use std::io::ErrorKind;
use std::sync::Arc;

use actix_web::web;
use webauthn_rs::{RegistrationState, Webauthn, WebauthnConfig};
use webauthn_rs::proto::{CreationChallengeResponse, Credential, RegisterPublicKeyCredential};

use crate::constants::APP_NAME;
use crate::data::app_config::AppConfig;
use crate::data::crypto_wrapper::CryptoWrapper;
use crate::data::user::{User, UserID};
use crate::utils::err::Res;

#[derive(Debug)]
struct WebAuthnAppConfig {
    origin: url::Url,
    relying_party_id: String,
}

impl WebauthnConfig for WebAuthnAppConfig {
    fn get_relying_party_name(&self) -> &str {
        APP_NAME
    }

    fn get_origin(&self) -> &url::Url {
        &self.origin
    }

    fn get_relying_party_id(&self) -> &str {
        &self.relying_party_id
    }
}

pub struct RegisterKeyRequest {
    pub opaque_state: String,
    pub creation_challenge: CreationChallengeResponse,
}

#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
pub struct WebauthnPubKey {
    creds: Credential,
}

#[derive(Debug, serde::Serialize, serde::Deserialize)]
struct RegisterKeyOpaqueData {
    registration_state: RegistrationState,
    user_id: UserID,
}

pub type WebAuthManagerReq = web::Data<Arc<WebAuthManager>>;

pub struct WebAuthManager {
    core: Webauthn<WebAuthnAppConfig>,
    crypto_wrapper: CryptoWrapper,
}

impl WebAuthManager {
    pub fn init(conf: &AppConfig) -> Self {
        Self {
            core: Webauthn::new(WebAuthnAppConfig {
                origin: url::Url::parse(&conf.website_origin)
                    .expect("Failed to parse configuration origin!"),
                relying_party_id: conf.domain_name().split_once(':')
                    .map(|s| s.0)
                    .unwrap_or(conf.domain_name())
                    .to_string(),
            }),
            crypto_wrapper: CryptoWrapper::new_random(),
        }
    }

    pub fn start_register(&self, user: &User) -> Res<RegisterKeyRequest> {
        let (creation_challenge, registration_state) = self.core.generate_challenge_register(
            &user.username,
            false,
        )?;

        Ok(RegisterKeyRequest {
            opaque_state: self.crypto_wrapper.encrypt(&RegisterKeyOpaqueData {
                registration_state,
                user_id: user.uid.clone(),
            })?,
            creation_challenge,
        })
    }

    pub fn finish_registration(&self, user: &User, opaque_state: &str,
                               pub_cred: RegisterPublicKeyCredential) -> Res<WebauthnPubKey> {
        let state: RegisterKeyOpaqueData = self.crypto_wrapper.decrypt(opaque_state)?;
        if state.user_id != user.uid {
            return Err(Box::new(
                std::io::Error::new(ErrorKind::Other, "Invalid user for pubkey!")));
        }

        let res = self.core
            .register_credential(&pub_cred, &state.registration_state, |_| Ok(false))?;

        Ok(WebauthnPubKey { creds: res.0 })
    }
}