"""
Channels API - Channel management and operations
"""

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session
from pydantic import BaseModel
from typing import List, Optional

from core.database import get_db
from core.models import Channel, User, ChannelType
from api.auth import get_current_user

router = APIRouter()

# Pydantic models
class ChannelCreate(BaseModel):
    name: str
    description: Optional[str] = None
    type: ChannelType = ChannelType.PUBLIC

class ChannelResponse(BaseModel):
    id: int
    name: str
    description: Optional[str]
    type: ChannelType
    member_count: int
    created_at: str
    
    class Config:
        from_attributes = True

class ChannelListResponse(BaseModel):
    id: int
    name: str
    description: Optional[str]
    type: ChannelType
    unread_count: int = 0  # TODO: Implement actual unread counting
    
    class Config:
        from_attributes = True

@router.post("/", response_model=ChannelResponse)
async def create_channel(
    channel_data: ChannelCreate,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """Create a new channel"""
    
    # Check if channel name already exists
    existing = db.query(Channel).filter(Channel.name == channel_data.name).first()
    if existing:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Channel name already exists"
        )
    
    # Create channel
    channel = Channel(
        name=channel_data.name,
        description=channel_data.description,
        type=channel_data.type,
        created_by=current_user.id
    )
    
    db.add(channel)
    db.commit()
    db.refresh(channel)
    
    # Add creator as member
    channel.members.append(current_user)
    db.commit()
    db.refresh(channel)
    
    return ChannelResponse(
        id=channel.id,
        name=channel.name,
        description=channel.description,
        type=channel.type,
        member_count=len(channel.members),
        created_at=channel.created_at.isoformat()
    )

@router.get("/", response_model=List[ChannelListResponse])
async def list_channels(
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """List all channels user is a member of"""
    
    channels = current_user.channels
    
    return [
        {
            "id": c.id,
            "name": c.name,
            "description": c.description,
            "type": c.type,
            "unread_count": 0  # TODO: Implement
        }
        for c in channels
    ]

@router.get("/{channel_id}", response_model=ChannelResponse)
async def get_channel(
    channel_id: int,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """Get channel details"""
    
    channel = db.query(Channel).filter(Channel.id == channel_id).first()
    if not channel:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Channel not found"
        )
    
    # Check if user is member (for private channels)
    if channel.type == ChannelType.PRIVATE:
        if current_user not in channel.members:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="Not a member of this channel"
            )
    
    return {
        **channel.__dict__,
        "member_count": len(channel.members),
        "created_at": channel.created_at.isoformat()
    }

@router.post("/{channel_id}/join")
async def join_channel(
    channel_id: int,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """Join a channel"""
    
    channel = db.query(Channel).filter(Channel.id == channel_id).first()
    if not channel:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Channel not found"
        )
    
    # Can't join private channels (must be invited)
    if channel.type == ChannelType.PRIVATE:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Cannot join private channel"
        )
    
    # Check if already a member
    if current_user in channel.members:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Already a member"
        )
    
    channel.members.append(current_user)
    db.commit()
    
    return {"message": f"Joined channel #{channel.name}"}

@router.post("/{channel_id}/leave")
async def leave_channel(
    channel_id: int,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """Leave a channel"""
    
    channel = db.query(Channel).filter(Channel.id == channel_id).first()
    if not channel:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Channel not found"
        )
    
    if current_user not in channel.members:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Not a member of this channel"
        )
    
    channel.members.remove(current_user)
    db.commit()
    
    return {"message": f"Left channel #{channel.name}"}