using System;
using System.Collections.Generic;
using System.IO;
using MonoMod.Utils;

namespace BepInEx.Unix
{
    internal static class UnixStreamHelper
    {
        public delegate int dupDelegate(int fd);

        public delegate int fcloseDelegate(IntPtr stream);

        public delegate IntPtr fdopenDelegate(int fd, string mode);

        public delegate int fflushDelegate(IntPtr stream);

        public delegate IntPtr freadDelegate(IntPtr ptr, IntPtr size, IntPtr nmemb, IntPtr stream);

        public delegate int fwriteDelegate(IntPtr ptr, IntPtr size, IntPtr nmemb, IntPtr stream);

        public delegate int isattyDelegate(int fd);

        [DynDllImport("libc")]
        public static dupDelegate dup;

        [DynDllImport("libc")]
        public static fdopenDelegate fdopen;

        [DynDllImport("libc")]
        public static freadDelegate fread;

        [DynDllImport("libc")]
        public static fwriteDelegate fwrite;

        [DynDllImport("libc")]
        public static fcloseDelegate fclose;

        [DynDllImport("libc")]
        public static fflushDelegate fflush;

        [DynDllImport("libc")]
        public static isattyDelegate isatty;

        static UnixStreamHelper()
        {
            var libcMapping = new Dictionary<string, List<DynDllMapping>>
            {
                ["libc"] = new()
                {
                    "libc.so.6",               // Ubuntu glibc
                    "libc",                    // Linux glibc
                    "/usr/lib/libSystem.dylib" // OSX POSIX
                }
            };

            typeof(UnixStreamHelper).ResolveDynDllImports(libcMapping);
        }

        public static Stream CreateDuplicateStream(int fileDescriptor)
        {
            var newFd = dup(fileDescriptor);

            return new UnixStream(newFd, FileAccess.Write);
        }
    }
}