Add dotnetVersion class for version parsing

src/Installer/dnup/DotnetVersion.cs

@@ -1,13 +1,356 @@
 // 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.Text;
+using System.Diagnostics;
+using Microsoft.Deployment.DotNet.Releases;
 
-namespace Microsoft.DotNet.Tools.Bootstrapper
+namespace Microsoft.DotNet.Tools.Bootstrapper;
+
+/// <summary>
+/// Represents the type of .NET version (SDK or Runtime).
+/// </summary>
+internal enum DotnetVersionType
+{
+    /// <summary>Automatically detect based on version format.</summary>
+    Auto,
+    /// <summary>SDK version (has feature bands, e.g., 8.0.301).</summary>
+    Sdk,
+    /// <summary>Runtime version (no feature bands, e.g., 8.0.7).</summary>
+    Runtime
+}
+
+/// <summary>
+/// Represents a .NET version string with specialized parsing, comparison, and manipulation capabilities.
+/// Acts like a string but provides version-specific operations like feature band extraction and semantic comparisons.
+/// Supports both SDK versions (with feature bands) and Runtime versions, and handles build hashes and preview versions.
+/// </summary>
+[DebuggerDisplay("{Value} ({VersionType})")]
+internal readonly record struct DotnetVersion : IComparable<DotnetVersion>, IComparable<string>, IEquatable<string>
 {
-    internal class DotnetVersion
+    private readonly ReleaseVersion? _releaseVersion;
+
+    /// <summary>Gets the original version string value.</summary>
+    public string Value { get; }
+
+    /// <summary>Gets the version type (SDK or Runtime).</summary>
+    public DotnetVersionType VersionType { get; }
+
+    /// <summary>Gets the major version component (e.g., "8" from "8.0.301").</summary>
+    public int Major => _releaseVersion?.Major ?? 0;
+
+    /// <summary>Gets the minor version component (e.g., "0" from "8.0.301").</summary>
+    public int Minor => _releaseVersion?.Minor ?? 0;
+
+    /// <summary>Gets the patch version component (e.g., "301" from "8.0.301").</summary>
+    public int Patch => _releaseVersion?.Patch ?? 0;
+
+    /// <summary>Gets the major.minor version string (e.g., "8.0" from "8.0.301").</summary>
+    public string MajorMinor => $"{Major}.{Minor}";
+
+    /// <summary>Gets whether this version represents a preview version (contains '-preview').</summary>
+    public bool IsPreview => Value.Contains("-preview", StringComparison.OrdinalIgnoreCase);
+
+    /// <summary>Gets whether this version represents a prerelease (contains '-' but not just build hash).</summary>
+    public bool IsPrerelease => Value.Contains('-') && !IsOnlyBuildHash();
+
+    /// <summary>Gets whether this is an SDK version (has feature bands).</summary>
+    public bool IsSdkVersion => VersionType == DotnetVersionType.Sdk || 
+        (VersionType == DotnetVersionType.Auto && DetectVersionType() == DotnetVersionType.Sdk);
+
+    /// <summary>Gets whether this is a Runtime version (no feature bands).</summary>
+    public bool IsRuntimeVersion => VersionType == DotnetVersionType.Runtime ||
+        (VersionType == DotnetVersionType.Auto && DetectVersionType() == DotnetVersionType.Runtime);
+
+    /// <summary>Gets whether this version contains a build hash.</summary>
+    public bool HasBuildHash => GetBuildHash() is not null;
+
+    /// <summary>Gets whether this version is fully specified (e.g., "8.0.301" vs "8.0" or "8.0.3xx").</summary>
+    public bool IsFullySpecified => _releaseVersion is not null &&
+        !Value.Contains('x') &&
+        Value.Split('.').Length >= 3;
+
+    /// <summary>Gets whether this version uses a non-specific feature band pattern (e.g., "8.0.3xx").</summary>
+    public bool IsNonSpecificFeatureBand => Value.EndsWith('x') && Value.Split('.').Length == 3;
+
+    /// <summary>Gets whether this is just a major or major.minor version (e.g., "8" or "8.0").</summary>
+    public bool IsNonSpecificMajorMinor => Value.Split('.').Length <= 2 &&
+        Value.Split('.').All(x => int.TryParse(x, out _));
+
+    /// <summary>
+    /// Initializes a new instance with the specified version string.
+    /// </summary>
+    /// <param name="value">The version string to parse.</param>
+    /// <param name="versionType">The type of version (SDK or Runtime). Auto-detects if not specified.</param>
+    public DotnetVersion(string? value, DotnetVersionType versionType = DotnetVersionType.Auto)
+    {
+        Value = value ?? string.Empty;
+        VersionType = versionType;
+        _releaseVersion = ReleaseVersion.TryParse(GetVersionWithoutBuildHash(), out var version) ? version : null;
+    }
+
+    /// <summary>
+    /// Gets the feature band number from the SDK version (e.g., "3" from "8.0.301").
+    /// Returns null if this is not an SDK version or doesn't contain a feature band.
