// mavend/tick.go — the proactive loop driver.
//
// Per spec the 60s schedule loop (`for { tick; sleep }`) lives in the daemon
// main, NOT in `internal/loop/` — that keeps the loop package pure + unit-
// testable without time side effects. the driver here is the ONE impure
// orchestrator: it gathers state under the store lock, runs the pure Tick,
// phrases the candidate, dispatches it, then handles reminders + sev4 repeats
// and runs the feedback auto-tuner on its own slow cadence.
package main

import (
	"context"
	"crypto/sha256"
	"errors"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"sort"
	"sync"
	"time"

	"github.com/kami/maven/internal/config"
	"github.com/kami/maven/internal/delivery"
	"github.com/kami/maven/internal/loop"
	"github.com/kami/maven/internal/morning"
	"github.com/kami/maven/internal/phraser"
	"github.com/kami/maven/internal/routine"
	"github.com/kami/maven/internal/store"
)

// QueuedNudge — a nudge held in the digest queue pending batch flush.
type QueuedNudge struct {
	Rule     string
	Severity int
	Body     string
	Key      string
	QueuedAt time.Time
}

// tickLoop — the impure driver. holds everything wired at daemon construction
// that the per-tick path needs. the rules slice is read-only here; the gatherer
// already captured it, but we keep it for a possible future re-seed path.
type tickLoop struct {
	store      *store.Store
	gatherer   *loop.Gatherer
	dispatcher *delivery.Dispatcher
	phraser    phraser.Phraser
	rules      []loop.Rule

	tickInterval     time.Duration
	repeatInterval   time.Duration
	autotuneInterval time.Duration // 0 ⇒ autotune disabled (gatherer falls back to static Base)

	// digestCfg — the digest/batching config. nil ⇒ every nudge is sent
	// immediately (legacy behaviour).
	digestCfg *config.DigestConfig

	// routines — operator-declared scheduled behaviors. fired through the
	// dispatcher when their cron crosses. routineLast tracks the per-routine
	// last-fire time across ticks (the driver owns it; routine.Due mutates it).
	routines    []routine.Routine
	routineLast map[string]time.Time

	// morningRoutines — daily checklists (see internal/morning). morningLast
	// tracks the per-routine last-nudge day, mirroring routineLast.
	morningRoutines []morning.Routine
	morningLast     map[string]time.Time

	// proposalCfg — announcement policy for routines the tick inferred itself.
	// nil ⇒ detect silently, never announce (the default). lastProposalAt is
	// the cooldown clock, in-memory on purpose: a restart is allowed to permit
	// one more announcement, and a restart-per-day loop is a bigger problem
	// than a duplicate proposal notice.
	proposalCfg    *config.PatternProposalConfig
	lastProposalAt time.Time

	// digestQ — in-memory queue of eligible nudges waiting for batch flush.
	// populated when digestCfg != nil && digestCfg.Enabled.
	digestQ []QueuedNudge

	// lastPhrase caches the phraser output per rule so the sev4 repeat path
	// can re-send roughly what the user was first alerted with (an alarm
	// that re-phrases differently every 5m is hostile; the same terse body
	// IS the insistence signal). keyed by rule name. nil phrase for a rule
	// = no successful initial dispatch yet (cold-start edge — fall back to
	// a generic body).
	mu         sync.Mutex
	lastPhrase map[string]delivery.PhrasedNudge
	lastTrace  *loop.TickTrace // cached from the most recent tick
}

func newTickLoop(
	st *store.Store,
	g *loop.Gatherer,
	d *delivery.Dispatcher,
	p phraser.Phraser,
	rules []loop.Rule,
	tickInterval, repeatInterval, autotuneInterval time.Duration,
	digestCfg *config.DigestConfig,
	routines []routine.Routine,
	morningRoutines []morning.Routine,
	proposalCfg *config.PatternProposalConfig,
) *tickLoop {
	return &tickLoop{
		store:            st,
		gatherer:         g,
		dispatcher:       d,
		phraser:          p,
		rules:            rules,
		tickInterval:     tickInterval,
		repeatInterval:   repeatInterval,
		autotuneInterval: autotuneInterval,
		digestCfg:        digestCfg,
		digestQ:          nil,
		routines:         routines,
		routineLast:      make(map[string]time.Time),
		morningRoutines:  morningRoutines,
		morningLast:      make(map[string]time.Time),
		proposalCfg:      proposalCfg,
		lastPhrase:       make(map[string]delivery.PhrasedNudge),
	}
}

