Implement a build tool for default messages extraction (#19620)

* Implement a build tool for default messages extraction

* Refactor extraction tool, resolve review comments, fix bugs

* Resolve comments, refactor extraction tool, fix bugs

* Add context to messages extraction tool

* Resolve comments

* Fix bugs

* Add messages extraction from .jade files, refactor code

* Add template literals parsing

* Return defaultMessages.json to plain structure

* Refactor utils

* Fix bugs

* Refactor code, resolve review comments, fix bugs

* Fix minor bug

* Get rid of '@babel/traverse' and add its native implementation

* Add handlebars messages extraction

* Fix mkdir on macOS

* Fix bugs, inject default formats, finalize the tool

* Fix filsystem permissions

* Refactor nodes traversal

* Update code style

* Downgrade @babel/types to fix build issues

* Resolve comments

* Fix minor bugs

package.json

@@ -224,6 +224,8 @@
     "yauzl": "2.7.0"
   },
   "devDependencies": {
+    "@babel/parser": "7.0.0-beta.52",
+    "@babel/types": "7.0.0-beta.31",
     "@elastic/eslint-config-kibana": "link:packages/eslint-config-kibana",
     "@elastic/eslint-plugin-kibana-custom": "link:packages/eslint-plugin-kibana-custom",
     "@kbn/es": "link:packages/kbn-es",
@@ -307,6 +309,7 @@
     "jest-raw-loader": "^1.0.1",
     "jimp": "0.2.28",
     "jsdom": "9.9.1",
+    "json5": "^1.0.1",
     "karma": "1.7.0",
     "karma-chrome-launcher": "2.1.1",
     "karma-coverage": "1.1.1",

scripts/extract_default_translations.js

@@ -0,0 +1,21 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+require('../src/setup_node_env');
+require('../src/dev/run_extract_default_translations');

src/dev/i18n/constants.js

@@ -0,0 +1,21 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+export const DEFAULT_MESSAGE_KEY = 'defaultMessage';
+export const CONTEXT_KEY = 'context';

src/dev/i18n/extract_code_messages.js

@@ -0,0 +1,71 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { parse } from '@babel/parser';
+import {
+  isCallExpression,
+  isIdentifier,
+  isJSXIdentifier,
+  isJSXOpeningElement,
+  isMemberExpression,
+} from '@babel/types';
+
+import { extractI18nCallMessages } from './extract_i18n_call_messages';
+import { isI18nTranslateFunction, traverseNodes } from './utils';
+import { extractIntlMessages, extractFormattedMessages } from './extract_react_messages';
+
+/**
+ * Detect Intl.formatMessage() function call (React).
+ *
+ * Example: `intl.formatMessage({ id: 'message-id', defaultMessage: 'Message text' });`
+ */
+function isIntlFormatMessageFunction(node) {
+  return (
+    isCallExpression(node) &&
+    isMemberExpression(node.callee) &&
+    isIdentifier(node.callee.object, { name: 'intl' }) &&
+    isIdentifier(node.callee.property, { name: 'formatMessage' })
+  );
+}
+
+/**
+ * Detect <FormattedMessage> elements in JSX.
+ *
+ * Example: `<FormattedMessage id="message-id" defaultMessage="Message text"/>`
+ */
+function isFormattedMessageElement(node) {
+  return isJSXOpeningElement(node) && isJSXIdentifier(node.name, { name: 'FormattedMessage' });
+}
+
+export function* extractCodeMessages(buffer) {
+  const content = parse(buffer.toString(), {
+    sourceType: 'module',
+    plugins: ['jsx', 'typescript', 'objectRestSpread', 'classProperties', 'asyncGenerators'],
+  });
+
+  for (const node of traverseNodes(content.program.body)) {
+    if (isI18nTranslateFunction(node)) {
+      yield extractI18nCallMessages(node);
+    } else if (isIntlFormatMessageFunction(node)) {
+      yield extractIntlMessages(node);
+    } else if (isFormattedMessageElement(node)) {
+      yield extractFormattedMessages(node);
+    }
+  }
+}

