package app

import (
	"strings"
	"time"
)

const (
	transportBackendActionTimeout = 20 * time.Second
	transportBackendHealthTimeout = 5 * time.Second
	transportBackendProbeTimeout  = 900 * time.Millisecond
)

var transportSystemdUnitsDir = "/etc/systemd/system"

type transportCommandRunner func(timeout time.Duration, name string, args ...string) (string, string, int, error)

var transportRunCommand transportCommandRunner = runCommandTimeout

type transportBackendActionResult struct {
	OK        bool
	Code      string
	Message   string
	ExitCode  int
	Stdout    string
	Stderr    string
	Retryable bool
}

type transportBackendHealthResult struct {
	OK        bool
	Code      string
	Message   string
	Status    TransportClientStatus
	LatencyMS int
	Retryable bool
}

type transportBackendAdapter interface {
	ID() string
	Action(client TransportClient, action string) transportBackendActionResult
	Health(client TransportClient) transportBackendHealthResult
	Provision(client TransportClient) transportBackendActionResult
	Cleanup(client TransportClient) transportBackendActionResult
}

func selectTransportBackend(client TransportClient) transportBackendAdapter {
	mode := transportRuntimeMode(client.Config)
	switch mode {
	case "exec":
		// Continue with current runner-based backend selection.
	case "embedded", "sidecar":
		return transportUnsupportedRuntimeBackend{mode: mode}
	default:
		return transportUnsupportedRuntimeBackend{mode: mode}
	}

	runner := strings.ToLower(strings.TrimSpace(transportConfigString(client.Config, "runner")))
	unit := strings.TrimSpace(transportConfigString(client.Config, "unit"))
	switch runner {
	case "systemd":
		return transportSystemdBackend{}
	case "mock":
		return transportMockBackend{}
	case "":
		if unit != "" {
			return transportSystemdBackend{}
		}
		return transportMockBackend{}
	default:
		return transportMockBackend{}
	}
}