"""Budget: Standard-Vorlage, geplante Einnahmen und die Monats-Soll/Ist-Ansicht."""

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session

from ..database import get_db
from ..deps import get_current_user, get_owned
from ..models import (
    Account,
    BudgetTemplateLine,
    Category,
    CategoryGroup,
    CategoryKind,
    PlannedIncomeLine,
    User,
)
from ..schemas import PlannedIncomeCreate, PlannedIncomeOut, PlannedIncomeUpdate
from ..services import budget
from .accounts import base_currency
from .settings import BUDGET_START_DAY_KEY, get_user_setting

router = APIRouter(prefix="/budget", tags=["budget"])


def _start_day(db: Session, user: User) -> int:
    return budget.start_tag(db, user)


def _require_expense_category(db: Session, user: User, category_id: int) -> Category:
    cat = get_owned(db, Category, category_id, user)
    if cat.type != CategoryKind.expense:
        raise HTTPException(status.HTTP_400_BAD_REQUEST, "Nur Ausgabe-Kategorien sind budgetierbar")
    return cat


# --- Standard-Vorlage ------------------------------------------------------


@router.get("/template")
def get_template(db: Session = Depends(get_db), user: User = Depends(get_current_user)) -> dict:
    lines = db.query(BudgetTemplateLine).filter(BudgetTemplateLine.owner_id == user.id).all()
    income = (
        db.query(PlannedIncomeLine)
        .filter(PlannedIncomeLine.owner_id == user.id)
        .order_by(PlannedIncomeLine.position, PlannedIncomeLine.id)
        .all()
    )
    return {
        "lines": [{"category_id": ln.category_id, "planned_cents": ln.planned_cents} for ln in lines],
        "income": [PlannedIncomeOut.model_validate(i).model_dump() for i in income],
    }


@router.put("/template/category/{category_id}")
def set_template_category(
    category_id: int,
    planned_cents: int,
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    _require_expense_category(db, user, category_id)
    line = (
        db.query(BudgetTemplateLine)
        .filter(BudgetTemplateLine.owner_id == user.id, BudgetTemplateLine.category_id == category_id)
        .first()
    )
    if planned_cents <= 0:
        if line is not None:
            db.delete(line)
            db.commit()
        return {"category_id": category_id, "planned_cents": 0}
    if line is None:
        line = BudgetTemplateLine(owner_id=user.id, category_id=category_id, planned_cents=planned_cents)
        db.add(line)
    else:
        line.planned_cents = planned_cents
    db.commit()
    return {"category_id": category_id, "planned_cents": planned_cents}


# --- Geplante Einnahmen ----------------------------------------------------


@router.post("/income", response_model=PlannedIncomeOut, status_code=status.HTTP_201_CREATED)
def create_income(
    payload: PlannedIncomeCreate, db: Session = Depends(get_db), user: User = Depends(get_current_user)
):
    if payload.category_id is not None:
        get_owned(db, Category, payload.category_id, user)
    if payload.target_account_id is not None:
        get_owned(db, Account, payload.target_account_id, user)
    max_pos = (
        db.query(PlannedIncomeLine.position)
        .filter(PlannedIncomeLine.owner_id == user.id)
        .order_by(PlannedIncomeLine.position.desc())
        .first()
    )
    line = PlannedIncomeLine(
        owner_id=user.id,
        label=payload.label.strip(),
        category_id=payload.category_id,
        target_account_id=payload.target_account_id,
        planned_cents=payload.planned_cents,
        position=(max_pos[0] + 1) if max_pos else 0,
    )
    db.add(line)
    db.commit()
    db.refresh(line)
    return line


@router.patch("/income/{income_id}", response_model=PlannedIncomeOut)
def update_income(
    income_id: int,
    payload: PlannedIncomeUpdate,
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
):
    line = get_owned(db, PlannedIncomeLine, income_id, user)
    data = payload.model_dump(exclude_unset=True)
    if "category_id" in data and data["category_id"] is not None:
        get_owned(db, Category, data["category_id"], user)
    if "target_account_id" in data and data["target_account_id"] is not None:
        get_owned(db, Account, data["target_account_id"], user)
    for key, value in data.items():
        setattr(line, key, value)
    db.commit()
    db.refresh(line)
    return line


@router.delete("/income/{income_id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_income(
    income_id: int, db: Session = Depends(get_db), user: User = Depends(get_current_user)
) -> None:
    line = get_owned(db, PlannedIncomeLine, income_id, user)
    db.delete(line)
    db.commit()


