//! Handle registration, logins, and managing account data.

use super::authorization::{login_is_authorized, RpcApiKey};
use super::errors::FrontendResult;
use crate::app::Web3ProxyApp;
use crate::user_queries::{
    get_aggregate_rpc_stats_from_params, get_detailed_stats, get_page_from_params,
};
use crate::user_queries::{get_chain_id_from_params, get_query_start_from_params};
use anyhow::Context;
use axum::{
    extract::{Path, Query},
    headers::{authorization::Bearer, Authorization},
    response::IntoResponse,
    Extension, Json, TypedHeader,
};
use axum_client_ip::ClientIp;
use axum_macros::debug_handler;
use entities::{revert_logs, user, user_keys};
use ethers::{prelude::Address, types::Bytes};
use hashbrown::HashMap;
use http::StatusCode;
use redis_rate_limiter::redis::AsyncCommands;
use sea_orm::{
    ActiveModelTrait, ColumnTrait, EntityTrait, PaginatorTrait, QueryFilter, QueryOrder,
    TransactionTrait,
};
use serde::Deserialize;
use serde_json::json;
use siwe::{Message, VerificationOpts};
use std::ops::Add;
use std::str::FromStr;
use std::sync::Arc;
use time::{Duration, OffsetDateTime};
use tracing::warn;
use ulid::Ulid;

/// `GET /user/login/:user_address` or `GET /user/login/:user_address/:message_eip` -- Start the "Sign In with Ethereum" (siwe) login flow.
///
/// `message_eip`s accepted:
///   - eip191_bytes
///   - eip191_hash
///   - eip4361 (default)
///
/// Coming soon: eip1271
///
/// This is the initial entrypoint for logging in. Take the response from this endpoint and give it to your user's wallet for singing. POST the response to `/user/login`.
///
/// Rate limited by IP address.
///
/// At first i thought about checking that user_address is in our db,
/// But theres no need to separate the registration and login flows.
/// It is a better UX to just click "login with ethereum" and have the account created if it doesn't exist.
/// We can prompt for an email and and payment after they log in.
#[debug_handler]
pub async fn user_login_get(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    ClientIp(ip): ClientIp,
    // TODO: what does axum's error handling look like if the path fails to parse?
    Path(mut params): Path<HashMap<String, String>>,
) -> FrontendResult {
    login_is_authorized(&app, ip).await?;

    // create a message and save it in redis
    // TODO: how many seconds? get from config?
    let expire_seconds: usize = 20 * 60;

    let nonce = Ulid::new();

    let issued_at = OffsetDateTime::now_utc();

    let expiration_time = issued_at.add(Duration::new(expire_seconds as i64, 0));

    // TODO: allow ENS names here?
    let user_address: Address = params
        .remove("user_address")
        // TODO: map_err so this becomes a 500. routing must be bad
        .context("impossible")?
        .parse()
        // TODO: map_err so this becomes a 401
        .context("bad input")?;

    // TODO: get most of these from the app config
    let message = Message {
        // TODO: should domain be llamanodes, or llamarpc, or the subdomain of llamarpc?
        domain: "staging.llamanodes.com".parse().unwrap(),
        address: user_address.to_fixed_bytes(),
        statement: Some("🦙🦙🦙🦙🦙".to_string()),
        uri: "https://staging.llamanodes.com/".parse().unwrap(),
        version: siwe::Version::V1,
        chain_id: 1,
        expiration_time: Some(expiration_time.into()),
        issued_at: issued_at.into(),
        nonce: nonce.to_string(),
        not_before: None,
        request_id: None,
        resources: vec![],
    };

    // TODO: if no redis server, store in local cache? at least give a better error. right now this seems to be a 502
    // the address isn't enough. we need to save the actual message so we can read the nonce
    // TODO: what message format is the most efficient to store in redis? probably eip191_bytes
    // we add 1 to expire_seconds just to be sure redis has the key for the full expiration_time
    // TODO: store a maximum number of attempted logins? anyone can request so we don't want to allow DOS attacks
    let session_key = format!("login_nonce:{}", nonce);
    app.redis_conn()
        .await?
        .set_ex(session_key, message.to_string(), expire_seconds + 1)
        .await?;

