from typing import Any

from sqlalchemy import text
from sqlalchemy.orm import Session

from app.core.config import get_settings
from app.modules.events.constants import EventStatus
from app.modules.events.service import EventService
from app.modules.observability.constants import (
    ObservabilityKey,
    ObservabilityMetricKey,
    ObservabilityStatus,
)
from app.modules.workflows.constants import WorkflowStatus
from app.modules.workflows.service import WorkflowService


class ObservabilityService:
    """Build health, readiness, and JSON metrics for V3 operations."""

    def __init__(self, db: Session):
        self.db = db

    def live(self) -> dict[str, str]:
        return {ObservabilityKey.STATUS: ObservabilityStatus.OK}

    def ready(self) -> dict[str, Any]:
        checks = {
            ObservabilityKey.DATABASE: self._database_check(),
            ObservabilityKey.REDIS: self._redis_check(),
            ObservabilityKey.EVENTS: self._events_check(),
            ObservabilityKey.WORKFLOWS: self._workflows_check(),
        }
        degraded = any(
            item[ObservabilityKey.STATUS]
            in {ObservabilityStatus.DEGRADED, ObservabilityStatus.ERROR}
            for item in checks.values()
        )
        return {
            ObservabilityKey.STATUS: (
                ObservabilityStatus.DEGRADED if degraded else ObservabilityStatus.OK
            ),
            ObservabilityKey.CHECKS: checks,
        }

    def metrics(self) -> dict[str, Any]:
        return {
            ObservabilityKey.METRICS: {
                ObservabilityKey.EVENTS: EventService(self.db).count_by_status(),
                ObservabilityKey.WORKFLOWS: WorkflowService(self.db).count_by_status(),
            }
        }

    def _database_check(self) -> dict[str, Any]:
        try:
            self.db.execute(text("select 1")).scalar()
        except Exception as exc:
            return {
                ObservabilityKey.STATUS: ObservabilityStatus.ERROR,
                ObservabilityMetricKey.ERROR: str(exc),
            }
        return {ObservabilityKey.STATUS: ObservabilityStatus.OK}

    def _redis_check(self) -> dict[str, Any]:
        settings = get_settings()
        if not settings.task_queue_enabled:
            return {ObservabilityKey.STATUS: ObservabilityStatus.SKIPPED}
        try:
            from redis import Redis

            Redis.from_url(settings.redis_url, socket_connect_timeout=1).ping()
        except Exception as exc:
            return {
                ObservabilityKey.STATUS: ObservabilityStatus.DEGRADED,
                ObservabilityMetricKey.ERROR: str(exc),
            }
        return {ObservabilityKey.STATUS: ObservabilityStatus.OK}

    def _events_check(self) -> dict[str, Any]:
        counts = EventService(self.db).count_by_status()
        failed = counts.get(EventStatus.FAILED, 0)
        return {
            ObservabilityKey.STATUS: (
                ObservabilityStatus.DEGRADED if failed else ObservabilityStatus.OK
            ),
            ObservabilityMetricKey.PENDING: counts.get(EventStatus.PENDING, 0),
            ObservabilityMetricKey.FAILED: failed,
        }

    def _workflows_check(self) -> dict[str, Any]:
        counts = WorkflowService(self.db).count_by_status()
        failed = counts.get(WorkflowStatus.FAILED, 0)
        return {
            ObservabilityKey.STATUS: (
                ObservabilityStatus.DEGRADED if failed else ObservabilityStatus.OK
            ),
            ObservabilityMetricKey.RUNNING: counts.get(WorkflowStatus.RUNNING, 0),
            ObservabilityMetricKey.FAILED: failed,
        }