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   1 """Database management."""
   2 from __future__ import annotations
   3 from os import listdir
   4 from os.path import isfile
   5 from difflib import Differ
   6 from sqlite3 import connect as sql_connect, Cursor, Row
   7 from typing import Any, Self, TypeVar, Generic
   8 from plomtask.exceptions import HandledException, NotFoundException
   9 from plomtask.dating import valid_date
  10
  11 EXPECTED_DB_VERSION = 5
  12 MIGRATIONS_DIR = 'migrations'
  13 FILENAME_DB_SCHEMA = f'init_{EXPECTED_DB_VERSION}.sql'
  14 PATH_DB_SCHEMA = f'{MIGRATIONS_DIR}/{FILENAME_DB_SCHEMA}'
  15
  16
  17 class UnmigratedDbException(HandledException):
  18     """To identify case of unmigrated DB file."""
  19
  20
  21 class DatabaseFile:
  22     """Represents the sqlite3 database's file."""
  23     # pylint: disable=too-few-public-methods
  24
  25     def __init__(self, path: str) -> None:
  26         self.path = path
  27         self._check()
  28
  29     @classmethod
  30     def create_at(cls, path: str) -> DatabaseFile:
  31         """Make new DB file at path."""
  32         with sql_connect(path) as conn:
  33             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
  34                 conn.executescript(f.read())
  35             conn.execute(f'PRAGMA user_version = {EXPECTED_DB_VERSION}')
  36         return cls(path)
  37
  38     @classmethod
  39     def migrate(cls, path: str) -> DatabaseFile:
  40         """Apply migrations from_version to EXPECTED_DB_VERSION."""
  41         migrations = cls._available_migrations()
  42         from_version = cls._get_version_of_db(path)
  43         migrations_todo = migrations[from_version+1:]
  44         for j, filename in enumerate(migrations_todo):
  45             with sql_connect(path) as conn:
  46                 with open(f'{MIGRATIONS_DIR}/{filename}', 'r',
  47                           encoding='utf-8') as f:
  48                     conn.executescript(f.read())
  49             user_version = from_version + j + 1
  50             with sql_connect(path) as conn:
  51                 conn.execute(f'PRAGMA user_version = {user_version}')
  52         return cls(path)
  53
  54     def _check(self) -> None:
  55         """Check file exists, and is of proper DB version and schema."""
  56         if not isfile(self.path):
  57             raise NotFoundException
  58         if self._user_version != EXPECTED_DB_VERSION:
  59             raise UnmigratedDbException()
  60         self._validate_schema()
  61
  62     @staticmethod
  63     def _available_migrations() -> list[str]:
  64         """Validate migrations directory and return sorted entries."""
  65         msg_too_big = 'Migration directory points beyond expected DB version.'
  66         msg_bad_entry = 'Migration directory contains unexpected entry: '
  67         msg_missing = 'Migration directory misses migration of number: '
  68         migrations = {}
  69         for entry in listdir(MIGRATIONS_DIR):
  70             if entry == FILENAME_DB_SCHEMA:
  71                 continue
  72             toks = entry.split('_', 1)
  73             if len(toks) < 2:
  74                 raise HandledException(msg_bad_entry + entry)
  75             try:
  76                 i = int(toks[0])
  77             except ValueError as e:
  78                 raise HandledException(msg_bad_entry + entry) from e
  79             if i > EXPECTED_DB_VERSION:
  80                 raise HandledException(msg_too_big)
  81             migrations[i] = toks[1]
  82         migrations_list = []
  83         for i in range(EXPECTED_DB_VERSION + 1):
  84             if i not in migrations:
  85                 raise HandledException(msg_missing + str(i))
  86             migrations_list += [f'{i}_{migrations[i]}']
  87         return migrations_list
  88
  89     @staticmethod
  90     def _get_version_of_db(path: str) -> int:
  91         """Get DB user_version, fail if outside expected range."""
  92         sql_for_db_version = 'PRAGMA user_version'
  93         with sql_connect(path) as conn:
  94             db_version = list(conn.execute(sql_for_db_version))[0][0]
  95         if db_version > EXPECTED_DB_VERSION:
  96             msg = f'Wrong DB version, expected '\
  97                     f'{EXPECTED_DB_VERSION}, got unknown {db_version}.'