src/dev/i18n/extract_default_translations.js

@@ -0,0 +1,120 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { resolve } from 'path';
+import { formats } from '@kbn/i18n';
+import JSON5 from 'json5';
+
+import { extractHtmlMessages } from './extract_html_messages';
+import { extractCodeMessages } from './extract_code_messages';
+import { extractJadeMessages } from './extract_jade_messages';
+import { extractHandlebarsMessages } from './extract_handlebars_messages';
+import { globAsync, makeDirAsync, accessAsync, readFileAsync, writeFileAsync } from './utils';
+
+function addMessageToMap(targetMap, key, value) {
+  const existingValue = targetMap.get(key);
+  if (targetMap.has(key) && existingValue.message !== value.message) {
+    throw new Error(
+      `There is more than one default message for the same id "${key}": "${existingValue}" and "${value}"`
+    );
+  }
+  targetMap.set(key, value);
+}
+
+export async function extractDefaultTranslations(inputPath) {
+  const entries = await globAsync('*.{js,jsx,jade,ts,tsx,html,hbs,handlebars}', {
+    cwd: inputPath,
+    matchBase: true,
+  });
+
+  const { htmlEntries, codeEntries, jadeEntries, hbsEntries } = entries.reduce(
+    (paths, entry) => {
+      const resolvedPath = resolve(inputPath, entry);
+
+      if (resolvedPath.endsWith('.html')) {
+        paths.htmlEntries.push(resolvedPath);
+      } else if (resolvedPath.endsWith('.jade')) {
+        paths.jadeEntries.push(resolvedPath);
+      } else if (resolvedPath.endsWith('.hbs') || resolvedPath.endsWith('.handlebars')) {
+        paths.hbsFiles.push(resolvedPath);
+      } else {
+        paths.codeEntries.push(resolvedPath);
+      }
+
+      return paths;
+    },
+    { htmlEntries: [], codeEntries: [], jadeEntries: [], hbsEntries: [] }
+  );
+
+  const defaultMessagesMap = new Map();
+
+  await Promise.all(
+    [
+      [htmlEntries, extractHtmlMessages],
+      [codeEntries, extractCodeMessages],
+      [jadeEntries, extractJadeMessages],
+      [hbsEntries, extractHandlebarsMessages],
+    ].map(async ([entries, extractFunction]) => {
+      const files = await Promise.all(
+        entries.map(async entry => {
+          return {
+            name: entry,
+            content: await readFileAsync(entry),
+          };
+        })
+      );
+
+      for (const { name, content } of files) {
+        try {
+          for (const [id, value] of extractFunction(content)) {
+            addMessageToMap(defaultMessagesMap, id, value);
+          }
+        } catch (error) {
+          throw new Error(`Error in ${name}\n${error.message || error}`);
+        }
+      }
+    })
+  );
+
+  // .slice(0, -1): remove closing curly brace from json to append messages
+  let jsonBuffer = Buffer.from(JSON5.stringify({ formats }, { quote: `'`, space: 2 }).slice(0, -1));
+
+  const defaultMessages = [...defaultMessagesMap].sort(([key1], [key2]) => {
+    return key1 < key2 ? -1 : 1;
+  });
+
+  for (const [mapKey, mapValue] of defaultMessages) {
+    jsonBuffer = Buffer.concat([
+      jsonBuffer,
+      Buffer.from(`  '${mapKey}': '${mapValue.message}',`),
+      Buffer.from(mapValue.context ? ` // ${mapValue.context}\n` : '\n'),
+    ]);
+  }
+
+  // append previously removed closing curly brace
+  jsonBuffer = Buffer.concat([jsonBuffer, Buffer.from('}\n')]);
+
+  try {
+    await accessAsync(resolve(inputPath, 'translations'));
+  } catch (_) {
+    await makeDirAsync(resolve(inputPath, 'translations'));
+  }
+
+  await writeFileAsync(resolve(inputPath, 'translations', 'en.json'), jsonBuffer);
+}

