# app/api/v1/endpoints/groups.py
import logging
from typing import List

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession

from app.database import get_db
from app.api.dependencies import get_current_user
from app.models import User as UserModel, UserRoleEnum # Import model and enum
from app.schemas.group import GroupCreate, GroupPublic
from app.schemas.invite import InviteCodePublic
from app.schemas.message import Message # For simple responses
from app.crud import group as crud_group
from app.crud import invite as crud_invite

logger = logging.getLogger(__name__)
router = APIRouter()

@router.post(
    "", # Route relative to prefix "/groups"
    response_model=GroupPublic,
    status_code=status.HTTP_201_CREATED,
    summary="Create New Group",
    tags=["Groups"]
)
async def create_group(
    group_in: GroupCreate,
    db: AsyncSession = Depends(get_db),
    current_user: UserModel = Depends(get_current_user),
):
    """Creates a new group, adding the creator as the owner."""
    logger.info(f"User {current_user.email} creating group: {group_in.name}")
    created_group = await crud_group.create_group(db=db, group_in=group_in, creator_id=current_user.id)
    # Load members explicitly if needed for the response (optional here)
    # created_group = await crud_group.get_group_by_id(db, created_group.id)
    return created_group


@router.get(
    "", # Route relative to prefix "/groups"
    response_model=List[GroupPublic],
    summary="List User's Groups",
    tags=["Groups"]
)
async def read_user_groups(
    db: AsyncSession = Depends(get_db),
    current_user: UserModel = Depends(get_current_user),
):
    """Retrieves all groups the current user is a member of."""
    logger.info(f"Fetching groups for user: {current_user.email}")
    groups = await crud_group.get_user_groups(db=db, user_id=current_user.id)
    return groups


@router.get(
    "/{group_id}",
    response_model=GroupPublic,
    summary="Get Group Details",
    tags=["Groups"]
)
async def read_group(
    group_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: UserModel = Depends(get_current_user),
):
    """Retrieves details for a specific group, including members, if the user is part of it."""
    logger.info(f"User {current_user.email} requesting details for group ID: {group_id}")
    # Check if user is a member first
    is_member = await crud_group.is_user_member(db=db, group_id=group_id, user_id=current_user.id)
    if not is_member:
        logger.warning(f"Access denied: User {current_user.email} not member of group {group_id}")
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not a member of this group")

    group = await crud_group.get_group_by_id(db=db, group_id=group_id)
    if not group:
         logger.error(f"Group {group_id} requested by member {current_user.email} not found (data inconsistency?)")
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Group not found")

    # Manually construct the members list with UserPublic schema if needed
    # Pydantic v2's from_attributes should handle this if relationships are loaded
    # members_public = [UserPublic.model_validate(assoc.user) for assoc in group.member_associations]
    # return GroupPublic.model_validate(group, update={"members": members_public})
    return group # Rely on Pydantic conversion and eager loading


@router.post(
    "/{group_id}/invites",
    response_model=InviteCodePublic,
    summary="Create Group Invite",
    tags=["Groups", "Invites"]
)
async def create_group_invite(
    group_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: UserModel = Depends(get_current_user),
):
    """Generates a new invite code for the group. Requires owner/admin role (MVP: owner only)."""
    logger.info(f"User {current_user.email} attempting to create invite for group {group_id}")
    user_role = await crud_group.get_user_role_in_group(db, group_id=group_id, user_id=current_user.id)

    # --- Permission Check (MVP: Owner only) ---
    if user_role != UserRoleEnum.owner:
        logger.warning(f"Permission denied: User {current_user.email} (role: {user_role}) cannot create invite for group {group_id}")
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Only group owners can create invites")

    # Check if group exists (implicitly done by role check, but good practice)
    group = await crud_group.get_group_by_id(db, group_id)
    if not group:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Group not found")

    invite = await crud_invite.create_invite(db=db, group_id=group_id, creator_id=current_user.id)
    if not invite:
         logger.error(f"Failed to generate unique invite code for group {group_id}")
         raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="Could not generate invite code")

    logger.info(f"Invite code created for group {group_id} by user {current_user.email}")
    return invite

@router.delete(
    "/{group_id}/leave",
    response_model=Message,
    summary="Leave Group",
    tags=["Groups"]
)
async def leave_group(
    group_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: UserModel = Depends(get_current_user),
):
    """Removes the current user from the specified group."""
    logger.info(f"User {current_user.email} attempting to leave group {group_id}")
    user_role = await crud_group.get_user_role_in_group(db, group_id=group_id, user_id=current_user.id)

    if user_role is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="You are not a member of this group")

    # --- MVP: Prevent owner leaving if they are the last member/owner ---
    if user_role == UserRoleEnum.owner:
        member_count = await crud_group.get_group_member_count(db, group_id)
        # More robust check: count owners. For now, just check member count.
        if member_count <= 1:
            logger.warning(f"Owner {current_user.email} attempted to leave group {group_id} as last member.")
            raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Owner cannot leave the group as the last member. Delete the group or transfer ownership.")

    # Proceed with removal
    deleted = await crud_group.remove_user_from_group(db, group_id=group_id, user_id=current_user.id)

    if not deleted:
        # Should not happen if role check passed, but handle defensively
        logger.error(f"Failed to remove user {current_user.email} from group {group_id} despite being a member.")
        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="Failed to leave group")

    logger.info(f"User {current_user.email} successfully left group {group_id}")
    return Message(detail="Successfully left the group")

# --- Optional: Remove Member Endpoint ---
@router.delete(
    "/{group_id}/members/{user_id_to_remove}",
    response_model=Message,
    summary="Remove Member From Group (Owner Only)",
    tags=["Groups"]
)
async def remove_group_member(
    group_id: int,
    user_id_to_remove: int,
    db: AsyncSession = Depends(get_db),
    current_user: UserModel = Depends(get_current_user),
):
    """Removes a specified user from the group. Requires current user to be owner."""
    logger.info(f"Owner {current_user.email} attempting to remove user {user_id_to_remove} from group {group_id}")
    owner_role = await crud_group.get_user_role_in_group(db, group_id=group_id, user_id=current_user.id)

    # --- Permission Check ---
    if owner_role != UserRoleEnum.owner:
        logger.warning(f"Permission denied: User {current_user.email} (role: {owner_role}) cannot remove members from group {group_id}")
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Only group owners can remove members")

    # Prevent owner removing themselves via this endpoint
    if current_user.id == user_id_to_remove:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Owner cannot remove themselves using this endpoint. Use 'Leave Group' instead.")

    # Check if target user is actually in the group
    target_role = await crud_group.get_user_role_in_group(db, group_id=group_id, user_id=user_id_to_remove)
    if target_role is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User to remove is not a member of this group")

    # Proceed with removal
    deleted = await crud_group.remove_user_from_group(db, group_id=group_id, user_id=user_id_to_remove)

    if not deleted:
        logger.error(f"Owner {current_user.email} failed to remove user {user_id_to_remove} from group {group_id}.")
        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="Failed to remove member")

    logger.info(f"Owner {current_user.email} successfully removed user {user_id_to_remove} from group {group_id}")
    return Message(detail="Successfully removed member from the group")