// SPDX-License-Identifier: AGPL-3.0-or-later

package main

import (
	"context"
	"log"
	"time"

	"comail/internal/adminclient"
	"comail/internal/featureflags"
)

// flagPullTimeout bounds a single overrides fetch.
const flagPullTimeout = 10 * time.Second

// flagPullInterval is how often cmd/web pulls live overrides from the relay.
// The relay owns the overrides file; web can't read it (separate user +
// state dir), so it pulls the snapshot over the tailnet admin channel and
// applies it to its own OpenFeature provider. ~30s latency on a live flip
// reaching web's /pricing gate + account card is acceptable.
const flagPullInterval = 30 * time.Second

// runOverridesPuller pulls the relay's live-override snapshot once
// immediately, then every flagPullInterval until ctx is done, applying each
// snapshot to web's provider. Best-effort: a failed pull is logged and the
// last good snapshot is kept (a transient relay blip never blanks web's
// overrides), self-healing on the next tick.
func runOverridesPuller(ctx context.Context, client *adminclient.Client) {
	pullOverridesOnce(ctx, client)

	ticker := time.NewTicker(flagPullInterval)
	defer ticker.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			pullOverridesOnce(ctx, client)
		}
	}
}

// pullOverridesOnce fetches the relay snapshot and applies it. Any failure
// is logged and swallowed; the provider keeps its current snapshot.
func pullOverridesOnce(parent context.Context, client *adminclient.Client) {
	ctx, cancel := context.WithTimeout(parent, flagPullTimeout)
	defer cancel()

	ov, err := client.FetchOverrides(ctx)
	if err != nil {
		log.Printf("web.flags.overrides_pull_failed: %v", err)
		return
	}
	featureflags.ApplyOverrides(ov)
}