feat: configure member number allocation strategy

src/ccma/storage/repository.py

@@ -2,9 +2,11 @@ from __future__ import annotations
 
 import json
 import os
+import re
 import shutil
 import unicodedata
 from collections.abc import Iterable
+from contextlib import contextmanager
 from datetime import date, datetime, timedelta
 from decimal import Decimal
 from pathlib import Path
@@ -93,6 +95,7 @@ DEFAULT_CONFIGURATION = {
     "member_number_policy": {
         "mode": "automatic",
         "pattern": DEFAULT_MEMBER_NUMBER_PATTERN,
+        "allocation_strategy": "next_free",
     },
     "member_number_sequences": {},
     "reminder_policy": {
@@ -160,6 +163,8 @@ class MemberRepository:
             policy = config.get("member_number_policy") or {}
             if str(policy.get("mode", "automatic")) not in {"automatic", "manual"}:
                 errors.append("repository.json: ungültiger Mitgliedsnummernmodus")
+            if str(policy.get("allocation_strategy", "next_free")) not in {"next_free", "max_plus_one"}:
+                errors.append("repository.json: ungültige Vergabestrategie für Mitgliedsnummern")
             validate_member_number_pattern(str(policy.get("pattern", DEFAULT_MEMBER_NUMBER_PATTERN)))
         except (OSError, ValueError, TypeError, json.JSONDecodeError, RepositoryError) as exc:
             errors.append(f"repository.json: {exc}")
@@ -290,6 +295,28 @@ class MemberRepository:
         phone: str = "",
         birth_date: str = "",
         member_number: str = "",
+    ) -> Member:
+        with self._member_number_lock():
+            return self._create_member_locked(
+                first_name=first_name,
+                last_name=last_name,
+                nickname=nickname,
+                email=email,
+                phone=phone,
+                birth_date=birth_date,
+                member_number=member_number,
+            )
+
+    def _create_member_locked(
+        self,
+        *,
+        first_name: str,
+        last_name: str,
+        nickname: str,
+        email: str,
+        phone: str,
+        birth_date: str,
+        member_number: str,
     ) -> Member:
         if not first_name.strip() or not last_name.strip():
             raise RepositoryError("Vorname und Nachname sind erforderlich.")
@@ -305,7 +332,9 @@ class MemberRepository:
         elif policy["mode"] == "manual":
             raise RepositoryError("Eine Mitgliedsnummer ist erforderlich.")
         else:
-            selected_number = self._allocate_member_number(policy["pattern"])
+            selected_number = self._allocate_member_number(
+                policy["pattern"], policy["allocation_strategy"]
+            )
         member_id = str(uuid4())
         directory = self._member_path(member_id)
         directory.mkdir(parents=True, exist_ok=False)
@@ -1703,15 +1732,30 @@ class MemberRepository:
         if mode not in {"automatic", "manual"}:
             mode = "automatic"
         pattern = str(policy.get("pattern", DEFAULT_MEMBER_NUMBER_PATTERN))
+        allocation_strategy = str(policy.get("allocation_strategy", "next_free"))
+        if allocation_strategy not in {"next_free", "max_plus_one"}:
+            allocation_strategy = "next_free"
         validate_member_number_pattern(pattern)
-        return {"mode": mode, "pattern": pattern}
+        return {
+            "mode": mode,
+            "pattern": pattern,
+            "allocation_strategy": allocation_strategy,
+        }
 
-    def save_member_number_policy(self, *, mode: str, pattern: str) -> None:
+    def save_member_number_policy(
+        self, *, mode: str, pattern: str, allocation_strategy: str = "next_free"
+    ) -> None:
         if mode not in {"automatic", "manual"}:
             raise RepositoryError("Ungültiger Mitgliedsnummernmodus.")
+        if allocation_strategy not in {"next_free", "max_plus_one"}:
+            raise RepositoryError("Ungültige Vergabestrategie für Mitgliedsnummern.")
         validate_member_number_pattern(pattern)
         config = read_json(self.root / "repository.json")
-        config["member_number_policy"] = {"mode": mode, "pattern": pattern.strip()}
+        config["member_number_policy"] = {
+            "mode": mode,
+            "pattern": pattern.strip(),
+            "allocation_strategy": allocation_strategy,
+        }
         config.setdefault("member_number_sequences", {})
         write_json_atomic(self.root / "repository.json", config)
 