// run drives the loop until ctx is canceled. one tick per tickInterval;
// the first tick fires immediately so a freshly-started daemon doesn't sit
// idle for 60s before its first evaluation (cold-start responsiveness). the
// feedback auto-tuner runs on its own slower ticker (autotuneInterval) so it
// doesn't write a feedback fact every tick — append-only facts would churn.
func (t *tickLoop) run(ctx context.Context) {
	t.tick(ctx, time.Now())
	ticker := time.NewTicker(t.tickInterval)
	defer ticker.Stop()

	var autotune *time.Ticker
	var autotuneC <-chan time.Time
	if t.autotuneInterval > 0 {
		autotune = time.NewTicker(t.autotuneInterval)
		defer autotune.Stop()
		autotuneC = autotune.C
	}

	for {
		select {
		case <-ctx.Done():
			return
		case now := <-ticker.C:
			t.tick(ctx, now)
		case <-autotuneC:
			t.tune(ctx)
		}
	}
}

// tick — one pass of the proactive loop. gathers, decides, phrases, delivers.
// errors at any sub-step are logged and the tick continues / aborts as the
// layer warrants: a gather failure aborts (no consistent snapshot ⇒ no
// decisions); a phrase/dispatch failure logs the failure and continues so a
// transient delivery fault doesn't kill the whole loop.
func (t *tickLoop) tick(ctx context.Context, now time.Time) {
	state, due, err := t.gatherer.GatherState(ctx, now)
	if err != nil {
		log.Printf("tick: gather: %v", err)
		return
	}
	t.savePresence(ctx, state, now)

	// proactive: at most one candidate, max severity.
	cand, trace := loop.ExplainTick(state, t.rules)
	t.mu.Lock()
	t.lastTrace = trace
	t.mu.Unlock()
	if cand != nil {
		if t.shouldQueue(cand) {
			t.queueNudge(ctx, cand, state, now)
		} else {
			pn, err := t.phraser.PhraseNudge(ctx, *cand)
			if err == nil {
				pn = guardNudge(pn, *cand)
			}
			if err != nil {
				log.Printf("tick: phrase nudge %s: %v", cand.Rule.Name, err)
			} else {
				t.cachePhrase(pn)
				if _, err := t.dispatcher.DispatchNudge(ctx, pn, now); err != nil {
					log.Printf("tick: dispatch nudge %s: %v", cand.Rule.Name, err)
				}
			}
		}
	}

	// digest flush: after candidate processing, flush if the window has
	// elapsed or MaxItems was reached. Processing the candidate first
	// (with dedup) avoids re-queueing the same rule after a flush.
	t.maybeFlush(ctx, now, state)

	// gate-suppressed digest (Vikunja #281): rules the restraint gate held
	// back this tick (quiet hours / away / calendar-busy), not because they
	// weren't due, but because it wasn't the moment. Some of those are worth
	// resurfacing later instead of just being lost — loop.DigestEligible
	// draws that line. This is a SEPARATE mechanism from the in-memory
	// digestQ above: that one batches candidates the gate already ALLOWED to
	// fire; this one durably holds candidates the gate BLOCKED.
	t.enqueueSuppressedDigest(ctx, trace, state, now)
	t.expireStaleDigest(ctx, now)
	t.maybeDrainDigest(ctx, state, now)

	// routines: operator-declared scheduled behaviors. fire the ones whose cron
	// crossed since last fire, delivered through the normal routing (voice when
	// present, away channels otherwise). bodies are literal operator text — not
	// LLM-phrased — so a routine can't hallucinate. severity comes from config.
	t.fireRoutines(ctx, now, state)

	// accepted routines: patterns the user confirmed. read straight from the
	// store each tick so the schedule survives a restart.
	t.fireAcceptedRoutines(ctx, now, state)