    // there are multiple ways to sign messages and not all wallets support them
    // TODO: default message eip from config?
    let message_eip = params
        .remove("message_eip")
        .unwrap_or_else(|| "eip4361".to_string());

    let message: String = match message_eip.as_str() {
        "eip191_bytes" => Bytes::from(message.eip191_bytes().unwrap()).to_string(),
        "eip191_hash" => Bytes::from(&message.eip191_hash().unwrap()).to_string(),
        "eip4361" => message.to_string(),
        _ => {
            // TODO: custom error that is handled a 401
            return Err(anyhow::anyhow!("invalid message eip given").into());
        }
    };

    Ok(message.into_response())
}

/// Query params for our `post_login` handler.
#[derive(Debug, Deserialize)]
pub struct PostLoginQuery {
    /// While we are in alpha/beta, we require users to supply an invite code.
    /// The invite code (if any) is set in the application's config.
    /// This may eventually provide some sort of referral bonus.
    pub invite_code: Option<String>,
}

/// JSON body to our `post_login` handler.
/// Currently only siwe logins that send an address, msg, and sig are allowed.
/// Email/password and other login methods are planned.
#[derive(Deserialize)]
pub struct PostLogin {
    sig: String,
    msg: String,
}

/// `POST /user/login` - Register or login by posting a signed "siwe" message.
/// It is recommended to save the returned bearer token in a cookie.
/// The bearer token can be used to authenticate other requests, such as getting the user's stats or modifying the user's profile.
#[debug_handler]
pub async fn user_login_post(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    ClientIp(ip): ClientIp,
    Json(payload): Json<PostLogin>,
    Query(query): Query<PostLoginQuery>,
) -> FrontendResult {
    login_is_authorized(&app, ip).await?;

    // TODO: this seems too verbose. how can we simply convert a String into a [u8; 65]
    let their_sig_bytes = Bytes::from_str(&payload.sig).context("parsing sig")?;
    if their_sig_bytes.len() != 65 {
        return Err(anyhow::anyhow!("checking signature length").into());
    }
    let mut their_sig: [u8; 65] = [0; 65];
    for x in 0..65 {
        their_sig[x] = their_sig_bytes[x]
    }

    // we can't trust that they didn't tamper with the message in some way. like some clients return it hex encoded
    // TODO: checking 0x seems fragile, but I think it will be fine. siwe message text shouldn't ever start with 0x
    let their_msg: Message = if payload.msg.starts_with("0x") {
        let their_msg_bytes = Bytes::from_str(&payload.msg).context("parsing payload message")?;

        // TODO: lossy or no?
        String::from_utf8_lossy(their_msg_bytes.as_ref())
            .parse::<siwe::Message>()
            .context("parsing hex string message")?
    } else {
        payload
            .msg
            .parse::<siwe::Message>()
            .context("parsing string message")?
    };

    // the only part of the message we will trust is their nonce
    // TODO: this is fragile. have a helper function/struct for redis keys
    let login_nonce_key = format!("login_nonce:{}", &their_msg.nonce);

    // fetch the message we gave them from our redis
    let mut redis_conn = app.redis_conn().await?;

    let our_msg: Option<String> = redis_conn.get(&login_nonce_key).await?;

    let our_msg: String = our_msg.context("login nonce not found")?;

    let our_msg: siwe::Message = our_msg.parse().context("parsing siwe message")?;

    // default options are fine. the message includes timestamp and domain and nonce
    let verify_config = VerificationOpts::default();

    // Check with both verify and verify_eip191
    if let Err(err_1) = our_msg
        .verify(&their_sig, &verify_config)
        .await
        .context("verifying signature against our local message")
    {
        // verification method 1 failed. try eip191
        if let Err(err_191) = our_msg
            .verify_eip191(&their_sig)
            .context("verifying eip191 signature against our local message")
        {
            return Err(anyhow::anyhow!(
                "both the primary and eip191 verification failed: {:#?}; {:#?}",
                err_1,
                err_191
            )
            .into());
        }
    }

    let db_conn = app.db_conn().context("Getting database connection")?;

