use anyhow::{anyhow, bail, Context};
use libjens::JMClient;
use log::{error, info, warn};
use matrix_sdk::{
    config::SyncSettings,
    deserialized_responses::SyncResponse,
    encryption::verification::Verification,
    room::Room,
    ruma::{
        api::client::r0::{
            session::login,
            uiaa::{AuthData, Password, UserIdentifier},
        },
        assign,
        events::{
            room::{
                member::StrippedRoomMemberEvent,
                message::{
                    MessageType,
                    RoomMessageEventContent,
                    SyncRoomMessageEvent,
                    TextMessageEventContent,
                },
            },
            AnyToDeviceEvent,
            SyncMessageEvent,
        },
        UserId,
    },
    Client,
    LoopCtrl,
};
use rand::{rngs::StdRng, SeedableRng};
use sled::Db;
use std::{
    path::PathBuf,
    sync::{
        atomic::{AtomicBool, AtomicU32},
        Arc,
    },
    time::Duration,
};
use structopt::StructOpt;
use tokio::sync::{Mutex, RwLock};

use config::Config;

mod config;
mod meme;
mod responder;
mod util;

#[derive(Debug, StructOpt)]
struct Opt {
    #[structopt(
        short,
        long,
        help = "config file to use",
        default_value = "~/.config/ruff/config.toml"
    )]
    config: PathBuf,
}

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    env_logger::init();

    let opt = Opt::from_args();
    let config = std::fs::read(&opt.config).map_err(|e| anyhow!("Error reading config: {}", e))?;
    let config =
        toml::from_slice::<Config>(&config).map_err(|e| anyhow!("Error parsing config: {}", e))?;
    let config = Arc::new(config);

    let client = Client::new(config.homeserver_url.clone())?;

    let device_name = config.device_name.as_ref().map(String::as_ref);

    let bot = Arc::new(Bot {
        client: client.clone(),
        jm_client: RwLock::new(JMClient::new()),
        memecache: sled::open(config.store_path.join("memecache"))
            .map_err(|e| anyhow!("error opening memecache: {}", e))?,
        config: Arc::clone(&config),
        meme_count: AtomicU32::new(0),
        rng: Mutex::new(StdRng::from_rng(rand::thread_rng())?),
    });

    client
        .register_event_handler(on_stripped_state_member)
        .await;
    let bot_ = Arc::clone(&bot);
    client
        .register_event_handler(move |ev, client, room| {
            on_room_message(ev, client, room, Arc::clone(&bot_))
        })
        .await;

    let login::Response { user_id, .. } = client
        .login(&config.user_id, &config.password, device_name, Some("ruff"))
        .await?;

    let initial = AtomicBool::from(true);
    let initial_ref = &initial;
    let client_ref = &client;
    let config_ref = &config;
    let user_id_ref = &user_id;

    client
        .sync_with_callback(SyncSettings::new(), |response| async move {
            if let Err(e) = on_response(&response, client_ref).await {
                error!("Error processing response: {}", e);
            }

            let initial = initial_ref;

            if initial.load(std::sync::atomic::Ordering::SeqCst) {
                if let Err(e) =
                    on_initial_response(client_ref, user_id_ref, &config_ref.password).await
                {
                    error!("Error processing initial response: {}", e);
                }

                initial.store(false, std::sync::atomic::Ordering::SeqCst);
            }

            LoopCtrl::Continue
        })
        .await;

    Ok(())
}

pub struct Bot {
    client: Client,
    jm_client: RwLock<JMClient>,
    memecache: Db,
    config: Arc<Config>,
    /// used to keep track of how many memes have been sent.
    /// this is reset once the threshold set in the config has been reached, and
    /// the JMClient cache is cleared.
    meme_count: AtomicU32,
    rng: Mutex<StdRng>,
}

async fn on_stripped_state_member(event: StrippedRoomMemberEvent, client: Client, room: Room) {
    if event.state_key == client.user_id().await.unwrap() {
        return;
    }

    if let Room::Invited(room) = room {
        info!("Autojoining room {}", room.room_id());
        let mut delay = 2;

        while let Err(err) = client.join_room_by_id(room.room_id()).await {
            // retry autojoin due to synapse sending invites, before the
            // invited user can join for more information see
            // https://github.com/matrix-org/synapse/issues/4345
            warn!(
                "Failed to join room {} ({:?}), retrying in {}s",
                room.room_id(),
                err,
                delay
            );

            tokio::time::sleep(Duration::from_secs(delay)).await;
            delay *= 2;

            if delay > 3600 {
                error!("Can't join room {} ({:?})", room.room_id(), err);
                break;
            }
        }

        info!("Successfully joined room {}", room.room_id());
    }
}

async fn on_room_message(msg: SyncRoomMessageEvent, client: Client, room: Room, bot: Arc<Bot>) {
    if client
        .user_id()
        .await
        .map(|u| u == msg.sender)
        .unwrap_or(true)
    {
        return;
    }

    if let SyncMessageEvent {
        content:
            RoomMessageEventContent {
                msgtype: MessageType::Text(TextMessageEventContent { body: msg_body, .. }),
                ..
            },
        ..
    } = msg
    {
        if let Err(e) = responder::on_msg(&msg_body, room, &bot).await {
            error!("Responder error: {}", e);
        }
    }
}

async fn on_initial_response(
    client: &Client,
    user_id: &UserId,
    password: &str,
) -> anyhow::Result<()> {
    bootstrap_cross_signing(client, user_id, password).await?;

    Ok(())
}

async fn on_response(response: &SyncResponse, client: &Client) -> anyhow::Result<()> {
    for event in response
        .to_device
        .events
        .iter()
        .filter_map(|e| e.deserialize().ok())
    {
        match event {
            AnyToDeviceEvent::KeyVerificationStart(e) => {
                info!("Starting verification");
                if let Some(Verification::SasV1(sas)) = &client
                    .get_verification(&e.sender, &e.content.transaction_id)
                    .await
                {
                    if let Err(e) = sas.accept().await {
                        error!("Error accepting key verification request: {}", e);
                    }
                }
            },

            AnyToDeviceEvent::KeyVerificationKey(e) => {
                if let Some(Verification::SasV1(sas)) = &client
                    .get_verification(&e.sender, &e.content.transaction_id)
                    .await
                {
                    if let Err(e) = sas.confirm().await {
                        error!("Error confirming key verification request: {}", e);
                    }
                }
            },

            _ => {},
        }
    }

    Ok(())
}

async fn bootstrap_cross_signing(
    client: &Client,
    user_id: &UserId,
    password: &str,
) -> anyhow::Result<()> {
    info!("bootstrapping e2e");
    if let Err(e) = client.bootstrap_cross_signing(None).await {
        if let Some(response) = e.uiaa_response() {
            let auth_data = AuthData::Password(assign!(
                Password::new(UserIdentifier::MatrixId(user_id.as_str()), password),
                { session: response.session.as_deref() }
            ));

            client
                .bootstrap_cross_signing(Some(auth_data))
                .await
                .context("Couldn't bootstrap cross signing")?;
        } else {
            bail!("Error during cross-signing bootstrap {:#?}", e);
        }
    }

    info!("bootstrapped e2e");

    Ok(())
}