// Copyright 2024 RustFS Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::plugin::PluginEvent;
use crate::{
    StoreError, Target,
    arn::TargetID,
    error::TargetError,
    runtime::tls::{
        ReloadableTargetTls, TargetTlsGeneration, TargetTlsInputSet, TlsReloadAdapter, config::ReloadApplyMode,
        validate_tls_material,
    },
    store::{Key, Store},
    target::{
        ChannelTargetType, EntityTarget, QueuedPayload, QueuedPayloadMeta, TargetDeliveryCounters, TargetDeliverySnapshot,
        TargetTlsState, TargetType, build_queued_payload_with_records, build_target_tls_fingerprint, is_connectivity_error,
        open_target_queue_store, persist_queued_payload_to_store, redacted_secret, sanitize_queue_dir_component,
        with_delivery_deadline,
    },
};
use async_trait::async_trait;
// Use parking_lot's Mutex for the synchronous client/TLS state guards: it does
// not poison on panic, so a panic while a guard is held cannot cascade into
// `.unwrap()` panics on every later access (backlog#983).
use parking_lot::Mutex;
use pulsar::{Authentication, Producer, Pulsar, TokioExecutor};
use rustfs_tls_runtime::load_cert_bundle_der_bytes;
use std::fmt;
use std::path::Path;
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, Ordering};
use std::time::Duration;
use tokio::sync::Mutex as AsyncMutex;
use tracing::{info, instrument, warn};
use url::Url;
use uuid::Uuid;

const PULSAR_DELIVERY_TIMEOUT: Duration = Duration::from_secs(30);
const PULSAR_FAILED_DELIVERY_CLEANUP_TIMEOUT: Duration = Duration::from_secs(1);

#[derive(Clone)]
pub struct PulsarArgs {
    pub enable: bool,
    pub broker: String,
    pub topic: String,
    pub auth_token: String,
    pub username: String,
    pub password: String,
    pub tls_ca: String,
    pub tls_allow_insecure: bool,
    pub tls_hostname_verification: bool,
    pub queue_dir: String,
    pub queue_limit: u64,
    pub target_type: TargetType,
}

impl fmt::Debug for PulsarArgs {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("PulsarArgs")
            .field("enable", &self.enable)
            .field("broker", &self.broker)
            .field("topic", &self.topic)
            .field("auth_token", &redacted_secret(&self.auth_token))
            .field("username", &self.username)
            .field("password", &redacted_secret(&self.password))
            .field("tls_ca", &self.tls_ca)
            .field("tls_allow_insecure", &self.tls_allow_insecure)
            .field("tls_hostname_verification", &self.tls_hostname_verification)
            .field("queue_dir", &self.queue_dir)
            .field("queue_limit", &self.queue_limit)
            .field("target_type", &self.target_type)
            .finish()
    }
}

impl PulsarArgs {
    pub fn validate(&self) -> Result<(), TargetError> {
        if !self.enable {
            return Ok(());
        }

        validate_pulsar_broker(&self.broker)?;

        if self.topic.trim().is_empty() {
            return Err(TargetError::Configuration("Pulsar topic cannot be empty".to_string()));
        }

        if !self.auth_token.is_empty() && (!self.username.is_empty() || !self.password.is_empty()) {
            return Err(TargetError::Configuration(
                "Pulsar supports either auth_token or username/password auth, not both".to_string(),
            ));
        }

        if self.username.is_empty() != self.password.is_empty() {
            return Err(TargetError::Configuration(
                "Pulsar username and password must be specified together".to_string(),
            ));
        }

        if !self.tls_ca.is_empty() && !Path::new(&self.tls_ca).is_absolute() {
            return Err(TargetError::Configuration("Pulsar tls_ca must be an absolute path".to_string()));
        }

        if !self.queue_dir.is_empty() && !Path::new(&self.queue_dir).is_absolute() {
            return Err(TargetError::Configuration("Pulsar queue directory must be an absolute path".to_string()));
        }