	// morning routines: daily checklists (medicine/water/pets/...), nagged at
	// most once per day per routine, and only for items still unevidenced at
	// nudge time. See internal/morning for the "why not four timers" rationale.
	t.fireMorningRoutines(ctx, now, state)

	// pattern detection: scan every action+object pair with recorded events
	// and propose a routine for any stable one not already decided (Vikunja
	// #43). This used to only run as a side effect of the voice fact-write
	// path, so a pattern already sitting in history went unnoticed until he
	// happened to mention it again by voice. See patterns.go and
	// detectPatterns below for how idempotence and dismissal are respected.
	t.detectPatterns(ctx, now, state)

	// reminders: gate-bypassing class. The presentation and retry clock live on
	// the reminder occurrence, so a transport outage neither spends the model
	// every tick nor changes what the reminder says after a restart.
	for _, d := range loop.RemindDecisions(state, due) {
		t.deliverReminder(ctx, d, now)
	}

	// sev4-away repeats: re-send un-acked telegram nudges per repeatInterval.
	// the source of ack truth IS the nudges table (outcome=pending ⇒ not
	// acked); store.UnackedTelegramRules surfaces the keys. body/summary come
	// from the cached phrase from the initial dispatch — see lastPhrase notes.
	// if not cached (cold-start mid-alarm), fall back to a terse generic body.
	keys, err := t.store.UnackedTelegramRules(ctx)
	if err != nil {
		log.Printf("tick: unacked telegram rules: %v", err)
		return
	}
	keys = t.repeatableRules(keys)
	keys = t.stopFinishedAlarms(ctx, keys, state, now)
	if len(keys) == 0 {
		return
	}
	for _, key := range keys {
		body, summary := t.repeatPhrase(key)
		if _, err := t.dispatcher.RepeatUnacked(ctx, []string{key}, now, t.repeatInterval, body, summary); err != nil {
			log.Printf("tick: repeat telegram %s: %v", key, err)
		}
	}
}

// deliverReminder advances one due reminder (or collapsed bundle) through the
// durable delivery state. A phrase is cached before the first external send;
// every definite failure advances the persisted bounded backoff.
func (t *tickLoop) deliverReminder(ctx context.Context, d loop.ReminderDecision, now time.Time) {
	originals := reminderOriginals(d.Reminder)
	pr, cached := cachedReminderPhrase(d, originals)
	if !cached {
		var err error
		pr, err = t.phraser.PhraseReminder(ctx, d)
		if err == nil && pr.Body == "" {
			err = errors.New("phraser returned an empty reminder body")
		}
		if err != nil {
			log.Printf("tick: phrase reminder %d: %v", d.Reminder.ID, err)
			t.scheduleReminderRetry(ctx, originals, now)
			return
		}
		if pr.Mood == "" {
			pr.Mood = "neutral"
		}
		group := reminderDeliveryGroup(originals)
		if err := t.store.CacheReminderPhrase(
			ctx, originals, group, pr.Body, pr.Summary, pr.Mood,
		); err != nil {
			// A cancellation or another completion can win while phrasing. Do
			// not send a presentation that no longer owns every original.
			log.Printf("tick: cache reminder %d phrase: %v", d.Reminder.ID, err)
			return
		}
		// The store now owns the phrase, but this tick's value predates that
		// write. Stamp the exact persisted occurrence identity onto the value
		// handed to the dispatcher so its outbox row can suppress an ambiguous
		// crash for both a real reminder and a synthetic collapsed bundle.
		for i := range originals {
			originals[i].DeliveryGroup = group
			originals[i].PhraseBody = pr.Body
			originals[i].PhraseSummary = pr.Summary
			originals[i].PhraseMood = pr.Mood
		}
		if d.Reminder.ID == 0 {
			d.Reminder.Collapsed = originals
		} else {
			d.Reminder = originals[0]
		}
	}
	// A phraser is not allowed to substitute the reminder decision. In
	// particular, the durable group stamped above must reach the outbox.
	pr.Decision = d

	if _, err := t.dispatcher.DispatchReminder(ctx, pr, now); err != nil {
		log.Printf("tick: dispatch reminder %d: %v", d.Reminder.ID, err)
		t.scheduleReminderRetry(ctx, originals, now)
	}
}

func (t *tickLoop) scheduleReminderRetry(ctx context.Context, originals []store.Reminder, now time.Time) {
	if err := t.store.ScheduleReminderRetry(ctx, originals, now); err != nil {
		log.Printf("tick: schedule reminder retry: %v", err)
	}
}

