import 'dart:convert';
import 'dart:io';

import 'package:args/args.dart';
import 'package:halkyon_learn_curator/src/sources/jlpt.dart';
import 'package:halkyon_learn_curator/src/sources/jmdict.dart';

/// Turns a dictionary download into a dictionary file for the server's
/// `dictionaries` folder (README.md):
///
///     dart run halkyon_learn_curator:curate jmdict \
///       --input jmdict-eng-3.6.2.json --jlpt original_data \
///       --output jmdict-en.jsonl.gz
Future<void> main(List<String> args) async {
  final parser = ArgParser()
    ..addOption('input', abbr: 'i', help: 'The source file, unpacked.')
    ..addOption(
      'jlpt',
      help: "yomitan-jlpt-vocab's original_data folder (n1.csv … n5.csv).",
    )
    ..addOption(
      'output',
      abbr: 'o',
      help: 'The dictionary file to write; gzipped when it ends in .gz.',
    );
  final ArgResults options;
  try {
    options = parser.parse(args);
  } on FormatException catch (error) {
    _fail('${error.message}\n${parser.usage}');
  }
  final [source, ...] = options.rest.isEmpty ? [''] : options.rest;
  final input = options.option('input');
  final output = options.option('output');
  if (source != 'jmdict' || input == null || output == null) {
    _fail(
      'Usage: curate jmdict --input <file> [--jlpt <folder>] --output '
      '<file>\n${parser.usage}',
    );
  }

  final jlpt = switch (options.option('jlpt')) {
    final folder? => await readJlptLevels(Directory(folder)),
    null => const <String, JlptLevel>{},
  };
  var entries = -1;
  final lines =
      jmdictDictionary(
        File(input).openRead().transform(utf8.decoder),
        jlpt: jlpt,
      ).map((line) {
        entries++;
        return line;
      });
  final bytes = lines.transform(utf8.encoder);
  await (output.endsWith('.gz') ? bytes.transform(gzip.encoder) : bytes).pipe(
    File(output).openWrite(),
  );
  stdout.writeln(
    'Wrote $entries entries to $output'
    '${jlpt.isEmpty ? '' : ' (${jlpt.length} with a JLPT level)'}.',
  );
}

Never _fail(String message) {
  stderr.writeln(message);
  exit(64);
}