"""
LEDGER CSV Importer
"""
from typing import Dict, List, Any
from datetime import date
from sqlalchemy.orm import Session

from .base import BaseCSVImporter, ImportValidationError
from app.models.ledger import Ledger
from app.models.files import File


class LedgerCSVImporter(BaseCSVImporter):
    """CSV importer for LEDGER table"""
    
    @property
    def table_name(self) -> str:
        return "ledger"
        
    @property
    def required_fields(self) -> List[str]:
        return ["file_no", "date", "t_code", "t_type", "empl_num", "amount"]
        
    @property
    def field_mapping(self) -> Dict[str, str]:
        """Map CSV headers to database field names"""
        return {
            "file_no": "file_no",
            "item_no": "item_no",
            "date": "date",
            "t_code": "t_code",
            "t_type": "t_type",
            "t_type_l": "t_type_l",
            "empl_num": "empl_num",
            "quantity": "quantity",
            "rate": "rate",
            "amount": "amount",
            "billed": "billed",
            "note": "note"
        }
        
    def create_model_instance(self, row_data: Dict[str, Any]) -> Ledger:
        """Create a Ledger instance from processed row data"""
        
        # Validate required fields
        required_checks = [
            ("file_no", "File number"),
            ("date", "Date"),
            ("t_code", "Transaction code"),
            ("t_type", "Transaction type"),
            ("empl_num", "Employee number"),
            ("amount", "Amount")
        ]
        
        for field, display_name in required_checks:
            if not row_data.get(field):
                raise ImportValidationError(f"{display_name} is required")
                
        # Validate foreign key exists (file number)
        file_exists = self.db_session.query(File).filter_by(file_no=row_data["file_no"]).first()
        if not file_exists:
            raise ImportValidationError(f"File number '{row_data['file_no']}' does not exist")
            
        # Parse date
        try:
            transaction_date = self.parse_date(row_data["date"])
        except ValueError as e:
            raise ImportValidationError(f"Invalid date: {e}")
            
        # Parse numeric fields
        try:
            item_no = 1  # Default
            if row_data.get("item_no"):
                item_no = self.parse_int(row_data["item_no"])
                if item_no < 1:
                    raise ImportValidationError("Item number must be positive")
        except ValueError as e:
            raise ImportValidationError(f"Invalid item number: {e}")
            
        try:
            quantity = self.parse_float(row_data.get("quantity", "0"))
            rate = self.parse_float(row_data.get("rate", "0"))
            amount = self.parse_float(row_data["amount"])
        except ValueError as e:
            raise ImportValidationError(f"Invalid numeric value: {e}")
            
        # Validate transaction code and type
        t_code = self.normalize_string(row_data["t_code"], 10)
        t_type = self.normalize_string(row_data["t_type"], 1)
        t_type_l = self.normalize_string(row_data.get("t_type_l", ""), 1)
        
        # Validate billed field (Y/N)
        billed = row_data.get("billed", "N").strip().upper()
        if billed not in ["Y", "N", ""]:
            billed = "N"  # Default to N if invalid
            
        # Create instance
        ledger = Ledger(
            file_no=self.normalize_string(row_data["file_no"], 45),
            item_no=item_no,
            date=transaction_date,
            t_code=t_code,
            t_type=t_type,
            t_type_l=t_type_l,
            empl_num=self.normalize_string(row_data["empl_num"], 10),
            quantity=quantity,
            rate=rate,
            amount=amount,
            billed=billed,
            note=row_data.get("note", "")  # Text field
        )
        
        return ledger