src/dev/i18n/extract_handlebars_messages.js

@@ -0,0 +1,71 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { formatJSString } from './utils';
+
+const HBS_REGEX = /(?<=\{\{)([\s\S]*?)(?=\}\})/g;
+const TOKENS_REGEX = /[^'\s]+|(?:'([^'\\]|\\[\s\S])*')/g;
+
+/**
+ * Example: `'{{i18n 'message-id' '{"defaultMessage": "Message text"}'}}'`
+ */
+export function* extractHandlebarsMessages(buffer) {
+  for (const expression of buffer.toString().match(HBS_REGEX) || []) {
+    const tokens = expression.match(TOKENS_REGEX);
+
+    const [functionName, idString, propertiesString] = tokens;
+
+    if (functionName !== 'i18n') {
+      continue;
+    }
+
+    if (tokens.length !== 3) {
+      throw new Error('Wrong arguments amount for handlebars i18n call.');
+    }
+
+    if (!idString.startsWith(`'`) || !idString.endsWith(`'`)) {
+      throw new Error('Message id should be a string literal.');
+    }
+
+    const messageId = formatJSString(idString.slice(1, -1));
+
+    if (!propertiesString.startsWith(`'`) || !propertiesString.endsWith(`'`)) {
+      throw new Error(
+        `Cannot parse "${messageId}" message: properties string should be a string literal.`
+      );
+    }
+
+    const properties = JSON.parse(propertiesString.slice(1, -1));
+    const message = formatJSString(properties.defaultMessage);
+
+    if (typeof message !== 'string') {
+      throw new Error(
+        `Cannot parse "${messageId}" message: defaultMessage value should be a string.`
+      );
+    }
+
+    const context = formatJSString(properties.context);
+
+    if (context != null && typeof context !== 'string') {
+      throw new Error(`Cannot parse "${messageId}" message: context value should be a string.`);
+    }
+
+    yield [messageId, { message, context }];
+  }
+}

src/dev/i18n/extract_html_messages.js

@@ -0,0 +1,142 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { jsdom } from 'jsdom';
+import { parse } from '@babel/parser';
+import { isDirectiveLiteral, isObjectExpression, isStringLiteral } from '@babel/types';
+
+import { isPropertyWithKey, formatHTMLString, formatJSString, traverseNodes } from './utils';
+import { DEFAULT_MESSAGE_KEY, CONTEXT_KEY } from './constants';
+
+/**
+ * Find all substrings of "{{ any text }}" pattern
+ */
+const ANGULAR_EXPRESSION_REGEX = /\{\{+([\s\S]*?)\}\}+/g;
+
+const I18N_FILTER_MARKER = '| i18n: ';
+
+/**
+ * Extract default message from an angular filter expression argument
+ * @param {string} expression JavaScript code containing a filter object
+ * @returns {string} Default message
+ */
+function parseFilterObjectExpression(expression) {
+  // parse an object expression instead of block statement
+  const nodes = parse(`+${expression}`).program.body;
+
+  for (const node of traverseNodes(nodes)) {
+    if (!isObjectExpression(node)) {
+      continue;
+    }
+
+    let message;
+    let context;
+
+    for (const property of node.properties) {
+      if (isPropertyWithKey(property, DEFAULT_MESSAGE_KEY)) {
+        if (!isStringLiteral(property.value)) {
+          throw new Error('defaultMessage value should be a string literal.');
+        }
+
+        message = formatJSString(property.value.value);
+      } else if (isPropertyWithKey(property, CONTEXT_KEY)) {
+        if (!isStringLiteral(property.value)) {
+          throw new Error('context value should be a string literal.');
+        }
+
+        context = formatJSString(property.value.value);
+      }
+    }
+
+    return { message, context };
+  }
+
+  return null;
+}
+
+function parseIdExpression(expression) {
+  for (const node of traverseNodes(parse(expression).program.directives)) {
+    if (isDirectiveLiteral(node)) {
+      return formatJSString(node.value);
+    }
+  }
+
+  return null;
+}
+
+function trimCurlyBraces(string) {
+  return string.slice(2, -2).trim();
+}
+
+function* getFilterMessages(htmlContent) {
+  const expressions = (htmlContent.match(ANGULAR_EXPRESSION_REGEX) || [])
+    .filter(expression => expression.includes(I18N_FILTER_MARKER))
+    .map(trimCurlyBraces);
+
+  for (const expression of expressions) {
+    const filterStart = expression.indexOf(I18N_FILTER_MARKER);
+    const idExpression = expression.slice(0, filterStart).trim();
+    const filterObjectExpression = expression.slice(filterStart + I18N_FILTER_MARKER.length).trim();
+
+    if (!filterObjectExpression || !idExpression) {
+      throw new Error(`Cannot parse i18n filter expression: {{ ${expression} }}`);
+    }
+
+    const messageId = parseIdExpression(idExpression);
+
+    if (!messageId) {
+      throw new Error('Empty "id" value in angular filter expression is not allowed.');
+    }
+
+    const { message, context } = parseFilterObjectExpression(filterObjectExpression) || {};
+
+    if (!message) {
+      throw new Error(`Cannot parse "${messageId}" message: default message is required`);
+    }
+
+    yield [messageId, { message, context }];
+  }
+}
+
+function* getDirectiveMessages(htmlContent) {
+  const document = jsdom(htmlContent, {
+    features: { ProcessExternalResources: false },
+  }).defaultView.document;
+
+  for (const element of document.querySelectorAll('[i18n-id]')) {
+    const messageId = formatHTMLString(element.getAttribute('i18n-id'));
+    if (!messageId) {
+      throw new Error('Empty "i18n-id" value is not allowed.');
+    }
+
+    const message = formatHTMLString(element.getAttribute('i18n-default-message'));
+    if (!message) {
+      throw new Error(`Cannot parse "${messageId}" message: default message is required.`);
+    }
+
+    const context = formatHTMLString(element.getAttribute('i18n-context'));
+    yield [messageId, { message, context }];
+  }
+}
+
+export function* extractHtmlMessages(buffer) {
+  const content = buffer.toString();
+  yield* getDirectiveMessages(content);
+  yield* getFilterMessages(content);
+}

