from datetime import datetime, timedelta

from sqlalchemy import or_, select
from sqlalchemy.orm import Session

from core_domain import ScheduledJobStatus, ScheduledJobType
from core_shared import JSONValue

from app.db.models import ScheduledJob


class ScheduledJobRepository:
    def __init__(self, db: Session) -> None:
        self.db = db

    def create(
        self,
        *,
        tenant_id: str,
        job_type: ScheduledJobType,
        name: str,
        description: str | None,
        target_service: str | None,
        target_url: str | None,
        method: str | None,
        payload_json: dict[str, JSONValue],
        schedule_time: datetime,
        max_attempts: int,
        metadata_json: dict[str, JSONValue],
    ) -> ScheduledJob:
        entity = ScheduledJob(
            tenant_id=tenant_id,
            job_type=job_type,
            name=name,
            description=description,
            target_service=target_service,
            target_url=target_url,
            method=method,
            payload_json=payload_json,
            schedule_time=schedule_time,
            max_attempts=max_attempts,
            metadata_json=metadata_json,
        )
        self.db.add(entity)
        self.db.commit()
        self.db.refresh(entity)
        return entity

    def list_by_scope(
        self,
        *,
        tenant_id: str,
        status: ScheduledJobStatus | None = None,
        job_type: ScheduledJobType | None = None,
        limit: int = 100,
    ) -> list[ScheduledJob]:
        stmt = select(ScheduledJob).where(ScheduledJob.tenant_id == tenant_id)
        if status is not None:
            stmt = stmt.where(ScheduledJob.status == status)
        if job_type is not None:
            stmt = stmt.where(ScheduledJob.job_type == job_type)
        stmt = stmt.order_by(ScheduledJob.schedule_time.asc()).limit(limit)
        return list(self.db.scalars(stmt))

    def get_by_id(self, *, tenant_id: str, job_id: str) -> ScheduledJob | None:
        stmt = (
            select(ScheduledJob)
            .where(ScheduledJob.tenant_id == tenant_id)
            .where(ScheduledJob.id == job_id)
        )
        return self.db.scalar(stmt)

    def claim_due_jobs(
        self,
        *,
        tenant_id: str,
        worker_key: str,
        lease_seconds: int,
        limit: int,
        now_time: datetime,
    ) -> list[ScheduledJob]:
        self.release_expired_leases(now_time=now_time)
        stmt = (
            select(ScheduledJob)
            .where(ScheduledJob.tenant_id == tenant_id)
            .where(ScheduledJob.status == "scheduled")
            .where(ScheduledJob.schedule_time <= now_time)
            .where(ScheduledJob.attempt_count < ScheduledJob.max_attempts)
            .order_by(ScheduledJob.schedule_time.asc())
            .limit(limit)
        )
        jobs = list(self.db.scalars(stmt))
        lease_expire_time = now_time + timedelta(seconds=lease_seconds)
        for job in jobs:
            job.status = "claimed"
            job.claimed_by = worker_key
            job.claimed_time = now_time
            job.lease_expire_time = lease_expire_time
            job.attempt_count += 1
        if jobs:
            self.db.commit()
            for job in jobs:
                self.db.refresh(job)
        return jobs

    def release_expired_leases(self, *, now_time: datetime, max_items: int = 100) -> int:
        stmt = (
            select(ScheduledJob)
            .where(ScheduledJob.status == "claimed")
            .where(
                or_(
                    ScheduledJob.lease_expire_time.is_(None),
                    ScheduledJob.lease_expire_time <= now_time,
                )
            )
            .limit(max_items)
        )
        jobs = list(self.db.scalars(stmt))
        for job in jobs:
            job.status = "scheduled" if job.attempt_count < job.max_attempts else "failed"
            job.claimed_by = None
            job.claimed_time = None
            job.lease_expire_time = None
            if job.status == "failed":
                job.last_error_message = "lease expired and max attempts reached"
        if jobs:
            self.db.commit()
        return len(jobs)

    def update_status(
        self,
        *,
        job_id: str,
        status: ScheduledJobStatus,
        last_error_message: str | None = None,
    ) -> ScheduledJob | None:
        entity = self.db.get(ScheduledJob, job_id)
        if entity is None:
            return None
        entity.status = status
        entity.last_error_message = last_error_message
        if status in {"completed", "failed", "cancelled"}:
            entity.completed_time = datetime.utcnow()
            entity.lease_expire_time = None
        self.db.commit()
        self.db.refresh(entity)
        return entity