[manifest-attribute-codegen] Automatically generate manifest attribut…

…es from Android SDK data.

build-tools/manifest-attribute-codegen/Extensions/StringExtensions.cs

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+using System.Text;
+using System.Xml.Linq;
+using Xamarin.SourceWriter;
+
+namespace Xamarin.Android.Tools.ManifestAttributeCodeGenerator;
+
+static class StringExtensions
+{
+	static StringExtensions ()
+	{
+		// micro unit testing, am so clever!
+		if (Hyphenate ("AndSoOn") != "and-so-on")
+			throw new InvalidOperationException ("Am so buggy 1 " + Hyphenate ("AndSoOn"));
+		if (Hyphenate ("aBigProblem") != "a-big-problem")
+			throw new InvalidOperationException ("Am so buggy 2");
+		if (Hyphenate ("my-two-cents") != "my-two-cents")
+			throw new InvalidOperationException ("Am so buggy 3");
+	}
+
+	public static string Hyphenate (this string s)
+	{
+		var sb = new StringBuilder (s.Length * 2);
+		for (int i = 0; i < s.Length; i++) {
+			if (char.IsUpper (s [i])) {
+				if (i > 0)
+					sb.Append ('-');
+				sb.Append (char.ToLowerInvariant (s [i]));
+			} else
+				sb.Append (s [i]);
+		}
+		return sb.ToString ();
+	}
+
+	const string prefix = "AndroidManifest";
+
+	public static string ToActualName (this string s)
+	{
+		s = s.IndexOf ('.') < 0 ? s : s.Substring (s.LastIndexOf ('.') + 1);
+
+		var ret = (s.StartsWith (prefix, StringComparison.Ordinal) ? s.Substring (prefix.Length) : s).Hyphenate ();
+		return ret.Length == 0 ? "manifest" : ret;
+	}
+
+	public static bool? GetAsBoolOrNull (this XElement element, string attribute)
+	{
+		var value = element.Attribute (attribute)?.Value;
+
+		if (value is null)
+			return null;
+
+		if (bool.TryParse (value, out var ret))
+			return ret;
+
+		return null;
+	}
+
+	public static bool GetAttributeBoolOrDefault (this XElement element, string attribute, bool defaultValue)
+	{
+		var value = element.Attribute (attribute)?.Value;
+
+		if (value is null)
+			return defaultValue;
+
+		if (bool.TryParse (value, out var ret))
+			return ret;
+
+		return defaultValue;
+	}
+
+	public static string GetRequiredAttributeString (this XElement element, string attribute)
+	{
+		var value = element.Attribute (attribute)?.Value;
+
+		if (value is null)
+			throw new InvalidDataException ($"Missing '{attribute}' attribute.");
+
+		return value;
+	}
+
+	public static string GetAttributeStringOrEmpty (this XElement element, string attribute)
+		=> element.Attribute (attribute)?.Value ?? string.Empty;
+
+	public static string Unhyphenate (this string s)
+	{
+		if (s.IndexOf ('-') < 0)
+			return s;
+
+		var sb = new StringBuilder ();
+
+		for (var i = 0; i < s.Length; i++) {
+			if (s [i] == '-') {
+				sb.Append (char.ToUpper (s [i + 1]));
+				i++;
+			} else {
+				sb.Append (s [i]);
+			}
+		}
+
+		return sb.ToString ();
+	}
+
+	public static string Capitalize (this string s)
+	{
+		return char.ToUpper (s [0]) + s.Substring (1);
+	}
+
+	public static void WriteAutoGeneratedHeader (this CodeWriter sw)
+	{
+		sw.WriteLine ("//------------------------------------------------------------------------------");
+		sw.WriteLine ("// <auto-generated>");
+		sw.WriteLine ("//     This code was generated by 'manifest-attribute-codegen'.");
+		sw.WriteLine ("//");
+		sw.WriteLine ("//     Changes to this file may cause incorrect behavior and will be lost if");
+		sw.WriteLine ("//     the code is regenerated.");
+		sw.WriteLine ("// </auto-generated>");
+		sw.WriteLine ("//------------------------------------------------------------------------------");
+		sw.WriteLine ();
+		sw.WriteLine ("#nullable enable"); // Roslyn turns off NRT for generated files by default, re-enable it
+	}
+}

build-tools/manifest-attribute-codegen/Models/AttributeDefinition.cs

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+using System.Xml.Linq;
+using Xamarin.SourceWriter;
+
+namespace Xamarin.Android.Tools.ManifestAttributeCodeGenerator;
+
+class AttributeDefinition
+{
+	public string ApiLevel { get; }
+	public string Name { get; }
+	public string Format { get; }
+	public List<EnumDefinition> Enums { get; } = new List<EnumDefinition> ();
+
+	public AttributeDefinition (string apiLevel, string name, string format)
+	{
+		ApiLevel = apiLevel;
+		Name = name;
+		Format = format;
+	}
+
+	public static AttributeDefinition FromElement (string api, XElement e)
+	{
+		var name = e.GetAttributeStringOrEmpty ("name");
+		var format = e.GetAttributeStringOrEmpty ("format");
+
+		var def = new AttributeDefinition (api, name, format);
+
+		var enums = e.Elements ("enum")
+			     .Select (n => new EnumDefinition (api, n.GetAttributeStringOrEmpty ("name"), n.GetAttributeStringOrEmpty ("value")));
+
+		def.Enums.AddRange (enums);
+
+		return def;
+	}
+
+	public void WriteXml (TextWriter w)
+	{
+		var format = Format.HasValue () ? $" format='{Format}'" : string.Empty;
+		var api_level = int.TryParse (ApiLevel, out var level) && level <= 10 ? string.Empty : $" api-level='{ApiLevel}'";
+
+		w.Write ($"        <a name='{Name}'{format}{api_level}");
+
+		if (Enums.Count > 0) {
+			w.WriteLine (">");
+			foreach (var e in Enums)
+				w.WriteLine ($"            <enum-definition name='{e.Name}' value='{e.Value}' api-level='{e.ApiLevel}' />");
+			w.WriteLine ("        </a>");
+		} else
+			w.WriteLine (" />");
+	}
+}