# --- Soll/Ist-Ansicht ------------------------------------------------------


def _build_view(db: Session, user: User, label: str) -> dict:
    base = base_currency(db, user)
    start_day = _start_day(db, user)
    start, end = budget.period_bounds(label, start_day)
    planned = budget.effective_planned(db, user, label)
    actual = budget.actual_expense_by_category(db, user, label, start, end, base)
    income_actual = budget.income_by_category(db, user, label, start, end, base)

    groups_out = []
    total_planned = total_actual = 0
    groups = (
        db.query(CategoryGroup)
        .filter(CategoryGroup.owner_id == user.id, CategoryGroup.kind == CategoryKind.expense)
        .order_by(CategoryGroup.position, CategoryGroup.name)
        .all()
    )
    for g in groups:
        cats = []
        g_planned = g_actual = 0
        for c in sorted(g.categories, key=lambda x: (x.position, x.name.lower())):
            if c.is_archived:
                continue
            p = planned.get(c.id, 0)
            a = actual.get(c.id, 0)
            g_planned += p
            g_actual += a
            cats.append({
                "category_id": c.id, "name": c.name, "icon": c.icon, "color": c.color,
                "planned_cents": p, "actual_cents": a, "delta_cents": p - a, "over": a > p,
                # "over" bleibt die nackte Tatsache; ob sie eine Warnung IST,
                # entscheidet die Kategorie. Wer mehr zuruecklegt als geplant,
                # hat nichts ueberzogen.
                "good": c.spending_is_good,
            })
        total_planned += g_planned
        total_actual += g_actual
        # Ueberschritten ist eine Gruppe an dem, was WIRKLICH zu viel war. Das
        # Sparen bleibt draussen: Sonst faerbt sich "Finanzen" rot, weil jemand
        # mehr zurueckgelegt hat als geplant – eine Warnung fuer etwas Gutes,
        # und daneben stuende die echte Ueberschreitung ununterscheidbar.
        # Angezeigt werden weiter die vollen Summen; nur das Urteil laesst das
        # Sparen aus.
        echt_geplant = sum(c["planned_cents"] for c in cats if not c["good"])
        echt_ist = sum(c["actual_cents"] for c in cats if not c["good"])
        groups_out.append({
            "id": g.id, "name": g.name, "icon": g.icon, "color": g.color,
            "planned_cents": g_planned, "actual_cents": g_actual,
            "over": echt_ist > echt_geplant,
            "good": bool(cats) and all(c["good"] for c in cats),
            "categories": cats,
        })

    income_lines = (
        db.query(PlannedIncomeLine)
        .filter(PlannedIncomeLine.owner_id == user.id)
        .order_by(PlannedIncomeLine.position, PlannedIncomeLine.id)
        .all()
    )
    income_out = []
    total_planned_income = total_received_income = 0
    for ln in income_lines:
        received = income_actual.get(ln.category_id, 0) if ln.category_id else 0
        total_planned_income += ln.planned_cents
        total_received_income += received
        income_out.append({
            "id": ln.id, "label": ln.label, "category_id": ln.category_id,
            "target_account_id": ln.target_account_id,
            "planned_cents": ln.planned_cents, "received_cents": received,
        })

    return {
        "label": label,
        "start": start.isoformat(),
        "end": end.isoformat(),
        "customized": budget.is_customized(db, user, label),
        "base_currency": base,
        "prev": budget.shift_label(label, -1),
        "next": budget.shift_label(label, 1),
        "groups": groups_out,
        "income": income_out,
        "totals": {
            "planned_expense": total_planned,
            "actual_expense": total_actual,
            "planned_income": total_planned_income,
            "received_income": total_received_income,
        },
    }


@router.get("/current")
def current(db: Session = Depends(get_db), user: User = Depends(get_current_user)) -> dict:
    return _build_view(db, user, budget.current_label(_start_day(db, user)))


@router.get("/{label}")
def view(label: str, db: Session = Depends(get_db), user: User = Depends(get_current_user)) -> dict:
    try:
        budget.parse_label(label)
    except (ValueError, IndexError):
        raise HTTPException(status.HTTP_400_BAD_REQUEST, "Ungültiges Monats-Label (YYYY-MM)")
    return _build_view(db, user, label)


@router.put("/{label}/category/{category_id}")
def set_month_category(
    label: str,
    category_id: int,
    planned_cents: int,
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    budget.parse_label(label)
    _require_expense_category(db, user, category_id)
    budget.set_month_category(db, user, label, category_id, max(0, planned_cents))
    return _build_view(db, user, label)


@router.delete("/{label}")
def reset_month(
    label: str, db: Session = Depends(get_db), user: User = Depends(get_current_user)
) -> dict:
    budget.parse_label(label)
    budget.reset_month(db, user, label)
    return _build_view(db, user, label)


# --- Kopieren Monat <-> Vorlage --------------------------------------------


@router.post("/template/from-month/{label}")
def template_from_month(
    label: str, db: Session = Depends(get_db), user: User = Depends(get_current_user)
) -> dict:
    """„Diesen Monat als Standard festlegen": Monat -> Vorlage."""
    budget.parse_label(label)
    budget.copy_month_to_template(db, user, label)
    return get_template(db, user)


@router.post("/{label}/from-template")
def month_from_template(
    label: str, db: Session = Depends(get_db), user: User = Depends(get_current_user)
) -> dict:
    """„Standard in diesen Monat übernehmen": Vorlage -> Monat (überschreibt)."""
    budget.parse_label(label)
    budget.copy_template_to_month(db, user, label)
    return _build_view(db, user, label)