Check for compatible updates in plugin (#832)

plugin/src/Version.lua

@@ -1,3 +1,7 @@
+local Packages = script.Parent.Parent.Packages
+local Http = require(Packages.Http)
+local Promise = require(Packages.Promise)
+
 local function compare(a, b)
 	if a > b then
 		return 1
@@ -30,7 +34,48 @@ function Version.compare(a, b)
 		return minor
 	end
 
-	return revision
+	if revision ~= 0 then
+		return revision
+	end
+
+	local aPrerelease = if a[4] == "" then nil else a[4]
+	local bPrerelease = if b[4] == "" then nil else b[4]
+
+	-- If neither are prerelease, they are the same
+	if aPrerelease == nil and bPrerelease == nil then
+		return 0
+	end
+
+	-- If one is prerelease it is older
+	if aPrerelease ~= nil and bPrerelease == nil then
+		return -1
+	end
+	if aPrerelease == nil and bPrerelease ~= nil then
+		return 1
+	end
+
+	-- If they are both prereleases, compare those based on number
+	local aPrereleaseNumeric = string.match(aPrerelease, "(%d+).*$")
+	local bPrereleaseNumeric = string.match(bPrerelease, "(%d+).*$")
+
+	if aPrereleaseNumeric == nil or bPrereleaseNumeric == nil then
+		-- If one or both lack a number, comparing isn't meaningful
+		return 0
+	end
+	return compare(tonumber(aPrereleaseNumeric) or 0, tonumber(bPrereleaseNumeric) or 0)
+end
+
+function Version.parse(versionString: string)
+	local version = { string.match(versionString, "^v?(%d+)%.(%d+)%.(%d+)(.*)$") }
+	for i, v in version do
+		version[i] = tonumber(v) or v
+	end
+
+	if version[4] == "" then
+		version[4] = nil
+	end
+
+	return version
 end
 
 function Version.display(version)
@@ -43,4 +88,64 @@ function Version.display(version)
 	return output
 end
 
+function Version.retrieveLatestCompatible(options: {
+	version: { number },
+	includePrereleases: boolean?,
+}): {
+	version: { number },
+	prerelease: boolean,
+	publishedUnixTimestamp: number,
+}?
+	local success, releases = Http.get("https://api.github.com/repos/rojo-rbx/rojo/releases?per_page=10")
+		:andThen(function(response)
+			if response.code >= 400 then
+				local message = string.format("HTTP %s:\n%s", tostring(response.code), response.body)
+
+				return Promise.reject(message)
+			end
+
+			return response
+		end)
+		:andThen(Http.Response.json)
+		:await()
+
+	if success == false or type(releases) ~= "table" or next(releases) ~= 1 then
+		return nil
+	end
+
+	-- Iterate through releases, looking for the latest compatible version
+	local latestCompatible = nil
+	for _, release in releases do
+		-- Skip prereleases if they are not requested
+		if (not options.includePrereleases) and release.prerelease then
+			continue
+		end
+
+		local releaseVersion = Version.parse(release.tag_name)
+
+		-- Skip releases that are potentially incompatible
+		if releaseVersion[1] > options.version[1] then
+			continue
+		end
+
+		-- Skip releases that are older than the latest compatible version
+		if latestCompatible ~= nil and Version.compare(releaseVersion, latestCompatible.version) <= 0 then
+			continue
+		end
+
+		latestCompatible = {
+			version = releaseVersion,
+			prerelease = release.prerelease,
+			publishedUnixTimestamp = DateTime.fromIsoDate(release.published_at).UnixTimestamp,
+		}
+	end
+
+	-- Don't return anything if the latest found is not newer than the current version
+	if latestCompatible == nil or Version.compare(latestCompatible.version, options.version) <= 0 then
+		return nil
+	end
+
+	return latestCompatible
+end
+
 return Version