import struct
import asyncio
from typing import Annotated

import redis.asyncio as aioredis
from fastapi import FastAPI, Path
from fastapi.responses import Response

from config import Config

config = Config('config.hjson')
redis = None

app = FastAPI()

@app.get(
  '/counter/{name}',
  responses = {
    200: {
      'content': {'image/png': {}}
    }
  },
  response_class=Response
)
async def get_counter(
  name: Annotated[
    str,
    Path(
      min_length=1,
      max_length=50,
      pattern=r'^[a-zA-Z0-9А-Яа-я\-\.,_@#:]+$'
    )
  ]
):
  if await redis.exists(name):
    number = await redis.get(name)
    number = int(number) + 1
  else:
    number = 1

  await redis.set(name, str(number))

  proc = await asyncio.create_subprocess_exec(
    config.CounterPath,
    stdin=asyncio.subprocess.PIPE,
    stdout=asyncio.subprocess.PIPE
  )

  stdout, _ = await proc.communicate(
    input=struct.pack('L', number)
  )

  return Response(
    content=stdout,
    media_type='image/png'
  )

@app.on_event('startup')
async def startup_event():
  global redis

  redis = await aioredis.from_url(
    config.RedisURL
  )

@app.on_event('shutdown')
async def shutdown_event():
  if redis is not None:
    await redis.close()