Insert Line Breaks.lua

script_name="Insert Line Breaks"
script_description=""
script_version="0.0.1"
script_author="line0"

local LineCollection = require("a-mo.LineCollection")
local util = require("aegisub.util")
local unicode = require("aegisub.unicode")
local l0Common = require("l0.Common")
local ASSTags = require("l0.ASSTags")
local re = require("aegisub.re")

local limit = 35

function insertLineBreaks(sub,sel)
    local lines = LineCollection(sub,sel)
    local curCnt, expr = limit, re.compile("\\s(?!.*\\s)")
    lines:runCallback(function(lines, line)
        local data = ASS.parse(line)
        data:callback(function(section)
            local j, n, len, split = 1, 1, unicode.len(section.value), {}
            while j<=len do
                local splitLen = math.min(curCnt,len-j+1)
                split[n], j = unicode.sub(section.value, j, j+splitLen-1), j+curCnt
                if splitLen-curCnt == 0 then
                    curCnt = limit
                    -- if the next character is a whitespace character, replace it with a line break
                    if re.match(unicode.sub(section.value,j,j), "\\s") then
                        j, split[n+1] = j+1, "\\N"
                    -- if it isn't, find the last whitespace character in our last <= n chars section
                    else
                        local matches = expr:find(split[n])
                        -- found one -> place the line break there and add the character count after that position
                        -- to the char count of the next section
                        if matches then
                            local pos = matches[1].last
                            split[n], split[n+1], split[n+2] = unicode.sub(split[n],1,pos-1), "\\N", unicode.sub(split[n],pos+1)
                            curCnt, n = curCnt-unicode.len(split[n+2]), n+1
                        -- no whitespace character found -> force the line break at n chars
                        else split[n+1] = "\\N" end
                    end
                    n=n+1
                end
                n=n+1
            end
            section.value = table.concat(split)
        end,ASSLineTextSection)
        data:commit()
    end)
    lines:replaceLines()
end
aegisub.register_macro(script_name, script_description, insertLineBreaks)