  98             raise HandledException(msg)
  99         assert isinstance(db_version, int)
 100         return db_version
 101
 102     @property
 103     def _user_version(self) -> int:
 104         """Get DB user_version."""
 105         return self._get_version_of_db(self.path)
 106
 107     def _validate_schema(self) -> None:
 108         """Compare found schema with what's stored at PATH_DB_SCHEMA."""
 109
 110         def reformat_rows(rows: list[str]) -> list[str]:
 111             new_rows = []
 112             for row in rows:
 113                 new_row = []
 114                 for subrow in row.split('\n'):
 115                     subrow = subrow.rstrip()
 116                     in_parentheses = 0
 117                     split_at = []
 118                     for i, c in enumerate(subrow):
 119                         if '(' == c:
 120                             in_parentheses += 1
 121                         elif ')' == c:
 122                             in_parentheses -= 1
 123                         elif ',' == c and 0 == in_parentheses:
 124                             split_at += [i + 1]
 125                     prev_split = 0
 126                     for i in split_at:
 127                         segment = subrow[prev_split:i].strip()
 128                         if len(segment) > 0:
 129                             new_row += [f'    {segment}']
 130                         prev_split = i
 131                     segment = subrow[prev_split:].strip()
 132                     if len(segment) > 0:
 133                         new_row += [f'    {segment}']
 134                 new_row[0] = new_row[0].lstrip()
 135                 new_row[-1] = new_row[-1].lstrip()
 136                 if new_row[-1] != ')' and new_row[-3][-1] != ',':
 137                     new_row[-3] = new_row[-3] + ','
 138                     new_row[-2:] = ['    ' + new_row[-1][:-1]] + [')']
 139                 new_rows += ['\n'.join(new_row)]
 140             return new_rows
 141
 142         sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
 143         msg_err = 'Database has wrong tables schema. Diff:\n'
 144         with sql_connect(self.path) as conn:
 145             schema_rows = [r[0] for r in conn.execute(sql_for_schema) if r[0]]
 146         schema_rows = reformat_rows(schema_rows)
 147         retrieved_schema = ';\n'.join(schema_rows) + ';'
 148         with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
 149             stored_schema = f.read().rstrip()
 150         if stored_schema != retrieved_schema:
 151             diff_msg = Differ().compare(retrieved_schema.splitlines(),
 152                                         stored_schema.splitlines())
 153             raise HandledException(msg_err + '\n'.join(diff_msg))
 154
 155
 156 class DatabaseConnection:
 157     """A single connection to the database."""
 158
 159     def __init__(self, db_file: DatabaseFile) -> None:
 160         self.conn = sql_connect(db_file.path)
 161
 162     def commit(self) -> None:
 163         """Commit SQL transaction."""
 164         self.conn.commit()
 165
 166     def exec(self, code: str, inputs: tuple[Any, ...] = tuple()) -> Cursor:
 167         """Add commands to SQL transaction."""
 168         return self.conn.execute(code, inputs)
 169
 170     def exec_on_vals(self, code: str, inputs: tuple[Any, ...]) -> Cursor:
 171         """Wrapper around .exec appending adequate " (?, …)" to code."""
 172         q_marks_from_values = '(' + ','.join(['?'] * len(inputs)) + ')'
 173         return self.exec(f'{code} {q_marks_from_values}', inputs)
 174
 175     def close(self) -> None:
 176         """Close DB connection."""
 177         self.conn.close()
 178
 179     def rewrite_relations(self, table_name: str, key: str, target: int | str,
 180                           rows: list[list[Any]], key_index: int = 0) -> None:
 181         # pylint: disable=too-many-arguments
 182         """Rewrite relations in table_name to target, with rows values.
 183
 184         Note that single rows are expected without the column and value
 185         identified by key and target, which are inserted inside the function
 186         at key_index.
 187         """
 188         self.delete_where(table_name, key, target)
 189         for row in rows:
 190             values = tuple(row[:key_index] + [target] + row[key_index:])
 191             self.exec_on_vals(f'INSERT INTO {table_name} VALUES', values)
 192
 193     def row_where(self, table_name: str, key: str,
 194                   target: int | str) -> list[Row]:
 195         """Return list of Rows at table where key == target."""
 196         return list(self.exec(f'SELECT * FROM {table_name} WHERE {key} = ?',
 197                               (target,)))
 198
 199     # def column_where_pattern(self,
 200     #                          table_name: str,
 201     #                          column: str,
 202     #                          pattern: str,
 203     #                          keys: list[str]) -> list[Any]:
 204     #     """Return column of rows where one of keys matches pattern."""
