from fastapi import APIRouter, Depends, HTTPException, status, File, UploadFile, Form
from sqlmodel import Session, select, or_, and_
from sqlalchemy.orm import joinedload
from typing import List, Optional
from app.database import get_session
from app.models import DirectMessage, User, Snippet, DirectMessageAttachment
from app.schemas import DirectMessageCreate, DirectMessageResponse, DirectMessageAttachmentResponse
from app.auth import get_current_user
from app.websocket import manager
import os
import uuid
from pathlib import Path

router = APIRouter(prefix="/direct-messages", tags=["Direct Messages"])


@router.post("/", response_model=DirectMessageResponse, status_code=status.HTTP_201_CREATED)
async def create_direct_message(
    message_data: DirectMessageCreate,
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Create a new direct message"""
    # Check if receiver exists
    receiver = session.get(User, message_data.receiver_id)
    if not receiver:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Receiver not found"
        )
    
    # Can't send message to yourself
    if message_data.receiver_id == current_user.id:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Cannot send message to yourself"
        )
    
    new_message = DirectMessage(
        content=message_data.content,
        sender_id=current_user.id,
        receiver_id=message_data.receiver_id,
        snippet_id=message_data.snippet_id,
        reply_to_id=message_data.reply_to_id
    )
    
    session.add(new_message)
    session.commit()
    session.refresh(new_message)
    
    # Load snippet data if present
    snippet_data = None
    if new_message.snippet_id:
        snippet = session.get(Snippet, new_message.snippet_id)
        if snippet:
            snippet_owner = session.get(User, snippet.owner_id)
            snippet_data = {
                "id": snippet.id,
                "title": snippet.title,
                "content": snippet.content,
                "language": snippet.language,
                "tags": snippet.tags,
                "visibility": snippet.visibility,
                "department_id": snippet.department_id,
                "owner_id": snippet.owner_id,
                "owner_username": snippet_owner.username if snippet_owner else "Unknown",
                "created_at": snippet.created_at,
                "updated_at": snippet.updated_at
            }
    
    # Load reply_to data if present
    reply_to_data = None
    if new_message.reply_to_id:
        reply_to_msg = session.get(DirectMessage, new_message.reply_to_id)
        if reply_to_msg:
            reply_sender = session.get(User, reply_to_msg.sender_id)
            reply_to_data = {
                "id": reply_to_msg.id,
                "content": reply_to_msg.content,
                "sender_username": reply_sender.username if reply_sender else "Unknown",
                "sender_full_name": reply_sender.full_name if reply_sender else None
            }
    
    # Build attachment data
    attachments_data = [
        {
            "id": att.id,
            "filename": att.filename,
            "original_filename": att.original_filename,
            "mime_type": att.mime_type,
            "file_size": att.file_size,
            "file_path": att.file_path,
            "direct_message_id": att.direct_message_id,
            "uploaded_at": att.uploaded_at,
            "upload_permission": att.upload_permission,
            "uploader_id": att.uploader_id,
            "is_editable": att.is_editable
        }
        for att in new_message.attachments
    ]
    
    # Build response using constructor
    response = DirectMessageResponse(
        id=new_message.id,
        content=new_message.content,
        sender_id=new_message.sender_id,
        receiver_id=new_message.receiver_id,
        snippet_id=new_message.snippet_id,
        created_at=new_message.created_at,
        is_read=new_message.is_read,
        sender_username=current_user.username,
        receiver_username=receiver.username,
        sender_full_name=current_user.full_name,
        sender_profile_picture=current_user.profile_picture,
        snippet=snippet_data,
        reply_to=reply_to_data,
        attachments=attachments_data
    )
    
    # Broadcast via WebSocket to receiver (using negative user ID as "channel")
    response_data = {
        "id": new_message.id,
        "content": new_message.content,
        "sender_id": new_message.sender_id,
        "receiver_id": new_message.receiver_id,
        "sender_username": current_user.username,
        "receiver_username": receiver.username,
        "sender_full_name": current_user.full_name,
        "sender_profile_picture": current_user.profile_picture,
        "created_at": new_message.created_at.isoformat(),
        "is_read": new_message.is_read,
        "snippet_id": new_message.snippet_id,
        "snippet": snippet_data,
        "reply_to_id": new_message.reply_to_id,
        "reply_to": reply_to_data,
        "attachments": attachments_data
    }
    
    # Broadcast to both sender and receiver using their user IDs as "channel"
    await manager.broadcast_to_channel(
        {"type": "direct_message", "message": response_data},
        -message_data.receiver_id  # Negative to distinguish from channel IDs
    )
    await manager.broadcast_to_channel(
        {"type": "direct_message", "message": response_data},
        -current_user.id
    )
    
    # Update user activity
    manager.update_activity(current_user.id)
    
    return response


@router.delete("/{message_id}", status_code=status.HTTP_200_OK)
async def delete_direct_message(
    message_id: int,
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Delete a direct message (only sender can delete)"""
    message = session.get(DirectMessage, message_id)
    if not message:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Message not found"
        )
    
    # Only sender can delete
    if message.sender_id != current_user.id:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You can only delete your own messages"
        )
    
