backend/app/loans/router.py

from typing import Optional

from fastapi import APIRouter, Depends, Query
from pydantic import BaseModel, Field
from sqlalchemy.orm import Session

from app.database.database import get_db
from app.database.models import User
from app.loans.service import analyze_loan

router = APIRouter(prefix="/api/loans", tags=["Loans"])


def _resolve_user(db: Session, user_id: Optional[str]) -> str:
    if user_id:
        return user_id
    user = db.query(User).first()
    if user:
        return user.id
    return "anonymous"


class LoanEligibilityRequest(BaseModel):
    salary: float = Field(gt=0, description="Annual salary in USD")
    credit_score: int = Field(ge=300, le=850)
    existing_loans: int = Field(ge=0, le=20)
    employment_years: float = Field(ge=0, le=50)
    age: int = Field(ge=18, le=80)
    loan_amount: float = Field(gt=0)


@router.post("/eligibility")
def loan_eligibility(
    body: LoanEligibilityRequest,
    user_id: Optional[str] = None,
    db: Session = Depends(get_db),
):
    _resolve_user(db, user_id)
    return analyze_loan(
        body.salary,
        body.credit_score,
        body.existing_loans,
        body.employment_years,
        body.age,
        body.loan_amount,
    )


@router.get("/comparison")
def loan_comparison(
    loan_amount: float = Query(..., gt=0),
    user_id: Optional[str] = None,
    db: Session = Depends(get_db),
):
    _resolve_user(db, user_id)
    result = analyze_loan(85000, 720, 1, 4, 32, loan_amount)
    return {"loan_amount": loan_amount, "comparison": result["comparison"]}