Implement adapters for settings customization

lippukala/adapter/__init__.py

@@ -0,0 +1,26 @@
+from __future__ import annotations
+
+from django.conf import settings
+from django.http import HttpRequest
+from django.utils.module_loading import import_string
+
+from lippukala.adapter.base import LippukalaAdapter
+
+try:
+    from functools import cache
+except ImportError:  # Remove this when deprecating Python 3.9 support
+    from functools import lru_cache
+
+    cache = lru_cache(maxsize=None)
+
+DEFAULT_ADAPTER_REFERENCE = "lippukala.adapter.default.DefaultLippukalaAdapter"
+
+
+@cache
+def get_adapter_class() -> type[LippukalaAdapter]:
+    adapter_class_name = getattr(settings, "LIPPUKALA_ADAPTER_CLASS", DEFAULT_ADAPTER_REFERENCE)
+    return import_string(adapter_class_name)
+
+
+def get_adapter(request: HttpRequest) -> LippukalaAdapter:
+    return get_adapter_class()(request)

lippukala/adapter/base.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+from abc import ABCMeta, abstractmethod
+
+from django.http import HttpRequest
+
+IMPLEMENT_IN_A_SUBCLASS = "Implement in a subclass"
+
+
+class LippukalaAdapter(metaclass=ABCMeta):
+    def __init__(self, request: HttpRequest | None) -> None:
+        self.request = request
+
+    @abstractmethod
+    def get_prefixes(self) -> dict[str, str]:
+        raise NotImplementedError(IMPLEMENT_IN_A_SUBCLASS)
+
+    @abstractmethod
+    def get_literate_keyspace(self, prefix: str | None) -> list[str] | None:
+        raise NotImplementedError(IMPLEMENT_IN_A_SUBCLASS)
+
+    @abstractmethod
+    def get_code_digit_range(self, prefix: str) -> range:
+        raise NotImplementedError(IMPLEMENT_IN_A_SUBCLASS)
+
+    @abstractmethod
+    def get_code_allow_leading_zeroes(self, prefix: str) -> bool:
+        raise NotImplementedError(IMPLEMENT_IN_A_SUBCLASS)
+
+    @abstractmethod
+    def get_print_logo_path(self, prefix: str) -> str | None:
+        raise NotImplementedError(IMPLEMENT_IN_A_SUBCLASS)
+
+    @abstractmethod
+    def get_print_logo_size_cm(self, prefix: str) -> tuple[float, float]:
+        raise NotImplementedError(IMPLEMENT_IN_A_SUBCLASS)
+
+    def get_prefix_may_be_blank(self) -> bool:
+        return not self.get_prefixes()

