//! BWE recovery mechanism tests (AIMD recovery after congestion).

use std::time::Duration;

use netem::{DataSize, NetemConfig};
use str0m::RtcError;
use str0m::bwe::Bitrate;

use crate::common::{BweTestContext, Step, connect_with_bwe, init_crypto_default, init_log};

#[test]
fn aimd_multiplicative_decrease_on_congestion() -> Result<(), RtcError> {
    init_log();
    init_crypto_default();

    let plan = vec![
        Step::Conditions {
            description: "Good network",
            config: NetemConfig::new()
                .latency(Duration::from_millis(20))
                .link(Bitrate::mbps(5), DataSize::kbytes(100))
                .seed(42),
        },
        Step::Media {
            description: "Send at 2 Mbps",
            desired_bitrate: Bitrate::mbps(5),
            media_send_rate: Bitrate::mbps(2),
        },
        Step::Run {
            description: "Establish baseline estimate",
            duration: Duration::from_secs(5),
        },
        Step::Check {
            description: "Baseline estimate around 2 Mbps",
            at_least: Bitrate::mbps(2),
        },
        // Introduce severe congestion
        Step::Conditions {
            description: "High latency causes overuse",
            config: NetemConfig::new()
                .latency(Duration::from_millis(150)) // Queuing delay
                .link(Bitrate::mbps(5), DataSize::kbytes(100))
                .seed(42),
        },
        Step::Run {
            description: "Wait for overuse detection and AIMD decrease",
            duration: Duration::from_secs(3),
        },
        Step::Check {
            description: "Estimate dropped via multiplicative decrease",
            at_least: Bitrate::kbps(500),
        },
    ];

    let (mut l, mut r) = connect_with_bwe(Bitrate::mbps(2), Bitrate::mbps(5));
    let mut ctx = BweTestContext::new(&mut l, &mut r);
    ctx.run_plan(&mut l, &mut r, &plan)?;

    Ok(())
}

#[test]
fn aimd_additive_increase_recovers_estimate() -> Result<(), RtcError> {
    init_log();
    init_crypto_default();

    let plan = vec![
        Step::Conditions {
            description: "Good network",
            config: NetemConfig::new()
                .latency(Duration::from_millis(20))
                .link(Bitrate::mbps(5), DataSize::kbytes(100))
                .seed(42),
        },
        Step::Media {
            description: "Send at 2 Mbps",
            desired_bitrate: Bitrate::mbps(5),
            media_send_rate: Bitrate::mbps(2),
        },
        Step::Run {
            description: "Establish baseline",
            duration: Duration::from_secs(5),
        },
        Step::Check {
            description: "Baseline around 2 Mbps",
            at_least: Bitrate::mbps(2),
        },
        // Cause congestion
        Step::Conditions {
            description: "Temporary congestion",
            config: NetemConfig::new()
                .latency(Duration::from_millis(150))
                .link(Bitrate::mbps(5), DataSize::kbytes(100))
                .seed(42),
        },
        Step::Run {
            description: "Trigger multiplicative decrease",
            duration: Duration::from_secs(3),
        },
        Step::Check {
            description: "Estimate dropped",
            at_least: Bitrate::kbps(500),
        },
        // Restore good network
        Step::Conditions {
            description: "Restore good conditions",
            config: NetemConfig::new()
                .latency(Duration::from_millis(20))
                .link(Bitrate::mbps(5), DataSize::kbytes(100))
                .seed(42),
        },
        Step::Run {
            description: "Allow AIMD additive increase to recover",
            duration: Duration::from_secs(10),
        },
        Step::Check {
            description: "Estimate recovers via additive increase",
            at_least: Bitrate::mbps(1),
        },
    ];

    let (mut l, mut r) = connect_with_bwe(Bitrate::mbps(2), Bitrate::mbps(5));
    let mut ctx = BweTestContext::new(&mut l, &mut r);
    ctx.run_plan(&mut l, &mut r, &plan)?;

    Ok(())
}

#[test]
fn aimd_recovery_reaches_original_estimate() -> Result<(), RtcError> {
    init_log();
    init_crypto_default();

    let plan = vec![
        Step::Conditions {
            description: "Good network",
            config: NetemConfig::new()
                .latency(Duration::from_millis(20))
                .link(Bitrate::mbps(3), DataSize::kbytes(100))
                .seed(42),
        },
        Step::Media {
            description: "Send at 2 Mbps",
            desired_bitrate: Bitrate::mbps(5),
            media_send_rate: Bitrate::mbps(2),
        },
        Step::Run {
            description: "Establish baseline",
            duration: Duration::from_secs(5),
        },
        Step::Check {
            description: "Baseline established",
            at_least: Bitrate::mbps(2),
        },
        // Brief congestion
        Step::Conditions {
            description: "Brief congestion event",
            config: NetemConfig::new()
                .latency(Duration::from_millis(150))
                .link(Bitrate::mbps(3), DataSize::kbytes(100))
                .seed(42),
        },
        Step::Run {
            description: "Drop estimate",
            duration: Duration::from_secs(2),
        },
        // Restore and allow full recovery
        Step::Conditions {
            description: "Restore network",
            config: NetemConfig::new()
                .latency(Duration::from_millis(20))
                .link(Bitrate::mbps(3), DataSize::kbytes(100))
                .seed(42),
        },
        Step::Run {
            description: "Allow full recovery via AIMD + probes",
            duration: Duration::from_secs(15),
        },
        Step::Check {
            description: "Estimate recovers to original level",
            at_least: Bitrate::mbps(2),
        },
    ];

    let (mut l, mut r) = connect_with_bwe(Bitrate::mbps(2), Bitrate::mbps(5));
    let mut ctx = BweTestContext::new(&mut l, &mut r);
    ctx.run_plan(&mut l, &mut r, &plan)?;

    Ok(())
}