config/essentials/vis/backup.lua


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local backup = {}

-- Return the backup path concatenated with the filename, replace / with %
backup.entire_path_with_double_percentage_signs =
    function(backup_dir, path)
        return backup_dir .. "/" .. string.gsub(path, "/", "%%")
    end

-- Return the backup path concatenated with the filename, replace / with %
-- and append the current time using time_format
backup.entire_path_with_double_percentage_signs_and_timestamp = function(
    backup_dir, path)
    return backup_dir .. "/" .. os.date(backup.time_format) ..
               string.gsub(path, "/", "%%")
end

-- Before saving the file, copy the current contents of the file to a backup file
vis.events.subscribe(vis.events.FILE_SAVE_PRE, function(file, path)
    if file.size > backup.byte_limit then return end

    -- E.g. when editing stdin as an interactive filter
    -- `vis -`
    if path == nil then return end

    local backup_path = backup.get_fname(backup.directory, path)

    local backup_file = io.open(backup_path, "w")
    local current_file = io.open(path)
    if backup_file == nil or current_file == nil then return end

    for line in current_file:lines() do backup_file:write(line .. "\n") end

    backup_file:close()
end)

-- Set defaults
backup.directory = os.getenv("XDG_DATA_HOME") .. "/Trash/vis-backups"

backup.get_fname = backup.entire_path_with_double_percentage_signs

backup.time_format = "%H-%M-"

-- Do not make backups if the file is greater than this
-- 1MB by default
backup.byte_limit = 1000000

return backup