"""Authentication endpoints."""

from datetime import datetime, timedelta
from typing import Any
from fastapi import APIRouter, Depends, HTTPException, status, Request
from fastapi.security import HTTPAuthorizationCredentials
from sqlalchemy.orm import Session
from slowapi import Limiter
from slowapi.util import get_remote_address

from app import crud, schemas
from app.dependencies import get_db, get_current_user, security
from app.core.security import create_access_token
from app.config import settings
from app.models.user import User


router = APIRouter()

# Rate limiter for auth endpoints
limiter = Limiter(key_func=get_remote_address)


def get_client_ip(request: Request) -> str:
    """Extract client IP from request, considering proxies."""
    forwarded = request.headers.get("X-Forwarded-For")
    if forwarded:
        return forwarded.split(",")[0].strip()
    return request.client.host if request.client else "unknown"


@router.post("/register", response_model=schemas.User, status_code=status.HTTP_201_CREATED)
@limiter.limit("5/minute")  # Limit registration attempts
def register(
    request: Request,
    *,
    db: Session = Depends(get_db),
    user_in: schemas.RegisterRequest
) -> Any:
    """
    Register a new user.

    Creates a new user account with the provided credentials.
    Registration can be disabled by administrators via settings.
    """
    ip_address = get_client_ip(request)
    user_agent = request.headers.get("User-Agent", "")[:500]

    # Check if this is the first user (always allow for initial setup)
    user_count = db.query(User).count()
    is_first_user = user_count == 0

    # If not the first user, check if registration is enabled
    if not is_first_user:
        registration_enabled_raw = crud.settings.get_setting_value(
            db,
            key="registration_enabled",
            default=True  # Default to enabled if setting doesn't exist
        )

        if isinstance(registration_enabled_raw, str):
            registration_enabled = registration_enabled_raw.strip().lower() in ("true", "1")
        else:
            registration_enabled = bool(registration_enabled_raw)

        if not registration_enabled:
            # Log failed registration attempt
            crud.audit_log.log_action(
                db,
                action="register",
                resource_type="user",
                details={"username": user_in.username, "reason": "registration_disabled"},
                ip_address=ip_address,
                user_agent=user_agent,
                status="failure"
            )
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="User registration is currently disabled"
            )

    # Check if username already exists
    user = crud.user.get_by_username(db, username=user_in.username)
    if user:
        crud.audit_log.log_action(
            db,
            action="register",
            resource_type="user",
            details={"username": user_in.username, "reason": "username_exists"},
            ip_address=ip_address,
            user_agent=user_agent,
            status="failure"
        )
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Username already registered"
        )

    # Check if email already exists
    user = crud.user.get_by_email(db, email=user_in.email)
    if user:
        crud.audit_log.log_action(
            db,
            action="register",
            resource_type="user",
            details={"username": user_in.username, "reason": "email_exists"},
            ip_address=ip_address,
            user_agent=user_agent,
            status="failure"
        )
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Email already registered"
        )

    # Validate password against policy
    from app.core.password_policy import get_password_policy, validate_password
    policy = get_password_policy(db)
    password_errors = validate_password(
        user_in.password,
        policy=policy,
        username=user_in.username,
        email=user_in.email
    )
    if password_errors:
        crud.audit_log.log_action(
            db,
            action="register",
            resource_type="user",
            details={"username": user_in.username, "reason": "weak_password"},
            ip_address=ip_address,
            user_agent=user_agent,
            status="failure"
        )
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail={"message": "Password does not meet requirements", "errors": password_errors}
        )

    # Create new user (first user becomes superuser)
    user_create = schemas.UserCreate(
        username=user_in.username,
        email=user_in.email,
        password=user_in.password,
        is_active=True,
        is_superuser=is_first_user  # First user is superuser
    )

    user = crud.user.create(db, obj_in=user_create)

    # Log successful registration
    crud.audit_log.log_action(
        db,
        user_id=user.id,
        username=user.username,
        action="register",
        resource_type="user",
        resource_id=user.id,
        details={"is_first_user": is_first_user},
        ip_address=ip_address,
        user_agent=user_agent,
        status="success"
    )

    return user


@router.post("/login")
@limiter.limit("10/minute")  # Stricter limit for login attempts
def login(
    request: Request,
    *,
    db: Session = Depends(get_db),
    credentials: schemas.LoginRequest
) -> Any:
    """
    Login and get access token.

