Add a deployment command group to the website script

This group has one command so far: next-tag. It looks at the git tag list and
figured out the next deployment tag. For the most part tags are named like so:

    deploy-%Y-%m-%d-NN

The middle segments are year-month-day, and the last segment is an incrementing
counter. For the most part this number will be 01. On days when I deploy more than
once, it will increment.

scripts/erynwells_me/deployment.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+# Eryn Wells <eryn@erynwells.me>
+
+import argparse
+import datetime
+import subprocess
+from typing import List
+from .scripting import Command
+
+
+DATE_FORMAT = "%Y-%m-%d"
+
+
+class DeploymentCommand(Command):
+    @property
+    def help(self) -> str:
+        return 'Deployment tools'
+
+    def add_arguments(self, parser: argparse.ArgumentParser):
+        commands = parser.add_subparsers(title="Deployment", required=True)
+
+        deployment_command = commands.add_parser(
+            'next-tag',
+            help='Calculate the next deployment tag for a given date, examining all other tags for that day'
+        )
+        deployment_command.add_argument(
+            '--date', '-d',
+            type=self.__class__.parse_date_argument,
+            default=datetime.date.today(),
+            help="date to calculate a new deployment tag for (default: today)"
+        )
+        deployment_command.set_defaults(handler=self.handle_next_deployment_tag_command)
+
+    @staticmethod
+    def parse_date_argument(date_string: str) -> datetime.date:
+        return datetime.datetime.strptime(date_string, DATE_FORMAT).date()
+
+    def handle_next_deployment_tag_command(self, args: argparse.Namespace):
+        next_deployment_tag = deployment_tag_for_date(args.date)
+        print(next_deployment_tag)
+
+def deployment_tag_for_date(date: datetime.date) -> str:
+    formatted_date = date.strftime(DATE_FORMAT)
+
+    def deploy_tag_filter(tag):
+        return tag.startswith("deploy-") and formatted_date in tag
+
+    filtered_tags = sorted(filter(deploy_tag_filter, git_tags()))
+
+    if len(filtered_tags) == 0:
+        return f"deploy-{formatted_date}-01"
+    else:
+        last_tag = filtered_tags[-1]
+        components = last_tag.split("-")
+        if len(components) == 5:
+            # A previous numbered deployment. Add one to the last deployment
+            # number.
+            deployment_number = int(components[-1]) + 1
+            return f"deploy-{formatted_date}-{deployment_number:02}"
+        else:
+            # An old style deployment tag that doesn't have a number. There
+            # should only ever be one of these.
+            assert len(filtered_tags) == 1
+            return f"deploy-{formatted_date}-02"
+
+
+def git_tags() -> List[str]:
+    return subprocess.check_output(
+        "git tag -l",
+        shell=True,
+        encoding="utf-8"
+    ).splitlines()

scripts/erynwells_me/scripting/command.py

@@ -20,5 +20,5 @@ class Command:
     def help(self) -> str:
         return ''
 
-    def add_arguments(self, _: argparse.ArgumentParser):
+    def add_arguments(self, parser: argparse.ArgumentParser):
         raise NotImplementedError()

scripts/website

@@ -9,10 +9,12 @@ import argparse
 from typing import List
 from erynwells_me.scripting import Command
 from erynwells_me.weeknotes import WeeknotesCommand
+from erynwells_me.deployment import DeploymentCommand
 
 
 COMMANDS: List[Command] = [
     WeeknotesCommand(),
+    DeploymentCommand(),
 ]