using System;
using System.Linq;

namespace hactoolnet
{
    internal static class CliParser
    {
        private static readonly CliOption[] CliOptions =
        {
            new CliOption("intype", 't', 1, (o, a) => o.InFileType = ParseFileType(a[0])),
            new CliOption("raw", 'r', 0, (o, a) => o.Raw = true),
            new CliOption("keyset", 'k', 1, (o, a) => o.Keyfile = a[0]),
            new CliOption("titlekeys", 1, (o, a) => o.TitleKeyFile = a[0]),
            new CliOption("section0", 1, (o, a) => o.SectionOut[0] = a[0]),
            new CliOption("section1", 1, (o, a) => o.SectionOut[1] = a[0]),
            new CliOption("section2", 1, (o, a) => o.SectionOut[2] = a[0]),
            new CliOption("section3", 1, (o, a) => o.SectionOut[3] = a[0]),
            new CliOption("section0dir", 1, (o, a) => o.SectionOutDir[0] = a[0]),
            new CliOption("section1dir", 1, (o, a) => o.SectionOutDir[1] = a[0]),
            new CliOption("section2dir", 1, (o, a) => o.SectionOutDir[2] = a[0]),
            new CliOption("section3dir", 1, (o, a) => o.SectionOutDir[3] = a[0]),
            new CliOption("exefs", 1, (o, a) => o.ExefsOut = a[0]),
            new CliOption("exefsdir", 1, (o, a) => o.ExefsOutDir = a[0]),
            new CliOption("romfs", 1, (o, a) => o.RomfsOut = a[0]),
            new CliOption("romfsdir", 1, (o, a) => o.RomfsOutDir = a[0]),
            new CliOption("outdir", 1, (o, a) => o.OutDir = a[0]),
            new CliOption("sdseed", 1, (o, a) => o.SdSeed = a[0]),
            new CliOption("sdpath", 1, (o, a) => o.SdPath = a[0]),
        };

        public static Options Parse(string[] args)
        {
            var options = new Options();
            var inputSpecified = false;

            for (int i = 0; i < args.Length; i++)
            {
                string arg;

                if (args[i].Length == 2 && (args[i][0] == '-' || args[i][0] == '/'))
                {
                    arg = args[i][1].ToString().ToLower();
                }
                else if (args[i].Length > 2 && args[i].Substring(0, 2) == "--")
                {
                    arg = args[i].Substring(2).ToLower();
                }
                else
                {
                    if (inputSpecified)
                    {
                        Console.WriteLine($"Unable to parse option {args[i]}");
                        return null;
                    }

                    options.InFile = args[i];
                    inputSpecified = true;
                    continue;
                }

                var option = CliOptions.FirstOrDefault(x => x.Long == arg || x.Short == arg);
                if (option == null)
                {
                    Console.WriteLine($"Unknown option {args[i]}");
                    return null;
                }

                if (i + option.ArgsNeeded >= args.Length)
                {
                    Console.WriteLine($"Need {option.ArgsNeeded} parameter{(option.ArgsNeeded == 1 ? "" : "s")} after {args[i]}");
                    return null;
                }

                var optionArgs = new string[option.ArgsNeeded];
                Array.Copy(args, i + 1, optionArgs, 0, option.ArgsNeeded);

                option.Assigner(options, optionArgs);
                i += option.ArgsNeeded;
            }

            if (!inputSpecified)
            {
                Console.WriteLine("Input file must be specified");
                return null;
            }

            return options;
        }

        private static FileType ParseFileType(string input)
        {
            if (!Enum.TryParse(input, true, out FileType type))
            {
                PrintWithUsage("Specified type is invalid.");
            }

            return type;
        }

        private static void PrintWithUsage(string toPrint)
        {
            Console.WriteLine(toPrint);
            // PrintUsage();
        }

        private class CliOption
        {
            public CliOption(string longName, char shortName, int argsNeeded, Action<Options, string[]> assigner)
            {
                Long = longName;
                Short = shortName.ToString();
                ArgsNeeded = argsNeeded;
                Assigner = assigner;
            }
            public CliOption(string longName, int argsNeeded, Action<Options, string[]> assigner)
            {
                Long = longName;
                ArgsNeeded = argsNeeded;
                Assigner = assigner;
            }

            public string Long { get; }
            public string Short { get; }
            public int ArgsNeeded { get; }
            public Action<Options, string[]> Assigner { get; }
        }
    }
}