// Phase 2d — table retention. Voir
// ~/.claude/plans/pour-les-notifications-on-inherited-seal.md § Phase 2.
package main

import (
	"context"
	"log"
	"time"
)

const (
	defaultDoneRetention   = 7 * 24 * time.Hour
	defaultStuckTimeout    = 30 * time.Minute
	defaultJanitorInterval = 1 * time.Hour
	janitorTickTimeout     = 30 * time.Second
)

// Janitor periodically purges old `done` rows and recovers `running` rows
// that have been stuck (pod crashed mid-job). Runs once immediately at
// startup so a fresh deploy reclaims any orphans from the previous pod.
type Janitor struct {
	queue         Queue
	doneRetention time.Duration
	stuckTimeout  time.Duration
	interval      time.Duration
}

func NewJanitor(queue Queue, doneRet, stuckTO, interval time.Duration) *Janitor {
	if doneRet <= 0 {
		doneRet = defaultDoneRetention
	}
	if stuckTO <= 0 {
		stuckTO = defaultStuckTimeout
	}
	if interval <= 0 {
		interval = defaultJanitorInterval
	}
	return &Janitor{
		queue:         queue,
		doneRetention: doneRet,
		stuckTimeout:  stuckTO,
		interval:      interval,
	}
}

func (j *Janitor) Run(ctx context.Context) {
	log.Printf("janitor started (purge done > %s, recover stuck > %s, every %s)",
		j.doneRetention, j.stuckTimeout, j.interval)

	// One immediate pass at boot — recovers anything left orphaned by the
	// previous pod before opening for new traffic.
	j.tick(ctx)

	t := time.NewTicker(j.interval)
	defer t.Stop()
	for {
		select {
		case <-ctx.Done():
			log.Print("janitor stopping")
			return
		case <-t.C:
			j.tick(ctx)
		}
	}
}

func (j *Janitor) tick(parent context.Context) {
	ctx, cancel := context.WithTimeout(parent, janitorTickTimeout)
	defer cancel()

	if n, err := j.queue.PurgeDone(ctx, j.doneRetention); err != nil {
		log.Printf("janitor PurgeDone error: %v", err)
	} else if n > 0 {
		log.Printf("janitor purged %d done rows older than %s", n, j.doneRetention)
	}

	if n, err := j.queue.RecoverStuck(ctx, j.stuckTimeout); err != nil {
		log.Printf("janitor RecoverStuck error: %v", err)
	} else if n > 0 {
		log.Printf("janitor recovered %d stuck running rows (> %s)", n, j.stuckTimeout)
	}
}