@@ -1727,11 +1771,15 @@ class MemberRepository:
         config["organization"] = organization
         write_json_atomic(self.root / "repository.json", config)
 
-    def preview_member_number(self, pattern: str | None = None) -> str:
-        selected_pattern = pattern or self.get_member_number_policy()["pattern"]
+    def preview_member_number(
+        self, pattern: str | None = None, allocation_strategy: str | None = None
+    ) -> str:
+        policy = self.get_member_number_policy()
+        selected_pattern = pattern or policy["pattern"]
+        selected_strategy = allocation_strategy or policy["allocation_strategy"]
         validate_member_number_pattern(selected_pattern)
         config = read_json(self.root / "repository.json")
-        return self._next_available_member_number(config, selected_pattern)[0]
+        return self._next_available_member_number(config, selected_pattern, selected_strategy)[0]
 
     def _member_directories(self) -> Iterable[Path]:
         if not self.members_root.exists():
@@ -1757,9 +1805,11 @@ class MemberRepository:
             raise RepositoryError("Ungültige Asset-ID.")
         return self.assets_root / asset_id
 
-    def _allocate_member_number(self, pattern: str) -> str:
+    def _allocate_member_number(self, pattern: str, allocation_strategy: str) -> str:
         config = read_json(self.root / "repository.json")
-        member_number, next_value = self._next_available_member_number(config, pattern)
+        member_number, next_value = self._next_available_member_number(
+            config, pattern, allocation_strategy
+        )
         sequences = config.get("member_number_sequences")
         if not isinstance(sequences, dict):
             sequences = {}
@@ -1768,15 +1818,20 @@ class MemberRepository:
         write_json_atomic(self.root / "repository.json", config)
         return member_number
 
-    def _next_available_member_number(self, config: dict, pattern: str) -> tuple[str, int]:
-        sequences = config.get("member_number_sequences")
-        if not isinstance(sequences, dict):
-            sequences = {}
-        try:
-            number = max(1, int(sequences.get(pattern, 1)))
-        except (TypeError, ValueError):
-            number = 1
+    def _next_available_member_number(
+        self, config: dict, pattern: str, allocation_strategy: str
+    ) -> tuple[str, int]:
+        if allocation_strategy not in {"next_free", "max_plus_one"}:
+            raise RepositoryError("Ungültige Vergabestrategie für Mitgliedsnummern.")
         existing = {member.member_number.casefold() for member in self.list_members() if member.member_number}
+        number = 1
+        if allocation_strategy == "max_plus_one":
+            used_values = (
+                value
+                for member_number in existing
+                if (value := _number_from_formatted_member_number(pattern, member_number)) is not None
+            )
+            number = max(used_values, default=0) + 1
         for _attempt in range(1_000_000):
             candidate = format_member_number(pattern, number)
             number += 1
@@ -1784,6 +1839,33 @@ class MemberRepository:
                 return candidate, number
         raise RepositoryError("Keine freie Mitgliedsnummer im konfigurierten Nummernbereich gefunden.")
 
