Add my existing implementation

tagtimerc.py

@@ -0,0 +1,98 @@
+import os
+import re
+import sys
+from dataclasses import dataclass, field
+from typing import List
+
+
+def get_tagtime_command() -> List[str]:
+    """
+    The original Perl implementation spawns another Perl script in a terminal
+    to ask the user for their current tags. To replicate this behavior we find
+    out the python executable and the location of the tagtime.py script.
+    """
+    python_exe = sys.executable
+    tagtimerc_py = os.path.abspath(__file__)
+    tagtime_py = tagtimerc_py.replace("tagtimerc.py", "tagtime.py")
+    return [python_exe, tagtime_py]
+
+
+@dataclass
+class TagTimeRc:
+    log_file: str
+    ed: str
+    xt: str
+    retrothresh: int
+    gap: int
+    urping: int
+    seed: int
+    linelen: int
+    catchup: int
+    tags_off: List[str] = field(default_factory=lambda:
+                                ["afk", "off", "RETRO"])
+    tags_afk: List[str] = field(default_factory=lambda: ["afk", "RETRO"])
+    tags_err: List[str] = field(default_factory=lambda: ["err"])
+    tagtimecmd: List[str] = field(default_factory=get_tagtime_command)
+
+
+def value_to_int(value: str) -> int:
+    """
+    The tagtimerc file is itself a Perl script. That means the assignments to
+    the configuration parameters can be Perl expressions. We could replicate
+    that behavior via `eval`, but we don't want to do that because it allows
+    arbitrary code execution. Instead we only support multiplication for now
+    (`45*60`).
+    """
+    try:
+        return int(value)
+    except ValueError:
+        pass
+    result = 1
+    for v in value.split("*"):
+        result *= int(v)
+    return result
+
+
+def parse_tagtimerc(tagtimerc_path: str) -> TagTimeRc:
+    """
+    Parses the configuration attributes from a tagtimerc file into Python.
+
+    All lines that start with a dollar sign are configuration lines. These
+    lines are than split into key and value. This function only considers
+    attributes that are part of TagTimeRc.
+    """
+    s = ("^\s*"       # potential leading whitespace
+         "\$(\w+)"    # key as group (variables in Perl start with $)
+         "\s*=\s*"    # equal sign including potential whitespaces around it
+         "\"?"        # potential opening quote
+         "([^\";]+)"  # value (everything that is not a semicolon or quote)
+         "\"?"        # potential closing quote
+         ";")         # semicolon to terminate key value pair
+    re_config_line = re.compile(s)
+    tagtimerc_path = os.path.expanduser(tagtimerc_path)
+    with open(tagtimerc_path, 'r') as f:
+        key_value_pairs = {m.groups()[0].lower(): m.groups()[1]
+                           for line in f.readlines()
+                           if (m := re_config_line.match(line))}
+
+    # Get dictionary of the TagTimeRc attribute types.
+    tagtimerc_types = TagTimeRc.__annotations__
+
+    # Process the key-value-pairs. Keep expected pairs and store them into
+    # kwarsg.
+    kwargs = {}
+    for key, value in key_value_pairs.items():
+        if key in tagtimerc_types and tagtimerc_types[key] is int:
+            kwargs[key] = value_to_int(value)
+        elif key == "logf":
+            # Give special treatman to logf, because it may contain other
+            # variables (`$logf = "$path$usr.log";`) Iterate over those
+            # variables and replace them with their value.
+            for variable in re.findall("\$\w+", value):
+                var = variable.replace("$", "")
+                value = value.replace(variable, key_value_pairs[var])
+            kwargs["log_file"] = value
+        elif key in tagtimerc_types:
+            kwargs[key] = value
+
+    return TagTimeRc(**kwargs)