//go:build linux

package host

import (
	"context"
	"github.com/carlosframework/platform/internal/instancefs"
	"os"
	"time"

	"github.com/carlosframework/platform/internal/hostbox"
	"github.com/carlosframework/platform/internal/instancectl"
	"golang.org/x/sys/unix"
)

func (f *servingParkFS) room() error {
	parent, _, err := f.parent()
	if err != nil {
		return err
	}
	defer parent.Close()
	return servingRoomFile(parent)
}

func servingRoomFile(parent *os.File) error {
	var s unix.Statfs_t
	if err := unix.Fstatfs(int(parent.Fd()), &s); err != nil {
		return err
	}
	if s.Bsize <= 0 || s.Blocks > ^uint64(0)/uint64(s.Bsize) || s.Bavail > ^uint64(0)/uint64(s.Bsize) {
		return hostbox.ErrChanged
	}
	if s.Bavail*uint64(s.Bsize) < instancectl.DiskFloor(s.Blocks*uint64(s.Bsize)) {
		return instancectl.ErrDiskFull
	}
	return nil
}

func (p *servingParkRoot) maintainServingParks(ctx context.Context, after string) (string, error) {
	fs, ok := p.ledger.fs.(*servingParkFS)
	if !ok {
		return after, hostbox.ErrUnsupported
	}
	return maintainServingParkPass(ctx, after, func(call context.Context) error { return p.ledger.maintainParks(call, fs.room) }, p.recoverServingParks, 10*time.Second)
}

func claimServingRoom(data string) error {
	parent, err := instancefs.OpenDirBeneath(data, "instances")
	if err != nil {
		return err
	}
	defer parent.Close()
	return servingRoomFile(parent)
}