collet 0.1.0

//! Slack adapter — reqwest (HTTP API) + tokio-tungstenite 0.26 (Socket Mode).
//!
//! Feature-gated behind `slack`. Max message: ~4000 chars.

use anyhow::{Context, Result};
use async_trait::async_trait;
use futures::{SinkExt, StreamExt};
use serde_json::{Value, json};
use tokio::sync::mpsc;
use tokio_tungstenite::tungstenite::Message as WsMessage;

use super::adapter::{ChannelId, IncomingCommand, PlatformAdapter};
use super::commands::parse_remote_command;

// ---------------------------------------------------------------------------
// WebSocket type aliases
// ---------------------------------------------------------------------------

type WsStream =
    tokio_tungstenite::WebSocketStream<tokio_tungstenite::MaybeTlsStream<tokio::net::TcpStream>>;
type WsSink = futures::stream::SplitSink<WsStream, WsMessage>;

// ---------------------------------------------------------------------------
// Adapter
// ---------------------------------------------------------------------------

pub struct SlackAdapter {
    bot_token: String,
    app_token: String,
    client: reqwest::Client,
}

impl SlackAdapter {
    pub fn new(bot_token: String, app_token: String) -> Self {
        Self {
            bot_token,
            app_token,
            client: reqwest::Client::new(),
        }
    }

    // -----------------------------------------------------------------------
    // HTTP helpers
    // -----------------------------------------------------------------------

    /// POST to `https://slack.com/api/{method}` with Bearer bot_token.
    async fn api_post(&self, method: &str, body: Value) -> Result<Value> {
        let url = format!("https://slack.com/api/{method}");
        let resp: Value = self
            .client
            .post(&url)
            .bearer_auth(&self.bot_token)
            .json(&body)
            .send()
            .await
            .with_context(|| format!("slack api request failed: {method}"))?
            .json()
            .await
            .with_context(|| format!("slack api response parse failed: {method}"))?;

        if resp.get("ok") != Some(&Value::Bool(true)) {
            let err = resp["error"].as_str().unwrap_or("unknown");
            anyhow::bail!("slack api {method} error: {err}");
        }

        Ok(resp)
    }

    /// Build the base JSON body for a message to a channel, including
    /// `thread_ts` when the channel has a thread set.
    fn message_body(channel: &ChannelId) -> Value {
        let mut body = json!({ "channel": channel.channel });
        if let Some(ref ts) = channel.thread {
            body["thread_ts"] = json!(ts);
        }
        body
    }

    // -----------------------------------------------------------------------
    // Socket Mode helpers
    // -----------------------------------------------------------------------

    /// Request a fresh WebSocket URL via `apps.connections.open` using the
    /// **app-level token** (not the bot token).
    async fn open_socket_url(&self) -> Result<String> {
        let resp: Value = self
            .client
            .post("https://slack.com/api/apps.connections.open")
            .bearer_auth(&self.app_token)
            .json(&json!({}))
            .send()
            .await
            .context("apps.connections.open request failed")?
            .json()
            .await
            .context("apps.connections.open parse failed")?;

        if resp.get("ok") != Some(&Value::Bool(true)) {
            let err = resp["error"].as_str().unwrap_or("unknown");
            anyhow::bail!("apps.connections.open error: {err}");
        }

        resp["url"]
            .as_str()
            .map(String::from)
            .context("apps.connections.open: missing url field")
    }

    /// Send an envelope acknowledgement over the WebSocket sink.
    async fn ack_envelope(sink: &mut WsSink, envelope_id: &str) -> Result<()> {
        let ack = json!({ "envelope_id": envelope_id }).to_string();
        sink.send(WsMessage::Text(ack.into())).await?;
        Ok(())
    }

    /// Dispatch a single Socket Mode envelope.
    fn handle_socket_event(envelope: &Value, command_tx: &mpsc::UnboundedSender<IncomingCommand>) {
        let event_type = match envelope["type"].as_str() {
            Some(t) => t,
            None => return,
        };

        match event_type {
            "hello" => {
                tracing::info!("[slack] socket mode connected (hello)");
            }
            "disconnect" => {
                tracing::warn!("[slack] server requested disconnect");
            }
            "events_api" => {
                Self::handle_events_api(envelope, command_tx);
            }
            "interactive" => {
                Self::handle_interactive(envelope, command_tx);
            }
            "slash_commands" => {
                Self::handle_slash_command(envelope, command_tx);
            }
            other => {
                tracing::debug!("[slack] unhandled envelope type: {other}");
            }
        }
    }