    // TODO: limit columns or load whole user?
    let u = user::Entity::find()
        .filter(user::Column::Address.eq(our_msg.address.as_ref()))
        .one(&db_conn)
        .await
        .unwrap();

    let (u, uks, status_code) = match u {
        None => {
            // user does not exist yet

            // check the invite code
            // TODO: more advanced invite codes that set different request/minute and concurrency limits
            if let Some(invite_code) = &app.config.invite_code {
                if query.invite_code.as_ref() != Some(invite_code) {
                    return Err(anyhow::anyhow!("checking invite_code").into());
                }
            }

            let txn = db_conn.begin().await?;

            // the only thing we need from them is an address
            // everything else is optional
            let u = user::ActiveModel {
                address: sea_orm::Set(our_msg.address.into()),
                ..Default::default()
            };

            let u = u.insert(&txn).await?;

            // create the user's first api key
            // TODO: rename to UserApiKey? RpcApiKey?
            let rpc_key = RpcApiKey::new();

            // TODO: variable requests per minute depending on the invite code
            let uk = user_keys::ActiveModel {
                user_id: sea_orm::Set(u.id),
                api_key: sea_orm::Set(rpc_key.into()),
                description: sea_orm::Set(Some("first".to_string())),
                requests_per_minute: sea_orm::Set(app.config.default_user_requests_per_minute),
                ..Default::default()
            };

            let uk = uk
                .insert(&txn)
                .await
                .context("Failed saving new user key")?;

            let uks = vec![uk];

            // save the user and key to the database
            txn.commit().await?;

            (u, uks, StatusCode::CREATED)
        }
        Some(u) => {
            // the user is already registered
            let uks = user_keys::Entity::find()
                .filter(user_keys::Column::UserId.eq(u.id))
                .all(&db_conn)
                .await
                .context("failed loading user's key")?;

            (u, uks, StatusCode::OK)
        }
    };

    // create a bearer token for the user.
    let bearer_token = Ulid::new();

    // json response with everything in it
    // we could return just the bearer token, but I think they will always request api keys and the user profile
    let response_json = json!({
        "api_keys": uks
            .into_iter()
            .map(|uk| (uk.id, uk))
            .collect::<HashMap<_, _>>(),
        "bearer_token": bearer_token,
        "user": u,
    });

    let response = (status_code, Json(response_json)).into_response();

    // add bearer to redis
    // TODO: use a helper function/struct for this
    let bearer_redis_key = format!("bearer:{}", bearer_token);

    // expire in 4 weeks
    // TODO: get expiration time from app config
    redis_conn
        .set_ex(bearer_redis_key, u.id.to_string(), 2_419_200)
        .await?;

    if let Err(err) = redis_conn.del::<_, u64>(&login_nonce_key).await {
        warn!(
            "Failed to delete login_nonce_key {}: {}",
            login_nonce_key, err
        );
    }

    Ok(response)
}

/// `POST /user/logout` - Forget the bearer token in the `Authentication` header.
#[debug_handler]
pub async fn user_logout_post(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    TypedHeader(Authorization(bearer)): TypedHeader<Authorization<Bearer>>,
) -> FrontendResult {
    let mut redis_conn = app.redis_conn().await?;

    // TODO: i don't like this. move this to a helper function so it is less fragile
    let bearer_cache_key = format!("bearer:{}", bearer.token());

    redis_conn.del(bearer_cache_key).await?;

    // TODO: what should the response be? probably json something
    Ok("goodbye".into_response())
}

/// `GET /user` -- Use a bearer token to get the user's profile.
///
/// - the email address of a user if they opted in to get contacted via email
///
/// TODO: this will change as we add better support for secondary users.
#[debug_handler]
pub async fn user_get(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    TypedHeader(Authorization(bearer_token)): TypedHeader<Authorization<Bearer>>,
) -> FrontendResult {
    let (user, _semaphore) = app.bearer_is_authorized(bearer_token).await?;

