import os
import toml
import binascii
from redis import Redis

from fastapi import FastAPI, Request, status
from fastapi.responses import JSONResponse, UJSONResponse

from slowapi.util import get_remote_address
from slowapi.middleware import SlowAPIMiddleware
from slowapi import Limiter, _rate_limit_exceeded_handler

from fastapi_cache import FastAPICache
from fastapi_cache.decorator import cache
from slowapi.errors import RateLimitExceeded
from fastapi_cache.backends.redis import RedisBackend

from fastapi_paseto_auth import AuthPASETO
from fastapi_paseto_auth.exceptions import AuthPASETOException

import app.controllers.Auth as Auth

from app.dependencies import load_config

from app.utils.RedisConnector import RedisConnector

import app.models.GeneralErrors as GeneralErrors

from app.routers import root
from app.routers import auth

"""Implements an API for our polling app"""

# Load config

config: dict = load_config()

# Create FastAPI instance

app = FastAPI(title=config['docs']['title'],
              description=config['docs']['description'],
              version=config['docs']['version'],
              license_info={"name": config['license']['name'],
                            "url": config['license']['url']
                            },
              default_response_class=UJSONResponse
              )

# Hook up rate limiter
limiter = Limiter(key_func=get_remote_address,
                  default_limits=[
                      config['slowapi']['limit']
                      ],
                  headers_enabled=True,
                  storage_uri=f"redis://{os.environ['REDIS_URL']}:{os.environ['REDIS_PORT']}/{config['slowapi']['database']}"
                  )
app.state.limiter = limiter
app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)
app.add_middleware(SlowAPIMiddleware)

# Setup routes

app.include_router(root.router)
app.include_router(auth.router)

# Setup cache

@cache()
async def get_cache() -> int:
    """Get cache TTL from config.
    Returns:
        int: Cache TTL
    """
    return 1

# Setup PASETO

@AuthPASETO.load_config
def get_config() -> Auth.PasetoSettings:
    """Get PASETO config from Auth module
    Returns:
        PasetoSettings: PASETO config
    """
    return Auth.PasetoSettings()

@AuthPASETO.token_in_denylist_loader
def check_if_token_in_denylist(decrypted_token):
    redis = Redis(host=os.environ['REDIS_URL'],
              port=os.environ['REDIS_PORT'],
              db=config['tokens']['database'],
              decode_responses=True)
    
    return redis.exists(decrypted_token["jti"])

# Setup custom error handlers

@app.exception_handler(AuthPASETOException)
async def authpaseto_exception_handler(request: Request, exc: AuthPASETOException) -> JSONResponse:
    """Handle AuthPASETOException
    Args:
        request (Request): Request
        exc (AuthPASETOException): Exception
    Returns:
        JSONResponse: Response
    """
    return JSONResponse(status_code=exc.status_code, content={"detail": exc.message})

@app.exception_handler(AttributeError)
async def validation_exception_handler(request, exc) -> JSONResponse:
    """Handle AttributeError
    Args:
        request (Request): Request
        exc (AttributeError): Exception
    Returns:
        JSONResponse: Response
    """
    return JSONResponse(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, content={
        "error": "Unprocessable Entity"
        })

@app.exception_handler(binascii.Error)
async def invalid_token_exception_handler(request, exc) -> JSONResponse:
    """Handle binascii.Error
    Args:
        request (Request): Request
        exc (binascii.Error): Exception
    Returns:
        JSONResponse: Response
    """
    return JSONResponse(status_code=status.HTTP_401_UNAUTHORIZED, content={
        "error": GeneralErrors.Unauthorized().error,
        "message": GeneralErrors.Unauthorized().message
        })

@app.on_event("startup")
async def startup() -> None:
    """Startup event handler"""
    
    FastAPICache.init(RedisBackend(RedisConnector.connect(config['cache']['database'])),
                      prefix="fastapi-cache")
    
    return None