//! Finding out what the server has and why: looking routes up, and seeing
//! what was refused.

use std::net::Ipv4Addr;
use std::time::Duration;

use bgp_integration_tests::default_policy;
use bgp_integration_tests::test_peer::TestPeer;
use bgp_integration_tests::test_server::TestServer;
use bgp_packet::message::{
    AsPathAttribute, Message, NextHopPathAttribute, OriginPathAttribute, PathAttribute,
    UpdateMessage,
};
use bgp_primitives::ip_prefix::IpPrefix;
use bgp_server::config::PeerConfig;
use bgp_server::family::FamilySet;
use bgp_server::policy::ImportPolicy;
use eyre::Result;
use serde_json::Value;
use tokio::net::TcpListener;

const TIMEOUT: Duration = Duration::from_secs(5);

fn announcement(prefixes: &[&str], as_path: &[u32]) -> Message {
    Message::Update(UpdateMessage {
        withdrawn_routes: vec![],
        path_attributes: vec![
            PathAttribute::Origin(OriginPathAttribute::IGP),
            AsPathAttribute::from_asns(as_path.to_vec()),
            PathAttribute::NextHop(NextHopPathAttribute(Ipv4Addr::new(192, 0, 2, 1))),
        ],
        announced_routes: prefixes
            .iter()
            .map(|p| IpPrefix::try_from(*p).unwrap().into())
            .collect(),
    })
}

/// The routes a query returns, as "prefix from AS, best or not".
async fn routes(client: &reqwest::Client, base: &str, query: &str) -> Result<Vec<String>> {
    let reply = client
        .get(format!("{base}/api/routes/received?{query}"))
        .send()
        .await?
        .error_for_status()?;
    let page: Value = reply.json().await?;
    Ok(page["routes"]
        .as_array()
        .unwrap()
        .iter()
        .map(|r| {
            format!(
                "{} AS{}{}",
                r["prefix"].as_str().unwrap(),
                r["peer_asn"],
                if r["best"] == true { " best" } else { "" }
            )
        })
        .collect())
}

/// The questions asked when something is wrong with a prefix: who sends it
/// and which route won, what covers an address, what is inside a block.
#[tokio::test]
async fn test_routes_can_be_looked_up() -> Result<()> {
    let server = TestServer::start(65000).await?;
    let (base, _http) = server.serve_http().await?;
    let client = reqwest::Client::new();

    let mut one = TestPeer::connect(server.addr).await?;
    one.handshake(65001, Ipv4Addr::new(10, 0, 0, 1), 90).await?;
    let mut two = TestPeer::connect(server.addr).await?;
    two.handshake(65002, Ipv4Addr::new(10, 0, 0, 2), 90).await?;
    one.send(&announcement(
        &["10.0.0.0/8", "10.1.0.0/16", "10.1.2.0/24", "192.0.2.0/24"],
        &[65001],
    ))
    .await?;
    // A longer path for one of the same prefixes: it loses.
    two.send(&announcement(&["10.1.0.0/16"], &[65002, 65003]))
        .await?;
    tokio::time::timeout(TIMEOUT, async {
        while server.rib.len() != 5 {
            tokio::time::sleep(Duration::from_millis(5)).await;
        }
    })
    .await?;

    // One prefix: every route for it, the best first.
    assert_eq!(
        routes(&client, &base, "prefix=10.1.0.0/16").await?,
        ["10.1.0.0/16 AS65001 best", "10.1.0.0/16 AS65002"]
    );
    assert!(
        routes(&client, &base, "prefix=10.2.0.0/16")
            .await?
            .is_empty()
    );

    // An address: every prefix that covers it, the most specific first.
    assert_eq!(
        routes(&client, &base, "address=10.1.2.3").await?,
        [
            "10.1.2.0/24 AS65001 best",
            "10.1.0.0/16 AS65001 best",
            "10.1.0.0/16 AS65002",
            "10.0.0.0/8 AS65001 best"
        ]
    );
    assert_eq!(
        routes(&client, &base, "address=10.200.0.1").await?,
        ["10.0.0.0/8 AS65001 best"]
    );

    // A block: itself and everything inside it.
    assert_eq!(
        routes(&client, &base, "within=10.1.0.0/16").await?,
        [
            "10.1.0.0/16 AS65001 best",
            "10.1.0.0/16 AS65002",
            "10.1.2.0/24 AS65001 best"
        ]
    );

    // Only what was chosen; and everything, in address order.
    assert_eq!(
        routes(&client, &base, "within=10.0.0.0/8&best=true").await?,
        [
            "10.0.0.0/8 AS65001 best",
            "10.1.0.0/16 AS65001 best",
            "10.1.2.0/24 AS65001 best"
        ]
    );
    assert_eq!(routes(&client, &base, "").await?.len(), 5);
    // A page holds whole prefixes: at most the limit, unless one prefix
    // alone has more.
    assert!((1..=2).contains(&routes(&client, &base, "limit=2").await?.len()));

    // One peer's routes, by its address; a peer that is not there has none.
    assert_eq!(routes(&client, &base, "peer=127.0.0.1").await?.len(), 5);
    assert!(routes(&client, &base, "peer=192.0.2.9").await?.is_empty());

    // A query that makes no sense says so.
    for (query, complaint) in [
        ("prefix=10.1.0.0", "is not a prefix"),
        ("address=example", "is not an IP address"),
        ("prefix=10.0.0.0/8&address=10.0.0.1", "at most one of"),
    ] {
        let reply = client
            .get(format!("{base}/api/routes/received?{query}"))
            .send()
            .await?;
        assert_eq!(reply.status(), 400, "{query}");
        let text = reply.text().await?;
        assert!(text.contains(complaint), "{query}: {text}");
    }
    Ok(())
}

