package activator

import (
	"context"
	"fmt"
	"os"
	"os/exec"

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

// ErrClaimIsolationUnavailable blocks every current launch shape until the
// root instance-control protocol can validate a durable role reservation.
var ErrClaimIsolationUnavailable = fmt.Errorf("%w: isolated root launcher cannot carry claim reservations", hostbox.ErrUnsupported)

type RoleProducer struct {
	Context context.Context
	Finish  func(error)
}

// RootRoleLauncher is the agent's client of the reservation-bearing
// isolated root launch protocol (claim Plan 11, R10). Root, not the agent,
// executes the role, in main's isolated instance unit.
type RootRoleLauncher interface {
	Capability(context.Context) (string, error)
	Launch(context.Context, hostbox.RoleLaunchRequest) (hostbox.RoleLaunchGrant, error)
	Stop(context.Context, hostbox.RoleLaunchRequest) error
}

type RoleLaunch struct {
	Unit *hostbox.UnitLaunchInputs
	Spec *hostbox.LaunchSpec
	// Root carries a reservation to root's isolated launcher. Nil keeps
	// every claimed launch refused.
	Root RootRoleLauncher
	// LaunchDir is the instance directory the isolated unit binds and runs
	// in; RunDir holds the app socket; LogSocket is the unit's stdout
	// socket; MemoryMax is the host slice tier.
	LaunchDir, RunDir, LogSocket string
	MemoryMax                    int64
	RegisterProducer             func(context.Context, string) (RoleProducer, error)
	Initialize                   func(context.Context) error
	InitializeUnlocked           func(context.Context) error
	Parent                       *cgroup.Prepared
	ParentPath                   string
	CgroupRoot                   string
	Target                       hostguard.FenceTarget
	Work                         hostwrite.Work
	Identity                     hostwrite.Identity
	Journal                      *hostbox.LaunchJournal
	Executable                   func(context.Context, *exec.Cmd) (*os.File, error)
}