"""core/shares.py — ONE grant registry for every shareable object (wave 20, owner ruling R10).

WHAT R10 ASKED FOR: folders and databases share with the **same two-role vocabulary views
already use** (specific users or everyone; role = view | edit), plus one manage-access editor
that can add or revoke people later, on any of the three.

WHY A REGISTRY RATHER THAN A FIELD ON EACH OBJECT. A view already carries its own `permissions`
(`core/table_store.py`) and that stays — moving it would rewrite every stored view for no gain.
But a FOLDER is a value inside one user's workspace blob and a DATABASE is a `user_tables`
definition; giving each its own grant field would put the same three-line permission decision in
three files owned by two sessions, which is how the three drift. One registry, one predicate,
three callers.

    shares.set_grants(kind, oid, entries, owner=…, st=…)   # replaces the whole grant set
    shares.grants(kind, oid, st=…)                         # -> {'owner': str, 'entries': [...]}
    shares.role_for(kind, oid, user, is_admin=…, st=…)     # -> 'owner'|'edit'|'view'|None
    shares.shared_with(user, kind=…, st=…)                 # -> [oid] this user was granted

THE ROLE VOCABULARY IS TWO WORDS AND THE DEFAULT IS THE NARROW ONE. `view` = may open and read;
`edit` = may also change the object's CONTENT. Neither ever means "may re-share": changing grants
is the OWNER's (or an admin's), which is `table_store._may_administer`'s existing rule promoted to
every kind. A collaborator who could rewrite grants could grant themselves sole ownership of
somebody else's object, or quietly widen a users-scoped share to everyone.

⛔ AN UNREADABLE GRANT IS NO GRANT. Every path here fails closed — junk in the bucket, a missing
owner, an unknown role string all resolve to None rather than to a default that opens something.
[[aios-permissioning]]: no fail-open defaults, ever.

⚠ THE BUCKET IS TENANT-SCOPED THROUGH `st`, like every other product-data write. Passing the
session's `TenantRuntime` is what keeps Nurilab's grants in Nurilab's store; the module default
(`core.store`) is tenant #0 and exists for the same reason it does everywhere else — the ~28
callers that predate multi-tenancy. (This is the D-5/D-16 residency shape, and this module does
NOT repeat their mistake: `st` is threaded from the first line rather than retrofitted.)
"""
import core.store as store

#: The store key. One bucket per tenant holds every kind's grants, because "what am I shared on"
#: is a question across kinds — the "Shared with me" folder (R10) is exactly that query, and
#: three separate buckets would make it three reads that can disagree about what a user can see.
SHARES_KEY = 'object_shares'

#: The shareable kinds. A CLOSED vocabulary: an unknown kind raises rather than creating a new
#: namespace by typo, which would silently grant nothing to nobody and read as "sharing is broken".
KINDS = ('view', 'folder', 'database')

#: `*` is "everyone who can already open the surface". It is NOT "every account on the platform".
#: Spelled as a single character so it can never collide with a username (usernames are lower-case
#: and non-empty by `core/users.py`, and are checked against this explicitly below).
#:
#: ⛔⛔ **AND WHAT THAT MEANS DEPENDS ON THE KIND — THE LINE THIS NOTE USED TO CARRY WAS FALSE FOR
#: ONE OF THE THREE** (W33-T30, `waves/wave32/sharing-audit.md` S-8). It read *"the module/table
#: wall runs FIRST and this never widens past it"*, flatly, and the audit's own words for that are
#: *"the third docstring in this audit describing a check that is not on the path"*. Corrected
#: here rather than deleted, because the sentence is TRUE of two kinds and the difference is the
#: whole point:
#:   * `kind='view'` / `kind='folder'` on a GOVERNED module (`customer_data`, `product_data`) —
#:     the sentence holds. `require_session` plus the topic's own gate run first, and the
#:     receiver's row scope and hidden-field closure are applied BEFORE any foreign view is
#:     merged, so a grant can only narrow-or-equal what that account could already reach.
#:   * `kind='database'` on a `ut_*` table — **THE SENTENCE IS FALSE AND THIS REGISTRY IS THE
#:     ONLY WALL.** `routes_admin._PERM_MODULES` is `("customer_data", "product_data")` and
#:     `_clean_perms` 400s anything else, so no row filter and no hidden field can even be
#:     DECLARED for a user table; `routes_tables.py` makes zero `perm_scope` calls and passes
#:     `hidden_keys=frozenset()`. A `database` grant is therefore ALL-OR-NOTHING — every row,
#:     every column — and an `*` database grant admits every account in the tenant to all of it.
#:
#: ⚠ THAT IS A REAL CAPABILITY, DELIBERATELY KEPT, not a hole to plug in passing. What was wrong
#: was a docstring promising a second wall that does not exist for this kind; scoping user tables
#: is booked (S-8), not done. `routes_shares.py`'s module docstring says the same thing at the
#: OTHER door — the audit's fix is "say so at both", and one door saying it is how the next reader
#: gets the confident half [[one-question-two-normalizers]].
EVERYONE = '*'

ROLES = ('view', 'edit')


def _st(st):
    return st if st is not None else store


def _check_kind(kind):
    k = str(kind or '').strip().lower()
    if k not in KINDS:
        raise ValueError(f'{kind!r} is not a shareable kind. Use one of {", ".join(KINDS)} — '
                         f'refusing to invent a namespace from a typo.')
    return k


def _clean_entries(entries):
    """Normalise + REJECT junk, returning [{'user': str, 'role': 'view'|'edit'}].

