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Add most basic Todo infrastructure.
[plomtask] / plomtask / db.py
1 """Database management."""
2 from os.path import isfile
3 from difflib import Differ
4 from sqlite3 import connect as sql_connect, Cursor
5 from typing import Any
6 from plomtask.exceptions import HandledException
7
8 PATH_DB_SCHEMA = 'scripts/init.sql'
9
10
11 class DatabaseFile:  # pylint: disable=too-few-public-methods
12     """Represents the sqlite3 database's file."""
13
14     def __init__(self, path: str) -> None:
15         self.path = path
16         self._check()
17
18     def remake(self) -> None:
19         """Create tables in self.path file as per PATH_DB_SCHEMA sql file."""
20         with sql_connect(self.path) as conn:
21             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
22                 conn.executescript(f.read())
23         self._check()
24
25     def _check(self) -> None:
26         """Check file exists and is of proper schema."""
27         self.exists = isfile(self.path)
28         if self.exists:
29             self._validate_schema()
30
31     def _validate_schema(self) -> None:
32         """Compare found schema with what's stored at PATH_DB_SCHEMA."""
33         sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
34         msg_err = 'Database has wrong tables schema. Diff:\n'
35         with sql_connect(self.path) as conn:
36             schema_rows = [r[0] for r in conn.execute(sql_for_schema) if r[0]]
37             retrieved_schema = ';\n'.join(schema_rows) + ';'
38             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
39                 stored_schema = f.read().rstrip()
40                 if stored_schema != retrieved_schema:
41                     diff_msg = Differ().compare(retrieved_schema.splitlines(),
42                                                 stored_schema.splitlines())
43                     raise HandledException(msg_err + '\n'.join(diff_msg))
44
45
46 class DatabaseConnection:
47     """A single connection to the database."""
48
49     def __init__(self, db_file: DatabaseFile) -> None:
50         self.file = db_file
51         self.conn = sql_connect(self.file.path)
52
53     def commit(self) -> None:
54         """Commit SQL transaction."""
55         self.conn.commit()
56
57     def exec(self, code: str, inputs: tuple[Any, ...] = tuple()) -> Cursor:
58         """Add commands to SQL transaction."""
59         return self.conn.execute(code, inputs)
60
61     def close(self) -> None:
62         """Close DB connection."""
63         self.conn.close()