+    /// </summary>
+    public string? GetFeatureBand()
+    {
+        if (!IsSdkVersion) return null;
+
+        var parts = GetVersionWithoutBuildHash().Split('.');
+        if (parts.Length < 3) return null;
+
+        var patchPart = parts[2].Split('-')[0]; // Remove prerelease suffix
+        return patchPart.Length > 0 ? patchPart[0].ToString() : null;
+    }
+
+    /// <summary>
+    /// Gets the feature band patch version (e.g., "01" from "8.0.301").
+    /// Returns null if this is not an SDK version or doesn't contain a feature band.
+    /// </summary>
+    public string? GetFeatureBandPatch()
     {
+        if (!IsSdkVersion) return null;
+
+        var parts = GetVersionWithoutBuildHash().Split('.');
+        if (parts.Length < 3) return null;
+
+        var patchPart = parts[2].Split('-')[0]; // Remove prerelease suffix
+        return patchPart.Length > 1 ? patchPart[1..] : null;
     }
+
+    /// <summary>
+    /// Gets the complete feature band including patch (e.g., "301" from "8.0.301").
+    /// Returns null if this is not an SDK version or doesn't contain a feature band.
+    /// </summary>
+    public string? GetCompleteBandAndPatch()
+    {
+        if (!IsSdkVersion) return null;
+
+        var parts = GetVersionWithoutBuildHash().Split('.');
+        if (parts.Length < 3) return null;
+
+        return parts[2].Split('-')[0]; // Remove prerelease suffix if present
+    }
+
+    /// <summary>
+    /// Gets the prerelease identifier if this is a prerelease version.
+    /// </summary>
+    public string? GetPrereleaseIdentifier()
+    {
+        var dashIndex = Value.IndexOf('-');
+        return dashIndex >= 0 ? Value[(dashIndex + 1)..] : null;
+    }
+
+    /// <summary>
+    /// Gets the build hash from the version if present (typically after a '+' or at the end of prerelease).
+    /// Examples: "8.0.301+abc123" -> "abc123", "8.0.301-preview.1.abc123" -> "abc123"
+    /// </summary>
+    public string? GetBuildHash()
+    {
+        // Build hash after '+'
+        var plusIndex = Value.IndexOf('+');
+        if (plusIndex >= 0)
+            return Value[(plusIndex + 1)..];
+
+        // Build hash in prerelease (look for hex-like string at the end)
+        var prerelease = GetPrereleaseIdentifier();
+        if (prerelease is null) return null;
+
+        var parts = prerelease.Split('.');
+        var lastPart = parts[^1];
+
+        // Check if last part looks like a build hash (hex string, 6+ chars)
+        if (lastPart.Length >= 6 && lastPart.All(c => char.IsAsciiHexDigit(c)))
+            return lastPart;
+
+        return null;
+    }
+
+    /// <summary>
+    /// Gets the version string without any build hash component.
+    /// </summary>
+    public string GetVersionWithoutBuildHash()
+    {
+        var buildHash = GetBuildHash();
+        if (buildHash is null) return Value;
+
+        // Remove build hash after '+'
+        var plusIndex = Value.IndexOf('+');
+        if (plusIndex >= 0)
+            return Value[..plusIndex];
+
+        // Remove build hash from prerelease
+        return Value.Replace($".{buildHash}", "");
+    }
+
+    /// <summary>
+    /// Detects whether this is an SDK or Runtime version based on the version format.
+    /// SDK versions typically have 3-digit patch numbers (feature bands), Runtime versions have 1-2 digit patch numbers.
+    /// </summary>
+    private DotnetVersionType DetectVersionType()
+    {
+        var parts = GetVersionWithoutBuildHash().Split('.', '-');
+        if (parts.Length < 3) return DotnetVersionType.Runtime;
+
+        var patchPart = parts[2];
+
+        // SDK versions typically have 3-digit patch numbers (e.g., 301, 201)
+        // Runtime versions have 1-2 digit patch numbers (e.g., 7, 12)
+        if (patchPart.Length >= 3 && patchPart.All(char.IsDigit))
+            return DotnetVersionType.Sdk;
+
+        return DotnetVersionType.Runtime;
+    }
+
+    /// <summary>
+    /// Checks if the version only contains a build hash (no other prerelease identifiers).
+    /// </summary>
+    private bool IsOnlyBuildHash()
+    {
+        var dashIndex = Value.IndexOf('-');
+        if (dashIndex < 0) return false;
+
+        var afterDash = Value[(dashIndex + 1)..];
+
+        // Check if what follows the dash is just a build hash
+        return afterDash.Length >= 6 && afterDash.All(c => char.IsAsciiHexDigit(c));
+    }
+
+    /// <summary>
+    /// Creates a new version with the specified patch version while preserving other components.
+    /// </summary>
+    public DotnetVersion WithPatch(int patch)
+    {
+        var parts = Value.Split('.');
+        if (parts.Length < 3)
+            return new DotnetVersion($"{Major}.{Minor}.{patch:D3}");
+
+        var prereleaseAndBuild = GetPrereleaseAndBuildSuffix();
+        return new DotnetVersion($"{Major}.{Minor}.{patch:D3}{prereleaseAndBuild}");
+    }
+
+    /// <summary>
+    /// Creates a new version with the specified feature band while preserving other components.
