//! Gateway I/O — the ONLY place in `service/gateway/` that may perform side effects.
//!
//! Side effects here include: reading/writing config and agent state files,
//! HTTP requests to project containers (proxying, health checks, polling),
//! spawning the Matrix bot task, and the notification poller background task.

use super::config::{GatewayConfig, ProjectEntry};
pub use reqwest::Client;
use serde_json::{Value, json};
use std::collections::{BTreeMap, HashMap};
use std::path::Path;

// ── Config I/O ───────────────────────────────────────────────────────────────

/// Load gateway config from a `projects.toml` file.
pub fn load_config(path: &Path) -> Result<GatewayConfig, String> {
    let contents = std::fs::read_to_string(path)
        .map_err(|e| format!("cannot read {}: {e}", path.display()))?;
    toml::from_str(&contents).map_err(|e| format!("invalid projects.toml: {e}"))
}

/// Persist the current projects map to `<config_dir>/projects.toml`.
/// Silently ignores write errors or skips when `config_dir` is empty.
///
/// Existing `[sled_tokens]` entries are preserved so that adding or removing
/// projects via the UI does not wipe the sled authentication tokens.
pub async fn save_config(projects: &BTreeMap<String, ProjectEntry>, config_dir: &Path) {
    if config_dir.as_os_str().is_empty() {
        return;
    }
    let path = config_dir.join("projects.toml");
    let sled_tokens = tokio::fs::read_to_string(&path)
        .await
        .ok()
        .and_then(|data| toml::from_str::<GatewayConfig>(&data).ok())
        .map(|c| c.sled_tokens)
        .unwrap_or_default();
    let config = GatewayConfig {
        projects: projects.clone(),
        sled_tokens,
    };
    if let Ok(data) = toml::to_string_pretty(&config) {
        let _ = tokio::fs::write(&path, data).await;
    }
}

// ── Bot config I/O ──────────────────────────────────────────────────────────

/// Read the current raw bot.toml as key/value pairs for the configuration UI.
/// Returns `None` values if the file does not exist.
pub fn read_bot_config_raw(config_dir: &Path) -> BotConfigFields {
    let path = config_dir.join(".huskies").join("bot.toml");
    let content = match std::fs::read_to_string(&path) {
        Ok(c) => c,
        Err(_) => return BotConfigFields::default(),
    };
    let table: toml::Value = match toml::from_str(&content) {
        Ok(v) => v,
        Err(_) => return BotConfigFields::default(),
    };
    let s = |key: &str| -> Option<String> {
        table
            .get(key)
            .and_then(|v| v.as_str())
            .map(|s| s.to_string())
    };
    BotConfigFields {
        transport: s("transport").unwrap_or_else(|| "matrix".to_string()),
        homeserver: s("homeserver"),
        username: s("username"),
        password: s("password"),
        slack_bot_token: s("slack_bot_token"),
        slack_signing_secret: s("slack_signing_secret"),
    }
}

/// Raw bot.toml fields for the configuration UI.
#[derive(Default)]
pub struct BotConfigFields {
    pub transport: String,
    pub homeserver: Option<String>,
    pub username: Option<String>,
    pub password: Option<String>,
    pub slack_bot_token: Option<String>,
    pub slack_signing_secret: Option<String>,
}

/// Write a `bot.toml` from the given content string.
pub fn write_bot_config(config_dir: &Path, content: &str) -> Result<(), String> {
    let huskies_dir = config_dir.join(".huskies");
    std::fs::create_dir_all(&huskies_dir)
        .map_err(|e| format!("cannot create .huskies dir: {e}"))?;
    let path = huskies_dir.join("bot.toml");
    std::fs::write(&path, content).map_err(|e| format!("cannot write bot.toml: {e}"))
}

