from fastapi import APIRouter, Depends
from sqlalchemy.orm import Session
from .. import models, schemas, auth
from ..database import get_db
import json

router = APIRouter(
    prefix="/sync",
    tags=["Sync"]
)


@router.post("/bulk-sync")
def bulk_sync(
    payload: schemas.SyncPayload,
    db: Session = Depends(get_db),
    current_user: auth.TokenData = Depends(auth.get_current_user)
):
    """[C-01] Bulk sync offline operations — only for authenticated users."""
    results = {"success": [], "errors": []}

    for op in payload.operations:
        try:
            # DEDUPLICATION CHECK: If this UUID already exists, skip it
            if op.uuid:
                existing = db.query(models.AuditLog).filter(models.AuditLog.uuid == op.uuid).first()
                if existing:
                    results["success"].append({"barcode": op.barcode, "type": op.type, "note": "Already synced"})
                    continue

            item = db.query(models.Item).filter(models.Item.barcode == op.barcode).first()
            if not item:
                results["errors"].append({"barcode": op.barcode, "error": "Item not found"})
                continue

            if op.type == "CHECK_IN":
                item.quantity += op.quantity
                change = op.quantity
            elif op.type == "CHECK_OUT" or op.type == "TRASH":
                if item.quantity < op.quantity:
                    results["errors"].append({"barcode": op.barcode, "error": f"Insufficient stock (Available: {item.quantity})"})
                    continue
                item.quantity -= op.quantity
                change = -op.quantity
            else:
                results["errors"].append({"barcode": op.barcode, "error": f"Invalid operation type: {op.type}"})
                continue

            # Log audit with original offline timestamp and UUID
            item_snapshot = {
                "barcode": item.barcode,
                "name": item.name,
                "category": item.category,
                "part_number": item.part_number
            }

            audit = models.AuditLog(
                user_id=current_user.sub,
                action=op.type,
                target_item_id=item.id,
                target_item_name=item.name,
                target_item_pn=item.part_number,
                target_item_barcode=item.barcode,
                target_snapshot=json.dumps(item_snapshot),
                quantity_change=change,
                timestamp=op.timestamp,
                uuid=op.uuid,
                details="Offline Synchronization"
            )
            db.add(audit)
            results["success"].append({"barcode": op.barcode, "type": op.type})

        except Exception as e:
            results["errors"].append({"barcode": op.barcode, "error": str(e)})

    db.commit()
    return results