 205     #     targets = tuple([f'%{pattern}%'] * len(keys))
 206     #     haystack = ' OR '.join([f'{k} LIKE ?' for k in keys])
 207     #     sql = f'SELECT {column} FROM {table_name} WHERE {haystack}'
 208     #     return [row[0] for row in self.exec(sql, targets)]
 209
 210     def column_where(self, table_name: str, column: str, key: str,
 211                      target: int | str) -> list[Any]:
 212         """Return column of table where key == target."""
 213         return [row[0] for row in
 214                 self.exec(f'SELECT {column} FROM {table_name} '
 215                           f'WHERE {key} = ?', (target,))]
 216
 217     def column_all(self, table_name: str, column: str) -> list[Any]:
 218         """Return complete column of table."""
 219         return [row[0] for row in
 220                 self.exec(f'SELECT {column} FROM {table_name}')]
 221
 222     def delete_where(self, table_name: str, key: str,
 223                      target: int | str) -> None:
 224         """Delete from table where key == target."""
 225         self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,))
 226
 227
 228 BaseModelId = TypeVar('BaseModelId', int, str)
 229 BaseModelInstance = TypeVar('BaseModelInstance', bound='BaseModel[Any]')
 230
 231
 232 class BaseModel(Generic[BaseModelId]):
 233     """Template for most of the models we use/derive from the DB."""
 234     table_name = ''
 235     to_save: list[str] = []
 236     to_save_versioned: list[str] = []
 237     to_save_relations: list[tuple[str, str, str, int]] = []
 238     id_: None | BaseModelId
 239     cache_: dict[BaseModelId, Self]
 240     to_search: list[str] = []
 241     _exists = True
 242
 243     def __init__(self, id_: BaseModelId | None) -> None:
 244         if isinstance(id_, int) and id_ < 1:
 245             msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}'
 246             raise HandledException(msg)
 247         if isinstance(id_, str) and "" == id_:
 248             msg = f'illegal {self.__class__.__name__} ID, must be non-empty'
 249             raise HandledException(msg)
 250         self.id_ = id_
 251
 252     def __hash__(self) -> int:
 253         hashable = [self.id_] + [getattr(self, name) for name in self.to_save]
 254         for definition in self.to_save_relations:
 255             attr = getattr(self, definition[2])
 256             hashable += [tuple(rel.id_ for rel in attr)]
 257         for name in self.to_save_versioned:
 258             hashable += [hash(getattr(self, name))]
 259         return hash(tuple(hashable))
 260
 261     def __eq__(self, other: object) -> bool:
 262         if not isinstance(other, self.__class__):
 263             return False
 264         return hash(self) == hash(other)
 265
 266     def __lt__(self, other: Any) -> bool:
 267         if not isinstance(other, self.__class__):
 268             msg = 'cannot compare to object of different class'
 269             raise HandledException(msg)
 270         assert isinstance(self.id_, int)
 271         assert isinstance(other.id_, int)
 272         return self.id_ < other.id_
 273
 274     @property
 275     def as_dict(self) -> dict[str, object]:
 276         """Return self as (json.dumps-coompatible) dict."""
 277         d: dict[str, object] = {'id': self.id_}
 278         if len(self.to_save_versioned) > 0:
 279             d['_versioned'] = {}
 280         for k in self.to_save:
 281             attr = getattr(self, k)
 282             if hasattr(attr, 'as_dict'):
 283                 d[k] = attr.as_dict
 284             d[k] = attr
 285         for k in self.to_save_versioned:
 286             attr = getattr(self, k)
 287             assert isinstance(d['_versioned'], dict)
 288             d['_versioned'][k] = attr.history
 289         for r in self.to_save_relations:
 290             attr_name = r[2]
 291             d[attr_name] = [x.as_dict for x in getattr(self, attr_name)]
 292         return d
 293
 294     # cache management
 295     # (we primarily use the cache to ensure we work on the same object in
 296     # memory no matter where and how we retrieve it, e.g. we don't want
 297     # .by_id() calls to create a new object each time, but rather a pointer
 298     # to the one already instantiated)
 299
 300     def __getattribute__(self, name: str) -> Any:
 301         """Ensure fail if ._disappear() was called, except to check ._exists"""
 302         if name != '_exists' and not super().__getattribute__('_exists'):
 303             raise HandledException('Object does not exist.')
