wind_tunnel_runner 0.1.0-alpha.2

use std::sync::Arc;
use std::time::Duration;

use anyhow::Context;
use wind_tunnel_core::prelude::ShutdownSignalError;
use wind_tunnel_instruments::ReportConfig;

use crate::monitor::start_monitor;
use crate::progress::start_progress;
use crate::{
    context::{AgentContext, RunnerContext, UserValuesConstraint},
    definition::ScenarioDefinitionBuilder,
    executor::Executor,
    shutdown::start_shutdown_listener,
};

pub fn run<RV: UserValuesConstraint, V: UserValuesConstraint>(
    definition: ScenarioDefinitionBuilder<RV, V>,
) -> anyhow::Result<()> {
    let definition = definition.build()?;

    log::info!("Running scenario: {}", definition.name);

    let runtime = tokio::runtime::Runtime::new().context("Failed to create Tokio runtime")?;

    let shutdown_handle = start_shutdown_listener(&runtime)?;

    let reporter = {
        let _h = runtime.handle().enter();
        let mut report_config = ReportConfig::default().enable_summary();

        if !definition.no_metrics {
            report_config = report_config.enable_metrics();
        }

        Arc::new(report_config.init_reporter(&runtime, shutdown_handle.new_listener())?)
    };
    let executor = Arc::new(Executor::new(runtime, shutdown_handle.clone()));
    let mut runner_context = RunnerContext::new(
        executor,
        reporter,
        shutdown_handle.clone(),
        definition.connection_string.clone(),
    );

    if let Some(setup_fn) = &definition.setup_fn {
        setup_fn(&mut runner_context)?;
    }

    // After the setup has run, and if this is a time bounded scenario, then we need to take additional actions
    if let Some(duration) = definition.duration_s {
        if !definition.no_progress {
            // If the scenario is time bounded then start the progress monitor to show the user how long is left
            start_progress(
                Duration::from_secs(duration),
                shutdown_handle.new_listener(),
            );
        }

        // Set a timer to shut down the test after the duration has elapsed
        let shutdown_handle = shutdown_handle.clone();
        runner_context.executor().spawn(async move {
            tokio::time::sleep(tokio::time::Duration::from_secs(duration)).await;
            shutdown_handle.shutdown();
        });
    }

    let runner_context = Arc::new(runner_context);
    let runner_context_for_teardown = runner_context.clone();

    // Ready to start spawning agents so start the resource monitor to report high usage by agents
    // which might lead to a misleading outcome.
    start_monitor(shutdown_handle.new_listener());

    let assigned_behaviours = definition.assigned_behaviours_flat();

    let mut handles = Vec::new();
    for (agent_index, assigned_behaviour) in assigned_behaviours.iter().enumerate() {
        // Read access to the runner context for each agent
        let runner_context = runner_context.clone();

        let setup_agent_fn = definition.setup_agent_fn;
        let agent_behaviour_fn = definition.agent_behaviour.get(assigned_behaviour).cloned();
        let teardown_agent_fn = definition.teardown_agent_fn;

        // For us to check if the agent should shut down between behaviour cycles
        let mut cycle_shutdown_receiver = shutdown_handle.new_listener();
        // For the behaviour implementation to listen for shutdown and respond appropriately
        let delegated_shutdown_listener = shutdown_handle.new_listener();

        let agent_id = format!("agent-{}", agent_index);

        handles.push(
            std::thread::Builder::new()
                .name(agent_id.clone())
                .spawn(move || {
                    // TODO synchronize these setups so that the scenario waits for all of them to complete before proceeding.
                    let mut context = AgentContext::new(
                        agent_id.clone(),
                        runner_context,
                        delegated_shutdown_listener,
                    );
                    if let Some(setup_agent_fn) = setup_agent_fn {
                        if let Err(e) = setup_agent_fn(&mut context) {
                            log::error!("Agent setup failed for agent {}: {:?}", agent_id, e);
                            return;
                        }
                    }

                    // TODO implement warmup
                    if let Some(behaviour) = agent_behaviour_fn {
                        loop {
                            if cycle_shutdown_receiver.should_shutdown() {
                                log::debug!("Stopping agent {}", agent_id);
                                break;
                            }

                            match behaviour(&mut context) {
                                Ok(()) => {}
                                Err(e) if e.is::<ShutdownSignalError>() => {
                                    // Do nothing, this is expected if the agent is being shutdown.
                                    // The check at the top of the loop will catch this and break out.
                                }
                                Err(e) => {
                                    log::error!("Agent behaviour failed: {:?}", e);
                                }
                            }
                        }
                    }

                    if let Some(teardown_agent_fn) = teardown_agent_fn {
                        if let Err(e) = teardown_agent_fn(&mut context) {
                            log::error!("Agent teardown failed for agent {}: {:?}", agent_id, e);
                        }
                    }
                })
                .expect("Failed to spawn thread for test agent"),
        );
    }

    for handle in handles {
        handle
            .join()
            .map_err(|e| anyhow::anyhow!("Error joining thread for test agent: {:?}", e))?;
    }

    if let Some(teardown_fn) = definition.teardown_fn {
        // Don't crash the runner if the teardown fails. We still want the reporting and runner
        // shutdown to happen cleanly. The hook is documented as 'best effort'
        if let Err(e) = teardown_fn(runner_context_for_teardown.clone()) {
            log::error!("Teardown failed: {:?}", e);
        }
    }

    runner_context_for_teardown.reporter().finalize();

    Ok(())
}