    Ok(Json(user).into_response())
}

/// the JSON input to the `post_user` handler.
#[derive(Deserialize)]
pub struct UserPost {
    // TODO: make sure the email address is valid. probably have a "verified" column in the database
    email: Option<String>,
}

/// `POST /user` -- modify the account connected to the bearer token in the `Authentication` header.
#[debug_handler]
pub async fn user_post(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    TypedHeader(Authorization(bearer_token)): TypedHeader<Authorization<Bearer>>,
    Json(payload): Json<UserPost>,
) -> FrontendResult {
    let (user, _semaphore) = app.bearer_is_authorized(bearer_token).await?;

    let mut user: user::ActiveModel = user.into();

    // update the email address
    if let Some(x) = payload.email {
        // TODO: only Set if no change
        if x.is_empty() {
            user.email = sea_orm::Set(None);
        } else {
            // TODO: do some basic validation
            // TODO: don't set immediatly, send a confirmation email first
            // TODO: compare first? or is sea orm smart enough to do that for us?
            user.email = sea_orm::Set(Some(x));
        }
    }

    // TODO: what else can we update here? password hash? subscription to newsletter?

    let user = if user.is_changed() {
        let db_conn = app.db_conn().context("Getting database connection")?;

        user.save(&db_conn).await?
    } else {
        // no changes. no need to touch the database
        user
    };

    let user: user::Model = user.try_into().context("Returning updated user")?;

    Ok(Json(user).into_response())
}

/// `GET /user/balance` -- Use a bearer token to get the user's balance and spend.
///
/// - show balance in USD
/// - show deposits history (currency, amounts, transaction id)
///
/// TODO: one key per request? maybe /user/balance/:api_key?
/// TODO: this will change as we add better support for secondary users.
#[debug_handler]
pub async fn user_balance_get(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    TypedHeader(Authorization(bearer)): TypedHeader<Authorization<Bearer>>,
) -> FrontendResult {
    todo!("user_balance_get");
}

/// `POST /user/balance/:txhash` -- Manually process a confirmed txid to update a user's balance.
///
/// We will subscribe to events to watch for any user deposits, but sometimes events can be missed.
///
/// TODO: rate limit by user
/// TODO: one key per request? maybe /user/balance/:api_key?
/// TODO: this will change as we add better support for secondary users.
#[debug_handler]
pub async fn user_balance_post(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    TypedHeader(Authorization(bearer_token)): TypedHeader<Authorization<Bearer>>,
) -> FrontendResult {
    todo!("user_balance_post");
}

/// `GET /user/keys` -- Use a bearer token to get the user's api keys and their settings.
///
/// TODO: one key per request? maybe /user/keys/:api_key?
#[debug_handler]
pub async fn user_keys_get(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    TypedHeader(Authorization(bearer_token)): TypedHeader<Authorization<Bearer>>,
) -> FrontendResult {
    let (user, _semaphore) = app.bearer_is_authorized(bearer_token).await?;

    let db_conn = app.db_conn().context("getting db to fetch user's keys")?;

    let uks = user_keys::Entity::find()
        .filter(user_keys::Column::UserId.eq(user.id))
        .all(&db_conn)
        .await
        .context("failed loading user's key")?;

    // TODO: stricter type on this?
    let response_json = json!({
        "user_id": user.id,
        "user_rpc_keys": uks
            .into_iter()
            .map(|uk| (uk.id, uk))
            .collect::<HashMap::<_, _>>(),
    });

    Ok(Json(response_json).into_response())
}

/// the JSON input to the `user_keys_post` handler.
#[derive(Deserialize)]
pub struct UserKeysPost {
    // TODO: make sure the email address is valid. probably have a "verified" column in the database
    existing_key_id: Option<u64>,
    existing_key: Option<RpcApiKey>,
    description: Option<String>,
}

