From f6b19273f8a740c716e9dcebba2246deb4531077 Mon Sep 17 00:00:00 2001
From: Ethan Paul <24588726+enpaul@users.noreply.github.com>
Date: Mon, 21 Sep 2020 23:10:44 -0400
Subject: [PATCH] Add initial config and constants modules

---
 imagemonk/configuration.py | 125 +++++++++++++++++++++++++++++++++++++
 imagemonk/constants.py     |  34 ++++++++++
 2 files changed, 159 insertions(+)
 create mode 100644 imagemonk/configuration.py
 create mode 100644 imagemonk/constants.py

diff --git a/imagemonk/configuration.py b/imagemonk/configuration.py
new file mode 100644
index 0000000..fb1debd
--- /dev/null
+++ b/imagemonk/configuration.py
@@ -0,0 +1,125 @@
+import json
+import os
+from dataclasses import dataclass
+from dataclasses import field
+from pathlib import Path
+from typing import Any
+from typing import Dict
+from typing import Optional
+from typing import Tuple
+
+from imagemonk import constants
+
+
+def _default_sqlite_pragmas() -> Dict[str, Any]:
+    """Default SQLite pragmas
+
+    .. note:: This needs to be a separate callout function to avoid setting a mutable type in the
+              dataclass signature.
+
+    .. note:: These settings are taken directly from
+              `the Peewee docs <http://docs.peewee-orm.com/en/latest/peewee/database.html#recommended-settings>`_.
+    """
+    return {
+        "journal_mode": "wal",
+        "cache_size": -1 * 64000,
+        "foreign_keys": 1,
+        "ignore_check_constraints": 0,
+        "synchronous": 0,
+    }
+
+
+@dataclass
+class _DBSqliteConfig:
+    path: Path = Path.cwd() / "imagemonk.db"
+    pragmas: Dict[str, Any] = field(default_factory=_default_sqlite_pragmas)
+
+    @classmethod
+    def build(cls):
+        return cls(
+            path=Path(os.environ.get(constants.ENV_CONF_DB_SQLITE_PATH, cls.path)),
+            pragmas=json.loads(os.environ[constants.ENV_CONF_DB_SQLITE_PRAGMAS])
+            if constants.ENV_CONF_DB_SQLITE_PRAGMAS in os.environ
+            else _default_sqlite_pragmas(),
+        )
+
+
+@dataclass
+class _DBMariaConfig:
+
+    hostname: str = "localhost"
+    username: str = "root"
+    password: Optional[str] = None
+    port: int = 3306
+    schema: str = "imagemonk"
+
+    @classmethod
+    def build(cls):
+        return cls(
+            hostname=os.getenv(constants.ENV_CONF_DB_MARIA_HOSTNAME, cls.hostname),
+            username=os.getenv(constants.ENV_CONF_DB_MARIA_USERNAME, cls.username),
+            password=os.environ.get(constants.ENV_CONF_DB_MARIA_PASSWORD, cls.password),
+            port=int(os.environ.get(constants.ENV_CONF_DB_MARIA_PORT, cls.port)),
+            schema=os.getenv(constants.ENV_CONF_DB_MARIA_SCHEMA, cls.schema),
+        )
+
+
+@dataclass
+class _DBConfig:
+
+    backend: constants.SupportedDatabaseBackend = (
+        constants.SupportedDatabaseBackend.SQLITE
+    )
+    sqlite: _DBSqliteConfig = field(default_factory=_DBSqliteConfig.build)
+    mariadb: _DBMariaConfig = field(default_factory=_DBMariaConfig.build)
+
+    @classmethod
+    def build(cls):
+        return cls(
+            backend=constants.SupportedDatabaseBackend[
+                os.environ[constants.ENV_CONF_DB_BACKEND]
+            ]
+            if constants.ENV_CONF_DB_BACKEND in os.environ
+            else cls.backend
+        )
+
+
+@dataclass
+class _UploadConfig:
+
+    size_limit: int = 1 * 1024 * 1024
+    formats: Tuple[str] = ("jpg", "jpeg")
+
+    @classmethod
+    def build(cls):
+        return cls(
+            size_limit=(int(os.environ[constants.ENV_CONF_FS_UPLOAD_MAX_SIZE]) * 1024)
+            if constants.ENV_CONF_FS_UPLOAD_MAX_SIZE in os.environ
+            else cls.size_limit,
+            formats=(
+                item.strip().lower()
+                for item in os.environ[constants.ENV_CONF_FS_UPLOAD_FORMATS].split(",")
+            )
+            if constants.ENV_CONF_FS_UPLOAD_MAX_SIZE in os.environ
+            else cls.formats,
+        )
+
+
+@dataclass
+class ImageMonkConfig:
+    database: _DBConfig = field(default_factory=_DBConfig.build)
+    upload: _UploadConfig = field(default_factory=_UploadConfig.build)
+    storage_path: Path = Path.cwd()
+
+    @classmethod
+    def build(cls):
+        return cls(
+            storage_path=Path(
+                os.getenv(constants.ENV_CONF_FS_STORAGE_PATH, cls.storage_path)
+            ).resolve()
+        )
+
+
+def load() -> ImageMonkConfig:
+
+    return ImageMonkConfig.build()
diff --git a/imagemonk/constants.py b/imagemonk/constants.py
new file mode 100644
index 0000000..7c6f3be
--- /dev/null
+++ b/imagemonk/constants.py
@@ -0,0 +1,34 @@
+import enum
+
+
+class SupportedDatabaseBackend(enum.Enum):
+
+    MARIADB = enum.auto()
+    SQLITE = enum.auto()
+
+
+HTTP_HEADER_RESPONSE_VERSION = "x-imagemonk-version"
+
+HTTP_HEADER_RESPONSE_DIGEST = "Digest"
+
+ENV_CONF_DB_BACKEND = "IMGMONK_DATABASE_BACKEND"
+
+ENV_CONF_DB_SQLITE_PATH = "IMGMONK_SQLITE_PATH"
+
+ENV_CONF_DB_SQLITE_PRAGMAS = "IMGMONK_SQLITE_PRAGMAS"
+
+ENV_CONF_DB_MARIA_HOSTNAME = "IMGMONK_MARIA_HOSTNAME"
+
+ENV_CONF_DB_MARIA_USERNAME = "IMGMONK_MARIA_USERNAME"
+
+ENV_CONF_DB_MARIA_PASSWORD = "IMGMONK_MARIA_PASSWORD"
+
+ENV_CONF_DB_MARIA_PORT = "IMGMONK_MARIA_PORT"
+
+ENV_CONF_DB_MARIA_SCHEMA = "IMGMONK_MARIA_SCHEMA"
+
+ENV_CONF_FS_STORAGE_PATH = "IMGMONK_STORAGE_PATH"
+
+ENV_CONF_FS_UPLOAD_MAX_SIZE = "IMGMONK_UPLOAD_LIMIT"
+
+ENV_CONF_FS_UPLOAD_FORMATS = "IMGMONK_UPLOAD_FORMATS"