"""Dashboard: pro Nutzer gespeichertes Karten-Layout und die Datenendpunkte je Karte."""

import json
from collections import defaultdict
from datetime import date, timedelta

from fastapi import APIRouter, Body, Depends, Query
from sqlalchemy.orm import Session

from ..database import get_db
from ..deps import get_current_user
from ..models import (
    Account,
    Category,
    CategoryGroup,
    CategoryKind,
    DashboardLayout,
    Transaction,
    TxnType,
    User,
)
from ..services import balances, budget, currency
from .accounts import base_currency
from .settings import BUDGET_START_DAY_KEY, get_user_setting

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

# Sinnvolles Standard-Layout (12-Spalten-Raster). Eine Karte je Typ.
DEFAULT_LAYOUT = [
    {"i": "account-balances", "type": "account-balances", "x": 0, "y": 0, "w": 4, "h": 5},
    {"i": "budget-donut", "type": "budget-donut", "x": 4, "y": 0, "w": 4, "h": 5},
    {"i": "income-expense", "type": "income-expense", "x": 8, "y": 0, "w": 4, "h": 2},
    {"i": "budget-progress", "type": "budget-progress", "x": 8, "y": 2, "w": 4, "h": 3},
    {"i": "net-worth", "type": "net-worth", "x": 0, "y": 5, "w": 8, "h": 4},
    {"i": "recent-transactions", "type": "recent-transactions", "x": 8, "y": 5, "w": 4, "h": 4},
]


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


def _label(db: Session, user: User) -> str:
    return budget.current_label(_start_day(db, user))


# --- Layout ----------------------------------------------------------------


@router.get("/layout")
def get_layout(db: Session = Depends(get_db), user: User = Depends(get_current_user)) -> dict:
    row = db.query(DashboardLayout).filter(DashboardLayout.owner_id == user.id).first()
    if row is None:
        return {"layout": DEFAULT_LAYOUT, "default": True}
    try:
        layout = json.loads(row.layout)
    except ValueError:
        layout = DEFAULT_LAYOUT
    return {"layout": layout, "default": False}


@router.put("/layout")
def save_layout(
    layout: list = Body(...),
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    row = db.query(DashboardLayout).filter(DashboardLayout.owner_id == user.id).first()
    if row is None:
        row = DashboardLayout(owner_id=user.id, layout=json.dumps(layout))
        db.add(row)
    else:
        row.layout = json.dumps(layout)
    db.commit()
    return {"layout": layout, "default": False}


@router.delete("/layout")
def reset_layout(db: Session = Depends(get_db), user: User = Depends(get_current_user)) -> dict:
    row = db.query(DashboardLayout).filter(DashboardLayout.owner_id == user.id).first()
    if row is not None:
        db.delete(row)
        db.commit()
    return {"layout": DEFAULT_LAYOUT, "default": True}


# --- Kartendaten -----------------------------------------------------------


def _expense_groups(db: Session, user: User) -> list[CategoryGroup]:
    return (
        db.query(CategoryGroup)
        .filter(CategoryGroup.owner_id == user.id, CategoryGroup.kind == CategoryKind.expense)
        .order_by(CategoryGroup.position, CategoryGroup.name)
        .all()
    )


def _units(groups: list[CategoryGroup], by_category: bool):
    """Liefert je Anzeige-Einheit (name, farbe, [kategorie-ids]). Bei ``by_category``
    ist jede Kategorie eine eigene Einheit, sonst jede Gruppe (Summe ihrer Kategorien)."""
    for g in groups:
        if by_category:
            for c in g.categories:
                if not c.is_archived:
                    yield (c.name, c.color, [c.id])
        else:
            yield (g.name, g.color, [c.id for c in g.categories if not c.is_archived])


def _kein_verlust(groups: list[CategoryGroup]) -> set[int]:
    """Kategorien, deren Ausgabe kein Verlust ist (Sparen, Ruecklagen).