+    /// </summary>
+    public DotnetVersion WithFeatureBand(int featureBand)
+    {
+        var currentPatch = GetFeatureBandPatch();
+        var patch = $"{featureBand}{currentPatch ?? "00"}";
+        var prereleaseAndBuild = GetPrereleaseAndBuildSuffix();
+        return new DotnetVersion($"{Major}.{Minor}.{patch}{prereleaseAndBuild}");
+    }
+
+    private string GetPrereleaseAndBuildSuffix()
+    {
+        var dashIndex = Value.IndexOf('-');
+        return dashIndex >= 0 ? Value[dashIndex..] : string.Empty;
+    }
+
+    /// <summary>
+    /// Validates that this version string represents a well-formed, fully specified version.
+    /// </summary>
+    public bool IsValidFullySpecifiedVersion()
+    {
+        if (!IsFullySpecified) return false;
+
+        var parts = Value.Split('.', '-')[0].Split('.');
+        if (parts.Length < 3 || Value.Length > 20) return false;
+
+        // Check that patch version is reasonable (1-2 digits for feature band, 1-2 for patch)
+        return parts.All(p => int.TryParse(p, out _)) && parts[2].Length is >= 2 and <= 3;
+    }
+
+    #region String-like behavior
+
+    public static implicit operator string(DotnetVersion version) => version.Value;
+    public static implicit operator DotnetVersion(string version) => new(version);
+
+    /// <summary>
+    /// Creates an SDK version from a string.
+    /// </summary>
+    public static DotnetVersion FromSdk(string version) => new(version, DotnetVersionType.Sdk);
+
+    /// <summary>
+    /// Creates a Runtime version from a string.
+    /// </summary>
+    public static DotnetVersion FromRuntime(string version) => new(version, DotnetVersionType.Runtime);
+
+    public override string ToString() => Value;
+
+    public bool Equals(string? other) => string.Equals(Value, other, StringComparison.Ordinal);
+
+    #endregion
+
+    #region IComparable implementations
+
+    public int CompareTo(DotnetVersion other)
+    {
+        // Use semantic version comparison if both are valid release versions
+        if (_releaseVersion is not null && other._releaseVersion is not null)
+            return _releaseVersion.CompareTo(other._releaseVersion);
+
+        // Fall back to string comparison
+        return string.Compare(Value, other.Value, StringComparison.Ordinal);
+    }
+
+    public int CompareTo(string? other)
+    {
+        if (other is null) return 1;
+        return CompareTo(new DotnetVersion(other));
+    }
+
+    #endregion
+
+    #region Static utility methods
+
+    /// <summary>
+    /// Determines whether the specified string represents a valid .NET version format.
+    /// </summary>
+    public static bool IsValidFormat(string? value)
+    {
+        if (string.IsNullOrWhiteSpace(value)) return false;
+        return new DotnetVersion(value).IsValidFullySpecifiedVersion() ||
+               new DotnetVersion(value).IsNonSpecificFeatureBand ||
+               new DotnetVersion(value).IsNonSpecificMajorMinor;
+    }
+
+    /// <summary>
+    /// Tries to parse a version string into a DotnetVersion.
+    /// </summary>
+    /// <param name="value">The version string to parse.</param>
+    /// <param name="version">The parsed version if successful.</param>
+    /// <param name="versionType">The type of version to parse. Auto-detects if not specified.</param>
+    public static bool TryParse(string? value, out DotnetVersion version, DotnetVersionType versionType = DotnetVersionType.Auto)
+    {
+        version = new DotnetVersion(value, versionType);
+        return IsValidFormat(value);
+    }
+
+    /// <summary>
+    /// Parses a version string into a DotnetVersion, throwing on invalid format.
+    /// </summary>
+    /// <param name="value">The version string to parse.</param>
+    /// <param name="versionType">The type of version to parse. Auto-detects if not specified.</param>
+    public static DotnetVersion Parse(string value, DotnetVersionType versionType = DotnetVersionType.Auto)
+    {
+        if (!TryParse(value, out var version, versionType))
+            throw new ArgumentException($"'{value}' is not a valid .NET version format.", nameof(value));
+        return version;
+    }
+
+    #endregion
+
+    #region String comparison operators
+
+    public static bool operator <(DotnetVersion left, DotnetVersion right) => left.CompareTo(right) < 0;
+    public static bool operator <=(DotnetVersion left, DotnetVersion right) => left.CompareTo(right) <= 0;
+    public static bool operator >(DotnetVersion left, DotnetVersion right) => left.CompareTo(right) > 0;
+    public static bool operator >=(DotnetVersion left, DotnetVersion right) => left.CompareTo(right) >= 0;
+
+    public static bool operator ==(DotnetVersion left, string? right) => left.Equals(right);
+    public static bool operator !=(DotnetVersion left, string? right) => !left.Equals(right);
+    public static bool operator ==(string? left, DotnetVersion right) => right.Equals(left);
+    public static bool operator !=(string? left, DotnetVersion right) => !right.Equals(left);
+
+    #endregion
 }