        let parsed = Url::parse(&self.broker)
            .map_err(|e| TargetError::Configuration(format!("Invalid Pulsar broker URL: {e} (value: '{}')", self.broker)))?;
        let tls_enabled = parsed.scheme() == "pulsar+ssl";
        // A CA bundle is TLS trust material a plaintext `pulsar://` broker
        // silently ignores, so treat it as a genuine misconfiguration. The
        // `tls_allow_insecure` / `tls_hostname_verification` toggles, however,
        // are inert on a non-TLS broker (they only take effect for
        // `pulsar+ssl`); rejecting non-default values would leave a persisted
        // target permanently offline after a restart even though the flags do
        // nothing — see issue #4796.
        if !tls_enabled && !self.tls_ca.is_empty() {
            return Err(TargetError::Configuration(
                "Pulsar tls_ca is only allowed with pulsar+ssl brokers".to_string(),
            ));
        }

        Ok(())
    }
}

pub fn validate_pulsar_broker(broker: &str) -> Result<Url, TargetError> {
    let url = Url::parse(broker)
        .map_err(|e| TargetError::Configuration(format!("Invalid Pulsar broker URL: {e} (value: '{broker}')")))?;

    match url.scheme() {
        "pulsar" | "pulsar+ssl" => {}
        _ => {
            return Err(TargetError::Configuration(
                "Pulsar broker must use pulsar:// or pulsar+ssl://".to_string(),
            ));
        }
    }

    if !url.username().is_empty() || url.password().is_some() {
        return Err(TargetError::Configuration(
            "Pulsar broker URL must not embed username or password".to_string(),
        ));
    }

    if url.host_str().is_none() {
        return Err(TargetError::Configuration("Pulsar broker is missing host".to_string()));
    }

    Ok(url)
}

fn pulsar_producer_name(target_id: &TargetID, target_type: TargetType, nonce: Uuid) -> String {
    let target_type = match target_type {
        TargetType::NotifyEvent => "notify",
        TargetType::AuditLog => "audit",
    };

    format!("rustfs-{target_type}-pulsar-{}-{nonce}", sanitize_queue_dir_component(&target_id.id))
}

pub async fn connect_pulsar(args: &PulsarArgs) -> Result<Pulsar<TokioExecutor>, TargetError> {
    args.validate()?;

    let mut builder = Pulsar::builder(args.broker.clone(), TokioExecutor);

    if !args.auth_token.is_empty() {
        builder = builder.with_auth(Authentication {
            name: "token".to_string(),
            data: args.auth_token.clone().into_bytes(),
        });
    } else if !args.username.is_empty() {
        builder =
            builder.with_auth_provider(pulsar::authentication::basic::BasicAuthentication::new(&args.username, &args.password));
    }

    if !args.tls_ca.is_empty() {
        let certs = load_cert_bundle_der_bytes(&args.tls_ca)
            .map_err(|e| TargetError::Configuration(format!("Failed to parse Pulsar tls_ca: {e}")))?;
        if certs.is_empty() {
            return Err(TargetError::Configuration(
                "Pulsar tls_ca did not contain any parsable certificates".to_string(),
            ));
        }
        builder = builder
            .with_certificate_chain_file(&args.tls_ca)
            .map_err(|e| TargetError::Configuration(format!("Failed to load Pulsar tls_ca: {e}")))?;
    }

    builder = builder
        .with_allow_insecure_connection(args.tls_allow_insecure)
        .with_tls_hostname_verification_enabled(args.tls_hostname_verification);

    builder
        .build()
        .await
        .map_err(|e| TargetError::Network(format!("Failed to connect to Pulsar broker: {e}")))
}

pub struct PulsarTarget<E>
where
    E: PluginEvent,
{
    id: TargetID,
    args: PulsarArgs,
    client: Mutex<Option<Pulsar<TokioExecutor>>>,
    tls_state: Mutex<TargetTlsState>,
    /// When set, the coordinator drives TLS reload; inline fingerprint check is skipped.
    tls_adapter: Option<TlsReloadAdapter<Pulsar<TokioExecutor>>>,
    producer: AsyncMutex<Option<Producer<TokioExecutor>>>,
    store: Option<Box<dyn Store<QueuedPayload, Error = StoreError, Key = Key> + Send + Sync>>,
    connected: AtomicBool,
    delivery_counters: Arc<TargetDeliveryCounters>,
    _phantom: std::marker::PhantomData<E>,
}