// ── MCP proxy I/O ───────────────────────────────────────────────────────────

/// Proxy a raw MCP request body to the given project URL.
pub async fn proxy_mcp_call(
    client: &Client,
    base_url: &str,
    request_bytes: &[u8],
) -> Result<Vec<u8>, String> {
    let mcp_url = format!("{}/mcp", base_url.trim_end_matches('/'));

    let resp = client
        .post(&mcp_url)
        .header("Content-Type", "application/json")
        .body(request_bytes.to_vec())
        .send()
        .await
        .map_err(|e| format!("failed to reach {mcp_url}: {e}"))?;

    resp.bytes()
        .await
        .map(|b| b.to_vec())
        .map_err(|e| format!("failed to read response from {mcp_url}: {e}"))
}

/// Proxy an MCP `tools/call` request to the sled with `Accept: text/event-stream`
/// and return the raw response for streaming.  No per-request timeout is applied
/// so long-running tool calls (e.g. `run_tests`, up to 1200 s) are not cut short.
///
/// The caller reads `.bytes_stream()` from the returned response and re-emits
/// each SSE `data:` line as a new event to the originating client.
pub async fn proxy_mcp_call_sse(
    client: &Client,
    base_url: &str,
    request_bytes: &[u8],
) -> Result<reqwest::Response, String> {
    let mcp_url = format!("{}/mcp", base_url.trim_end_matches('/'));
    client
        .post(&mcp_url)
        .header("Content-Type", "application/json")
        .header("Accept", "text/event-stream")
        .body(request_bytes.to_vec())
        .send()
        .await
        .map_err(|e| format!("failed to reach {mcp_url}: {e}"))
}

/// Fetch and aggregate pipeline status for a single project URL.
pub async fn fetch_one_project_pipeline_status(url: &str, client: &Client) -> Value {
    let mcp_url = format!("{}/mcp", url.trim_end_matches('/'));
    let rpc_body = json!({
        "jsonrpc": "2.0",
        "id": 1,
        "method": "tools/call",
        "params": {
            "name": "get_pipeline_status",
            "arguments": {}
        }
    });

    match client.post(&mcp_url).json(&rpc_body).send().await {
        Ok(resp) => match resp.json::<Value>().await {
            Ok(upstream) => {
                if let Some(text) = upstream
                    .get("result")
                    .and_then(|r| r.get("content"))
                    .and_then(|c| c.get(0))
                    .and_then(|c| c.get("text"))
                    .and_then(|t| t.as_str())
                {
                    match serde_json::from_str::<Value>(text) {
                        Ok(pipeline) => {
                            crate::service::pipeline::aggregate_pipeline_counts(&pipeline)
                        }
                        Err(_) => json!({ "error": "invalid pipeline JSON" }),
                    }
                } else {
                    json!({ "error": "unexpected response shape" })
                }
            }
            Err(e) => json!({ "error": format!("invalid response: {e}") }),
        },
        Err(e) => json!({ "error": format!("unreachable: {e}") }),
    }
}

/// Fetch `get_pipeline_status` from every registered project URL in parallel.
pub async fn fetch_all_project_pipeline_statuses(
    project_urls: &BTreeMap<String, String>,
    client: &Client,
) -> BTreeMap<String, Value> {
    use futures::future::join_all;

    let futures: Vec<_> = project_urls
        .iter()
        .map(|(name, url)| {
            let name = name.clone();
            let url = url.clone();
            let client = client.clone();
            async move {
                let result = fetch_one_project_pipeline_status(&url, &client).await;
                (name, result)
            }
        })
        .collect();

    join_all(futures).await.into_iter().collect()
}

/// Fetch pipeline items for a single project URL.
///
/// Returns `{ "active": [...], "backlog_count": N }` preserving individual
/// story items so the gateway UI can render them.  On error returns
/// `{ "error": "..." }`.  This is distinct from
/// `fetch_one_project_pipeline_status` which discards items and returns
/// aggregated counts.
pub async fn fetch_one_project_pipeline_items(url: &str, client: &Client) -> Value {
    let mcp_url = format!("{}/mcp", url.trim_end_matches('/'));
    let rpc_body = json!({
        "jsonrpc": "2.0",
        "id": 1,
        "method": "tools/call",
        "params": {
            "name": "get_pipeline_status",
            "arguments": {}
        }
    });

