from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from datetime import datetime, timedelta
from jose import JWTError, jwt
from passlib.context import CryptContext
from typing import List

from app.models.base import get_db
from app.models.admin import Admin
from app.models.question import Question
from app.models.category import Category
from app.schemas.admin import AdminCreate, Token, TokenData
from app.schemas.question import (
    QuestionCreate, QuestionUpdate, QuestionResponse,
    AIGenerateRequest
)
from app.services.ai_generator import ai_generator
from app.config import get_settings

router = APIRouter()
settings = get_settings()

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/admin/login")


def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password: str) -> str:
    return pwd_context.hash(password)


def create_access_token(data: dict) -> str:
    to_encode = data.copy()
    expire = datetime.utcnow() + timedelta(minutes=settings.jwt_expire_minutes)
    to_encode.update({"exp": expire})
    return jwt.encode(to_encode, settings.jwt_secret, algorithm=settings.jwt_algorithm)


async def get_current_admin(
    token: str = Depends(oauth2_scheme),
    db: AsyncSession = Depends(get_db)
) -> Admin:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(
            token, settings.jwt_secret, algorithms=[settings.jwt_algorithm]
        )
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception

    result = await db.execute(select(Admin).where(Admin.username == username))
    admin = result.scalar_one_or_none()
    if admin is None:
        raise credentials_exception
    return admin


@router.post("/login", response_model=Token)
async def login(
    form_data: OAuth2PasswordRequestForm = Depends(),
    db: AsyncSession = Depends(get_db)
):
    result = await db.execute(
        select(Admin).where(Admin.username == form_data.username)
    )
    admin = result.scalar_one_or_none()

    if not admin or not verify_password(form_data.password, admin.password_hash):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )

    access_token = create_access_token(data={"sub": admin.username})
    return {"access_token": access_token, "token_type": "bearer"}


@router.post("/register", response_model=Token)
async def register_admin(
    admin_data: AdminCreate,
    db: AsyncSession = Depends(get_db)
):
    # Check if admin exists
    result = await db.execute(
        select(Admin).where(Admin.username == admin_data.username)
    )
    if result.scalar_one_or_none():
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Username already registered"
        )

    # Create admin
    admin = Admin(
        username=admin_data.username,
        password_hash=get_password_hash(admin_data.password)
    )
    db.add(admin)
    await db.commit()

    access_token = create_access_token(data={"sub": admin.username})
    return {"access_token": access_token, "token_type": "bearer"}


# Question Management

@router.get("/questions", response_model=List[QuestionResponse])
async def get_questions(
    category_id: int = None,
    status: str = None,
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    query = select(Question)
    if category_id:
        query = query.where(Question.category_id == category_id)
    if status:
        query = query.where(Question.status == status)

    result = await db.execute(query.order_by(Question.created_at.desc()))
    return result.scalars().all()


@router.post("/questions", response_model=QuestionResponse)
async def create_question(
    question_data: QuestionCreate,
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    question = Question(
        **question_data.model_dump(),
        points=settings.default_points.get(question_data.difficulty, 300),
        time_seconds=settings.default_times.get(question_data.difficulty, 25)
    )
    db.add(question)
    await db.commit()
    await db.refresh(question)
    return question


@router.put("/questions/{question_id}", response_model=QuestionResponse)
async def update_question(
    question_id: int,
    question_data: QuestionUpdate,
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    result = await db.execute(select(Question).where(Question.id == question_id))
    question = result.scalar_one_or_none()

    if not question:
        raise HTTPException(status_code=404, detail="Question not found")

    for key, value in question_data.model_dump(exclude_unset=True).items():
        setattr(question, key, value)

    await db.commit()
    await db.refresh(question)
    return question


@router.delete("/questions/{question_id}")
async def delete_question(
    question_id: int,
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    result = await db.execute(select(Question).where(Question.id == question_id))
    question = result.scalar_one_or_none()

    if not question:
        raise HTTPException(status_code=404, detail="Question not found")

    await db.delete(question)
    await db.commit()
    return {"status": "deleted"}


@router.post("/questions/generate")
async def generate_questions(
    request: AIGenerateRequest,
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    # Get category name
    result = await db.execute(
        select(Category).where(Category.id == request.category_id)
    )
    category = result.scalar_one_or_none()

    if not category:
        raise HTTPException(status_code=404, detail="Category not found")

    # Generate questions with AI
    generated = await ai_generator.generate_questions(
        category_name=category.name,
        difficulty=request.difficulty,
        count=request.count
    )

    # Save to database as pending
    questions = []
    for q_data in generated:
        question = Question(
            category_id=request.category_id,
            question_text=q_data["question"],
            correct_answer=q_data["correct_answer"],
            alt_answers=q_data.get("alt_answers", []),
            difficulty=q_data["difficulty"],
            points=q_data["points"],
            time_seconds=q_data["time_seconds"],
            fun_fact=q_data.get("fun_fact"),
            status="pending"
        )
        db.add(question)
        questions.append(question)

    await db.commit()

    return {
        "generated": len(questions),
        "questions": [q.id for q in questions]
    }


@router.post("/questions/{question_id}/approve")
async def approve_question(
    question_id: int,
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    result = await db.execute(select(Question).where(Question.id == question_id))
    question = result.scalar_one_or_none()

    if not question:
        raise HTTPException(status_code=404, detail="Question not found")

    question.status = "approved"
    await db.commit()
    return {"status": "approved"}


@router.post("/questions/{question_id}/reject")
async def reject_question(
    question_id: int,
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    result = await db.execute(select(Question).where(Question.id == question_id))
    question = result.scalar_one_or_none()

    if not question:
        raise HTTPException(status_code=404, detail="Question not found")

    await db.delete(question)
    await db.commit()
    return {"status": "rejected"}


# Categories

@router.get("/categories")
async def get_categories(
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    result = await db.execute(select(Category))
    return result.scalars().all()


@router.post("/categories")
async def create_category(
    name: str,
    icon: str = None,
    color: str = None,
    db: AsyncSession = Depends(get_db),
    admin: Admin = Depends(get_current_admin)
):
    category = Category(name=name, icon=icon, color=color)
    db.add(category)
    await db.commit()
    await db.refresh(category)
    return category