src/dev/i18n/extract_i18n_call_messages.js

@@ -0,0 +1,70 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { isObjectExpression, isStringLiteral } from '@babel/types';
+
+import { isPropertyWithKey, formatJSString } from './utils';
+import { DEFAULT_MESSAGE_KEY, CONTEXT_KEY } from './constants';
+
+/**
+ * Extract messages from `funcName('id', { defaultMessage: 'Message text' })` call expression AST
+ */
+export function extractI18nCallMessages(node) {
+  const [idSubTree, optionsSubTree] = node.arguments;
+
+  if (!isStringLiteral(idSubTree)) {
+    throw new Error('Message id should be a string literal.');
+  }
+
+  const messageId = idSubTree.value;
+  let message;
+  let context;
+
+  if (!isObjectExpression(optionsSubTree)) {
+    throw new Error(
+      `Cannot parse "${messageId}" message: object with defaultMessage property is not provided.`
+    );
+  }
+
+  for (const prop of optionsSubTree.properties) {
+    if (isPropertyWithKey(prop, DEFAULT_MESSAGE_KEY)) {
+      if (!isStringLiteral(prop.value)) {
+        throw new Error(
+          `Cannot parse "${messageId}" message: defaultMessage value should be a string literal.`
+        );
+      }
+
+      message = formatJSString(prop.value.value);
+    } else if (isPropertyWithKey(prop, CONTEXT_KEY)) {
+      if (!isStringLiteral(prop.value)) {
+        throw new Error(
+          `Cannot parse "${messageId}" message: context value should be a string literal.`
+        );
+      }
+
+      context = formatJSString(prop.value.value);
+    }
+  }
+
+  if (!message) {
+    throw new Error(`Cannot parse "${messageId}" message: defaultMessage is required`);
+  }
+
+  return [messageId, { message, context }];
+}