    Authenticates user and returns a JWT access token.
    If 2FA is enabled, returns requires_2fa=True with a temp_token.
    """
    ip_address = get_client_ip(request)
    user_agent = request.headers.get("User-Agent", "")[:500]

    # Authenticate user
    user = crud.user.authenticate(
        db,
        username=credentials.username,
        password=credentials.password
    )

    if not user:
        # Log failed login attempt
        crud.audit_log.log_action(
            db,
            action="login",
            resource_type="auth",
            details={"username": credentials.username, "reason": "invalid_credentials"},
            ip_address=ip_address,
            user_agent=user_agent,
            status="failure"
        )
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )

    if not crud.user.is_active(user):
        # Log inactive user login attempt
        crud.audit_log.log_action(
            db,
            user_id=user.id,
            username=user.username,
            action="login",
            resource_type="auth",
            details={"reason": "inactive_user"},
            ip_address=ip_address,
            user_agent=user_agent,
            status="failure"
        )
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Inactive user"
        )

    # Check if 2FA is enabled
    if user.totp_enabled:
        # If TOTP code provided, verify it
        if credentials.totp_code:
            from app.api.v1.two_factor import verify_totp_or_backup
            if not verify_totp_or_backup(user, credentials.totp_code, db):
                crud.audit_log.log_action(
                    db,
                    user_id=user.id,
                    username=user.username,
                    action="login",
                    resource_type="auth",
                    details={"reason": "invalid_2fa_code"},
                    ip_address=ip_address,
                    user_agent=user_agent,
                    status="failure"
                )
                raise HTTPException(
                    status_code=status.HTTP_401_UNAUTHORIZED,
                    detail="Invalid 2FA code"
                )
        else:
            # No code provided, return temp token for 2FA verification
            temp_token_expires = timedelta(minutes=5)  # 5 minute expiry
            temp_token = create_access_token(
                data={"sub": user.id, "temp": True, "purpose": "2fa"},
                expires_delta=temp_token_expires
            )

            crud.audit_log.log_action(
                db,
                user_id=user.id,
                username=user.username,
                action="login_2fa_required",
                resource_type="auth",
                ip_address=ip_address,
                user_agent=user_agent,
                status="pending"
            )

            return {
                "access_token": None,
                "token_type": "bearer",
                "requires_2fa": True,
                "temp_token": temp_token
            }

    # Update last_login timestamp
    user.last_login = datetime.utcnow()
    db.add(user)
    db.commit()

    # Create access token
    access_token_expires = timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user.id},
        expires_delta=access_token_expires
    )

    # Track session for revocation / active sessions
    session = crud.session.create(
        db,
        user_id=user.id,
        token=access_token,
        user_agent=user_agent,
        ip_address=ip_address,
        expires_at=datetime.utcnow() + access_token_expires,
    )
    crud.session.mark_as_current(db, session_id=session.id, user_id=user.id)

    # Log successful login
    crud.audit_log.log_action(
        db,
        user_id=user.id,
        username=user.username,
        action="login",
        resource_type="auth",
        details={"session_id": session.id},
        ip_address=ip_address,
        user_agent=user_agent,
        status="success"
    )

    return {
        "access_token": access_token,
        "token_type": "bearer",
        "requires_2fa": False,
        "temp_token": None
    }


@router.post("/verify-2fa", response_model=schemas.Token)
def verify_2fa_login(
    request: Request,
    *,
    db: Session = Depends(get_db),
    verify_request: schemas.Verify2FARequest
) -> Any:
    """
    Complete login by verifying 2FA code.