impl<E> PulsarTarget<E>
where
    E: PluginEvent,
{
    pub fn clone_box(&self) -> Box<dyn Target<E> + Send + Sync> {
        Box::new(PulsarTarget::<E> {
            id: self.id.clone(),
            args: self.args.clone(),
            client: Mutex::new(self.client.lock().clone()),
            tls_state: Mutex::new(self.tls_state.lock().clone()),
            tls_adapter: self.tls_adapter.clone(),
            producer: AsyncMutex::new(None),
            store: self.store.as_ref().map(|s| s.boxed_clone()),
            connected: AtomicBool::new(self.connected.load(Ordering::SeqCst)),
            delivery_counters: Arc::clone(&self.delivery_counters),
            _phantom: std::marker::PhantomData,
        })
    }

    #[instrument(skip(args), fields(target_id_as_string = %id))]
    pub fn new(id: String, args: PulsarArgs) -> Result<Self, TargetError> {
        args.validate()?;
        let target_id = TargetID::new(id, ChannelTargetType::Pulsar.as_str().to_string());
        let queue_store = open_target_queue_store(
            &args.queue_dir,
            args.queue_limit,
            args.target_type,
            ChannelTargetType::Pulsar.as_str(),
            &target_id,
            "Failed to open store for Pulsar target",
        )?;

        Ok(Self {
            id: target_id,
            args,
            client: Mutex::new(None),
            tls_state: Mutex::new(TargetTlsState::default()),
            tls_adapter: None,
            producer: AsyncMutex::new(None),
            store: queue_store,
            connected: AtomicBool::new(false),
            delivery_counters: Arc::new(TargetDeliveryCounters::default()),
            _phantom: std::marker::PhantomData,
        })
    }

    fn clear_cached_client_connection(&self) {
        self.client.lock().take();
    }

    fn clear_cached_client(&self) {
        self.clear_cached_client_connection();
        self.tls_state.lock().reset();
    }

    async fn clear_failed_delivery_state(&self) {
        match tokio::time::timeout(PULSAR_FAILED_DELIVERY_CLEANUP_TIMEOUT, self.producer.lock()).await {
            Ok(mut producer) => {
                producer.take();
            }
            Err(_) => {
                warn!(
                    target_id = %self.id,
                    reason = "producer_cleanup_lock_timeout",
                    "Timed out clearing the Pulsar producer after a failed delivery"
                );
            }
        }
        self.clear_cached_client();
        self.connected.store(false, Ordering::SeqCst);
    }

    async fn get_or_connect_client(&self) -> Result<Pulsar<TokioExecutor>, TargetError> {
        // When a TLS reload adapter is attached, it drives client rebuilds
        // in the background. The inline per-send fingerprint check is skipped.
        if let Some(adapter) = &self.tls_adapter {
            let material = adapter.current_material();
            {
                let mut guard = self.client.lock();
                *guard = Some((*material).clone());
            }
        } else {
            let next_fingerprint = build_target_tls_fingerprint(&self.args.tls_ca, "", "").await?;
            let tls_changed = {
                let tls_state_guard = self.tls_state.lock();
                tls_state_guard.needs_update(&next_fingerprint)
            };
            if tls_changed {
                self.clear_cached_client_connection();
                self.tls_state.lock().refresh(next_fingerprint);
            }
        }

        if let Some(client) = self.client.lock().clone() {
            return Ok(client);
        }

        let client = connect_pulsar(&self.args).await?;
        self.connected.store(true, Ordering::SeqCst);
        let mut guard = self.client.lock();
        let shared = guard.get_or_insert_with(|| client.clone()).clone();
        Ok(shared)
    }

    async fn init_producer(&self) -> Result<(), TargetError> {
        if self.producer.lock().await.is_some() {
            return Ok(());
        }

        let client = self.get_or_connect_client().await?;
        let producer = client
            .producer()
            .with_topic(self.args.topic.clone())
            .with_name(pulsar_producer_name(&self.id, self.args.target_type, Uuid::new_v4()))
            .build()
            .await
            .map_err(|e| TargetError::Network(format!("Failed to create Pulsar producer: {e}")))?;

