local util = {}

function util.split_str(str, sep)
  local tbl = {}
  local n = 0
  if sep == nil then sep = "%S+" end
  for sub in string.gmatch(str, sep) do
    n = n + 1
    tbl[n] = sub
  end
  return tbl
end


function util.split_lines(str)
  local tbl = {}
  local si = 1
  for i = 1, #str do
    if string.find(string.sub(str, i, i), "\n") ~= nil then
      tbl[#tbl + 1] = string.sub(str, si, i - 1)
      si = i + 1
    end
  end
  return tbl
end


function util.extract_str(full_str, find_str, end_str)
  local fi1, fi2 = string.find(full_str, find_str, 1)
  local ei1, ei2 = string.find(full_str, end_str, fi2)
  if end_str == "\n" then
    return string.sub(full_str, fi2 + 1, ei1 - 2)
  else
    return string.sub(full_str, fi2 + 1, ei1 - 1)
  end
end


function util.to_bool(str)
  local bool = { ["true"] = true, ["false"] = false }
  return bool(str)
end


function util.table_keys(tbl)
  local keys = {}
  local n = 0
  for k, v in pairs(tbl) do
    n = n + 1
    keys[n] = k
  end
  return keys
end


function util.has_key(tbl, str)
  local keys = util.table_keys(tbl)
  for k = 1, #keys do
    if str == keys[k] then
      do return true end
    end
  end
  return false
end


function util.replace_vars(str, vars, vals)
  local text = str
  for k, v in pairs(vars) do
    text = string.gsub(text, v, vals[k])
  end
  return text
end


function util.replace_feed_entities(str, mode)
  -- Pre-processing before replacing feed variables
  -- "%" is a special character for string.gsub() and similar functions, and
  -- will cause an error if not escaped.
  local ents = {
    percent = { "%%", "%" },
  }
  -- Used post-processing of feed variables, remove empty log metadata tags
  if mode == "post" then
    ents = {
      percent = { "%", "%%" },
      author = { "  <author>\n  <name></name>\n  </author>\n", "" },
      subtitle = { "<subtitle></subtitle>\n", "" },
      title = { "<title></title>\n", "" },
    }
  end
  local text = str
  for e, c in pairs(ents) do
    text = string.gsub(text, c[1], c[2])
  end
  return text
end


function util.make_dir(dir)
  os.execute("test -d " .. dir .. " || mkdir -p " .. dir)
end


function util.ls_grep(dir, str)
  local ls_cmd = io.popen("ls " .. dir .. " | grep " .. str)
  return ls_cmd:read("*a")
end


function util.get_shell_var(str)
  local var = os.getenv(str)
  if var == "" then
    return nil
  else
    return var
  end
end


function util.replace_shell_vars(str)
  -- Replace common shell variable paths
  if string.find(str, "%$") ~= nil then
    local shell_vars = { "HOME", "USER" }
    for v = 1, #shell_vars do
      str = string.gsub(str, "$" .. shell_vars[v],
        util.get_shell_var(shell_vars[v]))
    end
  end
  return str
end


function util.extract_file_date(dir, file)
  -- Atom feed date format: 2022-01-15T00:00:00+00:00
  local ls_cmd = io.popen("ls -l --time-style=\"+%Y-%m-%dT%H:%M:%S%z\" " ..
    dir .. " | grep " .. file .. " | awk '{print $6}'")
  return ls_cmd:read("*a")
end


function util.read_file(file)
  local fh = io.open(file, "r")
  local text = ""
  if fh ~= nil then
    text = fh:read("*a")
    fh:close()
  end
  return text
end


function util.write_file(file, str)
  local fh = io.open(file, "w")
  fh:write(str)
  fh:close()
end

return util