use anyhow::Error;
use async_trait::async_trait;
use kube::Client;
use reqwest::Url;
use testing_framework_core::{
    scenario::{
        BlockFeedTask, CleanupGuard, Deployer, MetricsError, ObservabilityCapability, RunContext,
        Runner, Scenario,
    },
    topology::generation::GeneratedTopology,
};
use tracing::{error, info};

use crate::{
    infrastructure::{
        assets::{AssetsError, prepare_assets},
        cluster::{
            ClusterEnvironment, NodeClientError, PortSpecs, RemoteReadinessError,
            build_node_clients, cluster_identifiers, collect_port_specs, ensure_cluster_readiness,
            install_stack, kill_port_forwards, metrics_handle_from_endpoint,
            metrics_handle_from_url, wait_for_ports_or_cleanup,
        },
        helm::HelmError,
    },
    lifecycle::{block_feed::spawn_block_feed_with, cleanup::RunnerCleanup},
    wait::{ClusterWaitError, HostPort, PortForwardHandle},
};

/// Deploys a scenario into Kubernetes using Helm charts and port-forwards.
#[derive(Clone, Copy)]
pub struct K8sDeployer {
    readiness_checks: bool,
}

impl Default for K8sDeployer {
    fn default() -> Self {
        Self::new()
    }
}

impl K8sDeployer {
    #[must_use]
    /// Create a k8s deployer with readiness checks enabled.
    pub const fn new() -> Self {
        Self {
            readiness_checks: true,
        }
    }

    #[must_use]
    /// Enable/disable readiness probes before handing control to workloads.
    pub const fn with_readiness(mut self, enabled: bool) -> Self {
        self.readiness_checks = enabled;
        self
    }
}

#[derive(Debug, thiserror::Error)]
/// High-level runner failures returned to the scenario harness.
pub enum K8sRunnerError {
    #[error(
        "kubernetes runner requires at least one validator and one executor (validators={validators}, executors={executors})"
    )]
    UnsupportedTopology { validators: usize, executors: usize },
    #[error("failed to initialise kubernetes client: {source}")]
    ClientInit {
        #[source]
        source: kube::Error,
    },
    #[error(transparent)]
    Assets(#[from] AssetsError),
    #[error(transparent)]
    Helm(#[from] HelmError),
    #[error(transparent)]
    Cluster(#[from] Box<ClusterWaitError>),
    #[error(transparent)]
    Readiness(#[from] RemoteReadinessError),
    #[error(transparent)]
    NodeClients(#[from] NodeClientError),
    #[error(transparent)]
    Telemetry(#[from] MetricsError),
    #[error("k8s runner requires at least one node client to follow blocks")]
    BlockFeedMissing,
    #[error("failed to initialize block feed: {source}")]
    BlockFeed {
        #[source]
        source: Error,
    },
}

#[async_trait]
impl Deployer for K8sDeployer {
    type Error = K8sRunnerError;

    async fn deploy(&self, scenario: &Scenario) -> Result<Runner, Self::Error> {
        deploy_with_observability(self, scenario, None, None, None).await
    }
}

#[async_trait]
impl Deployer<ObservabilityCapability> for K8sDeployer {
    type Error = K8sRunnerError;

    async fn deploy(
        &self,
        scenario: &Scenario<ObservabilityCapability>,
    ) -> Result<Runner, Self::Error> {
        deploy_with_observability(
            self,
            scenario,
            scenario.capabilities().metrics_query_url.clone(),
            scenario.capabilities().metrics_query_grafana_url.clone(),
            scenario.capabilities().metrics_otlp_ingest_url.clone(),
        )
        .await
    }
}

fn cluster_prometheus_endpoint(cluster: &Option<ClusterEnvironment>) -> Option<&HostPort> {
    cluster
        .as_ref()
        .expect("cluster must be available")
        .prometheus_endpoint()
}