        let mut guard = self.producer.lock().await;
        if guard.is_none() {
            *guard = Some(producer);
        }
        Ok(())
    }

    fn build_queued_payload(&self, event: &EntityTarget<E>) -> Result<QueuedPayload, TargetError> {
        build_queued_payload_with_records(event, vec![event.clone()])
    }

    async fn send_body(&self, body: Vec<u8>) -> Result<(), TargetError> {
        let result = with_delivery_deadline(PULSAR_DELIVERY_TIMEOUT, "Pulsar delivery", async {
            self.init_producer().await?;
            let mut guard = self.producer.lock().await;
            let producer = guard
                .as_mut()
                .ok_or_else(|| TargetError::Configuration("Pulsar producer not initialized".to_string()))?;
            let receipt = producer
                .send_non_blocking(body)
                .await
                .map_err(|e| TargetError::Request(format!("Failed to send Pulsar message: {e}")))?;
            receipt
                .await
                .map_err(|e| TargetError::Request(format!("Failed to receive Pulsar receipt: {e}")))?;
            self.delivery_counters.record_success();
            Ok(())
        })
        .await;

        if let Err(err) = &result
            && is_connectivity_error(err)
        {
            self.clear_failed_delivery_state().await;
        }
        result
    }
}

/// Coordinated TLS hot-reload implementation for Pulsar targets.
///
/// Pulsar only uses a CA certificate (no client cert/key).
/// The coordinator calls these methods on a background poll loop to detect
/// TLS file changes and rebuild the client without restarting.
#[async_trait]
impl<E> ReloadableTargetTls for PulsarTarget<E>
where
    E: PluginEvent,
{
    type Material = Pulsar<TokioExecutor>;

    fn tls_input_set(&self) -> TargetTlsInputSet {
        TargetTlsInputSet {
            ca_path: self.args.tls_ca.clone(),
            client_cert_path: String::new(),
            client_key_path: String::new(),
            target_label: format!("pulsar:{}", self.id.id),
        }
    }

    async fn build_tls_material(&self) -> Result<Self::Material, TargetError> {
        connect_pulsar(&self.args).await
    }

    async fn apply_tls_material(
        &self,
        _generation: TargetTlsGeneration,
        material: Arc<Self::Material>,
        _mode: ReloadApplyMode,
    ) -> Result<(), TargetError> {
        // Pulsar client is Clone, so we clone from the Arc and store it.
        {
            let mut guard = self.client.lock();
            *guard = Some((*material).clone());
        }
        // Producer is bound to the old client; clear it so next send rebuilds.
        {
            let mut producer = self.producer.lock().await;
            *producer = None;
        }
        Ok(())
    }

    async fn validate_tls_files(&self) -> Result<(), TargetError> {
        // Pulsar only uses CA, no client cert/key.
        validate_tls_material(&self.args.tls_ca, "", "")
    }
}

#[async_trait]
impl<E> Target<E> for PulsarTarget<E>
where
    E: PluginEvent,
{
    fn id(&self) -> TargetID {
        self.id.clone()
    }

    async fn is_active(&self) -> Result<bool, TargetError> {
        self.init_producer().await?;
        let guard = self.producer.lock().await;
        let producer = guard
            .as_ref()
            .ok_or_else(|| TargetError::Configuration("Pulsar producer not initialized".to_string()))?;
        producer
            .check_connection()
            .await
            .map_err(|e| TargetError::Network(format!("Pulsar health check failed: {e}")))?;
        Ok(true)
    }

    async fn save(&self, event: Arc<EntityTarget<E>>) -> Result<(), TargetError> {
        let queued = match self.build_queued_payload(&event) {
            Ok(queued) => queued,
            Err(err) => {
                self.delivery_counters.record_final_failure();
                return Err(err);
            }
        };

        if let Some(store) = &self.store {
            if let Err(e) = persist_queued_payload_to_store(store.as_ref(), &queued) {
                self.delivery_counters.record_final_failure();
                return Err(e);
            }
            Ok(())
        } else {
            if let Err(err) = self.send_body(queued.body).await {
                self.delivery_counters.record_final_failure();
                return Err(err);
            }
            Ok(())
        }
    }

