from fastapi import APIRouter, Depends, HTTPException, status, UploadFile, File, Request
from sqlalchemy.orm import Session
from sqlalchemy import func
from typing import List
from slowapi import Limiter
from slowapi.util import get_remote_address
from .. import models, schemas, auth
from ..database import get_db

# [H-02] Rate limiter for extract-label endpoint
limiter = Limiter(key_func=get_remote_address)

router = APIRouter(
    prefix="/items",
    tags=["Items"]
)

@router.get("/stats")
def read_item_stats(
    db: Session = Depends(get_db),
    current_user: auth.TokenData = Depends(auth.get_current_user)
):
    """[C-01] Item statistics — only for authenticated users."""
    total_categories = db.query(models.Category).count()
    total_items = db.query(models.Item).count()

    # Count items per category string
    items_per_category = db.query(models.Item.category, func.count(models.Item.id))\
        .group_by(models.Item.category).all()

    return {
        "total_categories": total_categories,
        "total_items": total_items,
        "items_distribution": {cat: count for cat, count in items_per_category if cat}
    }

@router.get("/", response_model=List[schemas.Item])
def read_items(
    skip: int = 0,
    limit: int = 100,
    db: Session = Depends(get_db),
    current_user: auth.TokenData = Depends(auth.get_current_user)
):
    """[C-01] List of items — only for authenticated users."""
    items = db.query(models.Item).offset(skip).limit(limit).all()
    return items

@router.get("/{item_id}", response_model=schemas.Item)
def read_item(
    item_id: int,
    db: Session = Depends(get_db),
    current_user: auth.TokenData = Depends(auth.get_current_user)
):
    """[C-01] Get item — only for authenticated users."""
    item = db.query(models.Item).filter(models.Item.id == item_id).first()
    if item is None:
        raise HTTPException(status_code=404, detail="Item not found")
    return item

_ALLOWED_IMAGE_TYPES = {"image/jpeg", "image/png", "image/webp", "image/gif"}
_MAX_IMAGE_SIZE = 10 * 1024 * 1024  # 10 MB

@limiter.limit("10/minute")
@router.post("/extract-label")
async def extract_label(
    request: Request,
    file: UploadFile = File(...),
    current_user: auth.TokenData = Depends(auth.get_current_user)
):
    """[C-01] Extract label from image — only for authenticated users. [H-02] Rate limit: 10 req/min per IP."""
    from ..ai_vision import extract_label_info

    # [SECURITY FIX H-03] Validate MIME type and maximum size
    if file.content_type not in _ALLOWED_IMAGE_TYPES:
        raise HTTPException(
            status_code=status.HTTP_415_UNSUPPORTED_MEDIA_TYPE,
            detail=f"File type not allowed: {file.content_type}. Accepted: {', '.join(_ALLOWED_IMAGE_TYPES)}"
        )

    contents = await file.read()

    if len(contents) > _MAX_IMAGE_SIZE:
        raise HTTPException(
            status_code=status.HTTP_413_REQUEST_ENTITY_TOO_LARGE,
            detail="File exceeds 10MB limit."
        )

    result = extract_label_info(contents)
    return result

@router.post("/", response_model=schemas.Item, status_code=status.HTTP_201_CREATED)
def create_item(
    item: schemas.ItemCreate,
    db: Session = Depends(get_db),
    current_user: auth.TokenData = Depends(auth.get_current_user)
):
    """[C-01] Create item — only for authenticated users. [M-02] user_id from token."""
    # Check if barcode exists
    db_item = db.query(models.Item).filter(models.Item.barcode == item.barcode).first()
    if db_item:
        raise HTTPException(status_code=400, detail="Barcode already registered")

    db_item = models.Item(**item.model_dump())
    db.add(db_item)
    db.commit()
    db.refresh(db_item)

    # Audit log the creation — [M-02] user_id from token, not from body
    audit = models.AuditLog(
        user_id=current_user.sub,
        action="CREATE_ITEM",
        target_item_id=db_item.id,
        quantity_change=item.quantity
    )
    db.add(audit)
    db.commit()

    return db_item

@router.put("/{item_id}", response_model=schemas.Item)
def update_item(
    item_id: int,
    item: schemas.ItemCreate,
    db: Session = Depends(get_db),
    current_user: auth.TokenData = Depends(auth.get_current_user)
):
    """[C-01] Update item — only for authenticated users."""
    db_item = db.query(models.Item).filter(models.Item.id == item_id).first()
    if not db_item:
        raise HTTPException(status_code=404, detail="Item not found")

    update_data = item.model_dump(exclude_unset=True)
    for key, value in update_data.items():
        setattr(db_item, key, value)

    db.commit()
    db.refresh(db_item)
    return db_item

@router.delete("/{item_id}")
def delete_item(
    item_id: int,
    db: Session = Depends(get_db),
    current_user: auth.TokenData = Depends(auth.get_current_user)
):
    """[C-01] Delete item — only for authenticated users."""
    db_item = db.query(models.Item).filter(models.Item.id == item_id).first()
    if not db_item:
        raise HTTPException(status_code=404, detail="Item not found")

    db.delete(db_item)
    db.commit()
    return {"message": "Item deleted successfully"}