package hostguard

import (
	"context"
	"sort"
	"strings"
)

// GenerationInstallations enumerates independently of generation reservations.
// Pending or quarantined installations cannot certify a destructive snapshot.
func (a *RootAuthority) GenerationInstallations(ctx context.Context) ([]FenceView, error) {
	if a == nil || a.store == nil {
		return nil, ErrInvalidInput
	}
	names, err := a.store.Names()
	if err != nil {
		return nil, err
	}
	sort.Strings(names)
	var out []FenceView
	for _, name := range names {
		if err := ctx.Err(); err != nil {
			return nil, err
		}
		if strings.HasSuffix(name, ".lock") {
			continue
		}
		if !strings.HasSuffix(name, ".json") {
			return nil, ErrMalformedRecord
		}
		host := strings.TrimSuffix(name, ".json")
		view, err := a.generationInstallation(ctx, host)
		if err != nil {
			return nil, err
		}
		if view.Installation.InventoryRevision == 0 {
			return nil, ErrNoRecord
		}
		out = append(out, view)
	}
	return out, nil
}

func (a *RootAuthority) generationInstallation(ctx context.Context, host string) (FenceView, error) {
	unlock, err := a.store.Lock(ctx, host+".lock")
	if err != nil {
		return FenceView{}, err
	}
	defer unlock()
	r, err := a.read(host)
	if err != nil {
		return FenceView{}, err
	}
	view, err := a.viewLocked(host, Captured{Incarnation: r.Incarnation, Stamp: r.installation.Stamp})
	if err != nil {
		return FenceView{}, err
	}
	// A visible final rename may have failed its directory sync. Recommit under
	// the same host lock before these requirements can certify a generation read.
	if err := a.write(r); err != nil {
		return FenceView{}, err
	}
	return view, nil
}