    Use the temp_token from the login response along with the TOTP code.
    """
    from jose import JWTError
    from app.core.security import decode_access_token
    from app.api.v1.two_factor import verify_totp_or_backup

    ip_address = get_client_ip(request)
    user_agent = request.headers.get("User-Agent", "")[:500]

    try:
        payload = decode_access_token(verify_request.temp_token)
        user_id = payload.get("sub")
        is_temp = payload.get("temp")
        purpose = payload.get("purpose")

        if not user_id or not is_temp or purpose != "2fa":
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Invalid temporary token"
            )
    except JWTError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid or expired temporary token"
        )

    user = crud.user.get(db, id=user_id)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User not found"
        )

    # Verify TOTP code
    if not verify_totp_or_backup(user, verify_request.code, db):
        crud.audit_log.log_action(
            db,
            user_id=user.id,
            username=user.username,
            action="login_2fa_verify",
            resource_type="auth",
            details={"reason": "invalid_code"},
            ip_address=ip_address,
            user_agent=user_agent,
            status="failure"
        )
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid 2FA code"
        )

    # Update last_login timestamp
    user.last_login = datetime.utcnow()
    db.add(user)
    db.commit()

    # Create full access token
    access_token_expires = timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user.id},
        expires_delta=access_token_expires
    )

    # Track session for revocation / active sessions
    session = crud.session.create(
        db,
        user_id=user.id,
        token=access_token,
        user_agent=user_agent,
        ip_address=ip_address,
        expires_at=datetime.utcnow() + access_token_expires,
    )
    crud.session.mark_as_current(db, session_id=session.id, user_id=user.id)

    # Log successful login
    crud.audit_log.log_action(
        db,
        user_id=user.id,
        username=user.username,
        action="login",
        resource_type="auth",
        details={"method": "2fa", "session_id": session.id},
        ip_address=ip_address,
        user_agent=user_agent,
        status="success"
    )

    return {
        "access_token": access_token,
        "token_type": "bearer"
    }


@router.get("/me", response_model=schemas.User)
def read_users_me(
    current_user: User = Depends(get_current_user)
) -> Any:
    """
    Get current user.

    Returns the currently authenticated user's information.
    Requires a valid JWT token in the Authorization header.
    """
    return current_user


@router.post("/logout")
def logout(
    request: Request,
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
) -> Any:
    """
    Logout by revoking the current session.

    This invalidates the current access token server-side (session revocation).
    """
    ip_address = get_client_ip(request)
    user_agent = request.headers.get("User-Agent", "")[:500]
    token = credentials.credentials

    session = crud.session.get_by_token(db, token)
    if session:
        crud.session.revoke(db, id=session.id, user_id=current_user.id)

    crud.audit_log.log_action(
        db,
        user_id=current_user.id,
        username=current_user.username,
        action="logout",
        resource_type="auth",
        details={"session_id": session.id if session else None},
        ip_address=ip_address,
        user_agent=user_agent,
        status="success",
    )

    return {"message": "Logged out"}


@router.get("/registration-status")
def get_registration_status(
    db: Session = Depends(get_db)
) -> Any:
    """
    Check if user registration is enabled.

    This is a public endpoint that doesn't require authentication.
    Returns the registration_enabled setting value.
    """
    registration_enabled_raw = crud.settings.get_setting_value(
        db,
        key="registration_enabled",
        default=True
    )

    if isinstance(registration_enabled_raw, str):
        registration_enabled = registration_enabled_raw.strip().lower() in ("true", "1")
    else:
        registration_enabled = bool(registration_enabled_raw)

    return {"registration_enabled": registration_enabled}


@router.get("/password-requirements")
def get_password_requirements(
    db: Session = Depends(get_db)
) -> Any:
    """
    Get password requirements/policy.

    This is a public endpoint that returns the password policy
    for display during registration.
    """
    from app.core.password_policy import get_password_policy, get_password_requirements as get_reqs

    policy = get_password_policy(db)
    return get_reqs(policy)


@router.post("/check-password-strength")
def check_password_strength(
    password_data: dict,
    db: Session = Depends(get_db)
) -> Any:
    """
    Check password strength.

    This is a public endpoint that returns password strength analysis
    for real-time feedback during registration.
    """
    from app.core.password_policy import check_password_strength as check_strength

    password = password_data.get("password", "")
    if not password:
        return {
            "score": 0,
            "level": "weak",
            "feedback": ["Password is required"]
        }

    return check_strength(password)