use serde::Serialize;

use crate::{label, topic};
use config::rocketmq::RocketMqConfig;
use queue::{EVENT_PREFIX, Envelope, Labels, Publisher, QueueError, QueueResult, RocketMqConn};

pub const DURABLE_DOMAINS: &[&str] = &[
    "auth",
    "email",
    "guild",
    "chat",
    "git",
    "issue",
    "notify",
    "organization",
    "pull",
];

#[derive(Clone, Debug)]
pub struct EventHandler {
    publisher: Publisher,
}

impl EventHandler {
    pub fn new(mq: RocketMqConn) -> Self {
        Self {
            publisher: Publisher::new(mq),
        }
    }

    pub async fn connect(config: &RocketMqConfig) -> QueueResult<Self> {
        let conn = RocketMqConn::init(config).await?;
        Ok(Self::new(conn))
    }

    pub async fn optional(config: Option<&RocketMqConfig>) -> QueueResult<Option<Self>> {
        match config {
            Some(config) => Self::connect(config).await.map(Some),
            None => Ok(None),
        }
    }

    pub fn envelope<T>(&self, kind: &str, payload: T) -> Envelope<T> {
        Envelope::new(kind, payload)
    }

    #[tracing::instrument(skip_all, fields(kind = kind, request_id = %request_id.unwrap_or_default()))]
    pub async fn send_labeled<T>(
        &self,
        kind: &str,
        labels: Labels,
        payload: T,
        request_id: Option<&str>,
    ) -> QueueResult<()>
    where
        T: Serialize,
    {
        self.send_keyed(kind, labels, None, payload, request_id)
            .await
    }

    #[tracing::instrument(skip_all, fields(kind = kind, request_id = %request_id.unwrap_or_default()))]
    pub async fn send_keyed<T>(
        &self,
        kind: &str,
        labels: Labels,
        idempotency_key: Option<String>,
        payload: T,
        request_id: Option<&str>,
    ) -> QueueResult<()>
    where
        T: Serialize,
    {
        let mut envelope = self
            .envelope(kind, payload)
            .with_source(domain_of(kind))
            .with_labels(labels);
        if let Some(key) = idempotency_key {
            envelope = envelope.with_idempotency_key(key);
        }
        if let Some(trace_id) = envelope::context::request_id().or_else(|| {
            request_id
                .filter(|request_id| !request_id.is_empty())
                .map(str::to_owned)
        }) {
            envelope = envelope.with_trace_id(trace_id);
        }
        self.send_envelope(&envelope, request_id).await
    }

    #[tracing::instrument(skip_all, fields(request_id = %request_id.unwrap_or_default()))]
    pub async fn send_envelope<T>(
        &self,
        envelope: &Envelope<T>,
        request_id: Option<&str>,
    ) -> QueueResult<()>
    where
        T: Serialize,
    {
        let subject = format!("{EVENT_PREFIX}{}", envelope.kind);
        envelope.verify_subject(EVENT_PREFIX, &subject)?;
        self.dispatch(envelope, request_id).await
    }

    #[tracing::instrument(skip_all, fields(subject = %subject, request_id = %request_id.unwrap_or_default()))]
    pub async fn publish_durable<T: Serialize>(
        &self,
        subject: &str,
        envelope: &Envelope<T>,
        request_id: Option<&str>,
    ) -> QueueResult<()> {
        envelope.verify_event_subject(subject)?;
        self.dispatch(envelope, request_id).await
    }

    pub async fn shutdown(&self) -> QueueResult<()> {
        self.publisher.conn().shutdown().await;
        Ok(())
    }

    #[tracing::instrument(skip_all, fields(kind = %envelope.kind, request_id = %request_id.unwrap_or_default()))]
    async fn dispatch<T: Serialize>(
        &self,
        envelope: &Envelope<T>,
        request_id: Option<&str>,
    ) -> QueueResult<()> {
        ensure_kind(&envelope.kind)?;
        let payload = serde_json::to_value(&envelope.payload).map_err(QueueError::from)?;
        let area = topic::of(&envelope.kind);
        let tag = label::tag(&envelope.kind, Some(&payload));
        let request_id = envelope::context::request_id().or_else(|| {
            request_id
                .filter(|request_id| !request_id.is_empty())
                .map(str::to_owned)
        });
        let properties = envelope.properties(Some(&payload), request_id.as_deref());
        let topic = self.publisher.topic(area);
        let body = envelope.encode()?;

        self.publisher
            .publish(&topic, tag, vec![envelope.message_id()], properties, body)
            .await
    }
}

fn ensure_kind(kind: &str) -> QueueResult<()> {
    let mut parts = kind.split('.');
    let domain = parts.next().unwrap_or_default();
    let name = parts.next().unwrap_or_default();
    let operate = parts.next().unwrap_or_default();
    if domain.is_empty() || name.is_empty() || operate.is_empty() {
        return Err(QueueError::payload(format!(
            "event kind `{kind}` is not a concrete event"
        )));
    }
    Ok(())
}

fn domain_of(kind: &str) -> &str {
    kind.split('.').next().unwrap_or_default()
}