// reminderOriginals converts the synthetic ID=0 bundle back to real store
// rows. Keeping this in one helper makes it impossible to accidentally persist
// retry state against reminder zero.
func reminderOriginals(r store.Reminder) []store.Reminder {
	if r.ID == 0 {
		return append([]store.Reminder(nil), r.Collapsed...)
	}
	return []store.Reminder{r}
}

// cachedReminderPhrase reconstructs a PhrasedReminder only when every original
// agrees on one persisted group and presentation. That agreement is what lets
// a collapsed bundle survive a restart without being re-phrased.
func cachedReminderPhrase(d loop.ReminderDecision, originals []store.Reminder) (delivery.PhrasedReminder, bool) {
	if len(originals) == 0 || !originals[0].HasDeliveryPhrase() {
		return delivery.PhrasedReminder{}, false
	}
	first := originals[0]
	for _, r := range originals[1:] {
		if !r.HasDeliveryPhrase() ||
			r.DeliveryGroup != first.DeliveryGroup ||
			r.PhraseBody != first.PhraseBody ||
			r.PhraseSummary != first.PhraseSummary ||
			r.PhraseMood != first.PhraseMood {
			return delivery.PhrasedReminder{}, false
		}
	}
	mood := first.PhraseMood
	if mood == "" {
		mood = "neutral"
	}
	return delivery.PhrasedReminder{
		Decision: d,
		Body:     first.PhraseBody,
		Summary:  first.PhraseSummary,
		Mood:     mood,
	}, true
}

// reminderDeliveryGroup deterministically names one occurrence or collapsed
// set. The next-fire instant is part of the identity so a recurring reminder's
// later occurrence can never inherit the previous occurrence's phrase.
func reminderDeliveryGroup(originals []store.Reminder) string {
	ordered := append([]store.Reminder(nil), originals...)
	sort.Slice(ordered, func(i, j int) bool {
		if ordered[i].ID == ordered[j].ID {
			return ordered[i].NextFireTs.Before(ordered[j].NextFireTs)
		}
		return ordered[i].ID < ordered[j].ID
	})
	h := sha256.New()
	for _, r := range ordered {
		_, _ = fmt.Fprintf(h, "%d:%d;", r.ID, r.NextFireTs.UnixMilli())
	}
	sum := h.Sum(nil)
	return fmt.Sprintf("reminder:%x", sum[:12])
}

// savePresence writes back the bucket GatherState just resolved.
//
// It lives here and not in GatherState because that method holds a read-only
// transaction on purpose — one consistent snapshot per tick — and a write
// inside it would either break that guarantee or quietly upgrade the
// transaction. The tick is the layer that already owns writes.
//
// Nothing wrote this row before (Vikunja #532), and the row is the whole
// mechanism, so two things were broken at once. Hysteresis was dead: lastBucket
// read the cold-start Away on every tick, so store.Resolve only ever took the
// `last == Away` arm and demanded a full PresenceEnter score to say he is
// there. The 0.30-0.55 hold band the function exists to provide never applied
// once. And every readout lied: /dash and ipc.Presence read this row, so they
// showed "away — score 0.00 (never)" while desk_active facts were arriving
// every sixty seconds.
//
// A failure logs and the tick continues. The gate reads the in-memory bucket,
// which is why nudge routing kept working through all of this — losing the
// write costs the next tick's hysteresis, not this tick's decisions.
func (t *tickLoop) savePresence(ctx context.Context, state loop.State, now time.Time) {
	if err := t.store.SavePresenceState(ctx, state.Presence, state.PresenceScore, now); err != nil {
		log.Printf("tick: save presence state: %v", err)
	}
}

