1 files changed, 99 insertions, 4 deletions
diff --git a/error_handling.lua b/error_handling.lua
index b7d5d13..ecf6088 100644
--- a/error_handling.lua
+++ b/error_handling.lua
@@ -57,14 +57,109 @@ debug.getinfo = function(thread, f, what)
   end
   return info
 end
+local strdist
+strdist = function(a, b, cache)
+  if cache == nil then
+    cache = { }
+  end
+  if a == b then
+    return 0
+  end
+  if #a < #b then
+    a, b = b, a
+  end
+  if b == "" then
+    return #a
+  end
+  local k = a .. '\003' .. b
+  if not (cache[k]) then
+    cache[k] = math.min(strdist(a:sub(1, -2), b, cache) + 1, strdist(a, b:sub(1, -2), cache) + 1, strdist(a:sub(1, -2), b:sub(1, -2), cache) + (a:sub(-1) ~= b:sub(-1) and 1.1 or 0))
+    if #a >= 2 and #b >= 2 and a:sub(-1, -1) == b:sub(-2, -2) and a:sub(-2, -2) == b:sub(-1, -1) then
+      cache[k] = math.min(cache[k], strdist(a:sub(1, -3), b:sub(1, -3), cache) + 1)
+    end
+  end
+  return cache[k]
+end
 local enhance_error
-enhance_error = function(error_message, start_fn, stop_fn)
+enhance_error = function(error_message)
   if not (error_message and error_message:match("%d|")) then
     error_message = error_message or ""
     do
-      local fn = (error_message:match("attempt to call a nil value %(global '(.*)'%)") or error_message:match("attempt to call global '(.*)' %(a nil value%)"))
-      if fn then
-        error_message = "The action '" .. tostring(fn:from_lua_id()) .. "' is not defined."
+      local fn_name = (error_message:match("attempt to call a nil value %(global '(.*)'%)") or error_message:match("attempt to call global '(.*)' %(a nil value%)"))
+      if fn_name then
+        local action_name = fn_name:from_lua_id()
+        error_message = "The action '" .. tostring(action_name) .. "' is not defined."
+        local func = debug.getinfo(2, 'f').func
+        local ename, env = debug.getupvalue(func, 1)
+        if not (ename == "_ENV" or ename == "_G") then
+          func = debug.getinfo(3, 'f').func
+          ename, env = debug.getupvalue(func, 1)
+        end
+        local THRESHOLD = math.min(4.5, .9 * #action_name)
+        local candidates = { }
+        local cache = { }
+        for i = 1, 99 do
+          local k, v = debug.getlocal(2, i)
+          if k == nil then
+            break
+          end
+          if not (k:sub(1, 1) == "(" or type(v) ~= 'function') then
+            k = k:from_lua_id()
+            if strdist(k, action_name, cache) <= THRESHOLD and k ~= "" then
+              table.insert(candidates, k)
+            end
+          end
+        end
+        for i = 1, debug.getinfo(func, 'u').nups do
+          local k, v = debug.getupvalue(func, i)
+          if not (k:sub(1, 1) == "(" or type(v) ~= 'function') then
+            k = k:from_lua_id()
+            if strdist(k, action_name, cache) <= THRESHOLD and k ~= "" then
+              table.insert(candidates, k)
+            end
+          end
+        end
+        local scan
+        scan = function(t, is_lua_id)
+          for k, v in pairs(t) do
+            if type(k) == 'string' and type(v) == 'function' then
+              if not (is_lua_id) then
+                k = k:from_lua_id()
+              end
+              if strdist(k, action_name, cache) <= THRESHOLD and k ~= "" then
+                table.insert(candidates, k)
+              end
+            end
+          end
+        end
+        scan(env.COMPILE_RULES, true)
+        scan(env.COMPILE_RULES._IMPORTS, true)
+        scan(env)
+        scan(env._IMPORTS)
+        if #candidates > 0 then
+          for _index_0 = 1, #candidates do
+            local c = candidates[_index_0]
+            THRESHOLD = math.min(THRESHOLD, strdist(c, action_name, cache))
+          end
+          do
+            local _accum_0 = { }
+            local _len_0 = 1
+            for _index_0 = 1, #candidates do
+              local c = candidates[_index_0]
+              if strdist(c, action_name, cache) <= THRESHOLD then
+                _accum_0[_len_0] = c
+                _len_0 = _len_0 + 1
+              end
+            end
+            candidates = _accum_0
+          end
+          if #candidates == 1 then
+            error_message = error_message .. "\n\x1b[3mSuggestion: Maybe you meant '" .. tostring(candidates[1]) .. "'? "
+          elseif #candidates > 0 then
+            local last = table.remove(candidates)
+            error_message = error_message .. ("\n" .. C('italic', "Suggestion: Maybe you meant '" .. tostring(table.concat(candidates, "', '")) .. "'" .. tostring(#candidates > 1 and ',' or '') .. " or '" .. tostring(last) .. "'? "))
+          end
+        end
       end
     end
     local level = 2