// bebot -- a Gitlab -> Matrix event publisher
// Copyright (C) 2023-2025 Brian Tarricone <brian@tarricone.org>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

use std::{fmt, process::exit, time::Duration};

use matrix_sdk::{
    config::SyncSettings,
    room::Room,
    ruma::{OwnedRoomOrAliasId, OwnedUserId, RoomOrAliasId, UserId},
    BaseRoom, Client,
};
use serde::de;
use tokio::time::sleep;

use crate::config::Config;

async fn build_sync_settings() -> SyncSettings {
    SyncSettings::default().timeout(Duration::from_secs(30))
}

pub async fn connect(config: &Config) -> anyhow::Result<Client> {
    let client = Client::builder()
        .server_name(config.user_id.server_name())
        .user_agent(format!("{}/{}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION")))
        .build()
        .await?;
    client
        .matrix_auth()
        .login_username(&config.user_id, &config.password)
        .initial_device_display_name("Bebot")
        .await?;
    info!("Connected to matrix as {}; waiting for first sync", config.user_id);

    let settings = build_sync_settings().await;
    client.sync_once(settings).await?;
    info!("First matrix sync complete");

    let sync_client = client.clone();
    tokio::spawn(async move {
        let settings = build_sync_settings().await;
        if let Err(err) = sync_client.sync(settings).await {
            error!("Matrix sync failed: {err}");
            exit(1);
        }
    });

    Ok(client)
}

pub async fn ensure_room_joined(matrix_client: &Client, room_id: &OwnedRoomOrAliasId) -> anyhow::Result<Room> {
    fn room_matches(a_room: &BaseRoom, our_room: &OwnedRoomOrAliasId) -> bool {
        let our_room_str = our_room.as_str();
        a_room.room_id().as_str() == our_room_str
            || a_room
                .canonical_alias()
                .iter()
                .any(|alias| alias.as_str() == our_room_str)
            || a_room.alt_aliases().iter().any(|alias| alias.as_str() == our_room_str)
    }

    let mut room = matrix_client
        .joined_rooms()
        .iter()
        .find(|a_room| room_matches(a_room, room_id))
        .cloned();
    if room.is_none() {
        if let Some(invited) = matrix_client
            .invited_rooms()
            .iter()
            .find(|a_room| room_matches(a_room, room_id))
        {
            info!("Accepting invitation to room {room_id}");
            invited.join().await?;
        } else {
            info!("Joining room {room_id}");
            matrix_client.join_room_by_id_or_alias(room_id, &[]).await?;
        }

        for _ in 0..4 {
            let settings = build_sync_settings().await;
            matrix_client.sync_once(settings).await?;
            room = matrix_client
                .joined_rooms()
                .iter()
                .find(|a_room| room_matches(a_room, room_id))
                .cloned();
            if room.is_some() {
                break;
            }
            sleep(Duration::from_millis(500)).await;
        }
    }

    room.ok_or_else(|| anyhow!("Unable to join room {}", room_id))
}

pub fn deser_user_id<'de, D>(deserializer: D) -> Result<OwnedUserId, D::Error>
where
    D: de::Deserializer<'de>,
{
    struct UserIdVisitor;

    impl<'de> de::Visitor<'de> for UserIdVisitor {
        type Value = OwnedUserId;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("a matrix user ID")
        }

        fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            UserId::parse(v).map_err(E::custom)
        }
    }

    deserializer.deserialize_any(UserIdVisitor)
}

fn deser_room_or_alias_id<'de, D>(deserializer: D) -> Result<OwnedRoomOrAliasId, D::Error>
where
    D: de::Deserializer<'de>,
{
    struct RoomOrAliasIdVisitor;

    impl<'de> de::Visitor<'de> for RoomOrAliasIdVisitor {
        type Value = OwnedRoomOrAliasId;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("a matrix room ID")
        }

        fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            RoomOrAliasId::parse(v).map_err(E::custom)
        }
    }

    deserializer.deserialize_any(RoomOrAliasIdVisitor)
}

pub fn deser_optional_room_or_alias_id<'de, D>(deserializer: D) -> Result<Option<OwnedRoomOrAliasId>, D::Error>
where
    D: de::Deserializer<'de>,
{
    struct OptionalRoomOrAliasIdVisitor;

    impl<'de> de::Visitor<'de> for OptionalRoomOrAliasIdVisitor {
        type Value = Option<OwnedRoomOrAliasId>;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("null or matrix room ID")
        }

        fn visit_none<E>(self) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            Ok(None)
        }

        fn visit_some<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
        where
            D: serde::Deserializer<'de>,
        {
            Ok(Some(deser_room_or_alias_id(deserializer)?))
        }

        fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            RoomOrAliasId::parse(v).map(Some).map_err(E::custom)
        }
    }

    deserializer.deserialize_any(OptionalRoomOrAliasIdVisitor)
}