 304         return super().__getattribute__(name)
 305
 306     def _disappear(self) -> None:
 307         """Invalidate object, make future use raise exceptions."""
 308         assert self.id_ is not None
 309         if self._get_cached(self.id_):
 310             self._uncache()
 311         to_kill = list(self.__dict__.keys())
 312         for attr in to_kill:
 313             delattr(self, attr)
 314         self._exists = False
 315
 316     @classmethod
 317     def empty_cache(cls) -> None:
 318         """Empty class's cache."""
 319         cls.cache_ = {}
 320
 321     @classmethod
 322     def get_cache(cls: type[BaseModelInstance]) -> dict[Any, BaseModel[Any]]:
 323         """Get cache dictionary, create it if not yet existing."""
 324         if not hasattr(cls, 'cache_'):
 325             d: dict[Any, BaseModel[Any]] = {}
 326             cls.cache_ = d
 327         return cls.cache_
 328
 329     @classmethod
 330     def _get_cached(cls: type[BaseModelInstance],
 331                     id_: BaseModelId) -> BaseModelInstance | None:
 332         """Get object of id_ from class's cache, or None if not found."""
 333         # pylint: disable=consider-iterating-dictionary
 334         cache = cls.get_cache()
 335         if id_ in cache.keys():
 336             obj = cache[id_]
 337             assert isinstance(obj, cls)
 338             return obj
 339         return None
 340
 341     def _cache(self) -> None:
 342         """Update object in class's cache.
 343
 344         Also calls ._disappear if cache holds older reference to object of same
 345         ID, but different memory address, to avoid doing anything with
 346         dangling leftovers.
 347         """
 348         if self.id_ is None:
 349             raise HandledException('Cannot cache object without ID.')
 350         cache = self.get_cache()
 351         old_cached = self._get_cached(self.id_)
 352         if old_cached and id(old_cached) != id(self):
 353             # pylint: disable=protected-access
 354             # (cause we remain within the class)
 355             old_cached._disappear()
 356         cache[self.id_] = self
 357
 358     def _uncache(self) -> None:
 359         """Remove self from cache."""
 360         if self.id_ is None:
 361             raise HandledException('Cannot un-cache object without ID.')
 362         cache = self.get_cache()
 363         del cache[self.id_]
 364
 365     # object retrieval and generation
 366
 367     @classmethod
 368     def from_table_row(cls: type[BaseModelInstance],
 369                        # pylint: disable=unused-argument
 370                        db_conn: DatabaseConnection,
 371                        row: Row | list[Any]) -> BaseModelInstance:
 372         """Make from DB row (sans relations), update DB cache with it."""
 373         obj = cls(*row)
 374         assert obj.id_ is not None
 375         for attr_name in cls.to_save_versioned:
 376             attr = getattr(obj, attr_name)
 377             table_name = attr.table_name
 378             for row_ in db_conn.row_where(table_name, 'parent', obj.id_):
 379                 attr.history_from_row(row_)
 380         obj._cache()
 381         return obj
 382
 383     @classmethod
 384     def by_id(cls, db_conn: DatabaseConnection,
 385               id_: BaseModelId | None,
 386               # pylint: disable=unused-argument
 387               create: bool = False) -> Self:
 388         """Retrieve by id_, on failure throw NotFoundException.
 389
 390         First try to get from cls.cache_, only then check DB; if found,
 391         put into cache.
 392
 393         If create=True, make anew (but do not cache yet).
 394         """
 395         obj = None
 396         if id_ is not None:
 397             obj = cls._get_cached(id_)
 398             if not obj:
 399                 for row in db_conn.row_where(cls.table_name, 'id', id_):
 400                     obj = cls.from_table_row(db_conn, row)
 401                     break
 402         if obj:
 403             return obj
 404         if create:
 405             obj = cls(id_)
 406             return obj
 407         raise NotFoundException(f'found no object of ID {id_}')
 408
 409     @classmethod
 410     def all(cls: type[BaseModelInstance],
 411             db_conn: DatabaseConnection) -> list[BaseModelInstance]:
 412         """Collect all objects of class into list.
 413
 414         Note that this primarily returns the contents of the cache, and only
 415         _expands_ that by additional findings in the DB. This assumes the
 416         cache is always instantly cleaned of any items that would be removed
 417         from the DB.
