Add a helper script for localization (#15789)

* Add a helper script for localization

The script generates a report of outdated contents in
`content/<l10n-lang>` directory by comparing two l10n
team milestone branches.

* Add description for scripts/diff_l10n_branches.py

scripts/README.md

@@ -5,6 +5,9 @@
 - `test_examples.sh`: This script tests whether a change affects example files bundled in the website.
 - `check-headers-file.sh`: This script checks the headers if you are in a production environment.
 - `hugo-version-check.sh`: This script checks whether your local Hugo version matches the version used in production.
+- `diff_l10n_branches.py`: This script generates a report of outdated contents in `content/<l10n-lang>` directory 
+by comparing two l10n team milestone branches.
+
 
 ## Requirements
 
@@ -71,3 +74,22 @@ This script checks the headers if you are in a production environment.
 This script checks whether your local Hugo version matches the version used in production.
 
     ./scripts/hugo-version-check.sh
+
+## diff_l10n_branches.py
+
+```
+$ scripts/diff_l10n_branches.py --help
+Usage: diff_l10n_branches.py [OPTIONS] L10N_LANG L_COMMIT R_COMMIT
+
+  This script generates a report of outdated contents in `content/<l10n-
+  lang>` directory by comparing two l10n team milestone branches.
+
+  L10n team owners can open a GitHub issue with the report generated by this
+  script when they start a new team milestone.
+
+  ex: `scripts/diff_l10n_branches.py ko dev-1.15-ko.3 dev-1.15-ko.4`
+
+Options:
+  --src-lang TEXT  Source language
+  --help           Show this message and exit.
+```

scripts/diff_l10n_branches.py

@@ -0,0 +1,137 @@
+#!/usr/bin/env python
+
+import os
+import subprocess
+import jinja2
+import click
+
+DEVNULL = open(os.devnull, 'w')
+ISSUE_TEMPLATE = """\
+# This is a Bug Report
+## Problem
+Outdated files in the {{ r_commit }} branch.
+
+### {{ files_to_be_modified | count }} files to be modified 
+{% for m_file in files_to_be_modified -%}
+  1. [ ] {{ m_file.filepath }} {{ m_file.shortstat }}
+{% endfor %}
+
+### {{ files_to_be_renamed | count }} files to be renamed  
+{% for r_file in files_to_be_renamed -%}
+  1. [ ] {{ r_file.diff_status_letter }} {{ r_file.src_filepath }} -> {{ r_file.dest_filepath }}
+{% endfor %}
+
+### {{ files_to_be_deleted | count }} files to be deleted 
+{% for d_file in files_to_be_deleted -%}
+  1. [ ] {{ d_file }}
+{% endfor %}
+
+## Proposed Solution
+
+{% if files_to_be_modified %}
+
+Use `git diff` to check what is changed in the upstream. And apply the upstream changes manually 
+to the `{{ l10n_lang_path }}` of `{{ r_commit }}` branch.
+
+For example:
+```
+# checkout `{{ r_commit }}`
+...
+# check what is updated in the upstream 
+git diff {{ l_commit }} {{ r_commit }} -- {{ files_to_be_modified.0.filepath }}
+# apply changes to content/ko
+vi {{ files_to_be_modified.0.filepath | replace(src_lang_path, l10n_lang_path) }}
+...
+# commit and push
+...
+# make PR to `{{ r_commit }}`
+```
+
+{% endif %}
+
+## Pages to Update
+
+"""
+
+files_to_be_deleted = []
+files_to_be_renamed = []
+files_to_be_modified = []
+
+
+def git_diff(filepath, l_commit, r_commit, shortstat=False):
+    cmd = ["git", "diff", l_commit, r_commit, "--", filepath]
+
+    if shortstat:
+        cmd = ["git", "diff", l_commit, r_commit, "--shortstat", "--", filepath]
+
+    return subprocess.check_output(cmd).decode("UTF-8").strip()
+
+
+def git_exists(path, filepath):
+    cmd = ["git", "cat-file", "-e", "{}:{}".format(path, filepath)]
+    ret_code = subprocess.call(cmd, stderr=DEVNULL)
+    return ret_code == 0
+
+
+def process_diff_status(diff_status, l_commit, r_commit, src_lang_path,
+                        l10n_lang_path):
+    status_letter = diff_status[0]
+    filepath = diff_status[1]
+
+    if git_exists(r_commit, filepath.replace(src_lang_path, l10n_lang_path)):
+        if status_letter == 'D':
+            files_to_be_deleted.append(filepath)
+        elif status_letter.startswith('R'):
+            replaced = {"diff_status_letter": diff_status[0],
+                        "src_filepath": diff_status[1],
+                        "dest_filepath": diff_status[2]}
+            files_to_be_renamed.append(replaced)
+        elif status_letter == 'M':
+            modified = {"filepath": filepath,
+                        "shortstat": git_diff(filepath, l_commit, r_commit,
+                                              shortstat=True),
+                        "diff": git_diff(filepath, l_commit, r_commit)}
+            files_to_be_modified.append(modified)
+
+
+def git_diff_name_status(l_commit, r_commit, src_lang_path, l10n_lang_path):
+    cmd = ["git", "diff", l_commit, r_commit, "--name-status", "--",
+           src_lang_path]
+    name_status_output = subprocess.check_output(cmd).strip()
+    for line in name_status_output.decode('utf-8').splitlines():
+        diff_status = line.split()
+        process_diff_status(diff_status, l_commit, r_commit, src_lang_path,
+                            l10n_lang_path)
+
+
+@click.command()
+@click.argument("l10n-lang")
+@click.argument("l-commit")
+@click.argument("r-commit")
+@click.option("--src-lang", help="Source language", default="en")
+def main(l10n_lang, src_lang, l_commit, r_commit):
+    """
+    This script generates a report of outdated contents in `content/<l10n-lang>`
+    directory by comparing two l10n team milestone branches.
+
+    L10n team owners can open a GitHub issue with the report generated by this
+    script when they start a new team milestone.
+
+    ex: `scripts/diff_l10n_branches.py ko dev-1.15-ko.3 dev-1.15-ko.4`
+    """
+    l10n_lang_path = "content/" + l10n_lang
+    src_lang_path = "content/" + src_lang
+    git_diff_name_status(l_commit, r_commit, src_lang_path,
+                         l10n_lang_path)
+    issue_template = jinja2.Template(ISSUE_TEMPLATE)
+    ret = issue_template.render(l_commit=l_commit, r_commit=r_commit,
+                                src_lang_path=src_lang_path,
+                                l10n_lang_path=l10n_lang_path,
+                                files_to_be_deleted=files_to_be_deleted,
+                                files_to_be_modified=files_to_be_modified,
+                                files_to_be_renamed=files_to_be_renamed)
+    print(ret)
+
+
+if __name__ == "__main__":
+    main()