// maxAlarmAge — how long one un-acked telegram alarm may keep repeating.
//
// This is the floor brake and it applies to every rule, including one that
// says nothing about its own condition (Vikunja #535). Nothing in the tree can
// ack a telegram nudge: MarkAcked has no caller outside internal/store, and the
// only ack that exists is a voice "готово" on a box that runs no voice loop. So
// "repeat until acked" meant "repeat forever", and it did — every five minutes
// for over two hours.
//
// Two hours at the five-minute default is about 24 messages, which is already
// past the point of being read. An alarm nobody answered in two hours is not
// one more repeat away from being answered, and the right move is to stop
// talking, not to talk louder.
const maxAlarmAge = 2 * time.Hour

// stopFinishedAlarms returns the keys that may still repeat, and closes the
// rest.
//
// Two ways an alarm ends without him. The condition cleared, which the rule
// answers through StillTrue — deliberately NOT Predicate, which is
// edge-triggered and reads false one tick after the alarm is raised, so using
// it would cancel every alarm immediately. Or the alarm simply got old, which
// is the bound that does not need the rule's cooperation.
//
// A rule with no StillTrue is not treated as resolved. Silence about the
// condition is not evidence the condition cleared, so those keys only ever stop
// on age.
func (t *tickLoop) stopFinishedAlarms(ctx context.Context, keys []string, state loop.State, now time.Time) []string {
	if len(keys) == 0 {
		return nil
	}
	byName := t.rulesByName()
	live := keys[:0:0]
	for _, key := range keys {
		outcome := ""
		switch r := byName[key]; {
		case r.StillTrue != nil && !r.StillTrue(state):
			outcome = store.NudgeResolved
		case t.alarmIsOlderThan(ctx, key, maxAlarmAge, now):
			// Not "resolved": nothing says the thing got better. This is her
			// giving up on being answered, and /notifications should say so.
			outcome = store.NudgeIgnored
		}
		if outcome == "" {
			live = append(live, key)
			continue
		}
		n, err := t.store.ResolvePendingTelegram(ctx, key, outcome, now)
		if err != nil {
			// Could not close it, so do not drop it either: repeating is the
			// lesser fault against losing the alarm entirely.
			log.Printf("tick: stop alarm %s: %v", key, err)
			live = append(live, key)
			continue
		}
		log.Printf("tick: alarm %s ended (%s), %d pending nudge(s) closed", key, outcome, n)
	}
	return live
}

// alarmIsOlderThan reports whether the oldest un-acked send for this rule is
// past the cap. A read failure answers false: an alarm that repeats one more
// time is better than one silenced by a transient store error.
func (t *tickLoop) alarmIsOlderThan(ctx context.Context, rule string, age time.Duration, now time.Time) bool {
	oldest, err := t.store.OldestPendingTelegram(ctx, rule)
	if err != nil {
		if !errors.Is(err, store.ErrNudgeNotFound) {
			log.Printf("tick: oldest pending %s: %v", rule, err)
		}
		return false
	}
	return now.Sub(oldest) >= age
}

// repeatableRules drops keys whose rule is not wired any more.
//
// The repeat path reads the nudges table, not the rule set: any sev4 telegram
// row still at outcome=pending is re-sent every repeat_interval until it is
// acked. So turning a rule off in `disabled_rules` silenced new nudges and left
// the last un-acked one re-sending every five minutes, forever — a knob that
// stops the cause and not the symptom is worse than no knob. Found the evening
// of 2026-08-01, two messages after the rule was supposedly off.
//
// Filtering on the wired set rather than on the disabled list also covers the
// rule that was deleted from the code entirely: its orphan rows go quiet
// instead of nagging about a rule nobody can ack from the UI any more.
func (t *tickLoop) repeatableRules(keys []string) []string {
	if len(keys) == 0 {
		return nil
	}
	wired := t.rulesByName()
	out := keys[:0:0]
	for _, k := range keys {
		if _, ok := wired[k]; ok {
			out = append(out, k)
		}
	}
	return out
}

// rulesByName indexes the wired rule set by name, for the two lookups above
// that only care whether a key is still wired (repeatableRules) or need the
// rule itself (stopFinishedAlarms).
func (t *tickLoop) rulesByName() map[string]loop.Rule {
	byName := make(map[string]loop.Rule, len(t.rules))
	for _, r := range t.rules {
		byName[r.Name] = r
	}
	return byName
}

