debt-manager/backend/app/api/debts.py

from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func
from datetime import datetime
from app.core.database import get_db
from app.models.models import User, Debt, RepaymentPlan, RepaymentRecord, DebtStatus, PlanStatus
from app.schemas.schemas import (
    DebtCreate, DebtUpdate, DebtResponse,
    RepaymentPlanResponse, RepaymentRecordCreate, RepaymentRecordResponse,
)
from app.core.deps import get_current_user
from app.services.calculator import generate_repayment_plan

router = APIRouter(prefix="/debts", tags=["债务管理"])


def _naive(dt: datetime) -> datetime:
    if dt and dt.tzinfo:
        return dt.replace(tzinfo=None)
    return dt


async def _enrich(db: AsyncSession, d: Debt) -> DebtResponse:
    dr = DebtResponse.model_validate(d)
    pr = await db.execute(select(func.coalesce(func.sum(RepaymentRecord.amount), 0)).where(RepaymentRecord.debt_id == d.id))
    dr.total_paid = pr.scalar()
    ir = await db.execute(select(func.coalesce(func.sum(RepaymentPlan.interest_due), 0)).where(RepaymentPlan.debt_id == d.id))
    dr.total_interest = ir.scalar()
    owner = await db.execute(select(User.nickname, User.email).where(User.id == d.user_id))
    row = owner.first()
    dr.owner_name = row[0] or row[1] if row else ""
    return dr


@router.get("", response_model=list[DebtResponse])
async def list_debts(
    status: str | None = None,
    creditor: str | None = None,
    page: int = Query(1, ge=1),
    size: int = Query(20, ge=1, le=100),
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    q = select(Debt)
    if user.role != "admin":
        q = q.where(Debt.user_id == user.id)
    if status:
        q = q.where(Debt.status == status)
    if creditor:
        q = q.where(Debt.creditor_name.ilike(f"%{creditor}%"))
    q = q.order_by(Debt.created_at.desc()).offset((page - 1) * size).limit(size)
    result = await db.execute(q)
    debts = result.scalars().all()
    return [await _enrich(db, d) for d in debts]


@router.post("", response_model=DebtResponse, status_code=201)
async def create_debt(
    req: DebtCreate,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    debt = Debt(
        user_id=user.id, creditor_name=req.creditor_name, amount=req.amount,
        borrow_date=_naive(req.borrow_date), interest_rate=req.interest_rate,
        rate_type=req.rate_type, repayment_method=req.repayment_method,
        period_count=req.period_count, period_unit=req.period_unit, notes=req.notes,
    )
    db.add(debt)
    await db.flush()

    plans = generate_repayment_plan(
        req.amount, req.interest_rate, req.rate_type,
        req.repayment_method, req.period_count, req.period_unit,
        _naive(req.borrow_date),
    )
    for p in plans:
        db.add(RepaymentPlan(debt_id=debt.id, **p))
    await db.commit()
    await db.refresh(debt)
    return await _enrich(db, debt)


@router.get("/{debt_id}", response_model=DebtResponse)
async def get_debt(
    debt_id: int,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(select(Debt).where(Debt.id == debt_id))
    debt = result.scalar_one_or_none()
    if not debt:
        raise HTTPException(status_code=404, detail="债务不存在")
    if debt.user_id != user.id and user.role != "admin":
        raise HTTPException(status_code=403, detail="无权访问此债务")
    return await _enrich(db, debt)


@router.put("/{debt_id}", response_model=DebtResponse)
async def update_debt(
    debt_id: int,
    req: DebtUpdate,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(select(Debt).where(Debt.id == debt_id))
    debt = result.scalar_one_or_none()
    if not debt:
        raise HTTPException(status_code=404, detail="债务不存在")
    if debt.user_id != user.id and user.role != "admin":
        raise HTTPException(status_code=403, detail="无权修改此债务")
    if debt.status not in ("active",):
        raise HTTPException(status_code=400, detail="该债务不可修改")
    data = req.model_dump(exclude_unset=True)
    for k, v in data.items():
        setattr(debt, k, _naive(v) if k == "borrow_date" else v)
    if any(k in data for k in ["amount", "interest_rate", "rate_type", "repayment_method", "period_count", "period_unit", "borrow_date"]):
        await db.execute(select(RepaymentPlan).where(RepaymentPlan.debt_id == debt.id).delete())
        plans = generate_repayment_plan(
            debt.amount, debt.interest_rate, debt.rate_type,
            debt.repayment_method, debt.period_count, debt.period_unit,
            _naive(debt.borrow_date),
        )
        for p in plans:
            db.add(RepaymentPlan(debt_id=debt.id, **p))
    await db.commit()
    await db.refresh(debt)
    return await _enrich(db, debt)


@router.delete("/{debt_id}")
async def delete_debt(
    debt_id: int,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(select(Debt).where(Debt.id == debt_id))
    debt = result.scalar_one_or_none()
    if not debt:
        raise HTTPException(status_code=404, detail="债务不存在")
    if debt.user_id != user.id and user.role != "admin":
        raise HTTPException(status_code=403, detail="无权删除此债务")
    has_records = await db.execute(select(func.count(RepaymentRecord.id)).where(RepaymentRecord.debt_id == debt.id))
    if has_records.scalar() > 0:
        debt.status = DebtStatus.CLOSED.value
        await db.commit()
        return {"message": "已有还款记录，债务已归档"}
    await db.delete(debt)
    await db.commit()
    return {"message": "债务已删除"}


@router.get("/{debt_id}/plans", response_model=list[RepaymentPlanResponse])
async def get_plans(
    debt_id: int,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(select(Debt).where(Debt.id == debt_id))
    debt = result.scalar_one_or_none()
    if not debt:
        raise HTTPException(status_code=404, detail="债务不存在")
    if debt.user_id != user.id and user.role != "admin":
        raise HTTPException(status_code=403, detail="无权访问此债务")
    pr = await db.execute(select(RepaymentPlan).where(RepaymentPlan.debt_id == debt_id).order_by(RepaymentPlan.due_date))
    return pr.scalars().all()


@router.get("/{debt_id}/records", response_model=list[RepaymentRecordResponse])
async def get_records(
    debt_id: int,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(select(Debt).where(Debt.id == debt_id))
    debt = result.scalar_one_or_none()
    if not debt:
        raise HTTPException(status_code=404, detail="债务不存在")
    if debt.user_id != user.id and user.role != "admin":
        raise HTTPException(status_code=403, detail="无权访问此债务")
    rr = await db.execute(select(RepaymentRecord).where(RepaymentRecord.debt_id == debt_id).order_by(RepaymentRecord.paid_date.desc()))
    return rr.scalars().all()