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"""TAU Commander hierarchical file and record storage system.

System-level records are globally readable and writable, depending on the user's
system access level.  System-level is a good place for software package installations
and some system-specific configurations, e.g. target or compiler configurations.

User-level records are readable and writable by (at least) the user.  User-level is also
where software is installed when the user doesn't have write access to :any:`SYSTEM_PREFIX`.
It's a good place for user-specific records, i.e. preferences or encrypted login credentials.

Project-level records define the project and its member components.  The user may also
want to install software packages at the project level to avoid quotas or in situations
where :any:`USER_PREFIX` is not accessible from cluster compute nodes.
"""


import os
from taucmdr import SYSTEM_PREFIX, USER_PREFIX
from taucmdr.cf.storage import StorageError
from taucmdr.cf.storage.storage_dispatch import StorageDispatch, ProjectStorageDispatch

SYSTEM_STORAGE = StorageDispatch('system', SYSTEM_PREFIX)
"""System-level data storage."""

USER_STORAGE = StorageDispatch('user', USER_PREFIX)
"""User-level data storage."""

PROJECT_STORAGE = ProjectStorageDispatch()
"""Project-level data storage."""

ORDERED_LEVELS = (PROJECT_STORAGE, USER_STORAGE, SYSTEM_STORAGE)
"""All storage levels in their preferred order."""

STORAGE_LEVELS = {level.name: level for level in ORDERED_LEVELS}
"""All storage levels indexed by their names."""


[docs]def highest_writable_storage():
    try:
        return highest_writable_storage.value
    except AttributeError as err:
        for storage in reversed(ORDERED_LEVELS):
            if storage.is_writable():
                highest_writable_storage.value = storage
                break
        else:
            raise StorageError("No writable storage levels") from err
        return highest_writable_storage.value