    # Delete associated attachments and files
    attachments = session.query(DirectMessageAttachment).filter(
        DirectMessageAttachment.direct_message_id == message_id
    ).all()
    
    for attachment in attachments:
        # Delete file from disk
        file_path = Path(attachment.file_path)
        if file_path.exists():
            try:
                file_path.unlink()
            except Exception as e:
                print(f"Failed to delete file: {e}")
        session.delete(attachment)
    
    session.delete(message)
    session.commit()
    
    return {"success": True, "message": "Message deleted"}
@router.get("/conversation/{user_id}", response_model=List[DirectMessageResponse])
def get_conversation(
    user_id: int,
    limit: int = 50,
    offset: int = 0,
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Get direct messages between current user and another user"""
    # Check if other user exists
    other_user = session.get(User, user_id)
    if not other_user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )
    
    # Get messages where current_user is sender and user_id is receiver OR vice versa
    statement = (
        select(DirectMessage)
        .where(
            or_(
                and_(DirectMessage.sender_id == current_user.id, DirectMessage.receiver_id == user_id),
                and_(DirectMessage.sender_id == user_id, DirectMessage.receiver_id == current_user.id)
            )
        )
        .options(joinedload(DirectMessage.snippet))
        .order_by(DirectMessage.created_at.desc())
        .offset(offset)
        .limit(limit)
    )
    messages = session.exec(statement).all()
    
    # Mark messages as read if they were sent to current user
    for msg in messages:
        if msg.receiver_id == current_user.id and not msg.is_read:
            msg.is_read = True
            session.add(msg)
    session.commit()
    
    # Build responses
    responses = []
    for msg in messages:
        sender = session.get(User, msg.sender_id)
        receiver = session.get(User, msg.receiver_id)
        
        # Build reply_to data if it exists
        reply_to_data = None
        if msg.reply_to_id:
            reply_to_msg = session.get(DirectMessage, msg.reply_to_id)
            if reply_to_msg:
                reply_sender = session.get(User, reply_to_msg.sender_id)
                reply_to_data = {
                    "id": reply_to_msg.id,
                    "content": reply_to_msg.content,
                    "sender_username": reply_sender.username if reply_sender else "Unknown",
                    "sender_full_name": reply_sender.full_name if reply_sender else None
                }
        
        # Build attachment data
        attachments_data = [
            {
                "id": att.id,
                "filename": att.filename,
                "original_filename": att.original_filename,
                "mime_type": att.mime_type,
                "file_size": att.file_size,
                "file_path": att.file_path,
                "direct_message_id": att.direct_message_id,
                "uploaded_at": att.uploaded_at,
                "upload_permission": att.upload_permission,
                "uploader_id": att.uploader_id,
                "is_editable": att.is_editable
            }
            for att in msg.attachments
        ]
        
        # Build snippet data
        snippet_data = None
        if msg.snippet:
            snippet_owner = session.get(User, msg.snippet.owner_id)
            snippet_data = {
                "id": msg.snippet.id,
                "title": msg.snippet.title,
                "content": msg.snippet.content,
                "language": msg.snippet.language,
                "tags": msg.snippet.tags,
                "visibility": msg.snippet.visibility,
                "department_id": msg.snippet.department_id,
                "owner_id": msg.snippet.owner_id,
                "owner_username": snippet_owner.username if snippet_owner else "Unknown",
                "created_at": msg.snippet.created_at,
                "updated_at": msg.snippet.updated_at
            }
        
        # Create response using dict constructor
        msg_response = DirectMessageResponse(
            id=msg.id,
            content=msg.content,
            sender_id=msg.sender_id,
            receiver_id=msg.receiver_id,
            snippet_id=msg.snippet_id,
            created_at=msg.created_at,
            is_read=msg.is_read,
            sender_username=sender.username if sender else "Unknown",
            receiver_username=receiver.username if receiver else "Unknown",
            sender_full_name=sender.full_name if sender else None,
            sender_profile_picture=sender.profile_picture if sender else None,
            snippet=snippet_data,
            reply_to=reply_to_data,
            attachments=attachments_data
        )
        
        responses.append(msg_response)
    
    # Reverse to show oldest first
    return list(reversed(responses))


@router.get("/conversations", response_model=List[dict])
def get_conversations(
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Get list of users with whom current user has conversations"""
    # Get all direct messages involving current user
    statement = select(DirectMessage).where(
        or_(
            DirectMessage.sender_id == current_user.id,
            DirectMessage.receiver_id == current_user.id
        )
    )
    messages = session.exec(statement).all()
    
    # Extract unique user IDs
    user_ids = set()
    for msg in messages:
        if msg.sender_id != current_user.id:
            user_ids.add(msg.sender_id)
        if msg.receiver_id != current_user.id:
            user_ids.add(msg.receiver_id)
    
