// runDiagnostics performs the actual execution of diagnostics once they're built.
func runDiagnostics(logger *log.Logger, diagnostics []types.Diagnostic, warnCount int, errorCount int) (bool, error, int, int) {
	for _, diagnostic := range diagnostics {
		func() { // wrap diagnostic panic nicely in case of developer error
			defer func() {
				if r := recover(); r != nil {
					errorCount += 1
					stack := debug.Stack()
					logger.Error("CED5001",
						fmt.Sprintf("While running the %s diagnostic, a panic was encountered.\nThis is a bug in diagnostics. Error and stack trace follow: \n%s\n%s",
							diagnostic.Name(), fmt.Sprintf("%v", r), stack))
				}
			}()

			if canRun, reason := diagnostic.CanRun(); !canRun {
				if reason == nil {
					logger.Notice("CED5002", fmt.Sprintf("Skipping diagnostic: %s\nDescription: %s", diagnostic.Name(), diagnostic.Description()))
				} else {
					logger.Notice("CED5003", fmt.Sprintf("Skipping diagnostic: %s\nDescription: %s\nBecause: %s", diagnostic.Name(), diagnostic.Description(), reason.Error()))
				}
				return
			}

			logger.Notice("CED5004", fmt.Sprintf("Running diagnostic: %s\nDescription: %s", diagnostic.Name(), diagnostic.Description()))
			r := diagnostic.Check()
			for _, entry := range r.Logs() {
				logger.LogEntry(entry)
			}
			warnCount += len(r.Warnings())
			errorCount += len(r.Errors())
		}()
	}
	return errorCount > 0, nil, warnCount, errorCount
}

// determineRequestedDiagnostics determines which diagnostic the user wants to run
// based on the -d list and the available diagnostics.
// returns error or diagnostic names
func determineRequestedDiagnostics(available []string, requested []string, logger *log.Logger) (error, []string) {
	diagnostics := []string{}
	if len(requested) == 0 { // not specified, use the available list
		diagnostics = available
	} else if diagnostics = sets.NewString(requested...).Intersection(sets.NewString(available...)).List(); len(diagnostics) == 0 {
		logger.Error("CED6001", log.EvalTemplate("CED6001", "None of the requested diagnostics are available:\n  {{.requested}}\nPlease try from the following:\n  {{.available}}",
			log.Hash{"requested": requested, "available": available}))
		return fmt.Errorf("No requested diagnostics available"), diagnostics
	} else if len(diagnostics) < len(requested) {
		logger.Error("CED6002", log.EvalTemplate("CED6002", "Of the requested diagnostics:\n    {{.requested}}\nonly these are available:\n    {{.diagnostics}}\nThe list of all possible is:\n    {{.available}}",
			log.Hash{"requested": requested, "diagnostics": diagnostics, "available": available}))
		return fmt.Errorf("Not all requested diagnostics are available"), diagnostics
	} // else it's a valid list.
	return nil, diagnostics
}

func GetSystemdUnits(logger *log.Logger) map[string]types.SystemdUnit {
	systemdUnits := map[string]types.SystemdUnit{}

	if !HasSystemctl() {
		logger.Notice("DS1010", "Systemd not available, skipping unit discovery.")
		return systemdUnits
	}

	logger.Notice("DS1001", "Performing systemd discovery")
	for _, name := range []string{"openshift", "openshift-master", "openshift-node", "openshift-sdn-master", "openshift-sdn-node", "docker", "openvswitch", "iptables", "etcd", "kubernetes"} {
		systemdUnits[name] = discoverSystemdUnit(logger, name)

		if systemdUnits[name].Exists {
			logger.Debug("DS1002", fmt.Sprintf("Saw systemd unit %s", name))
		}
	}

	logger.Debug("DS1003", fmt.Sprintf("%v", systemdUnits))
	return systemdUnits
}

func discoverSystemdUnit(logger *log.Logger, name string) types.SystemdUnit {
	unit := types.SystemdUnit{Name: name, Exists: false}
	if output, err := exec.Command("systemctl", "show", name).Output(); err != nil {
		logger.Error("DS1004", fmt.Sprintf("Unable to run `systemctl show %s`: %s\nCannot analyze systemd units.", name, err.Error()))
	} else {
		attr := make(map[string]string)
		for _, line := range strings.Split(string(output), "\n") {
			elements := strings.SplitN(line, "=", 2) // Looking for "Foo=Bar" settings
			if len(elements) == 2 {                  // found that, record it...
				attr[elements[0]] = elements[1]
			}
		}

		if val := attr["LoadState"]; val != "loaded" {
			logger.Debug("DS1005", fmt.Sprintf("systemd unit '%s' does not exist. LoadState is '%s'", name, val))
			return unit // doesn't exist - leave everything blank

		} else {
			unit.Exists = true
		}

		if val := attr["UnitFileState"]; val == "enabled" {
			logger.Debug("DS1006", fmt.Sprintf("systemd unit '%s' is enabled - it will start automatically at boot.", name))
			unit.Enabled = true

		} else {
			logger.Debug("DS1007", fmt.Sprintf("systemd unit '%s' is not enabled - it does not start automatically at boot. UnitFileState is '%s'", name, val))
		}

		if val := attr["ActiveState"]; val == "active" {
			logger.Debug("DS1008", fmt.Sprintf("systemd unit '%s' is currently running", name))
			unit.Active = true

		} else {
			logger.Debug("DS1009", fmt.Sprintf("systemd unit '%s' is not currently running. ActiveState is '%s'; exit code was %d.", name, val, unit.ExitStatus))
		}

		fmt.Sscanf(attr["StatusErrno"], "%d", &unit.ExitStatus) // ignore errors...
	}
	return unit
}