"""Atomic permission catalogue + seed for the 3 default system groups.

Permissions follow the `<entity>.<action>` convention. They are the ground truth
checked by `@require_perm`; admins bypass everything (cf. `auth_decorators.py`).

This module is the single place that lists every permission code shipped with
the platform. To add a new perm in a future milestone:

  1. Add an entry to `PERMISSION_CATALOGUE`.
  2. Decide which system group(s) should get it by default — edit
     `_default_redteam_perms()` / `_default_blueteam_perms()` if relevant
     (admin always gets everything, so no edit needed there).
  3. The next boot picks it up; existing groups are *upgraded* (perms added),
     never downgraded (we never remove perms from a system group, even if you
     trim the catalogue — that would be a destructive op disguised as a seed).

The seed is idempotent and safe to call on every boot.
"""

from __future__ import annotations

import logging
from dataclasses import dataclass

from sqlalchemy import select

from app.db.session import session_scope
from app.models.auth import Group, GroupPermission, Permission
from app.services.bootstrap import (
    ADMIN_GROUP_NAME,
    BLUETEAM_GROUP_NAME,
    REDTEAM_GROUP_NAME,
)

log = logging.getLogger("metamorph.permissions")


@dataclass(frozen=True)
class PermissionDef:
    code: str
    description: str


# === Catalogue ================================================================
#
# Order is presentation-only; the seed is idempotent. Grouped by family to keep
# diffs reviewable and to mirror the admin UI grouping in M3.6.
#
PERMISSION_CATALOGUE: tuple[PermissionDef, ...] = (
    # users
    PermissionDef("user.read", "View users."),
    PermissionDef("user.create", "Create users (typically via invitation)."),
    PermissionDef("user.update", "Update user metadata (display name, locale, active flag)."),
    PermissionDef("user.delete", "Soft-delete a user."),
    # groups
    PermissionDef("group.read", "View groups and their permissions."),
    PermissionDef("group.create", "Create a custom group."),
    PermissionDef("group.update", "Edit a custom group (name, description, permissions, members)."),
    PermissionDef("group.delete", "Soft-delete a custom group."),
    # invitations
    PermissionDef("invitation.read", "View pending invitations."),
    PermissionDef("invitation.create", "Issue a new invitation URL."),
    PermissionDef("invitation.revoke", "Revoke an unconsumed invitation."),
    # test templates
    PermissionDef("test_template.read", "View the test-template catalogue."),
    PermissionDef("test_template.create", "Create a test template."),
    PermissionDef("test_template.update", "Edit a test template."),
    PermissionDef("test_template.delete", "Soft-delete a test template."),
    # scenario templates
    PermissionDef("scenario_template.read", "View the scenario-template catalogue."),
    PermissionDef("scenario_template.create", "Create a scenario template."),
    PermissionDef("scenario_template.update", "Edit a scenario template (and its ordered tests)."),
    PermissionDef("scenario_template.delete", "Soft-delete a scenario template."),
    # missions
    PermissionDef("mission.read", "View missions (server still filters by membership for non-admin)."),
    PermissionDef("mission.create", "Create a mission."),
    PermissionDef("mission.update", "Edit mission metadata, scenarios, members."),
    PermissionDef("mission.archive", "Move a mission to status=archived."),
    PermissionDef("mission.delete", "Soft-delete a mission."),
    PermissionDef("mission.write_red_fields", "Write red-side fields on a mission test."),
    PermissionDef("mission.write_blue_fields", "Write blue-side fields and upload evidence."),
    # detection levels + platform settings + MITRE sync
    PermissionDef("detection_level.read", "View the detection-level taxonomy."),
    PermissionDef("detection_level.update", "Edit the detection-level taxonomy."),
    PermissionDef("setting.read", "Read platform settings."),
    PermissionDef("setting.update", "Update platform settings."),
    PermissionDef("mitre.sync", "Trigger a MITRE ATT&CK Enterprise re-sync."),
)


def _default_redteam_perms() -> frozenset[str]:
    return frozenset(
        {
            # catalogue read-only
            "test_template.read",
            "scenario_template.read",
            # MITRE/detection refs
            "detection_level.read",
            # missions: full lifecycle on red side
            "mission.read",
            "mission.create",
            "mission.update",
            "mission.archive",
            "mission.write_red_fields",
        }
    )


def _default_blueteam_perms() -> frozenset[str]:
    return frozenset(
        {
            "test_template.read",
            "scenario_template.read",
            "detection_level.read",
            "mission.read",
            "mission.write_blue_fields",
        }
    )


def _all_perm_codes() -> frozenset[str]:
    return frozenset(p.code for p in PERMISSION_CATALOGUE)


def seed_permissions() -> dict[str, int]:
    """Insert any missing permissions. Returns counts: `created`, `total`."""
    created = 0
    with session_scope() as s:
        existing_codes = set(s.scalars(select(Permission.code)).all())
        for p in PERMISSION_CATALOGUE:
            if p.code in existing_codes:
                continue
            s.add(Permission(code=p.code, description=p.description))
            created += 1
    return {"created": created, "total": len(PERMISSION_CATALOGUE)}


def _assign_perms_to_group(group_name: str, codes: frozenset[str]) -> int:
    """Attach the named perms to the given system group. Returns added count.

    We never *remove* perms from a system group here — the seed is additive.
    Admins/operators who want to revoke must do so explicitly via the UI/API.
    """
    if not codes:
        return 0
    added = 0
    with session_scope() as s:
        group = s.scalar(select(Group).where(Group.name == group_name, Group.is_system.is_(True)))
        if group is None:
            raise RuntimeError(f"system group {group_name!r} missing — call ensure_system_groups() first")

        existing_codes = {p.code for p in group.permissions}
        perms = s.scalars(select(Permission).where(Permission.code.in_(codes))).all()
        for p in perms:
            if p.code in existing_codes:
                continue
            s.add(GroupPermission(group_id=group.id, permission_id=p.id))
            added += 1
    return added


def seed_default_group_permissions() -> dict[str, int]:
    """Bind the catalogue to the 3 default groups. Idempotent + additive."""
    counts: dict[str, int] = {}
    counts[ADMIN_GROUP_NAME] = _assign_perms_to_group(ADMIN_GROUP_NAME, _all_perm_codes())
    counts[REDTEAM_GROUP_NAME] = _assign_perms_to_group(REDTEAM_GROUP_NAME, _default_redteam_perms())
    counts[BLUETEAM_GROUP_NAME] = _assign_perms_to_group(BLUETEAM_GROUP_NAME, _default_blueteam_perms())
    return counts


def seed_all() -> dict[str, dict[str, int]]:
    """One-shot helper: catalogue + default group bindings."""
    perms = seed_permissions()
    bindings = seed_default_group_permissions()
    log.info(
        "metamorph.permissions.seeded",
        extra={"perms_created": perms["created"], "perms_total": perms["total"], "bindings": bindings},
    )
    return {"permissions": perms, "bindings": bindings}