add fuzzy search for packs

res/modules/search_utils.lua

@@ -0,0 +1,72 @@
+local M = {}
+
+-- Оценивает схожесть строк и возвращает целое число,
+-- чем оно больше, тем больше совпадение
+function M.fuzzy_score(sample, pattern)
+    if pattern == "" then return 0 end
+
+    local sample_lower = string.lower(sample)
+    local pattern_lower = string.lower(pattern)
+
+    local sample_len = #sample_lower
+    local pattern_len = #pattern_lower
+
+    if pattern_len > sample_len then return 0 end
+
+    local pattern_idx = 1
+    local consecutive = 0
+    local max_consecutive = 0
+    local matched_chars = 0
+    local total_distance = 0
+    local last_match_pos = -1
+
+    for i = 1, sample_len do
+        if pattern_idx <= pattern_len and
+            sample_lower:sub(i, i) == pattern_lower:sub(pattern_idx, pattern_idx) then
+            matched_chars = matched_chars + 1
+            consecutive = consecutive + 1
+            if consecutive > max_consecutive then
+                max_consecutive = consecutive
+            end
+
+            if last_match_pos ~= -1 then
+                total_distance = total_distance + (i - last_match_pos - 1)
+            end
+            last_match_pos = i
+
+            pattern_idx = pattern_idx + 1
+        else
+            consecutive = 0
+        end
+    end
+
+    if pattern_idx <= pattern_len then
+        return 0
+    end
+
+    local coverage = matched_chars / pattern_len * 20
+
+    local consecutive_bonus = max_consecutive * 10
+
+    local start_bonus = 0
+    if sample_lower:sub(1, 1) == pattern_lower:sub(1, 1) then
+        start_bonus = 15
+    end
+
+    local prefix_bonus = 0
+    if sample_lower:find(pattern_lower, 1, true) == 1 then
+        prefix_bonus = 25
+    end
+
+    local distance_penalty = total_distance * 2
+
+    local score = coverage + consecutive_bonus + start_bonus + prefix_bonus - distance_penalty
+
+    if sample_lower:find(pattern_lower, 1, true) then
+        score = score + 30
+    end
+
+    return math.max(0, score)
+end
+
+return M