// Author: Simon Gockner
// Created: 2020-02-08
// Copyright(c) 2020 SimonG. All Rights Reserved.

using System;
using System.IO;
using System.Net;
using System.Threading.Tasks;
using GBase.Logging;
using GBase.Server.Exceptions;
using GBase.Server.Interfaces;

namespace GBase.Server
{
    public class GBaseServerSettings : IGBaseServerSettings
    {
        public const string ENDPOINT_STARTUP_CONFIGURATION_PREFIX = "--endpoint";

        private const string PROTOCOL_ARGUMENT_PREFIX = "-pr";
        private const string IP_ADDRESS_ARGUMENT_PREFIX = "-ip";
        private const string PORT_ARGUMENT_PREFIX = "-p";
        private const string ENDPOINT_ARGUMENT_PREFIX = "-e";

        private const string LOG_FILE_PATH_ARGUMENT_PREFIX = "-lp";
        private const string LOG_FILE_NAME_ARGUMENT_PREFIX = "-ln";

        private const string HELP_ARGUMENT_PREFIX = "-help";
        
        private readonly string _defaultLogFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "GBase", "Server", "Logs");
        private readonly string _defaultLogFileName = $"GBaseServer_Log_{DateTime.Now:yyyy_MM_dd}_{DateTime.Now:hh_mm_ss}.txt";

        private bool _protocolInitialized;
        private bool _ipAddressInitialized;
        private bool _portInitialized;
        private bool _endpointInitialized;
        private bool _logFilePathInitialized;
        private bool _logFileNameInitialized;

        public ServerProtocol Protocol { get; private set; }
        public IPAddress IpAddress { get; private set; }
        public int Port { get; private set; }
        public string Endpoint { get; private set; }
        public string LogFilePath { get; private set; }
        public string LogFileName { get; private set; }


        public async Task ParseArguments(string[] args)
        {
            for (int index = 0; index < args.Length; index++)
            {
                if (args[index] == PROTOCOL_ARGUMENT_PREFIX)
                {
                    index++;
                    await VerifyArgsLength(index, args.Length);

                    Protocol = ServerProtocolExtensions.GetServerProtocolFromString(args[index]);
                    _protocolInitialized = true;
                }
                else if (args[index] == IP_ADDRESS_ARGUMENT_PREFIX)
                {
                    index++;
                    await VerifyArgsLength(index, args.Length);

                    IpAddress = ParseIpAddress(args[index]);
                    _ipAddressInitialized = true;
                }
                else if (args[index] == PORT_ARGUMENT_PREFIX)
                {
                    index++;
                    await VerifyArgsLength(index, args.Length);

                    Port = Convert.ToInt32(args[index]);
                    _portInitialized = true;
                }
                else if (args[index] == ENDPOINT_ARGUMENT_PREFIX)
                {
                    index++;
                    await VerifyArgsLength(index, args.Length);

                    Endpoint = args[index];
                    _endpointInitialized = true;
                }
                else if (args[index] == LOG_FILE_PATH_ARGUMENT_PREFIX)
                {
                    index++;
                    await VerifyArgsLength(index, args.Length);

                    LogFilePath = args[index];
                    _logFilePathInitialized = true;
                }
                else if (args[index] == LOG_FILE_NAME_ARGUMENT_PREFIX)
                {
                    index++;
                    await VerifyArgsLength(index, args.Length);

                    LogFileName = args[index];
                    _logFileNameInitialized = true;
                }
                else
                {
                    await PrintHelp();
                    throw new ArgumentOutOfRangeException(nameof(args), args[index], "Invalid argument.");
                }
            }

            if (!await VerifySettings())
                throw new IncompleteArgumentsException($"Not all mandatory arguments were passed. Check {HELP_ARGUMENT_PREFIX} to find out which arguments are mandatory.");
        }

        private async Task VerifyArgsLength(int index, int length)
        {
            if (length > index)
                return;

            await PrintHelp();
            throw new MissingArgumentException(PROTOCOL_ARGUMENT_PREFIX);
        }

        private async Task<bool> VerifySettings()
        {
            //optional settings
            if (!_logFilePathInitialized)
                LogFilePath = _defaultLogFilePath;

            if (!_logFileNameInitialized)
                LogFileName = _defaultLogFileName;

            //mandatory settings
            if (_protocolInitialized && _ipAddressInitialized && _portInitialized && _endpointInitialized)
                return true;

            await PrintHelp();
            return false;
        }

        private IPAddress ParseIpAddress(string ipAddressString)
        {
            string[] ipStringArray = ipAddressString.Split('.');
            byte[] ipByteArray = new byte[ipStringArray.Length];

            for (var i = 0; i < ipStringArray.Length; i++)
            {
                string @string = ipStringArray[i];
                ipByteArray[i] = Convert.ToByte(@string);
            }

            return new IPAddress(ipByteArray);
        }

        private async Task PrintHelp()
        {
            await Log.Write<GBaseServerSettings>("Mandatory Arguments:");
            await Log.Write<GBaseServerSettings>($"{PROTOCOL_ARGUMENT_PREFIX}: The used protocol (e.g 'http' or 'https')");
            await Log.Write<GBaseServerSettings>($"{IP_ADDRESS_ARGUMENT_PREFIX}: The used ip address");
            await Log.Write<GBaseServerSettings>($"{PORT_ARGUMENT_PREFIX}: The used port");
            await Log.Write<GBaseServerSettings>($"{ENDPOINT_ARGUMENT_PREFIX}: The used endpoint");
            await Log.Write<GBaseServerSettings>("");
            await Log.Write<GBaseServerSettings>("Optional Arguments:");
            await Log.Write<GBaseServerSettings>($"{LOG_FILE_PATH_ARGUMENT_PREFIX}: The path to the server log file (default: '{_defaultLogFilePath}')");
            await Log.Write<GBaseServerSettings>($"{LOG_FILE_NAME_ARGUMENT_PREFIX}: The name of the server log file (default: 'GBaseServer_Log_$day_$time.txt')");
        }
    }
}