from __future__ import annotations

from sqlalchemy.orm import Session

from govoplan_admin.backend.db.models import GovernanceTemplate, GovernanceTemplateAssignment
from govoplan_core.admin.common import AdminConflictError, AdminValidationError, slugify
from govoplan_core.core.access import (
    CAPABILITY_ACCESS_GOVERNANCE_MATERIALIZER,
    AccessGovernanceMaterializer,
    GovernanceTemplateMaterialization,
)
from govoplan_core.core.runtime import get_registry
from govoplan_core.security.permissions import validate_tenant_permissions
from govoplan_core.tenancy.scope import Tenant

TEMPLATE_KINDS = {"group", "role"}
ASSIGNMENT_MODES = {"available", "required"}


def _governance_materializer() -> AccessGovernanceMaterializer:
    registry = get_registry()
    if registry is None or not registry.has_capability(CAPABILITY_ACCESS_GOVERNANCE_MATERIALIZER):
        raise AdminValidationError("Access governance materializer capability is not configured.")
    capability = registry.require_capability(CAPABILITY_ACCESS_GOVERNANCE_MATERIALIZER)
    if not isinstance(capability, AccessGovernanceMaterializer):
        raise AdminValidationError("Access governance materializer capability is invalid.")
    return capability


def _materialization(
    item: GovernanceTemplate,
    *,
    tenant_id: str,
    required: bool = False,
) -> GovernanceTemplateMaterialization:
    return GovernanceTemplateMaterialization(
        template_id=item.id,
        kind=item.kind,  # type: ignore[arg-type]
        tenant_id=tenant_id,
        slug=item.slug,
        name=item.name,
        description=item.description,
        permissions=tuple(item.permissions or []),
        is_active=item.is_active,
        required=required,
    )


def validate_template(kind: str, permissions: list[str]) -> list[str]:
    if kind not in TEMPLATE_KINDS:
        raise AdminValidationError("Template kind must be group or role.")
    if kind == "group":
        if permissions:
            raise AdminValidationError("Group templates do not contain permissions; assign roles to groups inside each tenant.")
        return []
    try:
        return validate_tenant_permissions(permissions)
    except ValueError as exc:
        raise AdminValidationError(str(exc)) from exc


def create_template(
    session: Session,
    *,
    kind: str,
    slug: str,
    name: str,
    description: str | None,
    permissions: list[str],
    is_active: bool,
    assignments: list[dict[str, str]],
) -> GovernanceTemplate:
    normalized_slug = slugify(slug)
    permissions = validate_template(kind, permissions)
    exists = session.query(GovernanceTemplate).filter(
        GovernanceTemplate.kind == kind,
        GovernanceTemplate.slug == normalized_slug,
    ).first()
    if exists:
        raise AdminConflictError(f"A {kind} template with slug {normalized_slug!r} already exists.")
    item = GovernanceTemplate(
        kind=kind,
        slug=normalized_slug,
        name=name.strip(),
        description=description,
        permissions=permissions,
        is_active=is_active,
    )
    session.add(item)
    session.flush()
    set_template_assignments(session, item, assignments)
    return item


def update_template(
    session: Session,
    item: GovernanceTemplate,
    *,
    name: str,
    description: str | None,
    permissions: list[str],
    is_active: bool,
    assignments: list[dict[str, str]],
) -> GovernanceTemplate:
    item.name = name.strip()
    item.description = description
    item.permissions = validate_template(item.kind, permissions)
    item.is_active = is_active
    set_template_assignments(session, item, assignments)
    sync_template(session, item)
    return item


def set_template_assignments(
    session: Session,
    item: GovernanceTemplate,
    assignments: list[dict[str, str]],
) -> None:
    desired: dict[str, str] = {}
    for assignment in assignments:
        tenant_id = assignment.get("tenant_id", "")
        mode = assignment.get("mode", "available")
        if mode not in ASSIGNMENT_MODES:
            raise AdminValidationError("Template assignment mode must be available or required.")
        tenant = session.get(Tenant, tenant_id)
        if tenant is None:
            raise AdminValidationError(f"Unknown tenant: {tenant_id}")
        desired[tenant_id] = mode

    existing = {
        row.tenant_id: row
        for row in session.query(GovernanceTemplateAssignment)
        .filter(GovernanceTemplateAssignment.template_id == item.id)
        .all()
    }
    for tenant_id, row in list(existing.items()):
        if tenant_id in desired:
            row.mode = desired[tenant_id]
            continue
        _governance_materializer().remove_template(session, _materialization(item, tenant_id=tenant_id))
        session.delete(row)

    for tenant_id, mode in desired.items():
        if tenant_id not in existing:
            session.add(GovernanceTemplateAssignment(template_id=item.id, tenant_id=tenant_id, mode=mode))
    session.flush()
    sync_template(session, item)


def sync_template(session: Session, item: GovernanceTemplate) -> None:
    assignments = session.query(GovernanceTemplateAssignment).filter(
        GovernanceTemplateAssignment.template_id == item.id
    ).all()
    for assignment in assignments:
        required = assignment.mode == "required"
        _governance_materializer().sync_template(
            session,
            _materialization(item, tenant_id=assignment.tenant_id, required=required),
        )
    session.flush()


def delete_template(session: Session, item: GovernanceTemplate) -> None:
    assignments = session.query(GovernanceTemplateAssignment).filter(
        GovernanceTemplateAssignment.template_id == item.id
    ).all()
    for assignment in assignments:
        _governance_materializer().remove_template(session, _materialization(item, tenant_id=assignment.tenant_id))
    session.delete(item)