    # Get user details
    conversations = []
    for user_id in user_ids:
        user = session.get(User, user_id)
        if user:
            # Get last message with this user
            last_msg_stmt = (
                select(DirectMessage)
                .where(
                    or_(
                        and_(DirectMessage.sender_id == current_user.id, DirectMessage.receiver_id == user_id),
                        and_(DirectMessage.sender_id == user_id, DirectMessage.receiver_id == current_user.id)
                    )
                )
                .order_by(DirectMessage.created_at.desc())
                .limit(1)
            )
            last_msg = session.exec(last_msg_stmt).first()
            
            conversations.append({
                "user_id": user.id,
                "username": user.username,
                "full_name": user.full_name,
                "email": user.email,
                "last_message": last_msg.content if last_msg else None,
                "last_message_at": last_msg.created_at.isoformat() if last_msg else None
            })
    
    return conversations


@router.post("/{user_id}/upload", status_code=status.HTTP_201_CREATED)
async def upload_direct_message_file(
    user_id: int,
    file: UploadFile = File(...),
    content: str = Form(default=""),
    permission: str = Form(default="read"),
    reply_to_id: str = Form(default=""),
    session: Session = Depends(get_session),
    current_user: User = Depends(get_current_user)
):
    """Upload a file with a direct message"""
    # Convert reply_to_id from string to int or None
    parsed_reply_to_id: Optional[int] = None
    if reply_to_id and reply_to_id.strip():
        try:
            parsed_reply_to_id = int(reply_to_id)
        except ValueError:
            parsed_reply_to_id = None
    
    # Check if receiver exists
    receiver = session.get(User, user_id)
    if not receiver:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Receiver not found"
        )
    
    # Can't send message to yourself
    if user_id == current_user.id:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Cannot send message to yourself"
        )
    
    # Create uploads directory if it doesn't exist
    upload_dir = Path(__file__).parent.parent.parent / "uploads"
    upload_dir.mkdir(parents=True, exist_ok=True)
    
    # Generate unique filename
    file_ext = Path(file.filename).suffix
    unique_filename = f"{uuid.uuid4()}{file_ext}"
    file_path = upload_dir / unique_filename
    
    # Save file to disk
    file_content = await file.read()
    with open(file_path, 'wb') as f:
        f.write(file_content)
    
    # Create direct message
    new_message = DirectMessage(
        content=content or f"Shared file: {file.filename}",
        sender_id=current_user.id,
        receiver_id=user_id,
        reply_to_id=parsed_reply_to_id
    )
    
    session.add(new_message)
    session.commit()
    session.refresh(new_message)
    
    # Create file attachment
    attachment = DirectMessageAttachment(
        filename=unique_filename,
        original_filename=file.filename,
        mime_type=file.content_type or "application/octet-stream",
        file_size=len(file_content),
        file_path=str(file_path),
        direct_message_id=new_message.id,
        uploader_id=current_user.id,
        upload_permission=permission
    )
    
    session.add(attachment)
    session.commit()
    session.refresh(attachment)
    
    # Build response
    response = DirectMessageResponse.model_validate(new_message)
    response.sender_username = current_user.username
    response.receiver_username = receiver.username
    response.sender_full_name = current_user.full_name
    response.sender_profile_picture = current_user.profile_picture
    
    # Add attachment to response
    att_response = DirectMessageAttachmentResponse.model_validate(attachment)
    response.attachments = [att_response]
    
    # Load reply_to data if present
    reply_to_data = None
    if new_message.reply_to_id:
        reply_to_msg = session.get(DirectMessage, new_message.reply_to_id)
        if reply_to_msg:
            reply_sender = session.get(User, reply_to_msg.sender_id)
            reply_to_data = {
                "id": reply_to_msg.id,
                "content": reply_to_msg.content,
                "sender_username": reply_sender.username if reply_sender else "Unknown",
                "sender_full_name": reply_sender.full_name if reply_sender else None
            }
    
    # Broadcast via WebSocket
    response_data = {
        "id": new_message.id,
        "content": new_message.content,
        "sender_id": new_message.sender_id,
        "receiver_id": new_message.receiver_id,
        "sender_username": current_user.username,
        "receiver_username": receiver.username,
        "sender_full_name": current_user.full_name,
        "sender_profile_picture": current_user.profile_picture,
        "created_at": new_message.created_at.isoformat(),
        "is_read": new_message.is_read,
        "snippet_id": new_message.snippet_id,
        "snippet": None,
        "reply_to_id": new_message.reply_to_id,
        "reply_to": reply_to_data,
        "attachments": [{
            "id": attachment.id,
            "filename": attachment.filename,
            "original_filename": attachment.original_filename,
            "mime_type": attachment.mime_type,
            "file_size": attachment.file_size,
            "uploaded_at": attachment.uploaded_at.isoformat(),
            "direct_message_id": attachment.direct_message_id,
            "upload_permission": attachment.upload_permission,
            "uploader_id": attachment.uploader_id,
            "is_editable": attachment.is_editable
        }]
    }
    
    # Broadcast to both sender and receiver
    await manager.broadcast_to_channel(
        {"type": "direct_message", "message": response_data},
        -user_id
    )
    await manager.broadcast_to_channel(
        {"type": "direct_message", "message": response_data},
        -current_user.id
    )
    
    # Update user activity
    manager.update_activity(current_user.id)
    
    return response