use crate::ServerState;

use axum::body::Body;
use axum::extract::{Path, State};
use axum::http::header::CONTENT_TYPE;
use axum::http::StatusCode;
use axum::response::{IntoResponse, Response};
use futures::TryStreamExt;
use log::error;
use rayhunter::diag::DataType;
use rayhunter::gsmtap_parser;
use rayhunter::pcap::GsmtapPcapWriter;
use rayhunter::qmdl::QmdlReader;
use std::sync::Arc;
use std::{future, pin::pin};
use tokio::io::duplex;
use tokio_util::io::ReaderStream;

// Streams a pcap file chunk-by-chunk to the client by reading the QMDL data
// written so far. This is done by spawning a thread which streams chunks of
// pcap data to a channel that's piped to the client.
pub async fn get_pcap(
    State(state): State<Arc<ServerState>>,
    Path(qmdl_name): Path<String>,
) -> Result<Response, (StatusCode, String)> {
    let qmdl_store = state.qmdl_store_lock.read().await;
    let (entry_index, entry) = qmdl_store.entry_for_name(&qmdl_name).ok_or((
        StatusCode::NOT_FOUND,
        format!("couldn't find qmdl file with name {}", qmdl_name),
    ))?;
    if entry.qmdl_size_bytes == 0 {
        return Err((
            StatusCode::SERVICE_UNAVAILABLE,
            "QMDL file is empty, try again in a bit!".to_string(),
        ));
    }
    let qmdl_size_bytes = entry.qmdl_size_bytes;
    let qmdl_file = qmdl_store
        .open_entry_qmdl(entry_index)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("{:?}", e)))?;
    // the QMDL reader should stop at the last successfully written data chunk
    // (entry.size_bytes)
    let (reader, writer) = duplex(1024);
    let mut pcap_writer = GsmtapPcapWriter::new(writer).await.unwrap();
    pcap_writer.write_iface_header().await.unwrap();

    tokio::spawn(async move {
        let mut reader = QmdlReader::new(qmdl_file, Some(qmdl_size_bytes));
        let mut messages_stream = pin!(reader
            .as_stream()
            .try_filter(|container| future::ready(container.data_type == DataType::UserSpace)));

        while let Some(container) = messages_stream
            .try_next()
            .await
            .expect("failed getting QMDL container")
        {
            for maybe_msg in container.into_messages() {
                match maybe_msg {
                    Ok(msg) => {
                        let maybe_gsmtap_msg =
                            gsmtap_parser::parse(msg).expect("error parsing gsmtap message");
                        if let Some((timestamp, gsmtap_msg)) = maybe_gsmtap_msg {
                            pcap_writer
                                .write_gsmtap_message(gsmtap_msg, timestamp)
                                .await
                                .expect("error writing pcap packet");
                        }
                    }
                    Err(e) => error!("error parsing message: {:?}", e),
                }
            }
        }
    });

    let headers = [(CONTENT_TYPE, "application/vnd.tcpdump.pcap")];
    let body = Body::from_stream(ReaderStream::new(reader));
    Ok((headers, body).into_response())
}