    match client.post(&mcp_url).json(&rpc_body).send().await {
        Ok(resp) => match resp.json::<Value>().await {
            Ok(upstream) => {
                if let Some(text) = upstream
                    .get("result")
                    .and_then(|r| r.get("content"))
                    .and_then(|c| c.get(0))
                    .and_then(|c| c.get("text"))
                    .and_then(|t| t.as_str())
                {
                    match serde_json::from_str::<Value>(text) {
                        Ok(pipeline) => {
                            let active = pipeline.get("active").cloned().unwrap_or(json!([]));
                            let backlog = pipeline.get("backlog").cloned().unwrap_or(json!([]));
                            let backlog_count = pipeline
                                .get("backlog_count")
                                .and_then(|n| n.as_u64())
                                .unwrap_or(0);
                            let archived = pipeline.get("archived").cloned().unwrap_or(json!([]));
                            json!({ "active": active, "backlog": backlog, "backlog_count": backlog_count, "archived": archived })
                        }
                        Err(_) => json!({ "error": "invalid pipeline JSON" }),
                    }
                } else {
                    json!({ "error": "unexpected response shape" })
                }
            }
            Err(e) => json!({ "error": format!("invalid response: {e}") }),
        },
        Err(e) => json!({ "error": format!("unreachable: {e}") }),
    }
}

/// Fetch pipeline items from every registered project URL in parallel.
///
/// Returns per-project `{ "active": [...], "backlog_count": N }` objects
/// suitable for the gateway web UI.
pub async fn fetch_all_project_pipeline_items(
    project_urls: &BTreeMap<String, String>,
    client: &Client,
) -> BTreeMap<String, Value> {
    use futures::future::join_all;

    let futures: Vec<_> = project_urls
        .iter()
        .map(|(name, url)| {
            let name = name.clone();
            let url = url.clone();
            let client = client.clone();
            async move {
                let result = fetch_one_project_pipeline_items(&url, &client).await;
                (name, result)
            }
        })
        .collect();

    join_all(futures).await.into_iter().collect()
}

/// Fetch the pipeline status from a single project for the `gateway_status` tool.
pub async fn fetch_pipeline_status_for_project(
    client: &Client,
    base_url: &str,
) -> Result<Value, String> {
    let mcp_url = format!("{}/mcp", base_url.trim_end_matches('/'));
    let rpc_body = json!({
        "jsonrpc": "2.0",
        "id": 1,
        "method": "tools/call",
        "params": {
            "name": "get_pipeline_status",
            "arguments": {}
        }
    });

    let resp = client
        .post(&mcp_url)
        .json(&rpc_body)
        .send()
        .await
        .map_err(|e| format!("failed to reach {mcp_url}: {e}"))?;

    resp.json()
        .await
        .map_err(|e| format!("invalid upstream response: {e}"))
}

/// Check health of a single project URL via the read-RPC `health.check` method.
///
/// Sends an RPC request to the project's `/mcp` endpoint.  A successful
/// response (HTTP 2xx) indicates the project container is reachable and
/// serving requests.
pub async fn check_project_health(client: &Client, base_url: &str) -> Result<bool, String> {
    let mcp_url = format!("{}/mcp", base_url.trim_end_matches('/'));
    let rpc_body = json!({
        "jsonrpc": "2.0",
        "id": 1,
        "method": "tools/list",
        "params": {}
    });
    match client.post(&mcp_url).json(&rpc_body).send().await {
        Ok(resp) => Ok(resp.status().is_success()),
        Err(e) => Err(format!("unreachable: {e}")),
    }
}

