                        logger.warning(f"Could not parse dates {period_from_str} - {period_to_str}: {e}")
                        continue
                    
                    # Get amount - use gross amount if net is 0 (line items may have gross only)
                    amount = float(line.get('netAmount', 0))
                    if amount == 0:
                        amount = float(line.get('grossAmount', 0))
                    if amount == 0:
                        # Try unit net price * quantity as fallback
                        unit_price = float(line.get('unitNetPrice', 0))
                        qty = float(line.get('quantity', 1))
                        amount = unit_price * qty
                    
                    # Determine month key (use first month if multi-month)
                    year_month = period_from.strftime('%Y-%m')
                    if year_month not in all_months:
                        # Skip lines outside the displayed month range
                        continue
                    
                    # Calculate period label
                    period_label = self._format_period_label(period_from, period_to)
                    
                    # Initialize product if first time within range
                    if product_number not in product_matrix:
                        for month_key in all_months:
                            product_matrix[product_number][month_key] = {
                                "amount": 0.0,
                                "status": "missing",
                                "invoice_number": None,
                                "period_from": None,
                                "period_to": None,
                                "period_label": None
                            }

                    # Update cell
                    cell = product_matrix[product_number][year_month]
                    cell["amount"] = amount  # Take last amount (or sum if multiple?)
                    cell["status"] = self._determine_status(invoice_status)
                    cell["invoice_number"] = invoice_number
                    cell["period_from"] = period_from.isoformat().split('T')[0]
                    cell["period_to"] = period_to.isoformat().split('T')[0]
                    cell["period_label"] = period_label
        
        except Exception as e:
            logger.error(f"❌ Error aggregating data: {e}")
        
        # Convert to output format
        products = []
        for product_number, months_data in sorted(product_matrix.items()):
            rows = []
            total_amount: float = 0.0
            total_paid: float = 0.0
            
            for year_month in sorted(months_data.keys()):
                cell = months_data[year_month]
                rows.append({
                    "year_month": year_month,
                    "amount": cell["amount"],
                    "status": cell["status"],
                    "invoice_number": cell["invoice_number"],
                    "period_label": cell["period_label"],
                    "period_from": cell["period_from"],
                    "period_to": cell["period_to"]
                })
                total_amount += cell["amount"]
                if cell["status"] == "paid":
                    total_paid += cell["amount"]
            
            products.append({
                "product_number": product_number,
                "product_name": product_names[product_number],
                "rows": rows,
                "total_amount": total_amount,
                "total_paid": total_paid
            })
        
        return products
    
    @staticmethod
    def _generate_month_range(num_months: int) -> List[str]:
        """
        Generate list of month keys for the last N months
        
        Args:
            num_months: Number of months to generate (e.g., 12)
            
        Returns:
            Sorted list of 'YYYY-MM' strings going back from today
        """
        months = []
        today = datetime.now()
        
        for i in range(num_months):
            # Go back i months from today using calendar arithmetic
            year = today.year
            month = today.month - i
            
            # Adjust year and month if month goes negative
            while month <= 0:
                month += 12
                year -= 1
            
            month_key = f"{year:04d}-{month:02d}"
            months.append(month_key)
        
        # Return sorted chronologically (oldest first)
        return sorted(months)
    
    @staticmethod
    def _format_period_label(period_from: datetime, period_to: datetime) -> str:
        """Format period as readable label (e.g., 'Jan', 'Jan-Mar', etc)"""
        from_month = period_from.strftime('%b')
        to_month = period_to.strftime('%b')
        from_year = period_from.year
        to_year = period_to.year
        
        # Calculate number of months
        months_diff = (period_to.year - period_from.year) * 12 + (period_to.month - period_from.month)
        
        if months_diff == 0:
            # Same month
            return from_month
        elif from_year == to_year:
            # Same year, different months
            return f"{from_month}-{to_month}"
        else:
            # Different years
            return f"{from_month} {from_year} - {to_month} {to_year}"
    
    @staticmethod
    def _determine_status(invoice_status: str) -> str:
        """Map e-conomic invoice status to matrix status"""
        status_map = {
            "sent": "invoiced",
            "paid": "paid",
            "draft": "draft",
            "credited": "credited",
            "unpaid": "invoiced",
            "booked": "invoiced"
        }
        result = status_map.get(invoice_status.lower() if invoice_status else 'unknown', invoice_status or 'unknown')
        return result if result else "unknown"


# Singleton instance
_matrix_service_instance = None

def get_subscription_matrix_service() -> SubscriptionMatrixService:
    """Get singleton instance of SubscriptionMatrixService"""
    global _matrix_service_instance
    if _matrix_service_instance is None:
        _matrix_service_instance = SubscriptionMatrixService()
    return _matrix_service_instance