package execenv

import (
	"os"
	"path/filepath"
	"time"
)

// GC 删除未被 current、绑定或锁引用、且早于 ttl 的层目录。ttl<=0 时用 7 天。
func (b *Broker) GC(ttl time.Duration) ([]string, error) {
	if ttl <= 0 {
		ttl = 7 * 24 * time.Hour
	}
	keep := map[string]bool{}
	if id, err := b.Root.CurrentBase(); err != nil {
		return nil, err
	} else if id != "" {
		keep[id] = true
	}
	if b.Store != nil {
		binds, err := b.Store.ListExecEnvBindings()
		if err != nil {
			return nil, err
		}
		for _, bind := range binds {
			if bind.BaseID != "" {
				keep[bind.BaseID] = true
			}
			if bind.Isolated != "" {
				keep[bind.Isolated] = true
			}
			for _, id := range bind.Extensions {
				keep[id] = true
			}
		}
	}
	ents, err := os.ReadDir(b.Root.LayersDir())
	if err != nil {
		return nil, err
	}
	cut := time.Now().Add(-ttl)
	var removed []string
	for _, ent := range ents {
		if !ent.IsDir() || keep[ent.Name()] {
			continue
		}
		info, err := ent.Info()
		if err != nil {
			return removed, err
		}
		if info.ModTime().After(cut) {
			continue
		}
		if err := os.RemoveAll(filepath.Join(b.Root.LayersDir(), ent.Name())); err != nil {
			return removed, err
		}
		_ = os.Remove(filepath.Join(b.Root.LocksDir(), ent.Name()+".json"))
		removed = append(removed, ent.Name())
	}
	return removed, nil
}