// ── Gateway MCP JSON ────────────────────────────────────────────────────────

/// Write (or overwrite) a `.mcp.json` in `config_dir` that points Claude Code
/// CLI at the gateway's own `/mcp` endpoint.
pub fn write_gateway_mcp_json(config_dir: &Path, port: u16) -> Result<(), std::io::Error> {
    let host = std::env::var("HUSKIES_HOST").unwrap_or_else(|_| "127.0.0.1".to_string());
    let url = format!("http://{host}:{port}/mcp");
    let content = json!({
        "mcpServers": {
            "huskies": {
                "type": "http",
                "url": url
            }
        }
    });
    let path = config_dir.join(".mcp.json");
    std::fs::write(&path, serde_json::to_string_pretty(&content).unwrap())?;
    crate::slog!("[gateway] Wrote {} pointing to {}", path.display(), url);
    Ok(())
}

// ── Init project I/O ────────────────────────────────────────────────────────

/// Check if a path already has a `.huskies/` directory.
pub fn has_huskies_dir(path: &Path) -> bool {
    path.join(".huskies").exists()
}

/// Create a directory (and parents) if it does not exist.
pub fn ensure_directory(path: &Path) -> Result<(), String> {
    if !path.exists() {
        std::fs::create_dir_all(path)
            .map_err(|e| format!("failed to create directory '{}': {e}", path.display()))?;
    }
    Ok(())
}

/// Scaffold a huskies project at the given path.
pub fn scaffold_project(path: &Path) -> Result<(), String> {
    crate::io::fs::scaffold::scaffold_story_kit(path, 3001)
}

/// Initialise wizard state at the given path.
pub fn init_wizard_state(path: &Path) {
    crate::io::wizard::WizardState::init_if_missing(path);
}

// ── Notification poller ─────────────────────────────────────────────────────

/// Spawn a background task that reads [`super::GatewayStatusEvent`]s from the
/// gateway broadcast channel and forwards each one to the configured rooms via
/// `transport`, formatted with a `[project-name]` prefix.
///
/// Survives broadcaster back-pressure: when the receiver falls behind
/// ([`tokio::sync::broadcast::error::RecvError::Lagged`]), the task
/// re-subscribes so it does not permanently stall.
///
/// The task exits cleanly when the broadcast channel is closed (i.e. when
/// `GatewayState` is dropped).
pub fn spawn_gateway_broadcaster_forwarder(
    transport: std::sync::Arc<dyn crate::chat::ChatTransport>,
    room_ids: Vec<String>,
    mut rx: tokio::sync::broadcast::Receiver<super::GatewayStatusEvent>,
) {
    tokio::spawn(async move {
        loop {
            match rx.recv().await {
                Ok(event) => {
                    let (plain, html) =
                        super::polling::format_gateway_event(&event.project, &event.event);
                    for room_id in &room_ids {
                        if let Err(e) = transport.send_message(room_id, &plain, &html).await {
                            crate::slog!(
                                "[gateway-forwarder] Failed to forward event to {room_id}: {e}"
                            );
                        }
                    }
                }
                Err(tokio::sync::broadcast::error::RecvError::Lagged(n)) => {
                    crate::slog!(
                        "[gateway-forwarder] Broadcaster lagged by {n} messages; resubscribing"
                    );
                    rx = rx.resubscribe();
                }
                Err(tokio::sync::broadcast::error::RecvError::Closed) => {
                    crate::slog!("[gateway-forwarder] Broadcast channel closed; forwarder exiting");
                    break;
                }
            }
        }
    });
}