build-tools/manifest-attribute-codegen/Models/ElementDefinition.cs

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+using System.Xml.Linq;
+
+namespace Xamarin.Android.Tools.ManifestAttributeCodeGenerator;
+
+class ElementDefinition
+{
+	static readonly char [] sep = [' '];
+
+	public string ApiLevel { get; }
+	public string Name { get; }
+	public string[]? Parents { get;}
+	public List<AttributeDefinition> Attributes { get; } = new List<AttributeDefinition> ();
+
+	public string ActualElementName => Name.ToActualName ();
+
+	public ElementDefinition (string apiLevel, string name, string []? parents)
+	{
+		ApiLevel = apiLevel;
+		Name = name;
+		Parents = parents;
+	}
+
+	public static ElementDefinition FromElement (string api, XElement e)
+	{
+		var name = e.GetAttributeStringOrEmpty ("name");
+		var parents = e.Attribute ("parent")?.Value?.Split (sep, StringSplitOptions.RemoveEmptyEntries);
+		var def = new ElementDefinition (api, name, parents);
+
+		var attrs = e.Elements ("attr")
+			     .Select (a => AttributeDefinition.FromElement (api, a));
+
+		def.Attributes.AddRange (attrs);
+
+		return def;
+	}
+
+	public void WriteXml (TextWriter w)
+	{
+		w.WriteLine ($"    <e name='{ActualElementName}' api-level='{ApiLevel}'>");
+
+		if (Parents?.Any () == true)
+			foreach (var p in Parents)
+				w.WriteLine ($"        <parent>{p.ToActualName ()}</parent>");
+
+		foreach (var a in Attributes)
+			a.WriteXml (w);
+
+		w.WriteLine ("    </e>");
+	}
+}

build-tools/manifest-attribute-codegen/Models/EnumDefinition.cs

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+namespace Xamarin.Android.Tools.ManifestAttributeCodeGenerator;
+
+class EnumDefinition
+{
+	public string ApiLevel { get; set; }
+	public string Name { get; set; }
+	public string Value { get; set; }
+
+	public EnumDefinition (string apiLevel, string name, string value)
+	{
+		ApiLevel = apiLevel;
+		Name = name;
+		Value = value;
+	}
+}

build-tools/manifest-attribute-codegen/Models/ManifestDefinition.cs

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+using System.Xml.Linq;
+
+namespace Xamarin.Android.Tools.ManifestAttributeCodeGenerator;
+
+class ManifestDefinition
+{
+	public string ApiLevel { get; set; } = "0";
+	public List<ElementDefinition> Elements { get; } = new List<ElementDefinition> ();
+
+	// Creates a new ManifestDefinition for a single Android API from the given file path
+	public static ManifestDefinition FromFile (string filePath)
+	{
+		var dir_name = new FileInfo (filePath).Directory?.Parent?.Parent?.Parent?.Name;
+
+		if (dir_name is null)
+			throw new InvalidOperationException ($"Could not determine API level from {filePath}");
+
+		var manifest = new ManifestDefinition () {
+			ApiLevel = dir_name.Substring (dir_name.IndexOf ('-') + 1)
+		};
+
+		var elements = XDocument.Load (filePath).Root?.Elements ("declare-styleable")
+			.Select (e => ElementDefinition.FromElement (manifest.ApiLevel, e))
+			.ToList ();
+
+		if (elements is not null)
+			manifest.Elements.AddRange (elements);
+
+		return manifest;
+	}
+
+	public static ManifestDefinition FromSdkDirectory (string sdkPath)
+	{
+		// Load all the attrs_manifest.xml files from the Android SDK
+		var manifests = Directory.GetDirectories (Path.Combine (sdkPath, "platforms"), "android-*")
+			.Select (d => Path.Combine (d, "data", "res", "values", "attrs_manifest.xml"))
+			.Where (File.Exists)
+			.Order ()
+			.Select (FromFile)
+			.ToList ();
+
+		// Merge all the manifests into a single one
+		var merged = new ManifestDefinition ();
+
+		foreach (var def in manifests) {
+			foreach (var el in def.Elements) {
+				var element = merged.Elements.FirstOrDefault (_ => _.ActualElementName == el.ActualElementName);
+				if (element == null)
+					merged.Elements.Add (element = new ElementDefinition (
+						el.ApiLevel,
+						el.Name,
+						(string []?) el.Parents?.Clone ()
+					));
+				foreach (var at in el.Attributes) {
+					var attribute = element.Attributes.FirstOrDefault (_ => _.Name == at.Name);
+					if (attribute == null)
+						element.Attributes.Add (attribute = new AttributeDefinition (
+							at.ApiLevel,
+							at.Name,
+							at.Format
+						));
+					foreach (var en in at.Enums) {
+						var enumeration = at.Enums.FirstOrDefault (_ => _.Name == en.Name);
+						if (enumeration == null)
+							attribute.Enums.Add (new EnumDefinition (
+								en.ApiLevel,
+								en.Name,
+								en.Value
+							));
+					}
+				}
+			}
+		}
+
+		return merged;
+	}
+
+	public void WriteXml (TextWriter w)
+	{
+		w.WriteLine ("<m>");
+
+		foreach (var e in Elements)
+			e.WriteXml (w);
+
+		w.WriteLine ("</m>");
+	}
+}