//! This crate allows you to authenticate into Minecraft online services using a
//! Microsoft Oauth2 token. You can integrate it with [oauth2-rs](https://github.com/ramosbugs/oauth2-rs)
//! and build interactive authentication flows.
//!
//! # Example
//!
//! ```no_run
//! # use minecraft_msa_auth::MinecraftAuthorizationFlow;
//! # use oauth2::basic::BasicClient;
//! # use oauth2::devicecode::StandardDeviceAuthorizationResponse;
//! # use oauth2::reqwest::async_http_client;
//! # use oauth2::{AuthUrl, ClientId, DeviceAuthorizationUrl, Scope, TokenResponse, TokenUrl};
//! # use reqwest::Client;
//! #
//! # const DEVICE_CODE_URL: &str = "https://login.microsoftonline.com/consumers/oauth2/v2.0/devicecode";
//! # const MSA_AUTHORIZE_URL: &str = "https://login.microsoftonline.com/consumers/oauth2/v2.0/authorize";
//! # const MSA_TOKEN_URL: &str = "https://login.microsoftonline.com/common/oauth2/v2.0/token";
//! #
//! # #[tokio::main]
//! # async fn main() -> Result<(), Box<dyn std::error::Error>> {
//! # let client_id = std::env::args().nth(1).expect("client_id as first argument");
//! let client = BasicClient::new(
//!     ClientId::new(client_id),
//!     None,
//!     AuthUrl::new(MSA_AUTHORIZE_URL.to_string())?,
//!     Some(TokenUrl::new(MSA_TOKEN_URL.to_string())?),
//! )
//! .set_device_authorization_url(DeviceAuthorizationUrl::new(DEVICE_CODE_URL.to_string())?);
//!
//! let details: StandardDeviceAuthorizationResponse = client
//!     .exchange_device_code()?
//!     .add_scope(Scope::new("XboxLive.signin offline_access".to_string()))
//!     .request_async(async_http_client)
//!     .await?;
//!
//! println!(
//!     "Open this URL in your browser:\n{}\nand enter the code: {}",
//!     details.verification_uri().to_string(),
//!     details.user_code().secret().to_string()
//! );
//!
//! let token = client
//!     .exchange_device_access_token(&details)
//!     .request_async(async_http_client, tokio::time::sleep, None)
//!     .await?;
//! println!("microsoft token: {:?}", token);
//!
//! let mc_flow = MinecraftAuthorizationFlow::new(Client::new());
//! let mc_token = mc_flow.exchange_microsoft_token(token.access_token().secret()).await?;
//! println!("minecraft token: {:?}", mc_token);
//! # Ok(())
//! # }
//! ```
use std::collections::HashMap;

use getset::{CopyGetters, Getters};
use reqwest::{Client as HttpClient, Response, StatusCode};
use serde::Deserialize;
use serde_json::json;
use thiserror::Error;

const MINECRAFT_LOGIN_WITH_XBOX: &str = "https://api.minecraftservices.com/authentication/login_with_xbox";
const XBOX_USER_AUTHERNITATE: &str = "https://user.auth.xboxlive.com/user/authenticate";
const XBOX_XSTS_AUTHORIZE: &str = "https://xsts.auth.xboxlive.com/xsts/authorize";

/// Represents an error that can occur when authenticating with Minecraft.
#[derive(Error, Debug)]
pub enum MinecraftAuthorizationError {
    #[error("Http error: {0}")]
    Http(StatusCode, String),

    #[error(transparent)]
    Reqwest(#[from] reqwest::Error),
}

/// The response from Minecraft when attempting to authenticate with an xbox
/// token
#[derive(Deserialize, Debug, Getters, CopyGetters, Clone)]
pub struct MinecraftAuthenticationResponse {
    /// Some UUID of the account
    #[getset(get = "pub")]
    username: String,

    /// The minecraft JWT access token
    #[getset(get = "pub")]
    access_token: String,

    /// The type of access token
    #[getset(get = "pub")]
    token_type: String,

    /// How many seconds until the token expires
    #[getset(get_copy = "pub")]
    expires_in: u32,
}

/// The response from Xbox when authenticating with a Microsoft token
#[derive(Deserialize, Debug)]
#[serde(rename_all = "PascalCase")]
struct XboxLiveAuthenticationResponse {
    /// The xbox authentication token to use
    token: String,

    /// An object that contains a vec of `uhs` objects
    /// Looks like { "xui": [{"uhs": "xbl_token"}] }
    display_claims: HashMap<String, Vec<HashMap<String, String>>>,
}

/// The flow for authenticating with a Microsoft access token and getting a
/// Minecraft access token.
pub struct MinecraftAuthorizationFlow {
    http_client: HttpClient,
}

impl MinecraftAuthorizationFlow {
    /// Creates a new [MinecraftAuthorizationFlow].
    pub const fn new(http_client: HttpClient) -> Self {
        Self { http_client }
    }

    /// Authenticates with the Microsoft identity platform using the given
    /// Microsoft access token and returns a [MinecraftAuthenticationResponse]
    /// that contains the Minecraft access token.
    pub async fn exchange_microsoft_token(
        &self, microsoft_access_token: impl AsRef<str>,
    ) -> Result<MinecraftAuthenticationResponse, MinecraftAuthorizationError> {
        let xbox_authenticate_json = json!({
            "Properties": {
                "AuthMethod": "RPS",
                "SiteName": "user.auth.xboxlive.com",
                "RpsTicket": &format!("d={}", microsoft_access_token.as_ref())
            },
            "RelyingParty": "http://auth.xboxlive.com",
            "TokenType": "JWT"
        });

        let response = self
            .http_client
            .post(XBOX_USER_AUTHERNITATE)
            .json(&xbox_authenticate_json)
            .send()
            .await?;
        let response = error_for_status(response).await?;
        let xbox_resp: XboxLiveAuthenticationResponse = response.json().await?;

        let xbox_token = &xbox_resp.token;
        let user_hash = &xbox_resp.display_claims["xui"][0]["uhs"];

        let response = self
            .http_client
            .post(XBOX_XSTS_AUTHORIZE)
            .json(&json!({
                "Properties": {
                    "SandboxId": "RETAIL",
                    "UserTokens": [xbox_token]
                },
                "RelyingParty": "rp://api.minecraftservices.com/",
                "TokenType": "JWT"
            }))
            .send()
            .await?;
        let response = error_for_status(response).await?;
        let xbox_security_token_resp: XboxLiveAuthenticationResponse = response.json().await?;

        let xbox_security_token = &xbox_security_token_resp.token;
        let response = self
            .http_client
            .post(MINECRAFT_LOGIN_WITH_XBOX)
            .json(&json!({
                "identityToken":
                    format!(
                        "XBL3.0 x={user_hash};{xsts_token}",
                        user_hash = user_hash,
                        xsts_token = xbox_security_token
                    )
            }))
            .send()
            .await?;
        let response = error_for_status(response).await?;
        let minecraft_resp: MinecraftAuthenticationResponse = response.json().await?;
        Ok(minecraft_resp)
    }
}

async fn error_for_status(response: Response) -> Result<Response, MinecraftAuthorizationError> {
    let status = response.status();
    if !status.is_success() {
        let response = response.text().await?;
        return Err(MinecraftAuthorizationError::Http(status, response));
    }
    Ok(response)
}