/// Spawn a background task that polls events from all project servers.
pub fn spawn_gateway_notification_poller(
    transport: std::sync::Arc<dyn crate::chat::ChatTransport>,
    room_ids: Vec<String>,
    project_urls: BTreeMap<String, String>,
    poll_interval_secs: u64,
) {
    tokio::spawn(async move {
        let client = Client::builder()
            .timeout(std::time::Duration::from_secs(10))
            .build()
            .unwrap_or_else(|_| Client::new());
        let interval = std::time::Duration::from_secs(poll_interval_secs.max(1));

        let mut last_ts: HashMap<String, u64> = project_urls
            .keys()
            .map(|name| (name.clone(), 0u64))
            .collect();

        loop {
            for (project_name, base_url) in &project_urls {
                let since = last_ts.get(project_name).copied().unwrap_or(0);
                let url = format!("{base_url}/api/events?since={since}");

                let response = match client.get(&url).send().await {
                    Ok(r) => r,
                    Err(e) => {
                        crate::slog!(
                            "[gateway-poller] {project_name}: unreachable ({e}); skipping"
                        );
                        continue;
                    }
                };

                let events: Vec<crate::service::events::StoredEvent> = match response.json().await {
                    Ok(v) => v,
                    Err(e) => {
                        crate::slog!(
                            "[gateway-poller] {project_name}: failed to parse events: {e}"
                        );
                        continue;
                    }
                };

                for event in &events {
                    let ts = event.timestamp_ms();
                    if ts > *last_ts.get(project_name).unwrap_or(&0) {
                        last_ts.insert(project_name.clone(), ts);
                    }

                    let (plain, html) = super::polling::format_gateway_event(project_name, event);
                    for room_id in &room_ids {
                        if let Err(e) = transport.send_message(room_id, &plain, &html).await {
                            crate::slog!(
                                "[gateway-poller] Failed to send notification to {room_id}: {e}"
                            );
                        }
                    }
                }
            }

            tokio::time::sleep(interval).await;
        }
    });
}

// ── Gateway bot spawn ───────────────────────────────────────────────────────

/// Re-export type alias for the active project lock.
pub type ActiveProject = std::sync::Arc<tokio::sync::RwLock<String>>;

/// Attempt to spawn the Matrix bot against the gateway config directory.
///
/// `gateway_event_tx` — when `Some`, the bot will subscribe to the gateway
/// status broadcaster and forward [`super::GatewayStatusEvent`]s to its
/// configured Matrix rooms with a `[project-name]` prefix.
///
/// Returns `(abort_handle, shutdown_tx)`.  The caller **must** hold
/// `shutdown_tx` for the bot's lifetime and send `Some(ShutdownReason)` on it
/// before process exit so the bot can announce "going offline" to its rooms.
#[allow(clippy::too_many_arguments)]
pub fn spawn_gateway_bot(
    config_dir: &Path,
    active_project: ActiveProject,
    gateway_project_urls: BTreeMap<String, String>,
    gateway_projects_store: std::sync::Arc<tokio::sync::RwLock<BTreeMap<String, ProjectEntry>>>,
    port: u16,
    gateway_event_tx: Option<tokio::sync::broadcast::Sender<super::GatewayStatusEvent>>,
    perm_rx: std::sync::Arc<
        tokio::sync::Mutex<
            tokio::sync::mpsc::UnboundedReceiver<crate::http::context::PermissionForward>,
        >,
    >,
) -> (
    Option<tokio::task::AbortHandle>,
    tokio::sync::watch::Sender<Option<crate::rebuild::ShutdownReason>>,
) {
    use crate::agents::AgentPool;
    use crate::services::Services;
    use tokio::sync::broadcast;

    let (watcher_tx, _) = broadcast::channel::<crate::io::watcher::WatcherEvent>(16);
    let (shutdown_tx, shutdown_rx) =
        tokio::sync::watch::channel::<Option<crate::rebuild::ShutdownReason>>(None);
    // shutdown_tx is intentionally NOT forgotten — the caller holds it and
    // sends Some(reason) on gateway shutdown so the bot announces "going offline".

    let agents = std::sync::Arc::new(AgentPool::new(port, watcher_tx.clone()));

