[duetto meika] add deduetto meika macro

As implied by the name it should reverse what duetto meika does in a
subtitle file

duetto-meika.lua

@@ -60,4 +60,98 @@ function duetto(subs, sel)
     aegisub.set_undo_point(script_name)
 end
 
+
+function get_script_style(style, styles, ...)
+    subs = ({...})[1]
+    for key, i in pairs(styles) do
+        if subs == nil then
+            script_style = i
+        else
+            script_style = subs[i]
+        end
+
+        if (style.color1 == script_style.color1
+                and style.color2 == script_style.color2
+                and style.color3 == script_style.color3
+                and style.color4 == script_style.color4) then
+            return script_style
+        end
+    end
+    return nil
+end
+
+
+function deduetto_meika(subs, sel)
+    local styles = {}
+    local last_style = -1
+
+    -- create the style map
+    for i, line in ipairs(subs) do
+        if line.class == "style" then
+            styles[line.name] = i
+            last_style = i
+        end
+    end
+
+    local new_styles = {}
+
+    for _, i in ipairs(sel) do
+        local line = subs[i]
+        local current_style = subs[styles[line.style]]
+
+        local search_index = 1
+        while search_index < #line.text do
+            aegisub.log("remaining: " .. line.text:sub(search_index, #line.text) .. "\n")
+            local match_start, match_end = line.text:find("{[^}]*}", search_index)
+            if match_start == nil then
+                break
+            end
+
+            local bracketed = line.text:sub(match_start, match_end)
+            local new_style = false
+            for tag, color in bracketed:gmatch("\\(c[1-4]?)([^}\\]*)") do
+                new_style = true
+                if tag == "c" or tag == "c1" then
+                    current_style.color1 = color
+                elseif tag == "c2" then
+                    current_style.color2 = color
+                elseif tag == "c3" then
+                    current_style.color3 = color
+                elseif tag == "c4" then
+                    current_style.color4 = color
+                end
+            end
+
+            if new_style then
+                local script_style = get_script_style(current_style, styles, subs)
+                if script_style == nil then
+                    if get_script_style(current_style, new_styles) == nil then
+                        new_styles[#new_styles+1] = current_style
+                    end
+                else
+                    aegisub.log("changing line with style: " .. script_style.name .. "\n")
+                    bracketed = bracketed:gsub("\\c[1-4]?[^\\}]*", "")
+                    bracketed = "{s:" .. script_style.name .. bracketed:sub(2, #bracketed)
+                    line.text = line.text:sub(1, match_start-1) .. bracketed ..  line.text:sub(match_end + 1, #line.text)
+                end
+            end
+
+            search_index = match_start + 1
+        end
+
+        subs[i] = line
+    end
+
+    if #new_styles > 0 then
+        for i, new_style in ipairs(new_styles) do
+            last_style = last_style + 1
+            new_style.name = "Deduetto style " .. i
+            subs.insert(last_style, new_style)
+            aegisub.log("Created new style: " .. new_style.name .. "\n")
+        end
+    end
+
+end
+
 aegisub.register_macro(script_name, script_description, duetto)
+aegisub.register_macro(tr"Deduetto Meika", tr"Create styles from inline color tags", deduetto_meika)