fn cluster_grafana_endpoint(cluster: &Option<ClusterEnvironment>) -> Option<&HostPort> {
    cluster
        .as_ref()
        .expect("cluster must be available")
        .grafana_endpoint()
}

async fn fail_cluster(cluster: &mut Option<ClusterEnvironment>, reason: &str) {
    if let Some(env) = cluster.as_mut() {
        env.fail(reason).await;
    }
}

impl From<ClusterWaitError> for K8sRunnerError {
    fn from(value: ClusterWaitError) -> Self {
        Self::Cluster(Box::new(value))
    }
}

fn ensure_supported_topology(descriptors: &GeneratedTopology) -> Result<(), K8sRunnerError> {
    let validators = descriptors.validators().len();
    let executors = descriptors.executors().len();
    if validators == 0 || executors == 0 {
        return Err(K8sRunnerError::UnsupportedTopology {
            validators,
            executors,
        });
    }
    Ok(())
}

async fn deploy_with_observability<Caps>(
    deployer: &K8sDeployer,
    scenario: &Scenario<Caps>,
    metrics_query_url: Option<Url>,
    metrics_query_grafana_url: Option<Url>,
    metrics_otlp_ingest_url: Option<Url>,
) -> Result<Runner, K8sRunnerError> {
    let external_prometheus = match metrics_query_url {
        Some(url) => Some(url),
        None => match std::env::var("K8S_RUNNER_METRICS_QUERY_URL")
            .ok()
            .or_else(|| std::env::var("NOMOS_METRICS_QUERY_URL").ok())
            // Back-compat:
            .or_else(|| std::env::var("K8S_RUNNER_EXTERNAL_PROMETHEUS_URL").ok())
            .or_else(|| std::env::var("NOMOS_EXTERNAL_PROMETHEUS_URL").ok())
        {
            Some(raw) if !raw.trim().is_empty() => {
                Some(Url::parse(raw.trim()).map_err(|err| {
                    MetricsError::new(format!("invalid metrics query url: {err}"))
                })?)
            }
            _ => None,
        },
    };

    let external_prometheus_grafana_url = match metrics_query_grafana_url {
        Some(url) => Some(url),
        None => match std::env::var("K8S_RUNNER_METRICS_QUERY_GRAFANA_URL")
            .ok()
            .or_else(|| std::env::var("NOMOS_METRICS_QUERY_GRAFANA_URL").ok())
            // Back-compat:
            .or_else(|| std::env::var("K8S_RUNNER_EXTERNAL_PROMETHEUS_GRAFANA_URL").ok())
            .or_else(|| std::env::var("NOMOS_EXTERNAL_PROMETHEUS_GRAFANA_URL").ok())
        {
            Some(raw) if !raw.trim().is_empty() => Some(Url::parse(raw.trim()).map_err(|err| {
                MetricsError::new(format!("invalid metrics query grafana url: {err}"))
            })?),
            _ => None,
        },
    };

    let external_otlp_metrics_endpoint = match metrics_otlp_ingest_url {
        Some(url) => Some(url),
        None => match std::env::var("K8S_RUNNER_METRICS_OTLP_INGEST_URL")
            .ok()
            .or_else(|| std::env::var("NOMOS_METRICS_OTLP_INGEST_URL").ok())
            // Back-compat:
            .or_else(|| std::env::var("K8S_RUNNER_EXTERNAL_OTLP_METRICS_ENDPOINT").ok())
            .or_else(|| std::env::var("NOMOS_EXTERNAL_OTLP_METRICS_ENDPOINT").ok())
        {
            Some(raw) if !raw.trim().is_empty() => Some(Url::parse(raw.trim()).map_err(|err| {
                MetricsError::new(format!("invalid metrics OTLP ingest url: {err}"))
            })?),
            _ => None,
        },
    };

