package activator

import (
	"context"
	"os/exec"

	"github.com/carlosframework/platform/internal/cgroup"
	"github.com/carlosframework/platform/internal/hostwrite"
)

// newClaimProcessFor is newClaimProcess for the launcher that produced cmd.
// A root launch hands the agent no child and no containment: the agent
// watches the unit's main process and stops it only through root.
func newClaimProcessFor(cmd *exec.Cmd, p *cgroup.Prepared, root bool) *claimProcess {
	if !root {
		return newClaimProcess(cmd, p)
	}
	c := &claimProcess{cmd: cmd, root: true, done: make(chan struct{})}
	if cmd == nil || cmd.Process == nil {
		close(c.done)
	} else {
		watchRootProcess(cmd.Process, c.done)
	}
	return c
}

// stopRoot asks root to stop the reservation and waits for the unit's main
// process to be gone. Without root's settle there is no way to stop it, so
// it refuses rather than assumes.
func (p *claimProcess) stopRoot(ctx context.Context) error {
	if p.closed {
		return nil
	}
	if p.settle == nil {
		select {
		case <-p.done:
		default:
			return hostwrite.ErrUnavailable
		}
	} else if err := p.settle(ctx); err != nil {
		return err
	}
	select {
	case <-ctx.Done():
		return ctx.Err()
	case <-p.done:
	}
	p.closed = true
	if p.cmd != nil && p.cmd.Process != nil {
		_ = p.cmd.Process.Release()
	}
	if p.producerFinish != nil {
		p.producerFinish(nil)
	}
	return nil
}