+    @contextmanager
+    def _member_number_lock(self):
+        lock_path = self.root / ".member-number.lock"
+        lock_path.parent.mkdir(parents=True, exist_ok=True)
+        with lock_path.open("a+", encoding="utf-8") as handle:
+            if os.name == "nt":
+                import msvcrt
+
+                handle.seek(0)
+                if not handle.read(1):
+                    handle.write("\0")
+                    handle.flush()
+                handle.seek(0)
+                msvcrt.locking(handle.fileno(), msvcrt.LK_LOCK, 1)
+            else:
+                import fcntl
+
+                fcntl.flock(handle.fileno(), fcntl.LOCK_EX)
+            try:
+                yield
+            finally:
+                if os.name == "nt":
+                    handle.seek(0)
+                    msvcrt.locking(handle.fileno(), msvcrt.LK_UNLCK, 1)
+                else:
+                    fcntl.flock(handle.fileno(), fcntl.LOCK_UN)
+
     def _assert_member_number_available(
         self,
         member_number: str,
@@ -1941,6 +2023,26 @@ def validate_member_number_pattern(pattern: str) -> None:
         raise RepositoryError(f"Ungültiges Mitgliedsnummern-Pattern: {exc}") from exc
 
 
+def _number_from_formatted_member_number(pattern: str, member_number: str) -> int | None:
+    parts: list[str] = []
+    number_groups = 0
+    for literal, field_name, _format_spec, _conversion in Formatter().parse(pattern.strip()):
+        parts.append(re.escape(literal))
+        if field_name == "year":
+            parts.append(re.escape(str(date.today().year)))
+        elif field_name == "number":
+            parts.append(r"(\d+)")
+            number_groups += 1
+    match = re.fullmatch("".join(parts), member_number, flags=re.IGNORECASE)
+    if not match or not number_groups:
+        return None
+    values = [int(value) for value in match.groups()]
+    if any(value != values[0] for value in values[1:]):
+        return None
+    value = values[0]
+    return value if format_member_number(pattern, value).casefold() == member_number.casefold() else None
+
+
 def format_member_number(pattern: str, number: int, *, year: int | None = None) -> str:
     try:
         value = pattern.strip().format(number=number, year=year or date.today().year)

src/ccma/ui/options_dialog.py

@@ -47,6 +47,7 @@ class OptionsDialog(tk.Toplevel):
         number_policy = repository.get_member_number_policy()
         self.manual_numbers_var = tk.BooleanVar(value=number_policy["mode"] == "manual")
         self.number_pattern_var = tk.StringVar(value=number_policy["pattern"])
+        self.number_strategy_var = tk.StringVar(value=number_policy["allocation_strategy"])
         self.number_preview_var = tk.StringVar()
         organization = repository.get_configuration().get("organization") or {}
         if not isinstance(organization, dict):
@@ -280,19 +281,38 @@ class OptionsDialog(tk.Toplevel):
             text="Platzhalter: {number}, {number:04d} und optional {year}",
             style="Muted.TLabel",
         ).grid(row=2, column=1, sticky="w", pady=(0, 12))
-        ttk.Label(parent, text="Nächste Nummer").grid(row=3, column=0, sticky="w", padx=(0, 12), pady=6)
+        ttk.Label(parent, text="Vergabestrategie").grid(
+            row=3, column=0, sticky="nw", padx=(0, 12), pady=6
+        )
+        strategy_frame = ttk.Frame(parent)
+        strategy_frame.grid(row=3, column=1, sticky="w", pady=6)
+        ttk.Radiobutton(
+            strategy_frame,
+            text="Lücken füllen (nächste freie Nummer)",
+            variable=self.number_strategy_var,
+            value="next_free",
+            command=self._update_number_preview,
+        ).pack(anchor="w")
+        ttk.Radiobutton(
+            strategy_frame,
+            text="Immer Max++ (höchste Nummer + 1)",
+            variable=self.number_strategy_var,
+            value="max_plus_one",
+            command=self._update_number_preview,
+        ).pack(anchor="w", pady=(4, 0))
+        ttk.Label(parent, text="Nächste Nummer").grid(row=4, column=0, sticky="w", padx=(0, 12), pady=6)
         ttk.Label(parent, textvariable=self.number_preview_var, style="TimelineHeader.TLabel").grid(
-            row=3, column=1, sticky="w", pady=6
+            row=4, column=1, sticky="w", pady=6
         )
         ttk.Label(
             parent,
             text=(
-                "Der Zähler wird pro Pattern im Mitglieder-Store geführt. Bereits vergebene Nummern "
-                "werden niemals doppelt erzeugt."
+                "Die Strategie wird im Mitglieder-Store gespeichert. Die Vergabe ist gesperrt, "
+                "solange ein neues Mitglied angelegt wird, damit keine Nummer doppelt entsteht."
             ),
             style="Muted.TLabel",
             wraplength=620,
-        ).grid(row=4, column=0, columnspan=2, sticky="w", pady=(14, 0))
+        ).grid(row=5, column=0, columnspan=2, sticky="w", pady=(14, 0))
         self.number_pattern_var.trace_add("write", lambda *_args: self._update_number_preview())
         self._update_member_number_controls()
 
