ChallengeFind the version

time to read 2 min | 316 words

Okay, here is something that I had to deal with today. I had to implement the dated-rev-report command in SvnBridge. This command sends a date to the server, and get the first revision id that was committed before to that date. Because code is unambiguous, if we were using SQL, it would have been:

CREATE PROC DatedRevReport 
	@requestedDate DATETIME
AS
	SELECT TOP 1 RevisionId
	FROM Revisions
	WHERE CommittedDate < @requestedDate
	ORDER BY CommittedDate DESC

Simple, right? Except that the interface that I have to TFS is not SQL (and I would be pretty sad if it was, so that is a good thing). I have to go through the TFS API in order to get that result.

Here is the API that I have to work with (actually, that is a drastically simplified API, but it contains all the stuff required to solve this issue).

public interface ISourceControl
{
	int GetLatestId();
	LogItem QueryLog(VersionSpec from, VersionSpec to, int countToReturn);
}

public class LogItem
{
	public SourceItemHistory[] History;
}

public class History
{
	public int ChangeSetId;
	public DateTime CommitDateTime;
}

public class DateVersionSpec : VersionSpec
{
	public DateTime Date;
}

public class ChangesetVersionSpec : VersionSpec
{
	public int ChangesetId;
}

Your task, if you agree to accept it, is to build implement the following method:

public int GetVersionForDate(DateTime date)
{
	// your implementation here
}

One important consideration is that you should reduce remote calls. I managed to get it down to 4 remote calls for the worst case scenario. It could have been 3, but TFS has some... finicky date handling.

So, how would you solve the issue?

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