// 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.

#[cfg(feature = "pprof")]
pub mod handler {
    use std::num::NonZeroI32;
    use std::time::Duration;

    use axum::extract::Query;
    use axum::http::StatusCode;
    use axum::response::IntoResponse;
    use common_pprof::Profiling;
    use common_telemetry::info;
    use serde::{Deserialize, Serialize};
    use snafu::ResultExt;

    use crate::error::{DumpPprofSnafu, Result};

    /// Output format.
    #[derive(Debug, Serialize, Deserialize)]
    #[serde(rename_all = "snake_case")]
    pub enum Output {
        /// google’s pprof format report in protobuf.
        Proto,
        /// Simple text format.
        Text,
        /// svg flamegraph.
        Flamegraph,
    }

    #[derive(Serialize, Deserialize, Debug)]
    #[serde(default)]
    pub struct PprofQuery {
        seconds: u64,
        frequency: NonZeroI32,
        output: Output,
    }

    impl Default for PprofQuery {
        fn default() -> PprofQuery {
            PprofQuery {
                seconds: 5,
                // Safety: 99 is non zero.
                frequency: NonZeroI32::new(99).unwrap(),
                output: Output::Proto,
            }
        }
    }

    #[axum_macros::debug_handler]
    pub async fn pprof_handler(Query(req): Query<PprofQuery>) -> Result<impl IntoResponse> {
        info!("start pprof, request: {:?}", req);

        let profiling = Profiling::new(Duration::from_secs(req.seconds), req.frequency.into());
        let body = match req.output {
            Output::Proto => profiling.dump_proto().await.context(DumpPprofSnafu)?,
            Output::Text => {
                let report = profiling.dump_text().await.context(DumpPprofSnafu)?;
                report.into_bytes()
            }
            Output::Flamegraph => profiling.dump_flamegraph().await.context(DumpPprofSnafu)?,
        };

        info!("finish pprof");

        info!("Dump data success, size: {}", body.len());

        Ok((StatusCode::OK, body))
    }
}

#[cfg(not(feature = "pprof"))]
pub mod handler {
    use axum::http::StatusCode;
    use axum::response::IntoResponse;

    use crate::error::Result;

    #[axum_macros::debug_handler]
    pub async fn pprof_handler() -> Result<impl IntoResponse> {
        Ok((
            StatusCode::NOT_IMPLEMENTED,
            "The 'pprof' feature is disabled",
        ))
    }
}

pub use handler::pprof_handler;
