from __future__ import annotations

from contextlib import asynccontextmanager

from fastapi import FastAPI, Response, status

from hub_core import __version__
from hub_core.runtime.config import RuntimeSettings
from hub_core.runtime.compat import SQLCompatibilityStore, create_compatibility_router
from hub_core.runtime.models import HealthResponse, ReadinessResponse
from hub_core.runtime.ports import create_ports_router
from hub_core.runtime.repository_navigation import (
    ProjectionRejected,
    RepoProjectionClient,
    RepositoryNavigationService,
)
from hub_core.runtime.repository_navigation_routes import (
    create_repository_navigation_router,
)
from hub_core.runtime.store import InMemoryPortStore, PortStore
from hub_core.runtime.validation import ContractValidator
from hub_core.runtime.workload_projection import (
    WorkloadProjectionClient,
    WorkloadProjectionRejected,
    WorkloadProjectionService,
)
from hub_core.runtime.workload_projection_routes import create_workload_projection_router


def create_app(
    *,
    settings: RuntimeSettings | None = None,
    port_store: PortStore | None = None,
    repo_projection_client: RepoProjectionClient | None = None,
    workload_projection_client: WorkloadProjectionClient | None = None,
) -> FastAPI:
    resolved_settings = settings or RuntimeSettings.from_env()
    resolved_store = port_store or _create_store(resolved_settings)
    owns_store = port_store is None
    repository_navigation = RepositoryNavigationService(
        client=repo_projection_client,
        store=resolved_store,
    )
    workload_projection = WorkloadProjectionService(
        client=workload_projection_client,
        store=resolved_store,
    )

    @asynccontextmanager
    async def lifespan(_: FastAPI):
        if repo_projection_client is not None:
            try:
                await repository_navigation.refresh()
            except ProjectionRejected:
                # The readiness dependency reports the rejected or absent
                # projection while the API remains available for diagnosis.
                pass
        if workload_projection_client is not None:
            try:
                await workload_projection.refresh()
            except WorkloadProjectionRejected:
                pass
        yield
        if owns_store and (closer := getattr(resolved_store, "aclose", None)):
            await closer()

    app = FastAPI(
        title="Hub Core Runtime",
        version=__version__,
        description="HelixForge hub framework and named-port runtime.",
        lifespan=lifespan,
    )
    app.state.settings = resolved_settings
    app.state.port_store = resolved_store
    app.state.compat_store = (
        SQLCompatibilityStore(resolved_store)
        if resolved_store.backend_name == "postgresql"
        else None
    )
    app.state.contract_validator = ContractValidator()
    app.state.repository_navigation = repository_navigation
    app.state.workload_projection = workload_projection

    @app.get("/healthz", response_model=HealthResponse, tags=["system"])
    async def healthz() -> HealthResponse:
        return HealthResponse(
            service="core-hub" if resolved_settings.legacy_health else "hub-core",
            version=__version__,
        )

    @app.get("/readyz", response_model=ReadinessResponse, tags=["system"])
    async def readyz(response: Response) -> ReadinessResponse:
        dependency_checks = {
            **await resolved_store.readiness_checks(),
            **await repository_navigation.readiness_checks(),
            **await workload_projection.readiness_checks(),
        }
        ready = resolved_settings.is_ready(resolved_store.backend_name) and all(
            value in {"ok", "not_applicable"} for value in dependency_checks.values()
        )
        if not ready:
            response.status_code = status.HTTP_503_SERVICE_UNAVAILABLE
        return ReadinessResponse(
            status="ok" if ready else "degraded",
            checks={
                **resolved_settings.readiness_checks(resolved_store.backend_name),
                **dependency_checks,
            },
        )

    # Exact projection routes precede the generic /projections/{projection_id}
    # route so Starlette dispatch cannot shadow them.
    app.include_router(create_workload_projection_router())
    app.include_router(create_ports_router())
    app.include_router(create_repository_navigation_router())
    app.include_router(create_compatibility_router())
    return app


def _create_store(settings: RuntimeSettings) -> PortStore:
    if settings.backend == "memory":
        return InMemoryPortStore()
    if settings.backend == "postgresql":
        if not settings.database_url:
            raise RuntimeError("HUB_CORE_DATABASE_URL is required for PostgreSQL backend")
        from hub_core.runtime.postgres_store import PostgresPortStore

        return PostgresPortStore.from_url(settings.database_url)
    raise RuntimeError(f"Unsupported HUB_CORE_BACKEND '{settings.backend}'")


app = create_app()