from typing import List
from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.orm import Session

from app.db import get_db
from app.models.comment import Comment
from app.schemas.comment import CommentCreate, CommentResponse

router = APIRouter()

@router.post("/comments", response_model=CommentResponse, status_code=201)
def create_comment(comment: CommentCreate, db: Session = Depends(get_db)):
    db_comment = Comment(**comment.dict())
    db.add(db_comment)
    db.commit()
    db.refresh(db_comment)
    return db_comment

@router.get("/comments", response_model=List[CommentResponse])
def get_all_comments(db: Session = Depends(get_db)):
    comments = db.query(Comment).all()
    return comments

@router.get("/comments/{comment_id}", response_model=CommentResponse)
def get_comment(comment_id: int, db: Session = Depends(get_db)):
    comment = db.query(Comment).filter(Comment.id == comment_id).first()
    if not comment:
        raise HTTPException(status_code=404, detail="Comment not found")
    return comment

@router.put("/comments/{comment_id}", response_model=CommentResponse)
def update_comment(comment_id: int, comment: CommentCreate, db: Session = Depends(get_db)):
    db_comment = db.query(Comment).filter(Comment.id == comment_id).first()
    if not db_comment:
        raise HTTPException(status_code=404, detail="Comment not found")
    update_data = comment.dict(exclude_unset=True)
    for key, value in update_data.items():
        setattr(db_comment, key, value)
    db.commit()
    db.refresh(db_comment)
    return db_comment

@router.delete("/comments/{comment_id}", status_code=204)
def delete_comment(comment_id: int, db: Session = Depends(get_db)):
    comment = db.query(Comment).filter(Comment.id == comment_id).first()
    if not comment:
        raise HTTPException(status_code=404, detail="Comment not found")
    db.delete(comment)
    db.commit()
    return None

This code defines a set of CRUD (Create, Read, Update, Delete) endpoints for comments in a FastAPI application. Here's a breakdown of the functionality:

1. `create_comment` endpoint: Accepts a `CommentCreate` Pydantic model and creates a new comment in the database.
2. `get_all_comments` endpoint: Retrieves a list of all comments from the database.
3. `get_comment` endpoint: Retrieves a single comment by its ID. If the comment is not found, it raises an `HTTPException` with a 404 status code.
4. `update_comment` endpoint: Updates an existing comment by its ID. If the comment is not found, it raises an `HTTPException` with a 404 status code.
5. `delete_comment` endpoint: Deletes a comment by its ID. If the comment is not found, it raises an `HTTPException` with a 404 status code.


Note: You will need to import the required models and schemas in your application and ensure that the database connection is properly configured.