package com.it_jaros.jscanner;

import java.util.HashSet;
import java.util.Set;

public class CliParser {

    public ScanOptions parseArgs(String[] args) {
        if (args.length < 1 || args[0].trim().isEmpty()) {
            throw new IllegalArgumentException("No argument given");
        }

        Set<String> hostsArgv = new HashSet<>();
        String hostsFile = null;
        String ports = CliDefaults.PORTS;
        boolean bannerRecognition = CliDefaults.BANNER_RECOGNITION;
        boolean disableOnlineCheck = CliDefaults.DISABLE_HOST_CHECK;
        boolean quiet = CliDefaults.QUIET;
        boolean showFilteredPorts = CliDefaults.SHOW_FILTERED_PORTS;
        int delayInMillis = CliDefaults.DELAY_IN_MILLIS;
        int maxHostsLimit = CliDefaults.MAX_HOSTS_LIMIT;
        int maxWorkersPerHost = CliDefaults.MAX_WORKERS_PER_HOST;
        int socketLimit = CliDefaults.SOCKET_LIMIT;
        int timeoutInMillis = CliDefaults.TIMEOUT_IN_MILLIS;

        for (int i = 0; i < args.length; i++) {
            final String currentArg = args[i];
            if (!currentArg.startsWith("-")) {
                hostsArgv.add(currentArg);
                continue;
            }

            switch (currentArg) {
                case "--bannerRecognition", "-b":
                    bannerRecognition = true;
                    break;
                case "--delay", "-d":
                    delayInMillis = parseIntOption(args, ++i, currentArg);
                    break;
                case "--disableOnlineCheck", "-do":
                    disableOnlineCheck = true;
                    break;
                case "--help", "-h":
                    printUsageHelp();
                    throw new HelpRequested();
                case "--input", "-i":
                    hostsFile = getArgument(args, ++i, currentArg);
                    break;
                case "--maxHostsLimit", "-m":
                    maxHostsLimit = parseIntOption(args, ++i, currentArg);
                    break;
                case "--maxWorkersPerHost", "-mh":
                    maxWorkersPerHost = parseIntOption(args, ++i, currentArg);
                    break;
                case "--ports", "-p":
                    ports = getArgument(args, ++i, currentArg);
                    break;
                case "--quiet", "-q":
                    quiet = true;
                    break;
                case "--showFilteredPorts", "-sf":
                    showFilteredPorts = true;
                    break;
                case "--socketLimit", "-sl":
                    socketLimit = parseIntOption(args, ++i, currentArg);
                    break;
                case "--timeout", "-t":
                    timeoutInMillis = parseIntOption(args, ++i, currentArg);
                    break;
                default:
                    throw new IllegalArgumentException("No such param " + currentArg);
            }
        }

        if (hostsArgv.isEmpty() && hostsFile == null) {
           throw new IllegalArgumentException("No input provided. Check with --help for available options.");
        }

        return new ScanOptions(
                hostsArgv.stream().toList(),
                hostsFile,
                ports,
                bannerRecognition,
                disableOnlineCheck,
                quiet,
                showFilteredPorts,
                delayInMillis,
                maxHostsLimit,
                maxWorkersPerHost,
                socketLimit,
                timeoutInMillis
        );
    }

    private String getArgument(String[] args, int index, String option) {
        if (index >= args.length) {
            throw new IllegalArgumentException(String.format("Missing argument for option %s", option));
        }
        return args[index];
    }

    private int parseIntOption(String[] args, int index, String option) {
        String value = getArgument(args, index, option);
        try {
            return Integer.parseInt(value);
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException(String.format("Invalid argument %s for option %s", value, option));
        }
    }

    public void printUsageHelp() {
        StringBuilder usage = new StringBuilder();
        usage.append("""
                Usage:
                    java -jar jscanner.jar [OPTIONS] [<host>,...]

                Options:
                """);
        usage.append("""
                    --bannerRecognition, -b:\tEnable banner recognition to find out which service is running behind port (Default :%b)
                    --delay, -d:\t\tWaiting period in millis for connection attempts for a host (Default: %d)
                    --disableOnlineCheck, -do:\tDon't check if Host is reachable (Default: %b)
                    --input, -i:\t\tRead file to get host targets to scan. If set to "-" than Stdin is read (Default: null)
                    --maxHostsLimit, -m:\tMax number of hosts that are scanned at the same time (Default: %d)
                    --maxWorkersPerHost, -mh:\tVirtual Worker Threads run per Host. Higher doesn't mean necessarily faster. But the more you use the more RAM is required (Default: %d)
                    --ports, -p:\t\tDefine ports to be scanned (Default: %s)
                    --quiet, -q:\t\tDo not output progress bar (Default: %b)
                    --showFilteredPorts, -sf:\tShow also filtered ports (Default: %b)
                    --socketLimit, -sl:\t\tSocket limit in total. You can not scan more ports than allowed here (Default: %d)
                    --timeout, -t:\t\tTimeout in millis per connection attempt, 0 means infinite (Default: %d)
                """.formatted(CliDefaults.BANNER_RECOGNITION, CliDefaults.DELAY_IN_MILLIS, CliDefaults.DISABLE_HOST_CHECK, CliDefaults.MAX_HOSTS_LIMIT, CliDefaults.MAX_WORKERS_PER_HOST, CliDefaults.PORTS, CliDefaults.QUIET, CliDefaults.SHOW_FILTERED_PORTS, CliDefaults.SOCKET_LIMIT, CliDefaults.TIMEOUT_IN_MILLIS)
        );
        usage.append("""
                
                Examples:
                    java -jar jscanner.jar localhost
                    java -jar jscanner.jar fd00::1
                """);
        System.err.println(usage);
    }
}