// cachePhrase keeps the latest phrased nudge per rule for the sev4-repeat
// path. writing under a mutex; the repeat path reads under the same. the
// cache is bounded by the rule count (≤ ~30 per spec) so eviction is not a
// concern at this scale.
func (t *tickLoop) cachePhrase(pn delivery.PhrasedNudge) {
	t.mu.Lock()
	t.lastPhrase[pn.Candidate.Rule.Name] = pn
	t.mu.Unlock()
}

func (t *tickLoop) repeatPhrase(rule string) (body, summary string) {
	t.mu.Lock()
	pn, ok := t.lastPhrase[rule]
	t.mu.Unlock()
	if !ok || pn.Summary == "" {
		// cold-start mid-alarm: no cached phrase. a deliberately terse generic
		// body — the alarm IS the insistence; the wording repeats, the ring
		// is what changes. the LLM phraser impl will refresh this on its next
		// tick when the rule re-fires through Tick.
		return fmt.Sprintf("maven: %s still active", rule), rule
	}
	return pn.Body, pn.Summary
}

// tune — the feedback auto-tuner's impure step. runs on a slow cadence
// (autotuneInterval, see run) so it doesn't write a fact every tick. for each
// rule:
//  1. read store.RecentOutcomes for the last TuneSampleN resolved outcomes.
//  2. if there's not enough signal (TuneMinOutcomes), leave Base alone.
//  3. compute the tuned cooldown with loop.TuneCooldown (pure).
//  4. read the currently-persisted feedback fact; if the tuned value equals
//     it, skip the write (RecentOutcomes is itself steady ⇒ no churn).
//  5. else write a `facts (kind=config, source=feedback, key=cooldown:<rule>)`
//     row. the Gatherer reads it next tick.
//
// Error at any step logs + continues to the next rule — a transient store
// fault on one rule must not abort tuning for the rest.
func (t *tickLoop) tune(ctx context.Context) {
	now := time.Now()
	for _, r := range t.rules {
		outcomes, err := t.store.RecentOutcomes(ctx, r.Name, loop.TuneSampleN)
		if err != nil {
			log.Printf("tune: outcomes %s: %v", r.Name, err)
			continue
		}
		if len(outcomes) < loop.TuneMinOutcomes {
			continue // sparse — no signal yet, don't whipsaw on first sight.
		}
		tuned := loop.TuneCooldown(r, outcomes)

		// the currently-persisted tuned base, if any. equal ⇒ skip the write
		// (RecentOutcomes is monotone-steady between resolved outcomes).
		if cur, ok := t.currentTunedBase(ctx, r); ok && cur == tuned {
			continue
		}
		if _, err := t.store.SetValue(
			ctx, store.KindConfig, loop.FeedbackKey(r), loop.FeedbackSource,
			tuned, now,
		); err != nil {
			log.Printf("tune: persist %s: %v", r.Name, err)
			continue
		}
		log.Printf("tune: %s cooldown -> %v", r.Name, tuned)
	}
}

// currentTunedBase — read the persisted feedback cooldown fact back into a
// duration. (dur, false) when no feedback fact exists yet OR it's malformed;
// the caller treats that as "differ from anything we'd write — write."
func (t *tickLoop) currentTunedBase(ctx context.Context, r loop.Rule) (time.Duration, bool) {
	f, err := t.store.LatestFactBySource(ctx, loop.FeedbackKey(r), loop.FeedbackSource)
	if err != nil {
		return 0, false
	}
	return loop.ParseCooldownFact(f)
}

// defaultConfigPath — the config file path the daemon loads if -config wasn't
// passed. XDG_CONFIG_HOME/maven/mavend.json, falling back to ~/.config/maven.
func defaultConfigPath() string {
	if x := os.Getenv("XDG_CONFIG_HOME"); x != "" {
		return filepath.Join(x, "maven", "mavend.json")
	}
	home, err := os.UserHomeDir()
	if err != nil || home == "" {
		return "mavend.json"
	}
	return filepath.Join(home, ".config", "maven", "mavend.json")
}

// trace returns the most recent TickTrace, or nil if no tick has run yet.
func (t *tickLoop) trace() *loop.TickTrace {
	t.mu.Lock()
	defer t.mu.Unlock()
	return t.lastTrace
}