    Ihre Betraege stehen neutral statt rot, und mehr als geplant ist bei ihnen
    keine Warnung.
    """
    return {c.id for g in groups for c in g.categories if c.spending_is_good}


@router.get("/budget-donut")
def budget_donut(
    group_by: str = Query(default="group"),
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    base = base_currency(db, user)
    label = _label(db, user)
    start, end = budget.period_bounds(label, _start_day(db, user))
    planned = budget.effective_planned(db, user, label)
    groups = _expense_groups(db, user)
    by_category = group_by == "category"

    def collect(values: dict[int, int]):
        segs, tot = [], 0
        for name, color, ids in _units(groups, by_category):
            val = sum(values.get(i, 0) for i in ids)
            if val > 0:
                segs.append({"name": name, "value": val, "color": color})
                tot += val
        return segs, tot

    segments, total = collect(planned)
    mode = "planned"
    if total == 0:
        segments, total = collect(budget.actual_expense_by_category(db, user, label, start, end, base))
        mode = "actual"
    return {"segments": segments, "total": total, "currency": base, "mode": mode,
            "label": label, "group_by": "category" if by_category else "group"}


@router.get("/expense-share")
def expense_share(
    group_by: str = Query(default="category"),
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    """Tatsächliche Ausgaben des laufenden Budget-Monats je Kategorie/Gruppe.

    Anders als der Budget-Donut zeigt das rein die Ist-Ausgaben – unabhängig
    davon, ob für den Monat überhaupt geplant wurde. Die Anteile rechnet die
    Oberfläche aus `amount` und `total`, damit sich gerundete Prozente nicht zu
    99,9 % addieren."""
    base = base_currency(db, user)
    label = _label(db, user)
    start, end = budget.period_bounds(label, _start_day(db, user))
    actual = budget.actual_expense_by_category(db, user, label, start, end, base)
    # Das Geplante kommt mit, damit die Karte zeigen kann, ob ein Anteil noch
    # im Rahmen liegt. Ohne Plan wird nichts behauptet: „ueber Budget" waere
    # sonst die Aussage ueber jede Kategorie, fuer die nie eine gemacht wurde.
    planned = budget.effective_planned(db, user, label)
    by_category = group_by != "group"

    # Als Liste: ``_units`` ist ein Generator, und er wird hier zweimal
    # gebraucht – beim zweiten Mal waere er leer und das Geplante 0.
    gruppen = _expense_groups(db, user)
    gut = _kein_verlust(gruppen)
    einheiten = list(_units(gruppen, by_category))
    rows = []
    for name, color, ids in einheiten:
        val = sum(actual.get(i, 0) for i in ids)
        if val > 0:
            geplant = sum(planned.get(i, 0) for i in ids)
            # Ueberschritten ist die Zeile an dem, was WIRKLICH zu viel war –
            # das Sparen bleibt beim Urteil draussen, nicht beim Betrag.
            echt_geplant = sum(planned.get(i, 0) for i in ids if i not in gut)
            echt_ist = sum(actual.get(i, 0) for i in ids if i not in gut)
            rows.append({"name": name, "color": color, "amount": val,
                         "planned": geplant,
                         "over": echt_geplant > 0 and echt_ist > echt_geplant,
                         "good": bool(ids) and all(i in gut for i in ids),
                         # Womit sich die Zeile aufschluesseln laesst.
                         "ids": list(ids)})
    rows.sort(key=lambda r: r["amount"], reverse=True)

    # Das Geplante ueber ALLE Ausgaben-Einheiten, nicht nur die mit Ausgaben:
    # Der Monatsplan umfasst auch, wofuer noch nichts ausgegeben wurde.
    gesamt = sum(r["amount"] for r in rows)
    gesamt_geplant = sum(planned.get(i, 0) for _, _, ids in einheiten for i in ids)
    return {
        "rows": rows,
        "total": gesamt,
        "total_planned": gesamt_geplant,
        "total_over": gesamt_geplant > 0 and gesamt > gesamt_geplant,
        # Der Zeitraum gehoert dazu: Bei einem Budget-Monat, der nicht am
        # Ersten beginnt, ist sonst nicht nachvollziehbar, welche Buchungen
        # ueberhaupt gezaehlt wurden.
        "von": start.isoformat(),
        "bis": end.isoformat(),
        "currency": base,
        "label": label,
        "group_by": "category" if by_category else "group",
    }


@router.get("/expense-share/buchungen")
def expense_share_rows(
    ids: list[int] = Query(default=[]),
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    """Die einzelnen Buchungen hinter einem Anteil.

