// Copyright 2023 Greptime Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use api::v1::meta::{Error, HeartbeatRequest, Role};
use common_telemetry::warn;

use crate::error::Result;
use crate::handler::{HandleControl, HeartbeatAccumulator, HeartbeatHandler};
use crate::metasrv::Context;

pub struct CheckLeaderHandler;

#[async_trait::async_trait]
impl HeartbeatHandler for CheckLeaderHandler {
    fn is_acceptable(&self, _role: Role) -> bool {
        true
    }

    async fn handle(
        &self,
        req: &HeartbeatRequest,
        ctx: &mut Context,
        acc: &mut HeartbeatAccumulator,
    ) -> Result<HandleControl> {
        let Some(election) = &ctx.election else {
            return Ok(HandleControl::Continue);
        };

        if election.is_leader() {
            return Ok(HandleControl::Continue);
        }

        warn!(
            "A heartbeat was received {:?}, however, since the current node is not the leader,\
            this heartbeat will be disregarded.",
            req.header
        );

        if let Some(header) = &mut acc.header {
            header.error = Some(Error::is_not_leader());
        }

        return Ok(HandleControl::Done);
    }
}
