from fastapi import APIRouter, Depends, HTTPException, status
from sqlmodel import Session, select
from typing import List
from app.database import get_session
from app.models import Channel, Department, User, KanbanBoard, KanbanColumn
from app.schemas import ChannelCreate, ChannelResponse
from app.auth import get_current_user

router = APIRouter(prefix="/channels", tags=["Channels"])


@router.post("/", response_model=ChannelResponse, status_code=status.HTTP_201_CREATED)
def create_channel(
    channel_data: ChannelCreate,
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Create a new channel"""
    # Check if department exists
    department = session.get(Department, channel_data.department_id)
    if not department:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Department not found"
        )
    
    new_channel = Channel(
        name=channel_data.name,
        description=channel_data.description,
        department_id=channel_data.department_id
    )
    
    session.add(new_channel)
    session.commit()
    session.refresh(new_channel)
    
    # Automatically create a Kanban board for the new channel
    kanban_board = KanbanBoard(
        channel_id=new_channel.id,
        name=f"Kanban Board"
    )
    
    session.add(kanban_board)
    session.commit()
    session.refresh(kanban_board)
    
    # Create the 4 standard columns
    default_columns = [
        ("ToDo", 0),
        ("In Progress", 1),
        ("Waiting", 2),
        ("Done", 3)
    ]
    
    for name, position in default_columns:
        column = KanbanColumn(
            board_id=kanban_board.id,
            name=name,
            position=position
        )
        session.add(column)
    
    session.commit()
    
    return new_channel


@router.get("/", response_model=List[ChannelResponse])
def get_my_channels(
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Get all channels that current user has access to (based on departments)"""
    # Get user with departments
    statement = select(User).where(User.id == current_user.id)
    user = session.exec(statement).first()
    
    if not user or not user.departments:
        return []
    
    # Get all channels from user's departments
    channels = []
    for dept in user.departments:
        statement = select(Channel).where(Channel.department_id == dept.id)
        dept_channels = session.exec(statement).all()
        channels.extend(dept_channels)
    
    return channels


@router.get("/{channel_id}", response_model=ChannelResponse)
def get_channel(
    channel_id: int,
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Get a specific channel"""
    channel = session.get(Channel, channel_id)
    if not channel:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Channel not found"
        )
    
    # Check if user has access to this channel (via department)
    statement = select(User).where(User.id == current_user.id)
    user = session.exec(statement).first()
    
    user_dept_ids = [dept.id for dept in user.departments] if user else []
    if channel.department_id not in user_dept_ids:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You don't have access to this channel"
        )
    
    return channel


@router.get("/department/{department_id}", response_model=List[ChannelResponse])
def get_channels_by_department(
    department_id: int,
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Get all channels in a department"""
    # Check if user has access to this department
    statement = select(User).where(User.id == current_user.id)
    user = session.exec(statement).first()
    
    user_dept_ids = [dept.id for dept in user.departments] if user else []
    if department_id not in user_dept_ids:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You don't have access to this department"
        )
    
    statement = select(Channel).where(Channel.department_id == department_id)
    channels = session.exec(statement).all()
    
    return channels