@@ -309,7 +329,9 @@ class OptionsDialog(tk.Toplevel):
             return
         pattern = self.number_pattern_var.get()
         try:
-            preview = self.repository.preview_member_number(pattern)
+            preview = self.repository.preview_member_number(
+                pattern, self.number_strategy_var.get()
+            )
         except RepositoryError as exc:
             preview = f"UNGÜLTIG: {exc}"
         self.number_preview_var.set(preview)
@@ -409,7 +431,11 @@ class OptionsDialog(tk.Toplevel):
         )
         try:
             self.config_obj.save()
-            self.repository.save_member_number_policy(mode=number_mode, pattern=number_pattern)
+            self.repository.save_member_number_policy(
+                mode=number_mode,
+                pattern=number_pattern,
+                allocation_strategy=self.number_strategy_var.get(),
+            )
             self.repository.save_organization(
                 {key: variable.get() for key, variable in self.organization_vars.items()}
             )

tests/test_repository.py

@@ -1,4 +1,5 @@
 import json
+from concurrent.futures import ThreadPoolExecutor
 from decimal import Decimal
 
 import pytest
@@ -184,6 +185,43 @@ def test_custom_pattern_and_manual_mode(tmp_path) -> None:
         repository.create_member(first_name="Duplicate", last_name="Member", member_number="special-7")
 
 
+def test_member_number_strategy_fills_gaps_or_uses_max_plus_one(tmp_path) -> None:
+    repository = MemberRepository(tmp_path)
+    repository.initialize()
+    repository.create_member(first_name="One", last_name="Member", member_number="MA-001")
+    repository.create_member(first_name="Three", last_name="Member", member_number="MA-003")
+
+    repository.save_member_number_policy(
+        mode="automatic",
+        pattern="MA-{number:03d}",
+        allocation_strategy="next_free",
+    )
+    assert repository.preview_member_number() == "MA-002"
+    assert repository.get_member_number_policy()["allocation_strategy"] == "next_free"
+
+    repository.save_member_number_policy(
+        mode="automatic",
+        pattern="MA-{number:03d}",
+        allocation_strategy="max_plus_one",
+    )
+    assert repository.preview_member_number() == "MA-004"
+    created = repository.create_member(first_name="Four", last_name="Member")
+    assert created.member_number == "MA-004"
+
+
+def test_concurrent_automatic_member_numbers_are_unique(tmp_path) -> None:
+    MemberRepository(tmp_path).initialize()
+
+    def create(index: int) -> str:
+        repository = MemberRepository(tmp_path)
+        return repository.create_member(first_name=f"Member {index}", last_name="Concurrent").member_number
+
+    with ThreadPoolExecutor(max_workers=8) as executor:
+        numbers = list(executor.map(create, range(16)))
+
+    assert len(numbers) == len(set(numbers)) == 16
+
+
 @pytest.mark.parametrize("pattern", ["", "CCMA-{year}", "{unknown}-{number}", "{number!r}"])
 def test_invalid_member_number_patterns_are_rejected(pattern) -> None:
     with pytest.raises(RepositoryError):