    /// Handle an `events_api` envelope — currently only `message` events.
    fn handle_events_api(envelope: &Value, command_tx: &mpsc::UnboundedSender<IncomingCommand>) {
        let event = &envelope["payload"]["event"];

        // Only handle plain user messages (no bots, no subtypes like
        // message_changed, message_deleted, etc.)
        if event["type"].as_str() != Some("message") {
            return;
        }
        if event.get("bot_id").is_some() || event.get("subtype").is_some() {
            return;
        }

        let text = match event["text"].as_str() {
            Some(t) if !t.is_empty() => t,
            _ => return,
        };
        let ch = match event["channel"].as_str() {
            Some(c) => c,
            None => return,
        };
        let user = event["user"].as_str().unwrap_or("unknown");

        let mut channel = ChannelId::new("slack", ch);
        if let Some(ts) = event["thread_ts"].as_str() {
            channel = channel.with_thread(ts);
        }

        let command = parse_remote_command(text);
        let _ = command_tx.send(IncomingCommand {
            channel,
            user_id: user.to_string(),
            command,
        });
    }

    /// Handle an `interactive` envelope — button clicks (block actions).
    fn handle_interactive(envelope: &Value, command_tx: &mpsc::UnboundedSender<IncomingCommand>) {
        let payload = &envelope["payload"];
        let actions = match payload["actions"].as_array() {
            Some(a) => a,
            None => return,
        };

        let ch = match payload["channel"]["id"].as_str() {
            Some(c) => c,
            None => return,
        };
        let user = payload["user"]["id"].as_str().unwrap_or("unknown");

        let mut channel = ChannelId::new("slack", ch);
        if let Some(ts) = payload["message"]["thread_ts"].as_str() {
            channel = channel.with_thread(ts);
        }

        for action in actions {
            let action_id = match action["action_id"].as_str() {
                Some(a) => a,
                None => continue,
            };

            let command = parse_remote_command(action_id);
            let _ = command_tx.send(IncomingCommand {
                channel: channel.clone(),
                user_id: user.to_string(),
                command,
            });
        }
    }

    /// Handle a `slash_commands` envelope — native Slack slash commands.
    fn handle_slash_command(envelope: &Value, command_tx: &mpsc::UnboundedSender<IncomingCommand>) {
        let payload = &envelope["payload"];

        let command_name = match payload["command"].as_str() {
            Some(c) => c,
            None => return,
        };

        let ch = match payload["channel_id"].as_str() {
            Some(c) => c,
            None => return,
        };
        let user = payload["user_id"].as_str().unwrap_or("unknown");

        let channel = ChannelId::new("slack", ch);
        let command = parse_remote_command(command_name);

        let _ = command_tx.send(IncomingCommand {
            channel,
            user_id: user.to_string(),
            command,
        });
    }
}

// ---------------------------------------------------------------------------
// PlatformAdapter
// ---------------------------------------------------------------------------

#[async_trait]
impl PlatformAdapter for SlackAdapter {
    fn platform_name(&self) -> &str {
        "slack"
    }

    fn max_message_length(&self) -> usize {
        4000
    }

    async fn register_commands(&self, commands: &[(&str, &str)]) -> Result<()> {
        // Slack does not support runtime slash-command registration.
        // Slash commands must be pre-registered in the Slack App Dashboard.
        // Skill names are surfaced to users via /help instead.
        if !commands.is_empty() {
            tracing::info!(
                "[slack] {} skill(s) available via /help (Slack requires static app-dashboard registration)",
                commands.len()
            );
        }
        Ok(())
    }

    async fn send_message(&self, channel: &ChannelId, text: &str) -> Result<()> {
        let mut body = Self::message_body(channel);
        body["text"] = json!(text);
        self.api_post("chat.postMessage", body).await?;
        Ok(())
    }

    async fn send_long_message(
        &self,
        channel: &ChannelId,
        text: &str,
        filename: Option<&str>,
    ) -> Result<()> {
        if text.len() <= self.max_message_length() {
            return self.send_message(channel, text).await;
        }

        let name = filename.unwrap_or("response.txt");
        let filetype = if name.ends_with(".md") {
            "markdown"
        } else {
            "text"
        };

