from fastapi import APIRouter, Depends, HTTPException, status
from bson import ObjectId
from datetime import datetime, timezone
from typing import List

from app.database import get_db
from app.dependencies import get_current_user
from app.models.requirements import RequirementsIn, RequirementsOut

router = APIRouter(prefix="/api/requirements", tags=["requirements"])

@router.post("/", response_model=RequirementsOut, status_code=status.HTTP_201_CREATED)
async def create_requirements(
    req: RequirementsIn,
    db=Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    now = datetime.now(timezone.utc)
    doc = req.model_dump()
    doc["user_id"] = current_user["google_id"]
    doc["created_at"] = now
    doc["updated_at"] = now
    
    result = await db["requirements"].insert_one(doc)
    doc["id"] = str(result.inserted_id)
    return doc

@router.get("/", response_model=List[RequirementsOut])
async def list_requirements(
    db=Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    cursor = db["requirements"].find({"user_id": current_user["google_id"]}).sort("updated_at", -1)
    reqs = []
    async for doc in cursor:
        doc["id"] = str(doc.pop("_id"))
        reqs.append(doc)
    return reqs

@router.get("/{req_id}", response_model=RequirementsOut)
async def get_requirement(
    req_id: str,
    db=Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    try:
        oid = ObjectId(req_id)
    except:
        raise HTTPException(status_code=400, detail="Invalid ID")
        
    doc = await db["requirements"].find_one({"_id": oid, "user_id": current_user["google_id"]})
    if not doc:
        raise HTTPException(status_code=404, detail="Requirement not found")
        
    doc["id"] = str(doc.pop("_id"))
    return doc

@router.put("/{req_id}", response_model=RequirementsOut)
async def update_requirement(
    req_id: str,
    req: RequirementsIn,
    db=Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    try:
        oid = ObjectId(req_id)
    except:
        raise HTTPException(status_code=400, detail="Invalid ID")
        
    update_data = req.model_dump()
    update_data["updated_at"] = datetime.now(timezone.utc)
    
    result = await db["requirements"].find_one_and_update(
        {"_id": oid, "user_id": current_user["google_id"]},
        {"$set": update_data},
        return_document=True
    )
    
    if not result:
        raise HTTPException(status_code=404, detail="Requirement not found")
        
    result["id"] = str(result.pop("_id"))
    return result

@router.delete("/{req_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_requirement(
    req_id: str,
    db=Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    try:
        oid = ObjectId(req_id)
    except:
        raise HTTPException(status_code=400, detail="Invalid ID")
        
    result = await db["requirements"].delete_one({"_id": oid, "user_id": current_user["google_id"]})
    if result.deleted_count == 0:
        raise HTTPException(status_code=404, detail="Requirement not found")