src/dev/i18n/extract_jade_messages.js

@@ -0,0 +1,44 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { parse } from '@babel/parser';
+
+import { extractI18nCallMessages } from './extract_i18n_call_messages';
+import { isI18nTranslateFunction, traverseNodes } from './utils';
+
+/**
+ * Matches `i18n(...)` in `#{i18n('id', { defaultMessage: 'Message text' })}`
+ */
+const JADE_I18N_REGEX = /(?<=\#\{)i18n\((([^)']|'([^'\\]|\\.)*')*\)(?=\}))/g;
+
+/**
+ * Example: `#{i18n('message-id', { defaultMessage: 'Message text' })}`
+ */
+export function* extractJadeMessages(buffer) {
+  const expressions = buffer.toString().match(JADE_I18N_REGEX) || [];
+
+  for (const expression of expressions) {
+    for (const node of traverseNodes(parse(expression).program.body)) {
+      if (isI18nTranslateFunction(node)) {
+        yield extractI18nCallMessages(node);
+        break;
+      }
+    }
+  }
+}

src/dev/i18n/extract_react_messages.js

@@ -0,0 +1,123 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+*/
+
+import { isJSXIdentifier, isObjectExpression, isStringLiteral } from '@babel/types';
+
+import { isPropertyWithKey, formatJSString, formatHTMLString } from './utils';
+import { DEFAULT_MESSAGE_KEY, CONTEXT_KEY } from './constants';
+
+function extractMessageId(value) {
+  if (!isStringLiteral(value)) {
+    throw new Error('Message id should be a string literal.');
+  }
+
+  return value.value;
+}
+
+function extractMessageValue(value, id) {
+  if (!isStringLiteral(value)) {
+    throw new Error(`defaultMessage value should be a string literal for id: ${id}.`);
+  }
+
+  return value.value;
+}
+
+function extractContextValue(value, id) {
+  if (!isStringLiteral(value)) {
+    throw new Error(`context value should be a string literal for id: ${id}.`);
+  }
+
+  return value.value;
+}
+
+/**
+ * Extract default messages from ReactJS intl.formatMessage(...) AST
+ * @param node Babel parser AST node
+ * @returns {[string, string][]} Array of id-message tuples
+ */
+export function extractIntlMessages(node) {
+  const options = node.arguments[0];
+
+  if (!isObjectExpression(options)) {
+    throw new Error('Object with defaultMessage property is not passed to intl.formatMessage().');
+  }
+
+  const [messageIdProperty, messageProperty, contextProperty] = [
+    'id',
+    DEFAULT_MESSAGE_KEY,
+    CONTEXT_KEY,
+  ].map(key => options.properties.find(property => isPropertyWithKey(property, key)));
+
+  const messageId = messageIdProperty
+    ? formatJSString(extractMessageId(messageIdProperty.value))
+    : undefined;
+
+  if (!messageId) {
+    throw new Error('Empty "id" value in intl.formatMessage() is not allowed.');
+  }
+
+  const message = messageProperty
+    ? formatJSString(extractMessageValue(messageProperty.value, messageId))
+    : undefined;
+
+  if (!message) {
+    throw new Error(`Default message is required for id: ${messageId}.`);
+  }
+
+  const context = contextProperty
+    ? formatJSString(extractContextValue(contextProperty.value, messageId))
+    : undefined;
+
+  return [messageId, { message, context }];
+}
+
+/**
+ * Extract default messages from ReactJS <FormattedMessage> element
+ * @param node Babel parser AST node
+ * @returns {[string, string][]} Array of id-message tuples
+ */
+export function extractFormattedMessages(node) {
+  const [messageIdProperty, messageProperty, contextProperty] = [
+    'id',
+    DEFAULT_MESSAGE_KEY,
+    CONTEXT_KEY,
+  ].map(key => node.attributes.find(attribute => isJSXIdentifier(attribute.name, { name: key })));
+
+  const messageId = messageIdProperty
+    ? formatHTMLString(extractMessageId(messageIdProperty.value))
+    : undefined;
+
+  if (!messageId) {
+    throw new Error('Empty "id" value in <FormattedMessage> is not allowed.');
+  }
+
+  const message = messageProperty
+    ? formatHTMLString(extractMessageValue(messageProperty.value, messageId))
+    : undefined;
+
+  if (!message) {
+    throw new Error(`Default message is required for id: ${messageId}.`);
+  }
+
+  const context = contextProperty
+    ? formatHTMLString(extractContextValue(contextProperty.value, messageId))
+    : undefined;
+
+  return [messageId, { message, context }];
+}

