selection_autocomplete.luau

--!strict

local ScriptEditorService = game:GetService("ScriptEditorService")

type Request = {
	position: {
		line: number,
		character: number,
	},
	textDocument: {
		document: ScriptDocument?,
		script: LuaSourceContainer?,
	},
}

type ResponseItem = {
	label: string, -- The label
	kind: Enum.CompletionItemKind?,
	tags: {Enum.CompletionItemTag}?,
	detail: string?,
	documentation: {
		value: string,
	}?,
	overloads: number?,
	learnMoreLink: string?,
	codeSample: string?,
	preselect: boolean?,
	textEdit: {
		newText: string,
		insert: { start: { line: number, character: number }, ["end"]: { line: number, character: number } }?,
		replace: { start: { line: number, character: number }, ["end"]: { line: number, character: number } }?,
	}?,
}

type Response = {
	items: { ResponseItem },
}

ScriptEditorService:RegisterAutocompleteCallback("SelectionAutocomplete", 1, function(req: Request, res: Response): Response
	if (not req.textDocument.document) or (not req.textDocument.document:IsCommandBar()) then
		return res
	end
	
	local text = req.textDocument.document:GetLine(req.position.line)
	local upTo = string.sub(text, 1, req.position.character)
	local match = string.match(upTo, "%$(%d+)$")
	
	if not match then
		return res
	end
	
	local item: ResponseItem = {
		label = "Select " .. match,
		kind = Enum.CompletionItemKind.Snippet,
		tags = {Enum.CompletionItemTag.CommandLinePermissions},
		detail = `game:GetService("Selection"):Get()[{match}]`,
		preselect = true,
		textEdit = {
			newText = `game:GetService("Selection"):Get()[{match}]`,
			replace = {
				start = {
					line = req.position.line,
					character = req.position.character - (#match + 1),
				},
				["end"] = {
					line = req.position.line,
					character = req.position.character,
				}
			},
		},
	}
	
	table.insert(res.items, item)
	
	return res
end)

plugin.Unloading:Connect(function()
	ScriptEditorService:DeregisterAutocompleteCallback("SelectionAutocomplete")
end)