    // Read the gateway's bot.toml so display_name, ambient_rooms, and
    // permission_timeout_secs are honoured (matches the standard-mode
    // initialisation in main.rs). Previously this path hardcoded
    // `bot_name = "Assistant"` regardless of bot.toml's display_name,
    // breaking @-addressing for users who configured a different name.
    let bot_cfg = crate::chat::transport::matrix::BotConfig::load(config_dir);

    let services = std::sync::Arc::new(Services {
        project_root: config_dir.to_path_buf(),
        status: agents.status_broadcaster(),
        agents,
        bot_name: bot_cfg
            .as_ref()
            .and_then(|c| c.display_name.clone())
            .unwrap_or_else(|| "Assistant".to_string()),
        bot_user_id: String::new(),
        ambient_rooms: std::sync::Arc::new(std::sync::Mutex::new(
            bot_cfg
                .as_ref()
                .map(|c| c.ambient_rooms.iter().cloned().collect())
                .unwrap_or_default(),
        )),
        perm_rx,
        pending_perm_replies: std::sync::Arc::new(tokio::sync::Mutex::new(
            std::collections::HashMap::new(),
        )),
        permission_timeout_secs: bot_cfg
            .as_ref()
            .map(|c| c.permission_timeout_secs)
            .unwrap_or(120),
        chat_dispatcher: std::sync::Arc::new(crate::chat::dispatcher::ChatDispatcher::new(
            bot_cfg
                .as_ref()
                .map(|c| c.coalesce_window_ms)
                .unwrap_or(1_500),
        )),
    });

    let timer_store = std::sync::Arc::new(crate::service::timer::TimerStore::load(
        config_dir.join(".huskies").join("timers.json"),
    ));
    let gateway_event_rx = gateway_event_tx.map(|tx| tx.subscribe());
    let handle = crate::chat::transport::matrix::spawn_bot(
        config_dir,
        watcher_tx,
        services,
        shutdown_rx,
        Some(active_project),
        gateway_project_urls,
        Some(gateway_projects_store),
        timer_store,
        gateway_event_rx,
    );
    (handle, shutdown_tx)
}

// ── Tests ────────────────────────────────────────────────────────────────────

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

    /// Regression test for story 918: `spawn_gateway_bot` must return a live
    /// `shutdown_tx` (not one dropped via `std::mem::forget`) so that callers
    /// can signal `Some(reason)` and the bot's shutdown watcher receives it.
    #[tokio::test]
    async fn spawn_gateway_bot_shutdown_tx_not_forgotten() {
        let tmp = tempfile::tempdir().unwrap();
        let active = std::sync::Arc::new(tokio::sync::RwLock::new("proj".to_string()));
        let (event_tx, _) = tokio::sync::broadcast::channel(4);

        let (_perm_tx, perm_rx) =
            tokio::sync::mpsc::unbounded_channel::<crate::http::context::PermissionForward>();
        let perm_rx = std::sync::Arc::new(tokio::sync::Mutex::new(perm_rx));
        let projects_store =
            std::sync::Arc::new(tokio::sync::RwLock::new(std::collections::BTreeMap::new()));
        let (handle, shutdown_tx) = spawn_gateway_bot(
            tmp.path(),
            active,
            std::collections::BTreeMap::new(),
            projects_store,
            3001,
            Some(event_tx),
            perm_rx,
        );

        // No bot.toml in tmp → no abort handle spawned.
        assert!(handle.is_none());

        // The shutdown_tx must be live: subscribe a receiver and verify that
        // sending Some(reason) is observed — this would fail if the sender
        // had been forgotten (channel closed, send returns Err).
        let rx = shutdown_tx.subscribe();
        shutdown_tx
            .send(Some(crate::rebuild::ShutdownReason::Manual))
            .expect("shutdown_tx must not be closed (was previously std::mem::forget'd)");
        assert_eq!(
            *rx.borrow(),
            Some(crate::rebuild::ShutdownReason::Manual),
            "shutdown receiver must see the Manual reason"
        );
    }
}