        // files.upload uses multipart form, not JSON.
        let form = reqwest::multipart::Form::new()
            .text("channels", channel.channel.clone())
            .text("content", text.to_string())
            .text("filename", name.to_string())
            .text("filetype", filetype.to_string());

        let resp: Value = self
            .client
            .post("https://slack.com/api/files.upload")
            .bearer_auth(&self.bot_token)
            .multipart(form)
            .send()
            .await?
            .json()
            .await?;

        if resp.get("ok") != Some(&Value::Bool(true)) {
            tracing::warn!(
                "[slack] files.upload failed ({}), falling back to send_message",
                resp["error"].as_str().unwrap_or("unknown")
            );
            // Truncate to fit and send as a plain message.
            let truncated = if text.len() > self.max_message_length() {
                &text[..self.max_message_length()]
            } else {
                text
            };
            return self.send_message(channel, truncated).await;
        }

        Ok(())
    }

    async fn send_buttons(
        &self,
        channel: &ChannelId,
        text: &str,
        buttons: &[(String, String)],
    ) -> Result<()> {
        let button_elements: Vec<Value> = buttons
            .iter()
            .map(|(label, data)| {
                json!({
                    "type": "button",
                    "text": { "type": "plain_text", "text": label },
                    "action_id": data,
                })
            })
            .collect();

        let blocks = json!([
            {
                "type": "section",
                "text": { "type": "mrkdwn", "text": text },
            },
            {
                "type": "actions",
                "elements": button_elements,
            }
        ]);

        let mut body = Self::message_body(channel);
        body["text"] = json!(text);
        body["blocks"] = blocks;

        self.api_post("chat.postMessage", body).await?;
        Ok(())
    }

    async fn edit_message(
        &self,
        channel: &ChannelId,
        message_id: &str,
        new_text: &str,
    ) -> Result<bool> {
        let body = json!({
            "channel": channel.channel,
            "ts": message_id,
            "text": new_text,
        });
        self.api_post("chat.update", body).await?;
        Ok(true)
    }

    async fn run(&self, command_tx: mpsc::UnboundedSender<IncomingCommand>) -> Result<()> {
        tracing::info!("[slack] adapter starting with Socket Mode (tokio-tungstenite)");

        loop {
            match self.run_socket_connection(&command_tx).await {
                Ok(()) => {
                    tracing::info!("[slack] socket closed gracefully, reconnecting...");
                }
                Err(e) => {
                    tracing::warn!("[slack] socket error: {e:#}, reconnecting in 5s...");
                }
            }
            tokio::time::sleep(std::time::Duration::from_secs(5)).await;
        }
    }
}

impl SlackAdapter {
    /// Run a single Socket Mode connection until disconnect or error.
    async fn run_socket_connection(
        &self,
        command_tx: &mpsc::UnboundedSender<IncomingCommand>,
    ) -> Result<()> {
        let url = self.open_socket_url().await?;
        tracing::debug!("[slack] connecting to socket mode endpoint");

        let (ws_stream, _) = tokio_tungstenite::connect_async(&url)
            .await
            .context("websocket connect failed")?;

        let (mut sink, mut stream) = ws_stream.split();

        while let Some(msg) = stream.next().await {
            let msg = match msg {
                Ok(m) => m,
                Err(e) => {
                    tracing::warn!("[slack] websocket read error: {e}");
                    break;
                }
            };

            match msg {
                WsMessage::Text(text) => {
                    let envelope: Value = match serde_json::from_str(&text) {
                        Ok(v) => v,
                        Err(e) => {
                            tracing::debug!("[slack] invalid json envelope: {e}");
                            continue;
                        }
                    };

                    // Acknowledge the envelope before processing.
                    if let Some(id) = envelope["envelope_id"].as_str()
                        && let Err(e) = Self::ack_envelope(&mut sink, id).await
                    {
                        tracing::warn!("[slack] ack failed: {e}");
                        break;
                    }

                    // Check for disconnect request before dispatching.
                    if envelope["type"].as_str() == Some("disconnect") {
                        Self::handle_socket_event(&envelope, command_tx);
                        break;
                    }

                    Self::handle_socket_event(&envelope, command_tx);
                }
                WsMessage::Close(_) => {
                    tracing::info!("[slack] websocket close frame received");
                    break;
                }
                WsMessage::Ping(data) => {
                    let _ = sink.send(WsMessage::Pong(data)).await;
                }
                _ => {}
            }
        }

        Ok(())
    }
}