lippukala/adapter/default.py

@@ -0,0 +1,114 @@
+from __future__ import annotations
+
+import os
+from string import digits
+
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+
+from lippukala.adapter.base import LippukalaAdapter
+
+
+def get_setting(name, default=None):
+    return getattr(settings, f"LIPPUKALA_{name}", default)
+
+
+def get_integer_setting(name, default=0):
+    try:
+        value = get_setting(name, default)
+        return int(value)
+    except ValueError:  # pragma: no cover
+        raise ImproperlyConfigured(f"LIPPUKALA_{name} must be an integer (got {value!r})")
+
+
+class LippukalaSettings:
+    def __init__(self) -> None:
+        self.prefixes = get_setting("PREFIXES", {})
+        self.literate_keyspaces = get_setting("LITERATE_KEYSPACES", {})
+        self.code_min_n_digits = get_integer_setting("CODE_MIN_N_DIGITS", 10)
+        self.code_max_n_digits = get_integer_setting("CODE_MAX_N_DIGITS", 10)
+        self.code_allow_leading_zeroes = bool(get_setting("CODE_ALLOW_LEADING_ZEROES", True))
+        self.print_logo_path = get_setting("PRINT_LOGO_PATH")
+        self.print_logo_size_cm = get_setting("PRINT_LOGO_SIZE_CM")
+
+        if self.prefixes:
+            self.prefix_choices = [(p, f"{p} [{t}]") for (p, t) in sorted(self.prefixes.items())]
+            self.prefix_may_be_blank = False
+        else:
+            self.prefix_choices = [("", "---")]
+            self.prefix_may_be_blank = True
+
+    def validate(self) -> None:  # pragma: no cover
+        self._validate_code()
+        self._validate_prefixes()
+        self._validate_print()
+
+    def _validate_code(self) -> None:
+        if self.code_min_n_digits <= 5 or self.code_max_n_digits < self.code_min_n_digits:
+            raise ImproperlyConfigured(
+                f"The range ({self.code_min_n_digits} .. {self.code_max_n_digits}) for "
+                f"Lippukala code digits is invalid"
+            )
+
+    def _validate_prefixes(self):
+        key_lengths = [len(k) for k in self.prefixes]
+        if key_lengths and not all(k == key_lengths[0] for k in key_lengths):
+            raise ImproperlyConfigured("All LIPPUKALA_PREFIXES keys must be the same length!")
+        for prefix in self.prefixes:
+            if not all(c in digits for c in prefix):
+                raise ImproperlyConfigured(
+                    f"The prefix {prefix!r} has invalid characters. Only digits are allowed."
+                )
+        for prefix, literate_keyspace in list(self.literate_keyspaces.items()):
+            if isinstance(literate_keyspace, str):
+                raise ImproperlyConfigured(
+                    f"A string ({literate_keyspace!r}) was passed as the "
+                    f"literate keyspace for prefix {prefix!r}"
+                )
+            too_short_keys = any(len(key) <= 1 for key in literate_keyspace)
+            maybe_duplicate = len(set(literate_keyspace)) != len(literate_keyspace)
+            if too_short_keys or maybe_duplicate:
+                raise ImproperlyConfigured(
+                    f"The literate keyspace for prefix {prefix!r} has invalid or duplicate entries."
+                )
+
+    def _validate_print(self):
+        if not self.print_logo_path:
+            return
+        if not os.path.isfile(self.print_logo_path):
+            raise ImproperlyConfigured(
+                f"PRINT_LOGO_PATH was defined, but does not exist ({self.print_logo_path!r})"
+            )
+        if not all(float(s) > 0 for s in self.print_logo_size_cm):
+            raise ImproperlyConfigured(f"PRINT_LOGO_SIZE_CM values not valid: {self.print_logo_size_cm!r}")
+
+
+class DefaultLippukalaAdapter(LippukalaAdapter):
+    _settings: LippukalaSettings | None = None
+
+    @classmethod
+    def get_settings(cls) -> LippukalaSettings:
+        if not cls._settings:
+            cls._settings = LippukalaSettings()
+            cls._settings.validate()
+        return cls._settings
+
+    def get_prefixes(self) -> dict[str, str]:
+        return self.get_settings().prefixes
+
+    def get_literate_keyspace(self, prefix: str | None) -> list[str] | None:
+        literate_keyspaces = self.get_settings().literate_keyspaces
+        return literate_keyspaces.get(prefix)
+
+    def get_code_digit_range(self, prefix: str) -> range:
+        s = self.get_settings()
+        return range(s.code_min_n_digits, s.code_max_n_digits + 1)
+
+    def get_code_allow_leading_zeroes(self, prefix: str) -> bool:
+        return self.get_settings().code_allow_leading_zeroes
+
+    def get_print_logo_path(self, prefix: str) -> str | None:
+        return self.get_settings().print_logo_path
+
+    def get_print_logo_size_cm(self, prefix: str) -> tuple[float, float]:
+        return self.get_settings().print_logo_size_cm

lippukala/models/adapter_mixin.py

@@ -0,0 +1,12 @@
+from __future__ import annotations
+
+from lippukala.adapter import LippukalaAdapter
+
+
+class AdapterMixin:
+    _adapter: LippukalaAdapter | None = None
+
+    def get_adapter(self) -> LippukalaAdapter:
+        if not self._adapter:
+            raise ValueError(f"An adapter needs to be set on {self.__class__.__name__}")
+        return self._adapter

lippukala/models/code.py

@@ -4,7 +4,7 @@
 from django.db import models
 from django.utils.timezone import now
 
-import lippukala.settings as settings
+from lippukala.adapter import LippukalaAdapter
 from lippukala.consts import CODE_STATUS_CHOICES, UNUSED, USED
 from lippukala.excs import CantUseException
 
@@ -32,23 +32,30 @@ class Code(models.Model):
     def __str__(self):
         return f"Code {self.full_code} ({self.literate_code}) ({self.get_status_display()})"
 