 418         """
 419         items: dict[BaseModelId, BaseModelInstance] = {}
 420         for k, v in cls.get_cache().items():
 421             assert isinstance(v, cls)
 422             items[k] = v
 423         already_recorded = items.keys()
 424         for id_ in db_conn.column_all(cls.table_name, 'id'):
 425             if id_ not in already_recorded:
 426                 item = cls.by_id(db_conn, id_)
 427                 assert item.id_ is not None
 428                 items[item.id_] = item
 429         return list(items.values())
 430
 431     @classmethod
 432     def by_date_range_with_limits(cls: type[BaseModelInstance],
 433                                   db_conn: DatabaseConnection,
 434                                   date_range: tuple[str, str],
 435                                   date_col: str = 'day'
 436                                   ) -> tuple[list[BaseModelInstance], str,
 437                                              str]:
 438         """Return list of items in database within (open) date_range interval.
 439
 440         If no range values provided, defaults them to 'yesterday' and
 441         'tomorrow'. Knows to properly interpret these and 'today' as value.
 442         """
 443         start_str = date_range[0] if date_range[0] else 'yesterday'
 444         end_str = date_range[1] if date_range[1] else 'tomorrow'
 445         start_date = valid_date(start_str)
 446         end_date = valid_date(end_str)
 447         items = []
 448         sql = f'SELECT id FROM {cls.table_name} '
 449         sql += f'WHERE {date_col} >= ? AND {date_col} <= ?'
 450         for row in db_conn.exec(sql, (start_date, end_date)):
 451             items += [cls.by_id(db_conn, row[0])]
 452         return items, start_date, end_date
 453
 454     @classmethod
 455     def matching(cls: type[BaseModelInstance], db_conn: DatabaseConnection,
 456                  pattern: str) -> list[BaseModelInstance]:
 457         """Return all objects whose .to_search match pattern."""
 458         items = cls.all(db_conn)
 459         if pattern:
 460             filtered = []
 461             for item in items:
 462                 for attr_name in cls.to_search:
 463                     toks = attr_name.split('.')
 464                     parent = item
 465                     for tok in toks:
 466                         attr = getattr(parent, tok)
 467                         parent = attr
 468                     if pattern in attr:
 469                         filtered += [item]
 470                         break
 471             return filtered
 472         return items
 473
 474     # database writing
 475
 476     def save(self, db_conn: DatabaseConnection) -> None:
 477         """Write self to DB and cache and ensure .id_.
 478
 479         Write both to DB, and to cache. To DB, write .id_ and attributes
 480         listed in cls.to_save[_versioned|_relations].
 481
 482         Ensure self.id_ by setting it to what the DB command returns as the
 483         last saved row's ID (cursor.lastrowid), EXCEPT if self.id_ already
 484         exists as a 'str', which implies we do our own ID creation (so far
 485         only the case with the Day class, where it's to be a date string.
 486         """
 487         values = tuple([self.id_] + [getattr(self, key)
 488                                      for key in self.to_save])
 489         table_name = self.table_name
 490         cursor = db_conn.exec_on_vals(f'REPLACE INTO {table_name} VALUES',
 491                                       values)
 492         if not isinstance(self.id_, str):
 493             self.id_ = cursor.lastrowid  # type: ignore[assignment]
 494         self._cache()
 495         for attr_name in self.to_save_versioned:
 496             getattr(self, attr_name).save(db_conn)
 497         for table, column, attr_name, key_index in self.to_save_relations:
 498             assert isinstance(self.id_, (int, str))
 499             db_conn.rewrite_relations(table, column, self.id_,
 500                                       [[i.id_] for i
 501                                        in getattr(self, attr_name)], key_index)
 502
 503     def remove(self, db_conn: DatabaseConnection) -> None:
 504         """Remove from DB and cache, including dependencies."""
 505         if self.id_ is None or self._get_cached(self.id_) is None:
 506             raise HandledException('cannot remove unsaved item')
 507         for attr_name in self.to_save_versioned:
 508             getattr(self, attr_name).remove(db_conn)
 509         for table, column, attr_name, _ in self.to_save_relations:
 510             db_conn.delete_where(table, column, self.id_)
 511         self._uncache()
 512         db_conn.delete_where(self.table_name, 'id', self.id_)
 513         self._disappear()