from __future__ import annotations

from collections.abc import AsyncIterator
from contextlib import asynccontextmanager

from sqlalchemy import event, inspect, text
from sqlalchemy.ext.asyncio import (
    AsyncEngine,
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)

# Importing the generation models here guarantees that local SQLite metadata
# and production schema checks see the full security-owned domain even when a
# caller constructs SecurityDatabase without first building the application
# container.
from app.core.database_url import normalize_async_database_url
from app.security.models import Base

REQUIRED_SECURITY_TABLES = frozenset(
    {
        "api_keys",
        "audit_logs",
        "rate_limits",
        "users",
        "workspaces",
        "workspace_memberships",
        "api_key_principals",
        "media_assets",
        "media_asset_variants",
        "audit_events",
        "projects",
        "project_generation_jobs",
        "generation_requests",
        "generation_jobs",
        "generation_job_attempts",
        "project_editor_states",
        "project_render_jobs",
        "copilot_runs",
        "marketplace_templates",
        "marketplace_template_versions",
        "marketplace_template_applications",
        "brand_kits",
        "brand_kit_versions",
    }
)
REQUIRED_POSTGRES_SECURITY_INDEXES = frozenset(
    {
        "uq_generation_job_provider_external",
        "ix_projects_workspace",
        "ix_projects_workspace_status",
        "ix_projects_workspace_updated",
        "ix_projects_created_by",
        "ix_media_assets_workspace_project_created",
        "ix_project_generation_jobs_workspace_project_created",
        "uq_project_generation_job",
        "uq_project_editor_state_project",
        "ix_project_editor_states_workspace_project",
        "uq_project_render_idempotency",
        "ix_project_render_jobs_workspace_status",
        "ix_project_render_jobs_project_created",
        "ix_project_render_jobs_dispatch",
        "ix_generation_requests_workspace_project_created",
        "ix_generation_requests_workspace_surface_created",
        "uq_copilot_run_workspace_idempotency",
        "ix_copilot_runs_workspace_created",
        "ix_copilot_runs_workspace_status",
        "ix_copilot_runs_project_created",
        "uq_marketplace_template_workspace_slug",
        "ix_marketplace_templates_workspace_status",
        "ix_marketplace_templates_discovery",
        "uq_marketplace_template_version",
        "ix_marketplace_template_versions_template",
        "uq_marketplace_template_application_idempotency",
        "ix_marketplace_template_applications_project",
        "ix_marketplace_template_applications_template",
        "ix_brand_kits_workspace_updated",
        "ix_brand_kits_workspace_default",
        "uq_brand_kits_one_default",
        "uq_brand_kit_version",
        "ix_brand_versions_kit_created",
    }
)


class SecurityDatabase:
    """Owns the authentication database engine and short-lived async sessions."""

    def __init__(self, database_url: str, *, auto_migrate: bool = False) -> None:
        database_url = normalize_async_database_url(database_url)
        self.database_url = database_url
        self.auto_migrate = auto_migrate or database_url.startswith("sqlite")
        self.engine: AsyncEngine = create_async_engine(
            database_url,
            pool_pre_ping=True,
        )
        if database_url.startswith("sqlite"):
            event.listen(self.engine.sync_engine, "connect", self._configure_sqlite)
        self.session_factory = async_sessionmaker(
            self.engine, expire_on_commit=False, class_=AsyncSession
        )

    @staticmethod
    def _configure_sqlite(dbapi_connection: object, _record: object) -> None:
        cursor = dbapi_connection.cursor()  # type: ignore[attr-defined]
        cursor.execute("PRAGMA foreign_keys=ON")
        cursor.execute("PRAGMA journal_mode=WAL")
        cursor.execute("PRAGMA busy_timeout=5000")
        cursor.close()

    async def initialize(self) -> None:
        if not self.auto_migrate:
            return
        __import__("app.generation.models")
        __import__("app.projects.models")
        __import__("app.copilot.models")
        __import__("app.templates.marketplace_models")
        __import__("app.brand.models")
        async with self.engine.begin() as connection:
            await connection.run_sync(Base.metadata.create_all)

    async def close(self) -> None:
        await self.engine.dispose()

    @property
    def is_postgres(self) -> bool:
        return self.database_url.startswith(("postgresql", "postgres"))

    async def verify_execution_boundary(self, *, expected_role: str, enforce_rls: bool) -> None:
        """Ensure tenancy administration never uses the public tenant role."""
        if not self.is_postgres or not enforce_rls:
            return
        if not expected_role.strip():
            raise RuntimeError(
                "SECURITY_DATABASE_ROLE is required when SECURITY_ENFORCE_RLS is enabled."
            )
        async with self.engine.connect() as connection:
            row = (
                (
                    await connection.execute(
                        text(
                            "select current_user as role, r.rolbypassrls as bypass_rls, r.rolsuper as superuser "
                            "from pg_roles r where r.rolname = current_user"
                        )
                    )
                )
                .mappings()
                .one_or_none()
            )
        if row is None or row["role"] != expected_role.strip():
            raise RuntimeError("DATABASE_URL is not connected as SECURITY_DATABASE_ROLE.")
        if not row["bypass_rls"] and not row["superuser"]:
            raise RuntimeError(
                "SECURITY_DATABASE_ROLE must be backend-only and able to administer forced-RLS tenancy tables."
            )

    async def schema_ready(self) -> bool:
        return not await self.missing_schema_objects()

    async def missing_schema_objects(self) -> list[str]:
        """Return missing production schema requirements, including safety indexes."""

        async with self.engine.connect() as connection:
            tables = await connection.run_sync(lambda sync: set(inspect(sync).get_table_names()))
            if not self.is_postgres:
                indexes: set[str] = set()
            else:
                rows = await connection.execute(
                    text("select indexname from pg_indexes " "where schemaname = current_schema()")
                )
                indexes = set(rows.scalars().all())
        missing = sorted(REQUIRED_SECURITY_TABLES - tables)
        if self.is_postgres:
            missing.extend(
                f"index:{name}" for name in sorted(REQUIRED_POSTGRES_SECURITY_INDEXES - indexes)
            )
        return missing

    async def missing_tables(self) -> list[str]:
        async with self.engine.connect() as connection:
            tables = await connection.run_sync(lambda sync: set(inspect(sync).get_table_names()))
        return sorted(REQUIRED_SECURITY_TABLES - tables)

    @asynccontextmanager
    async def session(self) -> AsyncIterator[AsyncSession]:
        async with self.session_factory() as session:
            yield session

    @asynccontextmanager
    async def tenant_session(
        self, *, workspace_id: str, user_id: str
    ) -> AsyncIterator[AsyncSession]:
        """Explicit tenant context for RLS verification and scoped services."""
        if not workspace_id or not user_id:
            raise RuntimeError("A security tenant session requires workspace and user IDs.")
        async with self.session_factory() as session:
            if not self.engine.url.drivername.startswith("sqlite"):
                await session.execute(
                    text("select set_config('app.workspace_id', :workspace_id, true)"),
                    {"workspace_id": workspace_id},
                )
                await session.execute(
                    text("select set_config('app.user_id', :user_id, true)"),
                    {"user_id": user_id},
                )
            yield session