    Silently dropping a malformed entry is right here and wrong elsewhere: the caller is a UI
    that just listed the people it is about to grant, so a rejected row must not abort the whole
    save — but an entry with an unknown ROLE must not be stored as something else's default
    either. Dropped, never coerced.
    """
    out, seen = [], set()
    for e in entries or ():
        if not isinstance(e, dict):
            continue
        user = str(e.get('user') or '').strip().lower()
        role = str(e.get('role') or '').strip().lower()
        if not user or role not in ROLES or user in seen:
            continue
        seen.add(user)
        out.append({'user': user, 'role': role})
    return out


def grants(kind, oid, st=None):
    """`{'owner': str|None, 'entries': [{'user','role'}]}` — never raises on a junk bucket."""
    kind = _check_kind(kind)
    try:
        bucket = (_st(st).get(SHARES_KEY) or {}).get(kind) or {}
        rec = bucket.get(str(oid)) or {}
    except Exception:
        return {'owner': None, 'entries': []}
    if not isinstance(rec, dict):
        return {'owner': None, 'entries': []}
    return {'owner': (str(rec.get('owner')).strip().lower() if rec.get('owner') else None),
            'entries': _clean_entries(rec.get('entries'))}


def set_grants(kind, oid, entries, owner=None, st=None):
    """REPLACE the grant set for one object. Returns the stored record.

    ⚠ REPLACE, NOT MERGE, and that is the contract the UI needs: revoking is expressed by an
    entry's ABSENCE. A merge-only API cannot remove anybody without a second verb, and the
    manage-access editor R10 asks for is exactly "here is the list now".
    """
    kind = _check_kind(kind)
    oid = str(oid)
    clean = _clean_entries(entries)
    owner_l = str(owner).strip().lower() if owner else None

    def _apply(data):
        by_kind = dict(data.get(kind) or {})
        prior = by_kind.get(oid) if isinstance(by_kind.get(oid), dict) else {}
        # The owner is STICKY: set once, and a later save that omits it must not orphan the
        # object. An ownerless grant record cannot answer "who may re-share this", so every
        # administer check would fail closed and the object would become unmanageable.
        keep_owner = owner_l or (str(prior.get('owner')).strip().lower()
                                 if prior.get('owner') else None)
        if not clean and not keep_owner:
            by_kind.pop(oid, None)          # fully un-shared and unowned: leave no empty husk
        else:
            by_kind[oid] = {'owner': keep_owner, 'entries': clean}
        data[kind] = by_kind
        return data

    _st(st).update(SHARES_KEY, _apply, flush='async')
    return grants(kind, oid, st=st)


def role_for(kind, oid, user, is_admin=False, st=None):
    """`'owner'` | `'edit'` | `'view'` | `None` — the caller's effective role, fail-closed.

    An ADMIN reads as `'owner'`: an admin who could not administer an object could not
    administer the tenant either, which is `table_store._may_administer`'s existing rule and is
    kept identical here so the two cannot disagree about the same view.
    """
    user = str(user or '').strip().lower()
    if not user:
        return None
    rec = grants(kind, oid, st=st)
    if is_admin or (rec['owner'] and rec['owner'] == user):
        return 'owner'
    best = None
    for e in rec['entries']:
        if e['user'] == user or e['user'] == EVERYONE:
            # The STRONGER of the two wins when both a personal and an everyone grant exist:
            # naming somebody explicitly is how you RAISE them above the room, so an
            # everyone-view + alice-edit pair must leave alice editing.
            if e['role'] == 'edit':
                return 'edit'
            best = best or 'view'
    return best


def may_see(kind, oid, user, is_admin=False, st=None):
    return role_for(kind, oid, user, is_admin=is_admin, st=st) is not None


def may_edit(kind, oid, user, is_admin=False, st=None):
    return role_for(kind, oid, user, is_admin=is_admin, st=st) in ('owner', 'edit')


def may_administer(kind, oid, user, is_admin=False, st=None):
    """Only the owner or an admin may change grants or delete. See the module note on why this
    is deliberately narrower than `may_edit`."""
    return role_for(kind, oid, user, is_admin=is_admin, st=st) == 'owner'


def shared_with(user, kind=None, st=None):
    """Every object id this user has been granted (excluding what they own).

    This is the "Shared with me" query (R10). It EXCLUDES owned objects deliberately: a folder
    you made is not something shared *with* you, and listing it there would make the system
    folder a duplicate of the rail above it.
    """
    user = str(user or '').strip().lower()
    if not user:
        return {}
    try:
        data = _st(st).get(SHARES_KEY) or {}
    except Exception:
        return {}
    out = {}
    for k in ([_check_kind(kind)] if kind else KINDS):
        hits = []
        for oid, rec in (data.get(k) or {}).items():
            if not isinstance(rec, dict):
                continue
            owner = str(rec.get('owner') or '').strip().lower()
            if owner == user:
                continue
            for e in _clean_entries(rec.get('entries')):
                if e['user'] in (user, EVERYONE):
                    hits.append(str(oid))
                    break
        out[k] = sorted(hits)
    return out if kind is None else {_check_kind(kind): out[_check_kind(kind)]}


def drop_objects(pairs, st=None):
    """Remove whole grant RECORDS, owner husk included — wave 21, item 6a (C3).

    A deleted object's grants must die with it: `shared_with` would otherwise serve ghost ids
    into every receiver's "Shared with me" forever, and the ghost would 404 on open. One
    transaction for the whole sweep — a table delete drops its database grant plus a view
    grant per view that lived in its bucket."""
    want = {}
    for kind, oid in pairs or ():
        want.setdefault(_check_kind(kind), set()).add(str(oid))
    if not want:
        return

    def _apply(data):
        for kind, oids in want.items():
            by_kind = data.get(kind)
            if isinstance(by_kind, dict):
                for oid in oids:
                    by_kind.pop(oid, None)
        return data

    _st(st).update(SHARES_KEY, _apply, flush='async')