using NUnit.Framework;

using System;

using System.IO;

using System.Linq;

using System.Text;

using System.Text.RegularExpressions;

namespace DistributedLockCodeGen

{

[Category("CI")]

public class DocCommentGenerator

{

[Test]

public void GenerateDocComments()

{

var changes = CodeGenHelpers.EnumerateSolutionFiles()

.Select(f => (file: f, code: File.ReadAllText(f)))

.Select(t => (t.file, t.code, updatedCode: AddDocComments(t.code)))

.Where(t => CodeGenHelpers.NormalizeCodeWhitespace(t.updatedCode) != CodeGenHelpers.NormalizeCodeWhitespace(t.code))

.ToList();

changes.ForEach(t => File.WriteAllText(t.file, t.updatedCode));

Assert.IsEmpty(changes.Select(t => t.file));

}

internal static string AddDocComments(string code)

{

if (!CodeGenHelpers.HasPublicType(code, out var typeInfo)) { return code; }

var acquireMethods = Regex.Matches(

code,

$@"(?<docComment>([ \t]+///.*?\n)*)(?<indent> |\t\t){(typeInfo.isInterface ? "" : "public ")}(?<returnType>\S+) (?<name>([a-zA-Z])+)\("

+ @"((?<paramType>\S+) (?<paramName>([a-zA-Z])+)( = \S+)(, )?)+\)"

);

var updatedCode = code;

foreach (var acquireMethod in acquireMethods.Cast<Match>())

{

var name = acquireMethod.Groups["name"].Value;

if (!name.Contains("Acquire")) { continue; }

var isTry = name.StartsWith("Try");

var isAsync = name.EndsWith("Async");

var lockType = name.Contains("Upgradeable") ? LockType.Upgrade

: name.Contains("Write") ? LockType.Write

: name.Contains("Read") ? LockType.Read

: typeInfo.typeName.Contains("Semaphore") ? LockType.Semaphore

: LockType.Mutex;

var @object = lockType == LockType.Semaphore ? "semaphore" : "lock";

var handleObject = lockType == LockType.Semaphore ? "ticket" : "lock";

var lineStart = acquireMethod.Groups["indent"].Value + "/// ";

var docComment = new StringBuilder();

docComment.AppendLine(lineStart + "<summary>");

docComment.Append(lineStart);

if (isTry) { docComment.Append("Attempts to acquire "); }

else { docComment.Append("Acquires "); }

docComment.Append(lockType switch

{

LockType.Read => "a READ lock ",

LockType.Upgrade => "an UPGRADE lock ",

LockType.Write => "a WRITE lock ",

LockType.Mutex => "the lock ",

LockType.Semaphore => "a semaphore ticket ",

_ => throw new NotSupportedException()

});

docComment.Append(isAsync ? "asynchronously" : "synchronously");

docComment.Append(isTry ? ". " : ", failing with <see cref=\"TimeoutException\"/> if the attempt times out. ");

docComment.Append(lockType switch

{

LockType.Read => "Multiple readers are allowed. Not compatible with a WRITE lock. ",

LockType.Upgrade => "Not compatible with another UPGRADE lock or a WRITE lock. ",

LockType.Write => "Not compatible with another WRITE lock or an UPGRADE lock. ",

LockType.Mutex => "",

LockType.Semaphore => "",

_ => throw new NotSupportedException(),

});

docComment.AppendLine("Usage: ");

docComment.Append(lineStart).AppendLine("<code>");

docComment.Append(lineStart).Append($" {(isAsync ? "await " : "")}using (")

.Append(isTry ? "var handle = " : "")

.Append(isAsync ? "await " : "")

.Append($"my{char.ToUpper(@object[0])}{@object.Substring(1)}.")

.AppendLine($"{name}(...))");

docComment.Append(lineStart).AppendLine(" {");

docComment.Append(lineStart).Append(' ', 8)

.Append(isTry ? "if (handle != null) { " : "")

.Append($"/* we have the {handleObject}! */")

.AppendLine(isTry ? " }" : "");

docComment.Append(lineStart).AppendLine(" }");

docComment.Append(lineStart)

.Append($" // dispose releases the {handleObject}")

.AppendLine(isTry ? " if we took it" : "");

docComment.Append(lineStart).AppendLine("</code>");

docComment.Append(lineStart).AppendLine("</summary>");

docComment.Append(lineStart).Append("<param name=\"timeout\">How long to wait before giving up on the acquisition attempt. ")

.AppendLine($"Defaults to {(isTry ? "0" : "<see cref=\"Timeout.InfiniteTimeSpan\"/>")}</param>");

docComment.Append(lineStart).AppendLine("<param name=\"cancellationToken\">Specifies a token by which the wait can be canceled</param>");

var returnType = acquireMethod.Groups["returnType"].Value;

if (returnType.StartsWith("ValueTask<")) { returnType = returnType.Replace("ValueTask<", "").TrimEnd('>'); }

var useAn = "aeiou".Contains(char.ToLower(returnType[0]));

docComment.Append(lineStart).Append($"<returns>A{(useAn ? "n" : "")} <see cref=\"{returnType.TrimEnd('?')}\"/> which can be used to release the {handleObject}")

.Append(isTry ? " or null on failure" : "")

.AppendLine("</returns>");

updatedCode = updatedCode.Replace(acquireMethod.Value, docComment + acquireMethod.Value.Substring(acquireMethod.Groups["docComment"].Length));

}

return updatedCode;

}

}

internal enum LockType

{

Mutex,

Read,

Write,

Upgrade,

Semaphore,

}

}