legendary-doc-site/script/restore-timestamps
2021-04-24 12:01:33 -05:00

82 lines
2.3 KiB
Elixir
Executable file

#!/usr/bin/env elixir
defmodule TimestampRestorer do
@environment System.get_env("MIX_ENV", "dev")
@db_path "_build/#{@environment}/timestamp-database"
def sha_all(opts \\ []) do
timestamp_database = load_timestamp_database()
"**/*.{ex,exs,beam}"
|> Path.wildcard()
|> Enum.reduce(%{}, fn filename, acc ->
{sha, timestamp} = process(filename, timestamp_database, opts)
Map.put(acc, sha, timestamp)
end)
|> write_timestamp_database()
end
defp load_timestamp_database() do
if File.exists?(@db_path) do
@db_path
|> File.read!()
|> String.split("\n")
|> Enum.reduce(%{}, fn line, acc ->
[sha, timestamp_string] = String.split(line, ":")
{timestamp, ""} = Integer.parse(timestamp_string)
Map.put(acc, sha, timestamp)
end)
else
%{}
end
end
defp write_timestamp_database(database) do
File.mkdir_p!(Path.dirname(@db_path))
database
|> Enum.map(fn {key, value} -> "#{key}:#{value}" end)
|> Enum.join("\n")
|> (& File.write!(@db_path, &1)).()
end
defp process(filename, timestamp_database, opts) do
{verbose, _opts} = Keyword.pop(opts, :verbose, false)
sha = sha(filename)
{:ok, %{mtime: new_timestamp}} = File.lstat(filename, time: :posix)
case Map.get(timestamp_database, sha) do
nil ->
log("[NEW SHA ] #{filename}: #{new_timestamp}", verbose)
timestamp when timestamp < new_timestamp ->
log("[RESTORED ] #{filename}: #{timestamp}", verbose)
File.touch(filename, timestamp)
timestamp when timestamp >= new_timestamp ->
log("[UNCHANGED] #{filename}: #{timestamp}", verbose)
end
{sha, new_timestamp}
end
defp log(_message, false), do: :ok
defp log(message, true), do: :logger.debug(message)
defp sha(filename) do
hash_ref = :crypto.hash_init(:sha)
File.stream!(filename)
|> Enum.reduce(hash_ref, fn chunk, prev_ref->
new_ref = :crypto.hash_update(prev_ref, chunk)
new_ref
end)
|> :crypto.hash_final()
|> Base.encode16()
|> String.downcase()
end
end
{opts, _args, _errors} = OptionParser.parse(System.argv(), switches: [verbose: :boolean])
{time, _result} = :timer.tc(TimestampRestorer, :sha_all, [opts])
:logger.info("Restored timestamps in #{time / 1_000_000}s")