    async fn send_raw_from_store(&self, _key: Key, body: Vec<u8>, _meta: QueuedPayloadMeta) -> Result<(), TargetError> {
        self.send_body(body).await
    }

    async fn close(&self) -> Result<(), TargetError> {
        let mut producer = self.producer.lock().await;
        if let Some(producer) = producer.as_mut() {
            producer
                .close()
                .await
                .map_err(|e| TargetError::Network(format!("Failed to close Pulsar producer: {e}")))?;
        }
        *producer = None;
        self.clear_cached_client();
        self.connected.store(false, Ordering::SeqCst);
        // If a TLS reload adapter is attached, reset its error tracking
        // so that a future re-init does not inherit stale failure state.
        if let Some(adapter) = &self.tls_adapter {
            *adapter.runtime_state().last_error.write() = None;
        }
        info!(target_id = %self.id, "Pulsar target closed");
        Ok(())
    }

    fn store(&self) -> Option<&(dyn Store<QueuedPayload, Error = StoreError, Key = Key> + Send + Sync)> {
        self.store.as_deref()
    }

    fn clone_dyn(&self) -> Box<dyn Target<E> + Send + Sync> {
        self.clone_box()
    }

    async fn init(&self) -> Result<(), TargetError> {
        if !self.is_enabled() {
            return Ok(());
        }
        self.init_producer().await
    }

    fn is_enabled(&self) -> bool {
        self.args.enable
    }

    fn delivery_snapshot(&self) -> TargetDeliverySnapshot {
        self.delivery_counters.snapshot(
            self.store.as_deref().map_or(0, |store| store.len() as u64),
            // Pulsar targets record no terminal failures and keep no failed store.
            0,
        )
    }

    fn record_final_failure(&self) {
        self.delivery_counters.record_final_failure();
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::target::REDACTED_SECRET;

    fn base_args() -> PulsarArgs {
        PulsarArgs {
            enable: true,
            broker: "pulsar://127.0.0.1:6650".to_string(),
            topic: "persistent://public/default/rustfs-events".to_string(),
            auth_token: String::new(),
            username: String::new(),
            password: String::new(),
            tls_ca: String::new(),
            tls_allow_insecure: false,
            tls_hostname_verification: true,
            queue_dir: String::new(),
            queue_limit: 0,
            target_type: TargetType::NotifyEvent,
        }
    }

    #[tokio::test(start_paused = true)]
    async fn failed_delivery_cleanup_is_bounded_when_the_producer_lock_is_busy() {
        let target = Arc::new(PulsarTarget::<String>::new("pulsar:test".to_string(), base_args()).expect("target should build"));
        target.connected.store(true, Ordering::SeqCst);
        let producer_guard = target.producer.lock().await;
        let cleanup = {
            let target = Arc::clone(&target);
            tokio::spawn(async move { target.clear_failed_delivery_state().await })
        };

        cleanup.await.expect("cleanup task should not panic");

        assert!(!target.connected.load(Ordering::SeqCst));
        drop(producer_guard);
    }

    #[test]
    fn debug_redacts_pulsar_secret_fields() {
        let args = PulsarArgs {
            auth_token: "pulsar-token".to_string(),
            password: "pulsar-password".to_string(),
            ..base_args()
        };

        let rendered = format!("{args:?}");

        assert!(!rendered.contains("pulsar-token"));
        assert!(!rendered.contains("pulsar-password"));
        assert!(rendered.contains(REDACTED_SECRET));
        assert!(rendered.contains("persistent://public/default/rustfs-events"));
    }

    #[test]
    fn validate_pulsar_rejects_mixed_auth_methods() {
        let args = PulsarArgs {
            auth_token: "token".to_string(),
            username: "user".to_string(),
            password: "pass".to_string(),
            ..base_args()
        };
        assert!(args.validate().is_err());
    }

    #[test]
    fn validate_pulsar_rejects_relative_queue_dir() {
        let args = PulsarArgs {
            queue_dir: "relative/path".to_string(),
            ..base_args()
        };
        assert!(args.validate().is_err());
    }