    let descriptors = scenario.topology().clone();
    let validator_count = descriptors.validators().len();
    let executor_count = descriptors.executors().len();
    ensure_supported_topology(&descriptors)?;

    let client = Client::try_default()
        .await
        .map_err(|source| K8sRunnerError::ClientInit { source })?;

    info!(
        validators = validator_count,
        executors = executor_count,
        duration_secs = scenario.duration().as_secs(),
        readiness_checks = deployer.readiness_checks,
        metrics_query_url = external_prometheus.as_ref().map(|u| u.as_str()),
        metrics_query_grafana_url = external_prometheus_grafana_url.as_ref().map(|u| u.as_str()),
        metrics_otlp_ingest_url = external_otlp_metrics_endpoint.as_ref().map(|u| u.as_str()),
        "starting k8s deployment"
    );

    let port_specs = collect_port_specs(&descriptors);
    let mut cluster = Some(
        setup_cluster(
            &client,
            &port_specs,
            &descriptors,
            deployer.readiness_checks,
            external_prometheus.as_ref(),
            external_prometheus_grafana_url.as_ref(),
            external_otlp_metrics_endpoint.as_ref(),
        )
        .await?,
    );

    info!("building node clients");
    let node_clients = match build_node_clients(
        cluster
            .as_ref()
            .expect("cluster must be available while building clients"),
    ) {
        Ok(clients) => clients,
        Err(err) => {
            fail_cluster(&mut cluster, "failed to construct node api clients").await;
            error!(error = ?err, "failed to build k8s node clients");
            return Err(err.into());
        }
    };

    let telemetry = match external_prometheus.clone() {
        Some(url) => metrics_handle_from_url(url),
        None => cluster
            .as_ref()
            .and_then(|cluster| cluster.prometheus_endpoint())
            .ok_or_else(|| MetricsError::new("prometheus endpoint unavailable"))
            .and_then(metrics_handle_from_endpoint),
    };
    let telemetry = match telemetry {
        Ok(handle) => handle,
        Err(err) => {
            fail_cluster(
                &mut cluster,
                "failed to configure prometheus metrics handle",
            )
            .await;
            error!(error = ?err, "failed to configure prometheus metrics handle");
            return Err(err.into());
        }
    };

    let (block_feed, block_feed_guard) = match spawn_block_feed_with(&node_clients).await {
        Ok(pair) => pair,
        Err(err) => {
            fail_cluster(&mut cluster, "failed to initialize block feed").await;
            error!(error = ?err, "failed to initialize block feed");
            return Err(err);
        }
    };

    if let Some(url) = external_prometheus.as_ref() {
        info!(prometheus_url = %url.as_str(), "using external prometheus endpoint");
    } else if let Some(prometheus) = cluster_prometheus_endpoint(&cluster) {
        info!(
            prometheus_url = %format!("http://{}:{}/", prometheus.host, prometheus.port),
            "prometheus endpoint available on host"
        );
    }
    if let Some(grafana) = cluster_grafana_endpoint(&cluster) {
        info!(
            grafana_url = %format!("http://{}:{}/", grafana.host, grafana.port),
            "grafana dashboard available on host"
        );
    }

    if std::env::var("TESTNET_PRINT_ENDPOINTS").is_ok() {
        let prometheus = external_prometheus
            .as_ref()
            .map(|u| u.as_str().to_string())
            .or_else(|| {
                cluster_prometheus_endpoint(&cluster)
                    .map(|endpoint| format!("http://{}:{}/", endpoint.host, endpoint.port))
            })
            .unwrap_or_else(|| "<disabled>".to_string());
        let grafana = cluster_grafana_endpoint(&cluster);
        println!(
            "TESTNET_ENDPOINTS prometheus={} grafana={}",
            prometheus,
            grafana
                .map(|endpoint| format!("http://{}:{}/", endpoint.host, endpoint.port))
                .unwrap_or_else(|| "<disabled>".to_string())
        );

