KOREADER: A quick'n'dirty patch to allow overwriting the provided hyphenation pattern with a pattern file located in `/mnt/onboard/German.pattern`

10-UpdateGermanPattern.lua

-- A patch for updating a German.pattern file, if this is newer than the provide one.
-- quick and dirty; for my personal usage, will most likely not fit any other users needs

print("Update hyphenation patterns")

local language = "German" -- is someone wants to use this patch with another language
local xxx = "" -- add your location here

local lfs = require("libs/libkoreader-lfs")
local DataStorage = require("datastorage")
local ffiutil = require("ffi/util")

local data_dir = DataStorage:getDataDir()
local provided_pattern_path = data_dir .. "/data/hyph/" .. language .. ".pattern"

local pattern_path = {
    "/mnt/onboard/" .. language .. ".pattern", -- on a Kobo, for other devices feel free to add other paths
    "xxx/work/hyphenation/" .. language .. ".pattern", -- for tests in the emulator
    }

local function get_version_of_pattern_file(path)
    local date = ""
    if lfs.attributes(path, "mode") ~= "file" then
        -- most probably the file has been deleted or does not exist
        return date
    end
    for line in io.lines(path) do
        if line:find("<pattern>", 1, true) then
            break -- end of preamble
        end
        local _, version_pos = line:find("version. *") -- the version line looks like: "% version: 2022-12-24"
        if version_pos then
            local version = line:sub(version_pos + 1)
            local version_start, version_end = version:find("%d+-%d+-%d+")
            if version_end then
                version = version:sub(version_start, version_end)
                date = version
                break
            end
        end
    end
    return date
end

local provided_date
for pos = 1, #pattern_path do
    if lfs.attributes(pattern_path[pos], "mode") == "file" then
        print("Potential hyphenation pattern to update found at:", pattern_path[pos])

        provided_date = provided_date or get_version_of_pattern_file(provided_pattern_path) -- calc this late = here

        local candiate_date = get_version_of_pattern_file(pattern_path[pos])

        if not provided_date or provided_date < candiate_date then
            print("Copy pattern to", provided_pattern_path)
            ffiutil.copyFile(pattern_path[pos], provided_pattern_path)
        end
        break
    end
end