from fastapi import APIRouter
from fastapi.responses import JSONResponse
from sqlalchemy import text

from alembic.config import Config
from alembic.runtime.migration import MigrationContext
from alembic.script import ScriptDirectory

from app.persistence.db import engine
from app.settings import get_settings

router = APIRouter()


def _alembic_at_head() -> bool:
    config = Config("alembic.ini")
    script = ScriptDirectory.from_config(config)
    with engine.connect() as connection:
        context = MigrationContext.configure(connection)
        return set(context.get_current_heads()) == set(script.get_heads())


@router.get("/health/live")
def live() -> dict[str, str]:
    return {"status": "ok"}


@router.get("/health/ready", response_model=None)
def ready() -> JSONResponse | dict[str, str]:
    settings = get_settings()
    try:
        with engine.connect() as connection:
            connection.execute(text("SELECT 1"))
        if not _alembic_at_head():
            return JSONResponse(
                {"status": "not_ready", "reason": "migration_behind_head"},
                status_code=503,
            )
    except Exception:
        return JSONResponse({"status": "not_ready", "reason": "database"}, status_code=503)
    return {
        "status": "ready",
        "environment": settings.environment,
        "engine_build": settings.engine_build,
    }