        for (idx, client) in node_clients.validator_clients().iter().enumerate() {
            println!(
                "TESTNET_PPROF validator_{}={}/debug/pprof/profile?seconds=15&format=proto",
                idx,
                client.base_url()
            );
        }

        for (idx, client) in node_clients.executor_clients().iter().enumerate() {
            println!(
                "TESTNET_PPROF executor_{}={}/debug/pprof/profile?seconds=15&format=proto",
                idx,
                client.base_url()
            );
        }
    }

    let (cleanup, port_forwards) = cluster
        .take()
        .expect("cluster should still be available")
        .into_cleanup();
    let cleanup_guard: Box<dyn CleanupGuard> = Box::new(K8sCleanupGuard::new(
        cleanup,
        block_feed_guard,
        port_forwards,
    ));

    let context = RunContext::new(
        descriptors,
        None,
        node_clients,
        scenario.duration(),
        telemetry,
        block_feed,
        None,
    );

    info!(
        validators = validator_count,
        executors = executor_count,
        duration_secs = scenario.duration().as_secs(),
        "k8s deployment ready; handing control to scenario runner"
    );

    Ok(Runner::new(context, Some(cleanup_guard)))
}

async fn setup_cluster(
    client: &Client,
    specs: &PortSpecs,
    descriptors: &GeneratedTopology,
    readiness_checks: bool,
    external_prometheus: Option<&Url>,
    external_prometheus_grafana_url: Option<&Url>,
    external_otlp_metrics_endpoint: Option<&Url>,
) -> Result<ClusterEnvironment, K8sRunnerError> {
    let assets = prepare_assets(
        descriptors,
        external_prometheus,
        external_prometheus_grafana_url,
        external_otlp_metrics_endpoint,
    )?;
    let validators = descriptors.validators().len();
    let executors = descriptors.executors().len();

    let (namespace, release) = cluster_identifiers();
    info!(%namespace, %release, validators, executors, "preparing k8s assets and namespace");

    let mut cleanup_guard =
        Some(install_stack(client, &assets, &namespace, &release, validators, executors).await?);

    info!("waiting for helm-managed services to become ready");
    let cluster_ready = wait_for_ports_or_cleanup(
        client,
        &namespace,
        &release,
        specs,
        external_prometheus.is_none() && external_prometheus_grafana_url.is_none(),
        &mut cleanup_guard,
    )
    .await?;

    if let Some(prometheus) = cluster_ready.ports.prometheus.as_ref() {
        info!(prometheus = ?prometheus, "discovered prometheus endpoint");
    }

    let environment = ClusterEnvironment::new(
        client.clone(),
        namespace,
        release,
        cleanup_guard
            .take()
            .expect("cleanup guard must exist after successful cluster startup"),
        &cluster_ready.ports,
        cluster_ready.port_forwards,
    );

    if readiness_checks {
        info!("probing cluster readiness");
        ensure_cluster_readiness(descriptors, &environment).await?;
        info!("cluster readiness probes passed");
    }

    Ok(environment)
}

struct K8sCleanupGuard {
    cleanup: RunnerCleanup,
    block_feed: Option<BlockFeedTask>,
    port_forwards: Vec<PortForwardHandle>,
}

impl K8sCleanupGuard {
    const fn new(
        cleanup: RunnerCleanup,
        block_feed: BlockFeedTask,
        port_forwards: Vec<PortForwardHandle>,
    ) -> Self {
        Self {
            cleanup,
            block_feed: Some(block_feed),
            port_forwards,
        }
    }
}

impl CleanupGuard for K8sCleanupGuard {
    fn cleanup(mut self: Box<Self>) {
        if let Some(block_feed) = self.block_feed.take() {
            CleanupGuard::cleanup(Box::new(block_feed));
        }
        kill_port_forwards(&mut self.port_forwards);
        CleanupGuard::cleanup(Box::new(self.cleanup));
    }
}