Add translation validation script and update documentation

TRANSLATING.md

@@ -30,6 +30,20 @@ Check if the merges make sense, if so replace `<langcode>.po` with `<langcode>_m
 &nbsp;
 &nbsp;
 
+## Validate Your Translation
+Our project uses material icons and includes fmtstr to avoid crashes when loading po or missing icon symbols. Please use the following tools to check
+```sh
+# install dependencies
+pip install babel
+# validate
+python translation-validator.py -f tl/<langcode>.po
+# or validate all
+python translation-validator.py -a
+```
+
+&nbsp;
+&nbsp;
+
 ## I need to reorder format parameters
 To specify which format parameter you're indexing, use the `<index>$` operator.  
 Eg. `%2$s` will index the second entry of the format string.

translation-validator.py

@@ -0,0 +1,155 @@
+#/usr/bin/env python3
+import os
+import sys
+import glob
+import argparse
+
+from babel.messages.pofile import read_po
+
+"""
+# polib is broken, use babel instead
+# gettext not supported .po files
+
+pip install babel
+"""
+
+tl_files = glob.glob("tl/*.po")
+
+ignore = [
+    "tl/template.pot",
+]
+
+fmt_str_keywords = ['%s', '%d', '%f', '%u', '%lu']
+check_fuzzy = False
+ignore_empty = False
+
+def validate_string_formatting(msgid, msgstr) -> bool:
+    """
+    Check if the string formatting is correct
+    Note: currently not checking the order of the formatting, and not check %2$s etc
+    """
+    fmt_str_count = {}
+    fmt_target_count = {}
+    for fmt_str in fmt_str_keywords:
+        fmt_str_count[fmt_str] = msgid.count(fmt_str)
+        fmt_target_count[fmt_str] = msgstr.count(fmt_str)
+
+    for fmt_str in fmt_str_keywords:
+        if fmt_str_count[fmt_str] == 0:
+            continue
+        if fmt_str_count[fmt_str] != fmt_target_count[fmt_str]:
+            return False
+
+    return True
+
+def validate_non_ascii(msgstr, msgid) -> bool:
+    """
+    For example, English using non-ascii as icon (Google Material Icons)
+    """
+    non_ascii = [c for c in msgid if ord(c) > 127]
+    non_ascii_target = [c for c in msgstr  if ord(c) > 127]
+
+    for c in non_ascii:
+        if c not in non_ascii_target:
+            return False
+
+    return True
+
+class ValidationError(Exception):
+    def __init__(self, message, entry):
+        self.message = message
+        self.entry = entry
+
+    def __str__(self):
+        return self.message
+
+class Summary:
+    def __init__(self):
+        self.total = 0
+        self.success = 0
+
+    def print_summary(self):
+        print(f"Total: {self.total}, translated rate: {self.success}/{self.total} ({self.success/self.total*100:.2f}%)")
+
+def validate_string(entry, summary : Summary) -> bool:
+    summary.total += 1
+    if entry.string == "" and not ignore_empty:
+        raise ValidationError("msgstr is empty", entry)
+
+    if not validate_string_formatting(entry.id, entry.string):
+        raise ValidationError("msgstr fmtstr is incorrect", entry)
+
+    if not validate_non_ascii(entry.string, entry.id):
+        raise ValidationError("msgstr may lost icon", entry)
+
+    if entry.fuzzy and check_fuzzy:
+        raise ValidationError("msgstr is fuzzy", entry)
+
+    if not entry.fuzzy and entry.string != "":
+        summary.success += 1
+
+    return True
+
+escape_chars = {
+    "\n": "\\n", "\r": "\\r", "\t": "\\t",
+    "\"": "\\\""
+}
+escape_table = str.maketrans(escape_chars)
+
+def escape_string(s) -> str:
+    return s.translate(escape_table)
+
+def validate_file(file_path) -> int:
+    ret_code = 0
+    summary = Summary()
+    print("Validating file: " + file_path)
+
+    with open(file_path, 'r', encoding='utf-8') as file:
+        catalog = read_po(file)
+
+    for entry in catalog:
+        try:
+            validate_string(entry, summary)
+        except ValidationError as e:
+            msgid = escape_string(e.entry.id)
+            msgstr = escape_string(e.entry.string)
+            print("Validation Error: " + str(e) + f" ({file_path}:{e.entry.lineno})")
+            print(f"\tmsgid: \"{msgid}\"")
+            print(f"\tmsgstr: \"{msgstr}\"")
+            ret_code = 1
+
+    summary.print_summary()
+
+    return ret_code
+
+def validate_all() -> int:
+    ret_code = 0
+    for tl_file in tl_files:
+        ret_code += validate_file(tl_file)
+
+    return ret_code
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description='Validate translation files')
+    parser.add_argument('-a', '--all', action='store_true', help='Validate all files')
+    parser.add_argument('-f', '--file', type=str, help='Validate specific file')
+    parser.add_argument('--fuzzy', action='store_true', help='Check fuzzy entries')
+    parser.add_argument('--ignore-empty', action='store_true', help='Ignore empty msgstr')
+    args = parser.parse_args()
+
+    if args.fuzzy:
+        check_fuzzy = True
+
+    if args.ignore_empty:
+        ignore_empty = True
+
+    if args.all:
+        sys.exit(validate_all())
+    elif args.file:
+        sys.exit(validate_file(args.file))
+    else:
+        print("No arguments given")
+        parser.print_help()
+        sys.exit(1)
+
+