private void insertCommandAndOutput()

in freemarker-docgen-core/src/main/java/org/freemarker/docgen/core/PrintTextWithDocgenSubstitutionsDirective.java [303:411]
102 lines of code
13 McCabe index (conditional complexity)

        private void insertCommandAndOutput(InsertDirectiveType insertDirectiveType, InsertDirectiveArgs args)
                throws TemplateException, IOException {
            if (args.printCommand || insertDirectiveType == CHECK_COMMAND) {
                out.write("> ");
                out.write(DOCGEN_WD_TAG_AND_SLASH_PATTERN.matcher(StringUtil.chomp(args.body)).replaceAll(""));
                out.write("\n");
            }

            List<String> splitCmdLine = BashCommandLineArgsParser.parse(args.body);
            if (splitCmdLine.isEmpty()) {
                throw newErrorInDocgenTag("Command to execute was empty");
            }
            String cmdKey = splitCmdLine.get(0);
            Map<String, Transform.InsertableOutputCommandProperties> cmdPropsMap =
                    transform.getInsertableOutputCommands();
            Transform.InsertableOutputCommandProperties cmdProps = cmdPropsMap.get(cmdKey);
            if (cmdProps == null) {
                throw newErrorInDocgenTag(
                        "The " + Transform.SETTING_INSERTABLE_OUTPUT_COMMANDS
                                + " configuration setting doesn't have entry with key " + StringUtil.jQuote(cmdKey)
                                + ". "
                                + (cmdPropsMap.isEmpty()
                                        ? "That setting is empty."
                                        : "It has these keys: " + String.join(", ", cmdPropsMap.keySet())));
            }

            Method mainMethod = getMainMethod(cmdKey, cmdProps);

            String cmdRunExceptionShortMessage;
            TemplateException cmdRunException;
            Writer outCapturer;
            PrintStream prevOut = System.out;
            PrintStream prevErr = System.err;
            InputStream prevIn = System.in;
            Map<String, String> prevSystemProperties = new HashMap<>();
            try {
                outCapturer = insertDirectiveType != CHECK_COMMAND ? new StringWriter() : NullWriter.INSTANCE;
                PrintStream outCapturerPrintStream = new PrintStream(
                        new WriterOutputStream(outCapturer, Charset.defaultCharset()));
                System.setOut(outCapturerPrintStream);
                System.setErr(outCapturerPrintStream);
                System.setIn(ClosedInputStream.CLOSED_INPUT_STREAM);

                cmdProps.getSystemProperties().forEach((k, v) -> {
                    String prevValue = setOrClearSystemProperty(k, v);
                    prevSystemProperties.put(k, prevValue);
                });

                List<String> rawCmdArgs = splitCmdLine.subList(1, splitCmdLine.size());
                List<String> cmdArgs = ImmutableList.<String>builder()
                        .addAll(cmdProps.getPrependedArguments())
                        .addAll(rawCmdArgs)
                        .addAll(cmdProps.getAppendedArguments())
                        .build().stream()
                        .map(cmdArg -> {
                            Path wdSubst = cmdProps.getWdSubstitution();
                            if (wdSubst == null) {
                                return cmdArg;
                            }
                            return cmdArg.replace(DOCGEN_WD_TAG, wdSubst.toString());
                        })
                        .collect(Collectors.toList());

                Map<String, String> systemPropertiesToRestore = new HashMap<>();
                try {
                    Object cmdExitCode = withSystemPropertiesOverridden(
                            Optional.ofNullable(args.systemProperties).orElse(Collections.emptyMap()),
                            () -> mainMethod.invoke(null, (Object) cmdArgs.toArray(new String[0])));
                    if (cmdExitCode instanceof Integer && ((Integer) cmdExitCode) != 0) {
                        cmdRunExceptionShortMessage = "Command execution has returned with non-0 exit code " + cmdExitCode + ".";
                        cmdRunException = newErrorInInsertOutputCommandException(
                                cmdRunExceptionShortMessage,
                                cmdProps, cmdArgs,
                                null);
                    } else {
                        cmdRunExceptionShortMessage = null;
                        cmdRunException = null;
                    }
                } catch (Exception e) {
                    cmdRunExceptionShortMessage = "The main method has thrown this exception:\n" + e;
                    cmdRunException = newErrorInInsertOutputCommandException(
                            cmdRunExceptionShortMessage,
                            cmdProps, cmdArgs,
                            e);
                }

                outCapturerPrintStream.flush();
            } finally {
                prevSystemProperties.forEach(PrintTextWithDocgenSubstitutionsDirective::setOrClearSystemProperty);
                System.setIn(prevIn);
                System.setErr(prevErr);
                System.setOut(prevOut);
            }
            if (cmdRunException == null) {
                if (insertDirectiveType != CHECK_COMMAND) {
                    cutAndInsertContent(args, outCapturer.toString());
                }
            } else {
                out.write(
                        "--------------------\n" +
                        "Docgen " + INSERT_WITH_OUTPUT.directiveName + " directive failed: "
                                + cmdRunExceptionShortMessage + "\n"
                                + "The command was:\n"
                                + StringUtil.chomp(args.body) + "\n\n"
                                + "The output of the command (if any) until it failed:\n\n");
                HTMLOutputFormat.INSTANCE.output(outCapturer.toString(), out);
                throw cmdRunException;
            }
        }