from fastapi import APIRouter, HTTPException, Depends, Header
from typing import Optional
from api.models.schemas import (
    UserRegistration, UserCredentials, UserProfileUpdate,
    PasswordChange, TokenResponse, AuthResponse, UserProfile,
    Conversation, ConversationDetail
)
from api.services.auth_service import auth_service

router = APIRouter(tags=["auth"])


# ── Dependency for protected routes ────────────────────────────────────────────

def get_current_user(authorization: Optional[str] = Header(None)):
    """Extract user from JWT token"""
    if not authorization:
        raise HTTPException(status_code=401, detail="Missing authorization header")

    try:
        scheme, token = authorization.split()
        if scheme.lower() != "bearer":
            raise HTTPException(status_code=401, detail="Invalid auth scheme")
    except ValueError:
        raise HTTPException(status_code=401, detail="Invalid authorization header")

    payload = auth_service.verify_token(token)
    if not payload:
        raise HTTPException(status_code=401, detail="Invalid or expired token")

    return payload


# ────────────────────────────────────────────────────────────────────────────────
# PUBLIC ENDPOINTS
# ────────────────────────────────────────────────────────────────────────────────

@router.post("/register", response_model=AuthResponse)
async def register(user_data: UserRegistration):
    """Register new user"""
    success, message, user_id = auth_service.register_user(
        email=user_data.email,
        password=user_data.password,
        full_name=user_data.full_name,
        dob=user_data.dob,
        sex=user_data.sex,
        medical_history=user_data.medical_history,
        geolocation=user_data.geolocation
    )

    if not success:
        raise HTTPException(status_code=400, detail=message)

    return AuthResponse(
        success=True,
        message=message,
        data={"user_id": user_id}
    )


@router.post("/login", response_model=TokenResponse)
async def login(credentials: UserCredentials):
    """Login user and return JWT token"""
    success, message, user_data = auth_service.login_user(
        email=credentials.email,
        password=credentials.password
    )

    if not success:
        raise HTTPException(status_code=401, detail=message)

    access_token = auth_service.create_access_token(
        user_id=user_data["user_id"],
        email=user_data["email"]
    )

    return TokenResponse(
        access_token=access_token,
        user=UserProfile(**user_data)
    )


# ────────────────────────────────────────────────────────────────────────────────
# PROTECTED ENDPOINTS
# ────────────────────────────────────────────────────────────────────────────────

@router.get("/profile", response_model=UserProfile)
async def get_profile(current_user=Depends(get_current_user)):
    """Get current user profile"""
    user_data = auth_service.get_user_by_id(current_user["sub"])

    if not user_data:
        raise HTTPException(status_code=404, detail="User not found")

    return UserProfile(**user_data)


@router.put("/profile", response_model=AuthResponse)
async def update_profile(
    profile_data: UserProfileUpdate,
    current_user=Depends(get_current_user)
):
    """Update user profile"""
    success, message = auth_service.update_user_profile(
        user_id=current_user["sub"],
        email=profile_data.email,
        full_name=profile_data.full_name,
        dob=profile_data.dob,
        sex=profile_data.sex,
        medical_history=profile_data.medical_history,
        geolocation=profile_data.geolocation
    )

    if not success:
        raise HTTPException(status_code=400, detail=message)

    return AuthResponse(success=True, message=message)


@router.post("/change-password", response_model=AuthResponse)
async def change_password(
    pwd_change: PasswordChange,
    current_user=Depends(get_current_user)
):
    """Change user password"""
    success, message = auth_service.change_password(
        user_id=current_user["sub"],
        old_password=pwd_change.old_password,
        new_password=pwd_change.new_password
    )

    if not success:
        raise HTTPException(status_code=400, detail=message)

    return AuthResponse(success=True, message=message)


@router.delete("/account", response_model=AuthResponse)
async def delete_account(
    password: str,
    current_user=Depends(get_current_user)
):
    """Delete user account"""
    success, message = auth_service.delete_user(
        user_id=current_user["sub"],
        password=password
    )

    if not success:
        raise HTTPException(status_code=400, detail=message)

    return AuthResponse(success=True, message=message)


# ────────────────────────────────────────────────────────────────────────────────
# CONVERSATION ENDPOINTS
# ────────────────────────────────────────────────────────────────────────────────

@router.post("/conversations", response_model=AuthResponse)
async def create_conversation(
    title: Optional[str] = None,
    current_user=Depends(get_current_user)
):
    """Create new conversation"""
    success, message, conversation_id = auth_service.create_conversation(
        user_id=current_user["sub"],
        title=title or "New Conversation"
    )

    if not success:
        raise HTTPException(status_code=400, detail=message)

    return AuthResponse(
        success=True,
        message=message,
        data={"conversation_id": conversation_id}
    )


@router.get("/conversations", response_model=dict)
async def get_conversations(current_user=Depends(get_current_user)):
    """Get all user conversations"""
    success, message, conversations = auth_service.get_conversations(current_user["sub"])

    if not success:
        raise HTTPException(status_code=400, detail=message)

    return {
        "success": True,
        "message": message,
        "conversations": conversations
    }


@router.delete("/conversations/{conversation_id}", response_model=AuthResponse)
async def delete_conversation(
    conversation_id: str,
    current_user=Depends(get_current_user)
):
    """Delete conversation"""
    success, message = auth_service.delete_conversation(
        user_id=current_user["sub"],
        conversation_id=conversation_id
    )

    if not success:
        raise HTTPException(status_code=400, detail=message)

    return AuthResponse(success=True, message=message)


@router.get("/conversations/{conversation_id}")
async def get_conversation_detail(
    conversation_id: str,
    current_user=Depends(get_current_user)
):
    """Get conversation detail with all messages and diagnosis"""
    from api.services.database_interface import conversation_db

    conv_data = auth_service._load_conversation(current_user["sub"], conversation_id)
    if not conv_data:
        raise HTTPException(status_code=404, detail="Conversation not found")

    # Load messages from JSONL
    messages = conversation_db.get_conversation_messages(
        current_user["sub"],
        conversation_id
    )

    # Load diagnosis if exists
    diagnosis_data = conversation_db.get_diagnosis_from_conversation(
        current_user["sub"],
        conversation_id
    )

    return {
        "conversation_id": conversation_id,
        "title": conv_data.get("title"),
        "created_at": conv_data.get("created_at"),
        "messages": messages,
        "diagnosis": diagnosis_data.get("diagnosis") if diagnosis_data else None,
        "recommendations": diagnosis_data.get("recommendations") if diagnosis_data else None
    }