// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using Microsoft.NET.HostModel.AppHost;
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace Microsoft.NET.HostModel.Bundle
{
    /// <summary>
    /// TargetInfo: Information about the target for which the single-file bundle is built.
    /// 
    /// Currently the TargetInfo only tracks:
    ///   - the target operating system
    ///   - The target framework
    /// If necessary, the target architecture may be tracked in future.
    /// </summary>

    public class TargetInfo
    {
        public readonly OSPlatform OS;
        public readonly Version FrameworkVersion;
        public readonly uint BundleVersion;
        public readonly BundleOptions DefaultOptions;

        public TargetInfo(OSPlatform? os, Version targetFrameworkVersion)
        {
            Version net50 = new Version(5, 0);

            OS = os ?? HostOS;
            FrameworkVersion = targetFrameworkVersion ?? net50;

            Debug.Assert(IsLinux || IsOSX || IsWindows);

            if(FrameworkVersion.CompareTo(net50) >= 0)
            {
                BundleVersion = 2u;
                DefaultOptions = BundleOptions.None;
            }
            else if(FrameworkVersion.Major == 3 && (FrameworkVersion.Minor == 0 || FrameworkVersion.Minor == 1))
            {
                BundleVersion = 1u;
                DefaultOptions = BundleOptions.BundleAllContent;
            }
            else
            {
                throw new ArgumentException($"Invalid input: Unsupported Target Framework Version {targetFrameworkVersion}");
            }
        }

        public bool IsNativeBinary(string filePath)
        {
            return IsLinux ? ElfUtils.IsElfImage(filePath) : IsOSX ? MachOUtils.IsMachOImage(filePath) : PEUtils.IsPEImage(filePath);
        }

        public override string ToString()
        {
            string os = IsWindows ? "win" : IsLinux ? "linux" : "osx";
            return string.Format($"OS: {os} FrameworkVersion: {FrameworkVersion}");
        }

        static OSPlatform HostOS => RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ? OSPlatform.Linux :
                                    RuntimeInformation.IsOSPlatform(OSPlatform.OSX) ? OSPlatform.OSX : OSPlatform.Windows;

        public bool IsLinux => OS.Equals(OSPlatform.Linux);
        public bool IsOSX => OS.Equals(OSPlatform.OSX);
        public bool IsWindows => OS.Equals(OSPlatform.Windows);

        // The .net core 3 apphost doesn't care about semantics of FileType -- all files are extracted at startup.
        // However, the apphost checks that the FileType value is within expected bounds, so set it to the first enumeration.
        public FileType TargetSpecificFileType(FileType fileType) => (BundleVersion == 1) ? FileType.Unknown : fileType;
    }
}