"""Курсы валют: источник ЦБ РФ, 4 запроса в сутки (каждые 6 часов).

По ТЗ до подключения сервиса используются мок-курсы; источник выбирается
в настройках (cbr | mock). Значения хранятся в БД вместе с временем
обновления и выдаются наружу для вкладки «Валюта и курсы».
"""
from __future__ import annotations

import json
import logging
import time

import httpx

from .. import constants as C
from ..db import store

log = logging.getLogger("leadradar.rates")

_FETCH_INTERVAL_MS = 6 * C.HOUR_MS  # 4 раза в сутки


def get_rates() -> dict:
    row = store.query_one("SELECT rates, source, updated_at FROM rates WHERE id = 1")
    rates = json.loads(row["rates"]) if row else dict(C.MOCK_RATES)
    return {
        "base": "RUB",
        "rates": rates,
        "source": row["source"] if row else "mock",
        "updatedAt": row["updated_at"] if row else None,
    }


def save_rates(rates: dict, source: str) -> None:
    store.execute(
        "INSERT INTO rates(id, rates, source, updated_at) VALUES (1, ?, ?, ?) "
        "ON CONFLICT(id) DO UPDATE SET rates = excluded.rates, source = excluded.source, "
        "updated_at = excluded.updated_at",
        [json.dumps(rates), source, time.time_ns() // 1_000_000],
    )


async def fetch_cbr() -> dict | None:
    """Запрос к ЦБ РФ (JSON-зеркало daily_json.js). Возвращает rates к RUB."""
    try:
        async with httpx.AsyncClient(timeout=15) as client:
            resp = await client.get(C.CBR_URL)
            resp.raise_for_status()
            payload = resp.json()
        rates: dict = {"RUB": 1.0}
        for code, item in payload.get("Valute", {}).items():
            # 1 единица валюты в рублях: Nominal может быть > 1
            nominal = int(item.get("Nominal", 1)) or 1
            value = float(item.get("Value", 0))
            rates[code] = round(value / nominal, 6)
        return rates
    except Exception as exc:  # noqa: BLE001
        log.warning("CBR fetch failed: %s", exc)
        return None


async def refresh_rates(force_source: str | None = None) -> bool:
    """Ручное/фоновое обновление. Возвращает True при успехе (или при мок-режиме)."""
    source = force_source or store.get_setting("rateSource") or "cbr"
    if source == "mock":
        save_rates(dict(C.MOCK_RATES), "mock")
        recompute_conversions()
        return True
    rates = await fetch_cbr()
    if rates is None:
        return False
    save_rates(rates, "cbr")
    recompute_conversions()
    return True


def should_fetch() -> bool:
    row = store.query_one("SELECT updated_at, source FROM rates WHERE id = 1")
    if not row:
        return True
    if row["source"] == "mock" and store.get_setting("rateSource") == "cbr":
        return True
    return time.time_ns() // 1_000_000 - row["updated_at"] >= _FETCH_INTERVAL_MS


def _resolve_rate(rates: dict, code: str) -> float | None:
    """USDT приравниваем к USD (у ЦБ нет тикера USDT)."""
    if code == "USDT" and "USD" in rates:
        return float(rates["USD"])
    val = rates.get(code)
    return float(val) if val is not None else None


def convert_amount(amount: float | int | None, from_cur: str, to_cur: str) -> float | None:
    """amount в from_cur -> to_cur по актуальным курсам (к рублю)."""
    if amount is None:
        return None
    rates = json.loads(store.query_one("SELECT rates FROM rates WHERE id = 1")["rates"])
    rf = _resolve_rate(rates, from_cur)
    rt = _resolve_rate(rates, to_cur)
    if rf is None or rt is None:
        return None
    return round(float(amount) * rf / rt, 2)


def recompute_conversions() -> int:
    """Пересчёт старых карточек по актуальному курсу и целевой валюте.

    Пересчитываются карточки на канбане и в «Неразобранном»; архивные,
    корзинные и ушедшие в «Выбранные» (taken) не трогаем.
    """
    if not store.get_setting("conversionOn"):
        return 0
    target = store.get_setting("targetCurrency") or "RUB"
    rows = store.query(
        "SELECT id, budget_from, budget_to, budget_cur FROM leads "
        "WHERE budget_cur <> '' AND col NOT IN ('archive','trash','taken')",
    )
    updated = 0
    for r in rows:
        cf = convert_amount(r["budget_from"], r["budget_cur"], target)
        ct = convert_amount(r["budget_to"] if r["budget_to"] is not None else r["budget_from"], r["budget_cur"], target)
        if cf is None:
            continue
        store.execute(
            "UPDATE leads SET conv_from = ?, conv_to = ?, conv_cur = ? WHERE id = ?",
            [cf, ct, target, r["id"]],
        )
        updated += 1
    return updated