+    def get_adapter(self) -> LippukalaAdapter:
+        return self.order.get_adapter()
+
     def _generate_code(self):
         qs = self.__class__.objects
+        adapter = self.get_adapter()
+        digit_range = adapter.get_code_digit_range(self.prefix)
+        allow_leading_zeroes = adapter.get_code_allow_leading_zeroes(self.prefix)
+
         for attempt in range(500):  # 500 attempts really REALLY should be enough.
-            n_digits = randint(settings.CODE_MIN_N_DIGITS, settings.CODE_MAX_N_DIGITS + 1)
+            n_digits = randint(digit_range.start, digit_range.stop - 1)
             code = "".join(choice(digits) for x in range(n_digits))
-            if not settings.CODE_ALLOW_LEADING_ZEROES:
+            if not allow_leading_zeroes:
                 code = code.lstrip("0")
             # Leading zeroes could have dropped digits off the code, so recheck that.
-            if settings.CODE_MIN_N_DIGITS <= len(code) <= settings.CODE_MAX_N_DIGITS:
+            if len(code) in digit_range:
                 if not qs.filter(code=code).exists():
                     return code
 
         raise ValueError("Unable to find an unused code! Is the keyspace exhausted?")
 
     def _generate_literate_code(self):
-        default_literate_keyspace = settings.LITERATE_KEYSPACES.get(None)
-        keyspace = settings.LITERATE_KEYSPACES.get(self.prefix) or default_literate_keyspace
+        adapter = self.get_adapter()
+        keyspace = adapter.get_literate_keyspace(self.prefix) or adapter.get_literate_keyspace(None)
 
         # When absolutely no keyspaces can be found, assume (prefix+code) will do
         if not keyspace:
@@ -67,7 +74,7 @@ def _generate_literate_code(self):
 
         # Oh -- and if we had a prefix, add its literate counterpart now.
         if self.prefix:
-            bits.insert(0, settings.PREFIXES[self.prefix])
+            bits.insert(0, adapter.get_prefixes()[self.prefix])
 
         return " ".join(bits).strip()
 
@@ -81,10 +88,12 @@ def _check_sanity(self):
                 "Un-sane situation detected: full_code contains non-digits. "
                 "(This might mean a contaminated prefix configuration.)"
             )
-        if not settings.PREFIX_MAY_BE_BLANK and not self.prefix:
-            raise ValueError("Un-sane situation detected: prefix may not be blank")
-        if self.prefix and self.prefix not in settings.PREFIXES:
-            raise ValueError(f"Un-sane situation detected: prefix {self.prefix!r} is not in PREFIXES")
+        if not self.pk:  # If we've already saved the code, we will assume these are good
+            adapter = self.get_adapter()
+            if not adapter.get_prefix_may_be_blank() and not self.prefix:
+                raise ValueError("Un-sane situation detected: prefix may not be blank")
+            if self.prefix and self.prefix not in adapter.get_prefixes():
+                raise ValueError(f"Un-sane situation detected: prefix {self.prefix!r} is not in PREFIXES")
 
     def save(self, *args, **kwargs):
         if not self.code:

lippukala/models/order.py

@@ -1,7 +1,9 @@
 from django.db import models
 
+from lippukala.models.adapter_mixin import AdapterMixin
 
-class Order(models.Model):
+
+class Order(AdapterMixin, models.Model):
     """Encapsulates an order, which may contain zero or more codes.
 
     :var event: An (optional) event identifier for this order. May be used at the client app's discretion.
@@ -23,3 +25,9 @@ class Order(models.Model):
 
     def __str__(self):
         return "LK-%08d (ref %s)" % (self.pk, self.reference_number)
+
+    def __init__(self, *args, **kwargs) -> None:
+        adapter = kwargs.pop("adapter", None)
+        if adapter:
+            self._adapter = adapter
+        super().__init__(*args, **kwargs)

lippukala/printing.py

@@ -6,8 +6,6 @@
 from reportlab.lib.units import cm, mm
 from reportlab.pdfgen.canvas import Canvas
 
-from lippukala.settings import PRINT_LOGO_PATH, PRINT_LOGO_SIZE_CM
-
 
 class Bold(str):
     pass
@@ -61,7 +59,7 @@ class OrderPrinter:
 