    #[test]
    fn validate_pulsar_accepts_inert_tls_toggles_on_plaintext_broker() {
        // `tls_allow_insecure` / `tls_hostname_verification` are no-ops on a
        // `pulsar://` broker, so a target persisted with these non-default
        // values must still validate — otherwise it stays offline after a
        // restart (issue #4796).
        let args = PulsarArgs {
            tls_allow_insecure: true,
            tls_hostname_verification: false,
            ..base_args()
        };
        args.validate().expect("inert TLS toggles must not fail a plaintext broker");
    }

    #[test]
    fn validate_pulsar_rejects_tls_ca_on_plaintext_broker() {
        let args = PulsarArgs {
            tls_ca: "/etc/ssl/certs/ca.pem".to_string(),
            ..base_args()
        };
        assert!(args.validate().is_err());
    }

    #[test]
    fn pulsar_producer_name_keeps_target_context_and_unique_suffix() {
        let id = TargetID::new("test2".to_string(), ChannelTargetType::Pulsar.as_str().to_string());
        let nonce = Uuid::from_u128(0x12345678_90ab_cdef_1234_567890abcdef);

        let name = pulsar_producer_name(&id, TargetType::NotifyEvent, nonce);

        assert_eq!(name, "rustfs-notify-pulsar-test2-12345678-90ab-cdef-1234-567890abcdef");
    }

    #[test]
    fn pulsar_producer_name_includes_target_type() {
        let id = TargetID::new("audit-target".to_string(), ChannelTargetType::Pulsar.as_str().to_string());
        let nonce = Uuid::from_u128(0x12345678_90ab_cdef_1234_567890abcdef);

        let name = pulsar_producer_name(&id, TargetType::AuditLog, nonce);

        assert_eq!(name, "rustfs-audit-pulsar-audit-target-12345678-90ab-cdef-1234-567890abcdef");
    }

    #[test]
    fn pulsar_producer_name_sanitizes_target_id() {
        let raw_target_id = "tenant:alpha/beta";
        let id = TargetID::new(raw_target_id.to_string(), ChannelTargetType::Pulsar.as_str().to_string());
        let nonce = Uuid::from_u128(0x12345678_90ab_cdef_1234_567890abcdef);

        let name = pulsar_producer_name(&id, TargetType::NotifyEvent, nonce);

        assert!(!name.contains(':'));
        assert!(!name.contains('/'));
        assert_eq!(
            name,
            format!(
                "rustfs-notify-pulsar-{}-12345678-90ab-cdef-1234-567890abcdef",
                sanitize_queue_dir_component(raw_target_id)
            )
        );
    }

    #[test]
    fn pulsar_producer_name_changes_for_each_producer_generation() {
        let id = TargetID::new("test".to_string(), ChannelTargetType::Pulsar.as_str().to_string());
        let first = Uuid::from_u128(0x12345678_90ab_cdef_1234_567890abcdef);
        let second = Uuid::from_u128(0xfedcba09_8765_4321_fedc_ba0987654321);

        assert_ne!(
            pulsar_producer_name(&id, TargetType::NotifyEvent, first),
            pulsar_producer_name(&id, TargetType::NotifyEvent, second)
        );
    }

    #[test]
    fn init_producer_uses_generated_unique_producer_name_contract() {
        fn without_ascii_whitespace(value: &str) -> String {
            let mut compacted = String::with_capacity(value.len());
            compacted.extend(value.bytes().filter(|byte| !byte.is_ascii_whitespace()).map(char::from));
            compacted
        }

        let source = without_ascii_whitespace(include_str!(concat!(env!("CARGO_MANIFEST_DIR"), "/src/target/pulsar.rs")));
        let expected_name_call = [
            ".with_name(",
            "pulsar_producer_name(&self.id, self.args.target_type, Uuid::new_v4())",
            ")",
        ]
        .concat();
        let forbidden_target_id_call = [".with_name(", "self.id.id.clone()", ")"].concat();

        assert!(source.contains(&without_ascii_whitespace(&expected_name_call)));
        assert!(!source.contains(&without_ascii_whitespace(&forbidden_target_id_call)));
    }
}
