package main

import (
	"context"
	"errors"
	"log"

	"github.com/kami/maven/internal/ipc"
	"github.com/kami/maven/internal/router"
	"github.com/kami/maven/internal/zenmoney"
)

// Money questions (Vikunja #125).
//
// This is the whole read side: mavpoll holds the zenmoney token and writes
// facts(kind=env, source=poll:zenmoney); core reads them back when he asks.
// Core never sees the token, never calls zenmoney, and has no rule on these
// keys — a total is never a reason for Maven to speak first. Maven is not a
// nag, least of all about his money.
//
// Nothing here can reach the external search capability: the figures are read
// from the store and rendered locally, and his financial data is never search
// input.

// queryMoney — "сколько я потратил сегодня?", "покажи мои траты".
//
// Answers only from the latest fact the poller wrote. Three honest outcomes and
// no fourth: the figure, "the fact is old and here is its date", or "money
// tracking is not connected". It never computes, estimates or rounds a total of
// its own — an invented number about his money is the worst thing this could do.
func (h *reactiveHandler) queryMoney(ctx context.Context, t *queryTurn) (string, bool) {
	q, ok := router.ParseMoneyQuery(t.dec.Utterance)
	if !ok {
		return "", false
	}
	if q.Window == router.MoneyUnsupported {
		// Two windows are stored and no others. Answering "сколько я потратил
		// вчера?" with the month-to-date total answers a different question
		// with a real number, which is the shape of a lie he cannot spot.
		return "я храню только сегодняшние траты и за этот месяц.", true
	}
	key, phrase := zenmoney.KeySpentMonth, "в этом месяце"
	if q.Window == router.MoneyToday {
		key, phrase = zenmoney.KeySpentToday, "сегодня"
	}
	fact, err := h.api.LatestFactBySource(ctx, key, zenmoney.Source)
	if err != nil {
		// No fact at all is the normal state when the capability is off. Claim
		// the turn anyway: falling through to recall would answer a question
		// about money with whatever note happens to be nearest.
		if !isNoFactErr(err) {
			log.Printf("voice: money fact: %v", err)
		}
		return "я не отслеживаю траты — не подключено.", true
	}
	val, err := zenmoney.ParseFactValue(fact.Value)
	if err != nil {
		log.Printf("voice: money fact: decode: %v", err)
		return "не получилось прочитать траты.", true
	}
	now := h.now()
	if q.Window == router.MoneyToday && !val.CoversDay(now) {
		// The day window rolled over and the poller had nothing to write,
		// because he has not spent anything yet today. The fact is fresh by ts
		// and covers yesterday, so no staleness check can catch it — only the
		// window stamp inside the value can.
		return "сегодня пока ничего не вижу.", true
	}
	reply := val.FormatRU(phrase)
	if q.Income {
		reply = val.FormatIncomeRU(phrase)
	}
	if reply == "" {
		return "по тратам пока нечего сказать.", true
	}
	// A stale fact is reported as stale rather than spoken as today's number.
	// The age is measured from when the figure was last READ, not from when it
	// last changed: a month with no spending in it does not go stale.
	asOf := val.AsOf
	if asOf.IsZero() {
		asOf = fact.Ts
	}
	if now.Sub(asOf) > zenmoney.StaleAfter {
		return "данные от " + asOf.Local().Format("02.01") + ": " + reply, true
	}
	return reply, true
}

// isNoFactErr — ErrNoFact survives the wire wrapped, so unwrap for it. The
// hand-rolled loop this replaces missed any error implementing Is(error) bool.
func isNoFactErr(err error) bool {
	return errors.Is(err, ipc.ErrNoFact)
}