feat: fuzzy search based on hamming distance

scripts/uosc/elements/Menu.lua

@@ -645,15 +645,50 @@ function Menu:search_update_items()
 	self:reset_navigation()
 end
 
+local function substring_hamming_distance(text, p, p_n)
+	local best_score, t, t_n = p_n, utf8_chars(text)
+	for i = 1, t_n - p_n + 1 do
+		local score = 0
+		for j = 1, p_n do
+			if t[i + j - 1] ~= p[j] then
+				score = score + 1
+			end
+		end
+		if score < best_score then
+			best_score = score
+		end
+	end
+	return best_score
+end
+
+local function fuzzy_search(items, query)
+	local q, q_n = utf8_chars(query)
+
+	local t, n, threshold = {}, 1, q_n / 3 + 1e-9
+	for _, item in ipairs(items) do
+		local title = item.title and item.title:lower()
+		local hint = item.hint and item.hint:lower()
+		local td = title and substring_hamming_distance(title, q, q_n) or q_n
+		local hd = hint and substring_hamming_distance(hint, q, q_n) or q_n
+		local tcd = title and substring_hamming_distance(table.concat(first_word_chars(title)), q, q_n) or q_n
+		local hcd = hint and substring_hamming_distance(table.concat(first_word_chars(hint)), q, q_n) or q_n
+		local distance = math.min(td, hd, tcd, hcd)
+		if distance <= threshold then
+			t[n] = { distance, n, item }
+			n = n + 1
+		end
+	end
+	table.sort(t, function(a, b) return a[1] == b[1] and a[2] < b[2] or a[1] < b[1] end)
+	for i, e in ipairs(t) do
+		t[i] = e[3]
+	end
+	return t
+end
+
 ---@param menu MenuStack
 function Menu:search_internal(menu)
 	local query = menu.search.query:lower()
-	menu.items = query ~= '' and itable_filter(menu.search.source.items, function(item)
-		local title = item.title and item.title:lower() or ''
-		local hint = item.hint and item.hint:lower() or ''
-		return title:find(query, 1, true) or hint:find(query, 1, true) or
-			(table.concat(first_word_chars(title)) .. table.concat(first_word_chars(hint))):find(query, 1, true)
-	end) or menu.search.source.items
+	menu.items = query ~= '' and fuzzy_search(menu.search.source.items, query) or menu.search.source.items
 	self:search_update_items()
 end
 

scripts/uosc/lib/text.lua

@@ -74,6 +74,15 @@ local function utf8_iter(str)
 	end
 end
 
+function utf8_chars(s)
+	local t, i = {}, 0
+	for _, c in utf8_iter(s) do
+		i = i + 1
+		t[i] = c
+	end
+	return t, i
+end
+
 ---Extract Unicode code point from utf-8 character at index i in str
 ---@param str string
 ---@param i integer