     ONE_TICKET_PER_PAGE = False
 
-    def __init__(self, print_logo_path=PRINT_LOGO_PATH, print_logo_size_cm=PRINT_LOGO_SIZE_CM):
+    def __init__(self, *, print_logo_path, print_logo_size_cm):
         self.output = BytesIO()
         self.canvas = Canvas(self.output, pagesize=(self.PAGE_WIDTH, self.PAGE_HEIGHT))
         self.n_orders = 0

lippukala/settings.py

@@ -1,83 +1,4 @@
-import os
-from string import digits
-
-from django.conf import settings
-from django.core.exceptions import ImproperlyConfigured
-
-
-def get_setting(name, default=None):
-    return getattr(settings, f"LIPPUKALA_{name}", default)
-
-
-def get_integer_setting(name, default=0):
-    try:
-        value = get_setting(name, default)
-        return int(value)
-    except ValueError:  # pragma: no cover
-        raise ImproperlyConfigured(f"LIPPUKALA_{name} must be an integer (got {value!r})")
-
-
-PREFIXES = get_setting("PREFIXES", {})
-LITERATE_KEYSPACES = get_setting("LITERATE_KEYSPACES", {})
-CODE_MIN_N_DIGITS = get_integer_setting("CODE_MIN_N_DIGITS", 10)
-CODE_MAX_N_DIGITS = get_integer_setting("CODE_MAX_N_DIGITS", 10)
-CODE_ALLOW_LEADING_ZEROES = bool(get_setting("CODE_ALLOW_LEADING_ZEROES", True))
-PRINT_LOGO_PATH = get_setting("PRINT_LOGO_PATH")
-PRINT_LOGO_SIZE_CM = get_setting("PRINT_LOGO_SIZE_CM")
-
-if PREFIXES:
-    PREFIX_CHOICES = [(p, f"{p} [{t}]") for (p, t) in sorted(PREFIXES.items())]
-    PREFIX_MAY_BE_BLANK = False
-else:
-    PREFIX_CHOICES = [("", "---")]
-    PREFIX_MAY_BE_BLANK = True
-
-
-def validate_settings():  # pragma: no cover
-    _validate_code()
-    _validate_prefixes()
-    _validate_print()
-
-
-def _validate_code():
-    if CODE_MIN_N_DIGITS <= 5 or CODE_MAX_N_DIGITS < CODE_MIN_N_DIGITS:
-        raise ImproperlyConfigured(
-            "The range (%d .. %d) for Lippukala code digits is invalid"
-            % (CODE_MIN_N_DIGITS, CODE_MAX_N_DIGITS)
-        )
-
-
-def _validate_prefixes():
-    key_lengths = [len(k) for k in PREFIXES]
-    if key_lengths and not all(k == key_lengths[0] for k in key_lengths):
-        raise ImproperlyConfigured("All LIPPUKALA_PREFIXES keys must be the same length!")
-    for prefix in PREFIXES:
-        if not all(c in digits for c in prefix):
-            raise ImproperlyConfigured(
-                f"The prefix {prefix!r} has invalid characters. Only digits are allowed."
-            )
-    for prefix, literate_keyspace in list(LITERATE_KEYSPACES.items()):
-        if isinstance(literate_keyspace, str):
-            raise ImproperlyConfigured(
-                f"A string ({literate_keyspace!r}) was passed as the literate keyspace for prefix {prefix!r}"
-            )
-        too_short_keys = any(len(key) <= 1 for key in literate_keyspace)
-        maybe_duplicate = len(set(literate_keyspace)) != len(literate_keyspace)
-        if too_short_keys or maybe_duplicate:
-            raise ImproperlyConfigured(
-                f"The literate keyspace for prefix {prefix!r} has invalid or duplicate entries."
-            )
-
-
-def _validate_print():
-    if PRINT_LOGO_PATH:
-        if not os.path.isfile(PRINT_LOGO_PATH):
-            raise ImproperlyConfigured(
-                f"PRINT_LOGO_PATH was defined, but does not exist ({PRINT_LOGO_PATH!r})"
-            )
-        if not all(float(s) > 0 for s in PRINT_LOGO_SIZE_CM):
-            raise ImproperlyConfigured(f"PRINT_LOGO_SIZE_CM values not valid: {PRINT_LOGO_SIZE_CM!r}")
-
-
-validate_settings()
-del validate_settings  # aaaand it's gone
+raise NotImplementedError(
+    "Do not import anything from `lippukala.settings`! "
+    "Please migrate your code to use LippukalaAdapter subclasses."
+)