const fs = require('fs');
const path = require('path');
const parser = require('intl-messageformat-parser');
const { default: manageTranslations, readMessageFiles  } = require('react-intl-translations-manager');

const RFC5646_REGEXP = /^[a-z]{2,3}(?:-(?:x|[A-Za-z]{2,4}))*$/;

const rootDirectory = path.resolve(__dirname, '..');
const translationsDirectory = path.resolve(rootDirectory, 'app', 'soapbox', 'locales');
const messagesDirectory = path.resolve(rootDirectory, 'build', 'messages');
const availableLanguages = fs.readdirSync(translationsDirectory).reduce((languages, filename) => {
  const basename = path.basename(filename, '.json');
  if (RFC5646_REGEXP.test(basename)) {
    languages.push(basename);
  }
  return languages;
}, []);

const testRFC5646 = language => {
  if (!RFC5646_REGEXP.test(language)) {
    throw new Error('Not RFC5646 name');
  }
};

const testAvailability = language => {
  if (!availableLanguages.includes(language)) {
    throw new Error('Not an available language');
  }
};

const validateLanguages = (languages, validators) => {
  const invalidLanguages = languages.reduce((acc, language) => {
    try {
      validators.forEach(validator => validator(language));
    } catch (error) {
      acc.push({ language, error });
    }
    return acc;
  }, []);

  if (invalidLanguages.length > 0) {
    console.error(`
Error: Specified invalid LANGUAGES:
${invalidLanguages.map(({ language, error }) => `* ${language}: ${error.message}`).join('\n')}

Use yarn "manage:translations -- --help" for usage information
`);
    process.exit(1);
  }
};

const usage = `Usage: yarn manage:translations [OPTIONS] [LANGUAGES]

Manage JavaScript translation files in Soapbox FE. Generates and update translations in translationsDirectory: ${translationsDirectory}

LANGUAGES
The RFC5646 language tag for the language you want to test or fix. If you want to input multiple languages, separate them with space.

Available languages:
${availableLanguages.join(', ')}
`;

const { argv } = require('yargs')
  .usage(usage)
  .option('f', {
    alias: 'force',
    default: false,
    describe: 'force using the provided languages. create files if not exists.',
    type: 'boolean',
  });

// check if message directory exists
if (!fs.existsSync(messagesDirectory)) {
  console.error(`
Error: messagesDirectory not exists
(${messagesDirectory})
Try to run "yarn build" first`);
  process.exit(1);
}

// determine the languages list
const languages = (argv._.length > 0) ? argv._ : availableLanguages;

// validate languages
validateLanguages(languages, [
  testRFC5646,
  !argv.force && testAvailability,
].filter(Boolean));

// manage translations
manageTranslations({
  messagesDirectory,
  translationsDirectory,
  detectDuplicateIds: false,
  singleMessagesFile: true,
  languages,
  jsonOptions: {
    trailingNewline: true,
  },
});


// Check variable interpolations and print error messages if variables are
// used in translations which are not used in the default message.
/* eslint-disable no-console */

function findVariablesinAST(tree) {
  const result = new Set();
  tree.forEach((element) => {
    switch (element.type) {
    case parser.TYPE.argument:
    case parser.TYPE.number:
      result.add(element.value);
      break;
    case parser.TYPE.plural:
      result.add(element.value);
      Object.values(element.options)
        .map(option => option.value)
        .forEach(subtree =>
          findVariablesinAST(subtree)
            .forEach(variable => result.add(variable)));
      break;
    case parser.TYPE.literal:
      break;
    default:
      console.log('unhandled element=', element);
      break;
    }
  });
  return result;
}

function findVariables(string) {
  return findVariablesinAST(parser.parse(string));
}

const extractedMessagesFiles = readMessageFiles(translationsDirectory);
const extractedMessages = extractedMessagesFiles.reduce((acc, messageFile) => {
  messageFile.descriptors.forEach((descriptor) => {
    descriptor.descriptors.forEach((item) => {
      const variables = findVariables(item.defaultMessage);
      acc.push({
        id: item.id,
        defaultMessage: item.defaultMessage,
        variables: variables,
      });
    });
  });
  return acc;
}, []);

const translations = languages.map((language) => {
  return {
    language: language,
    data : JSON.parse(fs.readFileSync(path.join(translationsDirectory, language + '.json'), 'utf8')),
  };
});

function difference(a, b) {
  return new Set([...a].filter(x => !b.has(x)));
}

function pushIfUnique(arr, newItem) {
  if (arr.every((item) => {
    return (JSON.stringify(item) !== JSON.stringify(newItem));
  })) {
    arr.push(newItem);
  }
}

const problems = translations.reduce((acc, translation) => {
  extractedMessages.forEach((message) => {
    try {
      const translationVariables = findVariables(translation.data[message.id]);
      if ([...difference(translationVariables, message.variables)].length > 0) {
        pushIfUnique(acc, {
          language: translation.language,
          id: message.id,
          severity: 'error',
          type: 'missing variable      ',
        });
      } else if ([...difference(message.variables, translationVariables)].length > 0) {
        pushIfUnique(acc, {
          language: translation.language,
          id: message.id,
          severity: 'warning',
          type: 'inconsistent variables',
        });
      }
    } catch (error) {
      pushIfUnique(acc, {
        language: translation.language,
        id: message.id,
        severity: 'error',
        type: 'syntax error          ',
      });
    }
  });
  return acc;
}, []);

if (problems.length > 0) {
  console.error(`${problems.length} messages found with errors or warnings:`);
  console.error('\nLoc\tIssue            \tMessage ID');
  console.error('-'.repeat(60));

  problems.forEach((problem) => {
    const color = (problem.severity === 'error') ? '\x1b[31m' : '';
    console.error(`${color}${problem.language}\t${problem.type}\t${problem.id}\x1b[0m`);
  });
  console.error('\n');
  if (problems.find((item) => {
    return item.severity === 'error';
  })) {
    process.exit(1);
  }
}