import math
from typing import List
from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.orm import Session

from app.db.session import get_db
from app.schemas.calculation import CalculationCreate, CalculationResponse
from app.crud import calculation

router = APIRouter()

def perform_calculation(calc: CalculationCreate) -> float:
    """Perform the calculation based on the operation and numbers provided."""
    if calc.operation == "add":
        if calc.second_number is None:
            raise HTTPException(status_code=400, detail="Second number is required for addition")
        return calc.first_number + calc.second_number
    
    elif calc.operation == "subtract":
        if calc.second_number is None:
            raise HTTPException(status_code=400, detail="Second number is required for subtraction")
        return calc.first_number - calc.second_number
    
    elif calc.operation == "multiply":
        if calc.second_number is None:
            raise HTTPException(status_code=400, detail="Second number is required for multiplication")
        return calc.first_number * calc.second_number
    
    elif calc.operation == "divide":
        if calc.second_number is None:
            raise HTTPException(status_code=400, detail="Second number is required for division")
        if calc.second_number == 0:
            raise HTTPException(status_code=400, detail="Cannot divide by zero")
        return calc.first_number / calc.second_number
    
    elif calc.operation == "square_root":
        if calc.first_number < 0:
            raise HTTPException(status_code=400, detail="Cannot calculate square root of a negative number")
        return math.sqrt(calc.first_number)
    
    else:
        raise HTTPException(
            status_code=400, 
            detail="Invalid operation. Supported operations: add, subtract, multiply, divide, square_root"
        )

@router.post("/", response_model=CalculationResponse)
def calculate(calc: CalculationCreate, db: Session = Depends(get_db)):
    """
    Perform a calculation and store it in the database.
    
    - **operation**: add, subtract, multiply, divide, or square_root
    - **first_number**: First operand
    - **second_number**: Second operand (not required for square_root)
    """
    result = perform_calculation(calc)
    db_calc = calculation.create_calculation(db=db, calc=calc, result=result)
    return db_calc

@router.get("/history", response_model=List[CalculationResponse])
def get_calculation_history(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
    """
    Retrieve calculation history.
    """
    calcs = calculation.get_calculations(db, skip=skip, limit=limit)
    return calcs

@router.get("/{calculation_id}", response_model=CalculationResponse)
def get_calculation_by_id(calculation_id: int, db: Session = Depends(get_db)):
    """
    Retrieve a specific calculation by ID.
    """
    db_calc = calculation.get_calculation(db, calculation_id=calculation_id)
    if db_calc is None:
        raise HTTPException(status_code=404, detail="Calculation not found")
    return db_calc