package agent

import (
	"context"
	"os"
	"os/exec"
	"path/filepath"

	"git.wntrmute.dev/mc/mcp/internal/config"
	"git.wntrmute.dev/mc/mcp/internal/runtime"
)

// unikernelSupported reports whether this node can run Nanos unikernels:
// it needs KVM (/dev/kvm) and the `ops` toolchain on PATH.
func unikernelSupported() bool {
	if _, err := os.Stat("/dev/kvm"); err != nil {
		return false
	}
	if _, err := exec.LookPath("ops"); err != nil {
		return false
	}
	return true
}

// homeDir returns the agent's working directory (where images/ and vm/ live),
// derived from the registry database path (e.g. /srv/mcp/mcp.db -> /srv/mcp).
func homeDir(cfg *config.AgentConfig) string {
	if cfg != nil && cfg.Database.Path != "" {
		return filepath.Dir(cfg.Database.Path)
	}
	if h := os.Getenv("HOME"); h != "" {
		return h
	}
	return "/srv/mcp"
}

// runtimeFor selects the runtime backend for a component's declared runtime.
// Unknown or empty runtimes fall back to the container runtime. If a service
// requests "unikernel" but this node lacks the unikernel runtime, it falls
// back to the container runtime (the master should not place it here).
func (a *Agent) runtimeFor(rt string) runtime.Runtime {
	if rt == "unikernel" && a.Unikernel != nil {
		return a.Unikernel
	}
	return a.Runtime
}

// listAllContainers returns the observed state across every configured
// runtime (containers + unikernel VMs) so reconciliation, status, and drift
// detection see the whole picture.
func (a *Agent) listAllContainers(ctx context.Context) ([]runtime.ContainerInfo, error) {
	infos, err := a.Runtime.List(ctx)
	if err != nil {
		return nil, err
	}
	if a.Unikernel != nil {
		vms, vmErr := a.Unikernel.List(ctx)
		if vmErr == nil {
			infos = append(infos, vms...)
		} else if a.Logger != nil {
			a.Logger.Warn("list unikernel VMs failed", "err", vmErr)
		}
	}
	return infos, nil
}