Support serving of backend translations (#12453)

* Add view to support backend translation fetching

* Load backend translations from component json

* Translations for season sensor

* Scripts to merge and unpack Lokalise translations

* Fix copy paste error

* Serve post-lokalise translations to frontend

* Linting

* Auto-deploy translations with Travis

* Commit post-lokalise translation files

* Split logic into more helper functions

* Fall back to English for missing keys

* Move local translation copies to `.translations`

* Linting

* Initial tests

* Remove unnecessary file check

* Convert translation helper to async/await

* Convert translation helper tests to async/await

* Use set subtraction to find missing_components

* load_translation_files use component->file mapping

* Remove duplicated resources fetching

Get to take advantage of the slick Python 3.5 dict merging here.

* Switch to live project ID

script/translations_upload_merge.py

@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+"""Merge all translation sources into a single JSON file."""
+import glob
+import itertools
+import os
+import re
+
+from homeassistant.util import json as json_util
+
+FILENAME_FORMAT = re.compile(r'strings\.(?P<suffix>\w+)\.json')
+
+
+def find_strings_files():
+    """Return the paths of the strings source files."""
+    return itertools.chain(
+        glob.iglob("strings*.json"),
+        glob.iglob("*{}strings*.json".format(os.sep)),
+    )
+
+
+def get_component_platform(path):
+    """Get the component and platform name from the path."""
+    directory, filename = os.path.split(path)
+    match = FILENAME_FORMAT.search(filename)
+    suffix = match.group('suffix') if match else None
+    if directory:
+        return directory, suffix
+    else:
+        return suffix, None
+
+
+def get_translation_dict(translations, component, platform):
+    """Return the dict to hold component translations."""
+    if not component:
+        return translations['component']
+
+    if component not in translations:
+        translations['component'][component] = {}
+
+    if not platform:
+        return translations['component'][component]
+
+    if 'platform' not in translations['component'][component]:
+        translations['component'][component]['platform'] = {}
+
+    if platform not in translations['component'][component]['platform']:
+        translations['component'][component]['platform'][platform] = {}
+
+    return translations['component'][component]['platform'][platform]
+
+
+def main():
+    """Main section of the script."""
+    if not os.path.isfile("requirements_all.txt"):
+        print("Run this from HA root dir")
+        return
+
+    root = os.getcwd()
+    os.chdir(os.path.join("homeassistant", "components"))
+
+    translations = {
+        'component': {}
+    }
+
+    paths = find_strings_files()
+    for path in paths:
+        component, platform = get_component_platform(path)
+        parent = get_translation_dict(translations, component, platform)
+        strings = json_util.load_json(path)
+        parent.update(strings)
+
+    os.chdir(root)
+
+    os.makedirs("build", exist_ok=True)
+
+    json_util.save_json(
+        os.path.join("build", "translations-upload.json"), translations)
+
+
+if __name__ == '__main__':
+    main()