// mavend/memoryeval.go — the driver for background memory evaluation
// (Vikunja #248). The evaluator itself is pure-ish and lives in
// internal/memeval; this is the one impure part: a ticker, the store, and the
// resident model's base URL.
//
// It is its own goroutine and NOT a step on the main tick, deliberately. The
// tick runs every 60s and has a delivery deadline behind it; an evaluation is
// a multi-second LLM round-trip on the same llama-server that answers voice
// turns, and it happens hourly at most. Bolting it onto the tick would make
// every hour's tick the slow one for no benefit.
package main

import (
	"context"
	"log"
	"time"

	"github.com/kami/maven/internal/config"
	"github.com/kami/maven/internal/memeval"
	"github.com/kami/maven/internal/phraser"
	"github.com/kami/maven/internal/store"
)

// memoryEvalTimeout — the per-request deadline on one evaluation.
//
// It used to be five minutes, on the grounds that nobody waits for the answer.
// Nobody waits for the evaluation, but there is ONE resident model behind one
// llama-server, so a voice turn that arrives mid-evaluation waits behind it:
// five minutes of evaluation is five minutes of a mute assistant. Sixty seconds
// is long enough for a Thinking model on this prompt and short enough that the
// worst collision is one turn answered late rather than a turn abandoned. An
// evaluation cut off here costs nothing: it is retried at the next interval.
const memoryEvalTimeout = 60 * time.Second

// memoryEvalWorker — ticker + evaluator.
type memoryEvalWorker struct {
	eval     *memeval.Evaluator
	interval time.Duration
}

// newMemoryEvalWorker wires the evaluation loop, or returns nil when it should
// not run at all. nil is the normal case and every caller must handle it:
//
//   - no memory_eval config block ⇒ off (a capability is off unless configured);
//   - no LLM phraser ⇒ nothing to evaluate with. There is no template fallback
//     here on purpose: a "memory evaluation" assembled from string templates
//     would be a fixed sentence pretending to be an observation.
func newMemoryEvalWorker(st *store.Store, phr phraser.Phraser, cfg *config.Config) *memoryEvalWorker {
	if cfg.MemoryEval == nil {
		return nil
	}
	lp, ok := phr.(*phraser.LLMPhraser)
	if !ok {
		log.Printf("memory eval: configured but no llama-server phraser — evaluation disabled")
		return nil
	}
	interval := time.Duration(cfg.MemoryEval.Interval)
	if interval <= 0 {
		interval = config.DefaultMemoryEvalInterval
	}
	client := llmClientFor(lp, memoryEvalTimeout)
	ev := memeval.NewEvaluator(st, st, client, memeval.Config{
		MaxItems:      cfg.MemoryEval.MaxItems,
		MinConfidence: cfg.MemoryEval.MinConfidence,
		ContextBlock:  contextBlockFn(cfg, time.Now),
	})
	log.Printf("memory eval: enabled, every %s", interval)
	return &memoryEvalWorker{eval: ev, interval: interval}
}

// run evaluates every interval until ctx is canceled.
//
// The first evaluation waits a full interval rather than firing at startup, the
// opposite of the tick loop's cold-start behaviour. A tick that fires late is a
// nudge that arrives late; an evaluation that fires late is nothing at all, and
// the alternative is a heavy LLM call competing with startup — including with
// the first voice turn after a restart.
func (w *memoryEvalWorker) run(ctx context.Context) {
	ticker := time.NewTicker(w.interval)
	defer ticker.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case now := <-ticker.C:
			obs, err := w.eval.Evaluate(ctx, now)
			if err != nil {
				log.Printf("memory eval: %v", err)
				continue
			}
			for _, o := range obs {
				log.Printf("memory eval: noted (%.2f, %s): %s", o.Conf, o.Action, o.Text)
			}
		}
	}
}