    Eine Zahl, die man nicht aufschluesseln kann, muss man glauben. Diese hier
    kommt aus derselben Stelle wie die Summe auf der Karte – was hier steht,
    ist genau das, was dort gezaehlt wurde, nicht eine zweite Suche mit
    aehnlichen Bedingungen.
    """
    base = base_currency(db, user)
    label = _label(db, user)
    start, end = budget.period_bounds(label, _start_day(db, user))
    gesucht = set(ids)

    konten = {a.id: a for a in db.query(Account).filter(Account.owner_id == user.id)}
    zeilen = []
    for cat_id, txn, cents in budget.expense_rows(db, user, label, start, end, base):
        if gesucht and cat_id not in gesucht:
            continue
        konto = konten.get(txn.account_id)
        zeilen.append({
            "id": txn.id,
            "date": txn.date.isoformat(),
            "title": txn.payee or txn.description or "",
            "account": konto.name if konto else "",
            # Beides: Der Betrag, wie er auf dem Konto steht, UND der, mit dem
            # gerechnet wurde. Weichen sie ab, liegt es an der Umrechnung – und
            # das sieht man dann sofort.
            "amount_cents": txn.amount_cents,
            "currency": konto.currency if konto else base,
            "base_cents": cents,
            "type": txn.type.value,
            "budget_period_manuell": txn.budget_period is not None,
        })
    zeilen.sort(key=lambda z: (z["date"], z["id"]))
    return {"rows": zeilen, "total": sum(z["base_cents"] for z in zeilen),
            "currency": base, "von": start.isoformat(), "bis": end.isoformat()}


@router.get("/budget-progress")
def budget_progress(
    group_by: str = Query(default="group"),
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    base = base_currency(db, user)
    label = _label(db, user)
    start, end = budget.period_bounds(label, _start_day(db, user))
    planned = budget.effective_planned(db, user, label)
    actual = budget.actual_expense_by_category(db, user, label, start, end, base)
    by_category = group_by == "category"
    gruppen = _expense_groups(db, user)
    gut = _kein_verlust(gruppen)
    rows = []
    for name, color, ids in _units(gruppen, by_category):
        gp = sum(planned.get(i, 0) for i in ids)
        ga = sum(actual.get(i, 0) for i in ids)
        if gp > 0 or ga > 0:
            echt_geplant = sum(planned.get(i, 0) for i in ids if i not in gut)
            echt_ist = sum(actual.get(i, 0) for i in ids if i not in gut)
            rows.append({"name": name, "color": color, "planned": gp, "actual": ga,
                         "over": echt_ist > echt_geplant,
                         "good": bool(ids) and all(i in gut for i in ids)})
    return {"rows": rows, "currency": base, "label": label,
            "group_by": "category" if by_category else "group"}


@router.get("/income-expense")
def income_expense(db: Session = Depends(get_db), user: User = Depends(get_current_user)) -> dict:
    base = base_currency(db, user)
    label = _label(db, user)
    start, end = budget.period_bounds(label, _start_day(db, user))
    expense = sum(budget.actual_expense_by_category(db, user, label, start, end, base).values())
    income = sum(budget.income_by_category(db, user, label, start, end, base).values())
    return {"income": income, "expense": expense, "net": income - expense, "currency": base, "label": label}


@router.get("/balances")
def dashboard_balances(db: Session = Depends(get_db), user: User = Depends(get_current_user)) -> dict:
    base = base_currency(db, user)
    today = date.today()
    accounts = (
        db.query(Account)
        .filter(Account.owner_id == user.id)
        .order_by(Account.position, Account.name)
        .all()
    )
    rows = []
    total = 0
    gebunden = 0
    for a in accounts:
        bb = balances.account_balance_base_cents(db, a, base, today)
        rows.append({
            "id": a.id, "name": a.name, "icon": a.icon, "color": a.color,
            "currency": a.currency, "balance_cents": balances.account_balance_cents(db, a),
            "balance_base_cents": bb, "archived": a.is_archived, "locked": a.is_locked,
        })
        if a.is_archived:
            continue
        # Gesperrtes Geld steht neben der Summe, nicht darin: Die Frage, die
        # diese Zahl beantwortet, ist „wie viel habe ich zur Verfuegung".
        # Verschwinden darf es trotzdem nicht – es gehoert dem Nutzer.
        if a.is_locked:
            gebunden += bb
        else:
            total += bb
    return {"accounts": rows, "total": total, "gebunden": gebunden, "currency": base}