/// A refused route is not in the table, so it has to be findable somewhere
/// else: which peer, which prefix, with what path, and why. And there is
/// something to alert on.
#[tokio::test]
async fn test_refused_routes_can_be_seen_and_counted() -> Result<()> {
    let listener = TcpListener::bind((Ipv4Addr::LOCALHOST, 0)).await?;
    let endpoint = listener.local_addr()?;
    let server = TestServer::start_with(1299, |c| {
        c.accept_unconfigured_peers = false;
        c.peers = vec![PeerConfig {
            name: "refused-demo".into(),
            endpoint: endpoint.into(),
            remote_asn: 3333,
            hold_time_secs: 90,
            local_address: None,
            families: FamilySet::supported(),
            add_path: None,
            import: ImportPolicy {
                max_prefixes: Some(100),
                ..default_policy()
            },
            role: None,
            require_role: false,
        }];
    })
    .await?;
    let (base, _http) = server.serve_http().await?;
    let client = reqwest::Client::new();
    let get = |path: &str| {
        let request = client.get(format!("{base}{path}"));
        async move { Ok::<_, eyre::Report>(request.send().await?.error_for_status()?) }
    };

    let refused: Value = get("/api/routes/rejected").await?.json().await?;
    assert_eq!(refused, serde_json::json!([]), "nothing refused yet");

    let mut peer = TestPeer::connect(server.addr).await?;
    peer.handshake(3333, Ipv4Addr::new(10, 0, 0, 2), 90).await?;
    peer.send(&announcement(&["193.0.0.0/21", "10.0.0.0/8"], &[3333]))
        .await?;
    peer.send(&announcement(
        &["194.0.1.0/24", "194.0.2.0/24"],
        &[3333, 64512],
    ))
    .await?;
    peer.send(&announcement(&["193.0.9.0/25"], &[3333, 2121]))
        .await?;
    tokio::time::timeout(TIMEOUT, async {
        while server
            .registry
            .list()
            .first()
            .map(|s| s.counters.rejected())
            != Some(4)
        {
            tokio::time::sleep(Duration::from_millis(5)).await;
        }
    })
    .await?;

    let refused: Value = get("/api/routes/rejected").await?.json().await?;
    let record = &refused[0];
    assert_eq!(record["peer"], "refused-demo");
    assert_eq!(record["peer_addr"], "127.0.0.1");
    assert_eq!(record["total"], 4);
    assert_eq!(
        record["by_reason"],
        serde_json::json!({"bogon AS in path": 2, "bogon prefix": 1, "prefix too specific": 1})
    );
    // The latest first, each with the path it came with.
    let recent: Vec<(String, String, String)> = record["recent"]
        .as_array()
        .unwrap()
        .iter()
        .map(|r| {
            (
                r["prefix"].as_str().unwrap().to_string(),
                r["reason"].as_str().unwrap().to_string(),
                r["as_path"].to_string(),
            )
        })
        .collect();
    let row = |p: &str, why: &str, path: &str| (p.to_string(), why.to_string(), path.to_string());
    assert_eq!(
        recent,
        [
            row("193.0.9.0/25", "prefix too specific", "[3333,2121]"),
            row("194.0.2.0/24", "bogon AS in path", "[3333,64512]"),
            row("194.0.1.0/24", "bogon AS in path", "[3333,64512]"),
            row("10.0.0.0/8", "bogon prefix", "[3333]"),
        ]
    );
    // Asked for by peer, by name or by address.
    for peer in ["refused-demo", "127.0.0.1"] {
        let one: Value = get(&format!("/api/routes/rejected?peer={peer}"))
            .await?
            .json()
            .await?;
        assert_eq!(one.as_array().unwrap().len(), 1, "{peer}");
    }
    let none: Value = get("/api/routes/rejected?peer=someone-else")
        .await?
        .json()
        .await?;
    assert_eq!(none, serde_json::json!([]));

    // The peer's line in the list of peers has the numbers too.
    let peers: Value = get("/api/peers").await?.json().await?;
    assert_eq!(peers[0]["routes"], 1);
    assert_eq!(peers[0]["rejected_routes"], 4);

    // What an alert would be made from.
    let metrics = get("/metricz").await?.text().await?;
    for line in [
        r#"bgp_routes_rejected_total{peer="refused-demo",reason="bogon AS in path"} 2"#,
        r#"bgp_routes_rejected_total{peer="refused-demo",reason="bogon prefix"} 1"#,
        r#"bgp_peer_routes{peer="refused-demo"} 1"#,
        r#"bgp_peer_max_prefixes{peer="refused-demo"} 100"#,
    ] {
        assert!(metrics.contains(line), "{line} is not in:\n{metrics}");
    }

    // The record outlives the session; the count of routes does not.
    drop(peer);
    tokio::time::timeout(TIMEOUT, async {
        while !server.registry.list().is_empty() {
            tokio::time::sleep(Duration::from_millis(5)).await;
        }
    })
    .await?;
    let refused: Value = get("/api/routes/rejected").await?.json().await?;
    assert_eq!(refused[0]["total"], 4);
    let metrics = get("/metricz").await?.text().await?;
    assert!(!metrics.contains(r#"bgp_peer_routes{peer="refused-demo"}"#));
    Ok(())
}