// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using Microsoft.Build.Framework;

#nullable disable

namespace Microsoft.Build.Utilities
{
    /// <summary>
    /// Structure to represent a target platform sdk
    /// </summary>
    [SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "SDK", Justification = "Dev11 Beta (go-live) is shipping this way")]
    public class TargetPlatformSDK : IEquatable<TargetPlatformSDK>
    {
        /// <summary>
        /// Path to the platform sdk may be null if not a platform sdk.
        /// </summary>
        private string _path;

        /// <summary>
        /// Object containing the properties in the SDK manifest
        /// </summary>
        private SDKManifest _manifest;

        /// <summary>
        /// Cache for min Visual Studio version from manifest
        /// </summary>
        private Version _minVSVersion;

        /// <summary>
        /// Cache for min OS version from manifest
        /// </summary>
        private Version _minOSVersion;

        /// <summary>
        /// Constructor
        /// </summary>
        public TargetPlatformSDK(string targetPlatformIdentifier, Version targetPlatformVersion, string path)
        {
            ArgumentNullException.ThrowIfNull(targetPlatformIdentifier);
            ArgumentNullException.ThrowIfNull(targetPlatformVersion);
            TargetPlatformIdentifier = targetPlatformIdentifier;
            TargetPlatformVersion = targetPlatformVersion;
            Path = path;
            ExtensionSDKs = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
            Platforms = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
        }

        /// <summary>
        /// Min Visual Studio version from manifest
        /// </summary>
        public Version MinVSVersion
        {
            get
            {
                if (_minVSVersion == null && Manifest?.MinVSVersion != null)
                {
                    if (!Version.TryParse(Manifest.MinVSVersion, out _minVSVersion))
                    {
                        _minVSVersion = null;
                    }
                }

                return _minVSVersion;
            }
        }

        /// <summary>
        /// Min OS version from manifest
        /// </summary>
        public Version MinOSVersion
        {
            get
            {
                if (_minOSVersion == null && Manifest?.MinOSVersion != null)
                {
                    if (!Version.TryParse(Manifest.MinOSVersion, out _minOSVersion))
                    {
                        _minOSVersion = null;
                    }
                }

                return _minOSVersion;
            }
        }

        /// <summary>
        /// Target platform identifier
        /// </summary>
        public string TargetPlatformIdentifier { get; }

        /// <summary>
        /// Target platform version
        /// </summary>
        public Version TargetPlatformVersion { get; }

        /// <summary>
        /// Path to target platform sdk if it exists, it may not if there is no target platform is installed
        /// </summary>
        public string Path
        {
            get => _path;
            set => _path = value != null ? FileUtilities.EnsureTrailingSlash(value) : null;
        }

        /// <summary>
        /// The SDK's display name, or null if one is not defined.
        /// </summary>
        public string DisplayName => Manifest?.DisplayName;

        /// <summary>
        /// Extension sdks within this platform,
        /// </summary>
        internal Dictionary<string, string> ExtensionSDKs { get; }

        /// <summary>
        /// Set of platforms supported by this SDK.
        /// </summary>
        internal Dictionary<string, string> Platforms { get; }

        /// <summary>
        /// Reference to manifest object
        /// Makes it is instantiated only once
        /// </summary>
        private SDKManifest Manifest
        {
            get
            {
                // Load manifest from disk the first time it is needed
                if (_manifest == null && _path != null)
                {
                    _manifest = new SDKManifest(_path);
                }

                return _manifest;
            }
        }

        /// <summary>
        /// Override GetHashCode
        /// </summary>
        public override int GetHashCode()
            => StringComparer.OrdinalIgnoreCase.GetHashCode(TargetPlatformIdentifier) ^ TargetPlatformVersion.GetHashCode();

        /// <summary>
        /// Override equals
        /// </summary>
        public override bool Equals(object obj)
        {
            if (!(obj is TargetPlatformSDK moniker))
            {
                return false;
            }

            if (ReferenceEquals(this, moniker))
            {
                return true;
            }

            return Equals(moniker);
        }

        /// <summary>
        /// Implement IEquatable
        /// </summary>
        public bool Equals(TargetPlatformSDK other)
        {
            if (other == null)
            {
                return false;
            }

            return TargetPlatformIdentifier.Equals(other.TargetPlatformIdentifier, StringComparison.OrdinalIgnoreCase) && TargetPlatformVersion.Equals(other.TargetPlatformVersion);
        }

        /// <summary>
        /// Returns true if this SDK supports the given platform, or false otherwise.
        /// </summary>
        public bool ContainsPlatform(string targetPlatformIdentifier, string targetPlatformVersion)
        {
            string sdkKey = GetSdkKey(targetPlatformIdentifier, targetPlatformVersion);
            return Platforms.ContainsKey(sdkKey);
        }

        /// <summary>
        /// Given an identifier and version, construct a string to use as a key for that combination.
        /// </summary>
        internal static string GetSdkKey(string sdkIdentifier, string sdkVersion) => $"{sdkIdentifier}, Version={sdkVersion}";
    }
}