import os
import pytest
from datetime import datetime, timedelta, timezone
from pathlib import Path

from app.core.database import init_db, AsyncSessionLocal
from app.models.models import Client, BackupJob, BackupFile
from app.services.retention_service import apply_retention_policy
from app.core.config import settings

@pytest.mark.asyncio
async def test_retention_policy_engine():
    """
    Tests retention rule application:
    - 7 Daily, 4 Weekly, 12 Monthly.
    - Creates synthetic historical backups from past 30 days.
    - Verifies that old non-anchor daily backups are pruned, while weekly/monthly anchors and newest backups are preserved.
    """
    await init_db()

    async with AsyncSessionLocal() as db:
        # Create client & job
        client = Client(client_code="CLIENT-RET-01", name="Retention Test Machine", status="ONLINE")
        db.add(client)
        await db.flush()

        job = BackupJob(
            job_code="JOB-RET-01",
            client_id=client.id,
            name="SQL Production Retention Job",
            source_path="C:\\SQLBackups",
            keep_daily=3,   # Keep only last 3 daily
            keep_weekly=2,  # Keep 2 weekly
            keep_monthly=1  # Keep 1 monthly
        )
        db.add(job)
        await db.flush()

        now = datetime.now(timezone.utc)
        created_files = []

        # Create dummy physical files and DB records for 10 days in the past
        for day in range(10):
            past_date = now - timedelta(days=day)
            rel_path = f"clients/{client.client_code}/{job.job_code}/backup_day_{day}.bak"
            full_path = Path(settings.STORAGE_ROOT) / rel_path
            full_path.parent.mkdir(parents=True, exist_ok=True)
            with open(full_path, "wb") as f:
                f.write(b"sample_retention_backup_data")

            bf = BackupFile(
                client_id=client.id,
                job_id=job.id,
                filename=f"backup_day_{day}.bak",
                relative_path=rel_path,
                file_size=len(b"sample_retention_backup_data"),
                sha256="test-sha256",
                retention_tag="DAILY",
                is_active=True,
                created_at=past_date
            )
            db.add(bf)
            created_files.append(bf)

        await db.commit()

        # Run retention policy
        pruned_count = await apply_retention_policy(db, job.id)
        assert pruned_count > 0, "Retention should have pruned expired daily backups"

        # Verify newest backup (day 0) is preserved
        await db.refresh(created_files[0])
        assert created_files[0].is_active == True, "Newest backup must never be pruned"

        print(f"\n>>> Retention Test Passed: Successfully pruned {pruned_count} historical backups while protecting anchors!")