src/dev/i18n/utils.js

@@ -0,0 +1,94 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import {
+  isCallExpression,
+  isIdentifier,
+  isObjectProperty,
+  isMemberExpression,
+  isNode,
+} from '@babel/types';
+import fs from 'fs';
+import glob from 'glob';
+import { promisify } from 'util';
+
+const ESCAPE_LINE_BREAK_REGEX = /(?<!\\)\\\n/g;
+const ESCAPE_SINGLE_QUOTE_REGEX = /\\([\s\S])|(')/g;
+const HTML_LINE_BREAK_REGEX = /[\s]*\n[\s]*/g;
+
+export const readFileAsync = promisify(fs.readFile);
+export const writeFileAsync = promisify(fs.writeFile);
+export const globAsync = promisify(glob);
+export const makeDirAsync = promisify(fs.mkdir);
+export const accessAsync = promisify(fs.access);
+
+export function isPropertyWithKey(property, identifierName) {
+  return isObjectProperty(property) && isIdentifier(property.key, { name: identifierName });
+}
+
+/**
+ * Detect angular i18n service call or `@kbn/i18n` translate function call.
+ *
+ * Service call example: `i18n('message-id', { defaultMessage: 'Message text'})`
+ *
+ * `@kbn/i18n` example: `i18n.translate('message-id', { defaultMessage: 'Message text'})`
+ */
+export function isI18nTranslateFunction(node) {
+  return (
+    isCallExpression(node) &&
+    (isIdentifier(node.callee, { name: 'i18n' }) ||
+      (isMemberExpression(node.callee) &&
+        isIdentifier(node.callee.object, { name: 'i18n' }) &&
+        isIdentifier(node.callee.property, { name: 'translate' })))
+  );
+}
+
+export function formatJSString(string) {
+  return (string || '')
+    .replace(ESCAPE_LINE_BREAK_REGEX, '')
+    .replace(ESCAPE_SINGLE_QUOTE_REGEX, '\\$1$2')
+    .replace('\n', '\\n');
+}
+
+export function formatHTMLString(string) {
+  return (string || '')
+    .replace(ESCAPE_SINGLE_QUOTE_REGEX, '\\$1$2')
+    .replace(HTML_LINE_BREAK_REGEX, ' ');
+}
+
+/**
+ * Traverse an array of nodes using default depth-first traversal algorithm.
+ * We don't use `@babel/traverse` because of its bug: https://github.com/babel/babel/issues/8262
+ *
+ * @generator
+ * @param {object[]} nodes array of nodes or objects with Node values
+ * @yields {Node} each node
+ */
+export function* traverseNodes(nodes) {
+  for (const node of nodes) {
+    if (isNode(node)) {
+      yield node;
+    }
+
+    // if node is an object / array, traverse all of its object values
+    if (node && typeof node === 'object') {
+      yield* traverseNodes(Object.values(node).filter(value => value && typeof value === 'object'));
+    }
+  }
+}

src/dev/run_extract_default_translations.js

@@ -0,0 +1,27 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { run } from './run';
+import { extractDefaultTranslations } from './i18n/extract_default_translations';
+
+run(async () => {
+  for (const inputPath of process.argv.slice(2)) {
+    await extractDefaultTranslations(inputPath);
+  }
+});

yarn.lock

@@ -39,6 +39,10 @@
     esutils "^2.0.2"
     js-tokens "^3.0.0"
 
+"@babel/parser@7.0.0-beta.52":
+  version "7.0.0-beta.52"
+  resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.0.0-beta.52.tgz#4e935b62cd9bf872bd37bcf1f63d82fe7b0237a2"
+
 "@babel/template@7.0.0-beta.31":
   version "7.0.0-beta.31"
   resolved "https://registry.yarnpkg.com/@babel/template/-/template-7.0.0-beta.31.tgz#577bb29389f6c497c3e7d014617e7d6713f68bda"