@router.get("/net-worth")
def net_worth(
    days: int = Query(default=90, ge=7, le=365),
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    base = base_currency(db, user)
    end = date.today()
    start = end - timedelta(days=days - 1)

    accounts = db.query(Account).filter(Account.owner_id == user.id, Account.is_archived == False).all()  # noqa: E712
    acc_by_id = {a.id: a for a in accounts}

    def to_eur(cents: int, ccy: str, on: date) -> int:
        v = currency.to_eur_cents(db, cents, ccy, on)
        return v if v is not None else cents

    opening_eur = sum(to_eur(a.opening_balance_cents, a.currency, a.opening_date or start) for a in accounts)

    def zaehlt(acc: Account | None, on: date) -> bool:
        """Buchungen bis zum Stichtag stecken schon im Anfangssaldo."""
        return acc is not None and (acc.opening_date is None or on > acc.opening_date)

    def eur_effect(t: Transaction) -> int:
        # Jede Seite wird für sich geprüft: Der Stichtag des Quellkontos kann
        # anders liegen als der des Zielkontos.
        effekt = 0
        if zaehlt(acc_by_id.get(t.account_id), t.date):
            effekt += t.amount_eur_cents if t.type == TxnType.income else -t.amount_eur_cents
        if t.type == TxnType.transfer:
            to_acc = acc_by_id.get(t.to_account_id) if t.to_account_id else None
            if zaehlt(to_acc, t.date):
                credited = t.to_amount_cents if t.to_amount_cents is not None else t.amount_cents
                effekt += to_eur(credited, to_acc.currency, t.date)
        return effekt

    txns = db.query(Transaction).filter(
        Transaction.owner_id == user.id, Transaction.account_id.in_(list(acc_by_id.keys()) or [0])
    ).all() if acc_by_id else []

    before = sum(eur_effect(t) for t in txns if t.date < start)
    deltas: dict[date, int] = defaultdict(int)
    for t in txns:
        if start <= t.date <= end:
            deltas[t.date] += eur_effect(t)

    running = opening_eur + before
    labels: list[str] = []
    values_eur: list[int] = []
    d = start
    while d <= end:
        running += deltas.get(d, 0)
        labels.append(d.isoformat())
        values_eur.append(running)
        d += timedelta(days=1)

    if base != "EUR":
        rate = currency.rate_on(db, base, end)
        if rate is not None:
            values_eur = [int(round(v * float(rate))) for v in values_eur]
    return {"labels": labels, "values": values_eur, "currency": base}


@router.get("/recent")
def recent(
    limit: int = Query(default=8, le=50),
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    base = base_currency(db, user)
    accs = {a.id: a for a in db.query(Account).filter(Account.owner_id == user.id)}
    cats = {c.id: c for c in db.query(Category).filter(Category.owner_id == user.id)}
    rows = (
        db.query(Transaction)
        .filter(Transaction.owner_id == user.id)
        .order_by(Transaction.date.desc(), Transaction.id.desc())
        .limit(limit)
        .all()
    )
    out = []
    for t in rows:
        acc = accs.get(t.account_id)
        if t.type == TxnType.transfer:
            to = accs.get(t.to_account_id)
            title = f"{acc.name if acc else '?'} → {to.name if to else '?'}"
            icon, color, sign = "arrow-left-right", "#6b7480", None
        else:
            cat = cats.get(t.category_id) if t.category_id else None
            title = cat.name if cat else (t.payee or "—")
            icon = cat.icon if cat else "more-horizontal"
            color = cat.color if cat else "#6b7480"
            sign = "pos" if t.type == TxnType.income else "neg"
        out.append({
            "id": t.id, "date": t.date.isoformat(), "type": t.type.value,
            "title": title, "icon": icon, "color": color, "sign": sign,
            "amount_cents": t.amount_cents, "currency": acc.currency if acc else "EUR",
            "amount_base_cents": t.amount_eur_cents if base == "EUR"
            else (currency.from_eur_cents(db, t.amount_eur_cents, base, t.date) or t.amount_eur_cents),
        })
    return {"transactions": out, "currency": base}