"""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:
    try:
        return max(1, min(31, int(get_user_setting(db, user, BUDGET_START_DAY_KEY) or "1")))
    except ValueError:
        return 1


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])


@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, 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, start, end, base)
    by_category = group_by != "group"

    rows = []
    for name, color, ids in _units(_expense_groups(db, user), by_category):
        val = sum(actual.get(i, 0) for i in ids)
        if val > 0:
            rows.append({"name": name, "color": color, "amount": val})
    rows.sort(key=lambda r: r["amount"], reverse=True)
    return {
        "rows": rows,
        "total": sum(r["amount"] for r in rows),
        "currency": base,
        "label": label,
        "group_by": "category" if by_category else "group",
    }


@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, start, end, base)
    by_category = group_by == "category"
    rows = []
    for name, color, ids in _units(_expense_groups(db, user), 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:
            rows.append({"name": name, "color": color, "planned": gp, "actual": ga, "over": ga > gp})
    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, start, end, base).values())
    income = sum(budget.income_by_category(db, user, 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
    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,
        })
        if not a.is_archived:
            total += bb
    return {"accounts": rows, "total": total, "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}