-- local l = require("pandoc.logging")
local json = pandoc.json

assert(#arg > 1, "\n" ..
  "[ERROR] usage: pandoc lua sitemap.lua <destination file> <input file>...")
local destination_filepath
local input_filepaths = {}
for _, option in ipairs(arg) do
  if destination_filepath == nil then
    destination_filepath = option
  else
    table.insert(input_filepaths, option)
  end
end

local data = json.encode(input_filepaths)
local f = io.open(destination_filepath)
if f == nil or f:read("a") ~= data then
  local f = assert(io.open(destination_filepath, "w"), "\n" ..
    "[ERROR] could not open " .. destination_filepath .. " for writing")
  f:write(data)
  f:close()
end