/// `POST /user/keys` -- Use a bearer token to create a new key or modify an existing key.
///
/// TODO: read json from the request body
/// TODO: one key per request? maybe /user/keys/:api_key?
#[debug_handler]
pub async fn user_keys_post(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    TypedHeader(Authorization(bearer_token)): TypedHeader<Authorization<Bearer>>,
    Json(payload): Json<UserKeysPost>,
) -> FrontendResult {
    let (user, _semaphore) = app.bearer_is_authorized(bearer_token).await?;

    if let Some(existing_key_id) = payload.existing_key_id {
        // get the key and make sure it belongs to the user
        todo!("existing by id");
    } else if let Some(existing_key) = payload.existing_key {
        // get the key and make sure it belongs to the user
        todo!("existing by key");
    } else {
        // make a new key
        // TODO: limit to 10 keys?
        let rpc_key = RpcApiKey::new();

        todo!("new key");
    }
}

/// `GET /user/revert_logs` -- Use a bearer token to get the user's revert logs.
#[debug_handler]
pub async fn user_revert_logs_get(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    TypedHeader(Authorization(bearer_token)): TypedHeader<Authorization<Bearer>>,
    Query(params): Query<HashMap<String, String>>,
) -> FrontendResult {
    let (user, _semaphore) = app.bearer_is_authorized(bearer_token).await?;

    let chain_id = get_chain_id_from_params(app.as_ref(), &params)?;
    let query_start = get_query_start_from_params(&params)?;
    let page = get_page_from_params(&params)?;

    // TODO: page size from config
    let page_size = 200;

    let mut response = HashMap::new();

    response.insert("page", json!(page));
    response.insert("page_size", json!(page_size));
    response.insert("chain_id", json!(chain_id));
    response.insert("query_start", json!(query_start.timestamp() as u64));

    let db_conn = app.db_conn().context("getting db for user's revert logs")?;

    let uks = user_keys::Entity::find()
        .filter(user_keys::Column::UserId.eq(user.id))
        .all(&db_conn)
        .await
        .context("failed loading user's key")?;

    // TODO: only select the ids
    let uks: Vec<_> = uks.into_iter().map(|x| x.id).collect();

    // get paginated logs
    let q = revert_logs::Entity::find()
        .filter(revert_logs::Column::Timestamp.gte(query_start))
        .filter(revert_logs::Column::UserKeyId.is_in(uks))
        .order_by_asc(revert_logs::Column::Timestamp);

    let q = if chain_id == 0 {
        // don't do anything
        q
    } else {
        // filter on chain id
        q.filter(revert_logs::Column::ChainId.eq(chain_id))
    };

    let revert_logs = q.paginate(&db_conn, page_size).fetch_page(page).await?;

    response.insert("revert_logs", json!(revert_logs));

    Ok(Json(response).into_response())
}

/// `GET /user/stats/detailed` -- Use a bearer token to get the user's key stats such as bandwidth used and methods requested.
///
/// If no bearer is provided, detailed stats for all users will be shown.
/// View a single user with `?user_id=$x`.
/// View a single chain with `?chain_id=$x`.
///
/// Set `$x` to zero to see all.
///
/// TODO: this will change as we add better support for secondary users.
#[debug_handler]
pub async fn user_stats_detailed_get(
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    bearer: Option<TypedHeader<Authorization<Bearer>>>,
    Query(params): Query<HashMap<String, String>>,
) -> FrontendResult {
    let x = get_detailed_stats(&app, bearer, params).await?;

    Ok(Json(x).into_response())
}

/// `GET /user/stats/aggregate` -- Public endpoint for aggregate stats such as bandwidth used and methods requested.
#[debug_handler]
pub async fn user_stats_aggregate_get(
    bearer: Option<TypedHeader<Authorization<Bearer>>>,
    Extension(app): Extension<Arc<Web3ProxyApp>>,
    Query(params): Query<HashMap<String, String>>,
) -> FrontendResult {
    let x = get_aggregate_rpc_stats_from_params(&app, bearer, params).await?;

    Ok(Json(x).into_response())
}