//! Gateway HTTP handlers — thin transport shells for the gateway service.
//!
//! Each handler calls `service::gateway::*` for business logic and formats
//! the response. No inline business logic, no `reqwest`, no filesystem access.

use crate::service::gateway::{self, GatewayState};
use futures::StreamExt;
use poem::handler;
use poem::http::StatusCode;
use poem::web::Path as PoemPath;
use poem::web::Query;
use poem::web::websocket::{Message as WsMessage, WebSocket};
use poem::web::{Data, Json};
use poem::{Body, Request, Response};
use serde::{Deserialize, Serialize};
use serde_json::{Value, json};
use std::collections::BTreeMap;
use std::sync::Arc;

// ── JSON-RPC types ──────────────────────────────────────────────────────────

/// JSON-RPC request.
#[derive(Deserialize)]
struct JsonRpcRequest {
    jsonrpc: String,
    id: Option<Value>,
    method: String,
    #[serde(default)]
    params: Value,
}

/// JSON-RPC response.
#[derive(Serialize)]
pub(crate) struct JsonRpcResponse {
    jsonrpc: &'static str,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub(crate) id: Option<Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub(crate) result: Option<Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub(crate) error: Option<JsonRpcError>,
}

#[derive(Debug, Serialize)]
pub(crate) struct JsonRpcError {
    code: i64,
    pub(crate) message: String,
}

impl JsonRpcResponse {
    pub(crate) fn success(id: Option<Value>, result: Value) -> Self {
        Self {
            jsonrpc: "2.0",
            id,
            result: Some(result),
            error: None,
        }
    }

    pub(crate) fn error(id: Option<Value>, code: i64, message: String) -> Self {
        Self {
            jsonrpc: "2.0",
            id,
            result: None,
            error: Some(JsonRpcError { code, message }),
        }
    }
}

fn to_json_response(resp: JsonRpcResponse) -> Response {
    let body = serde_json::to_vec(&resp).unwrap_or_default();
    Response::builder()
        .status(StatusCode::OK)
        .header("Content-Type", "application/json")
        .body(Body::from(body))
}

// ── MCP tool definitions ─────────────────────────────────────────���──────────

/// Gateway-specific MCP tools exposed alongside the proxied tools.
const GATEWAY_TOOLS: &[&str] = &[
    "switch_project",
    "gateway_status",
    "gateway_health",
    "init_project",
    "aggregate_pipeline_status",
];

/// Gateway tool definitions.
pub(crate) fn gateway_tool_definitions() -> Vec<Value> {
    vec![
        json!({
            "name": "switch_project",
            "description": "Switch the active project. All subsequent MCP tool calls will be proxied to this project's container.",
            "inputSchema": {
                "type": "object",
                "properties": {
                    "project": {
                        "type": "string",
                        "description": "Name of the project to switch to (must exist in projects.toml)"
                    }
                },
                "required": ["project"]
            }
        }),
        json!({
            "name": "gateway_status",
            "description": "Show pipeline status for the active project by proxying the get_pipeline_status tool call.",
            "inputSchema": {
                "type": "object",
                "properties": {}
            }
        }),
        json!({
            "name": "gateway_health",
            "description": "Health check aggregation across all registered projects. Returns the health status of every project container.",
            "inputSchema": {
                "type": "object",
                "properties": {}
            }
        }),
        json!({
            "name": "init_project",
            "description": "Initialize a new huskies project at the given path by scaffolding .huskies/ and related files — the same as running `huskies init <path>`. Prefer this tool over asking the user to run the CLI. If `name` and `url` are supplied the project is also registered in projects.toml so switch_project can reach it immediately.",
            "inputSchema": {
                "type": "object",
                "properties": {
                    "path": {
                        "type": "string",
                        "description": "Absolute filesystem path to the project directory to initialise. The directory is created if it does not exist."
                    },
                    "name": {
                        "type": "string",
                        "description": "Optional: short name to register the project under in projects.toml (e.g. 'my-app'). Requires `url`."
                    },
                    "url": {
                        "type": "string",
                        "description": "Optional: base URL of the huskies container that will serve this project (e.g. 'http://my-app:3001'). Required when `name` is given."
                    }
                },
                "required": ["path"]
            }
        }),
        json!({
            "name": "aggregate_pipeline_status",
            "description": "Fetch pipeline status from ALL registered projects in parallel and return an aggregated report. For each project: stage counts (backlog/current/qa/merge/done) and a list of blocked or failing items with triage detail. Unreachable projects are included with an error state rather than failing the whole call.",
            "inputSchema": {
                "type": "object",
                "properties": {}
            }
        }),
    ]
}

// ── MCP POST handler ────────────────────────────────────────────────────────

/// Main MCP POST handler for the gateway. Intercepts gateway-specific tools and
/// proxies everything else to the active project's container.
#[handler]
pub async fn gateway_mcp_post_handler(
    req: &Request,
    body: Body,
    state: Data<&Arc<GatewayState>>,
) -> Response {
    let content_type = req.header("content-type").unwrap_or("");
    if !content_type.is_empty() && !content_type.contains("application/json") {
        return to_json_response(JsonRpcResponse::error(
            None,
            -32700,
            "Unsupported Content-Type; expected application/json".into(),
        ));
    }

    let bytes = match body.into_bytes().await {
        Ok(b) => b,
        Err(_) => {
            return to_json_response(JsonRpcResponse::error(None, -32700, "Parse error".into()));
        }
    };

    let rpc: JsonRpcRequest = match serde_json::from_slice(&bytes) {
        Ok(r) => r,
        Err(_) => {
            return to_json_response(JsonRpcResponse::error(None, -32700, "Parse error".into()));
        }
    };

    if rpc.jsonrpc != "2.0" {
        return to_json_response(JsonRpcResponse::error(
            rpc.id,
            -32600,
            "Invalid JSON-RPC version".into(),
        ));
    }

    if rpc.id.is_none() || rpc.id.as_ref() == Some(&Value::Null) {
        if rpc.method.starts_with("notifications/") {
            return Response::builder()
                .status(StatusCode::ACCEPTED)
                .body(Body::empty());
        }
        return to_json_response(JsonRpcResponse::error(None, -32600, "Missing id".into()));
    }

    match rpc.method.as_str() {
        "initialize" => to_json_response(handle_initialize(rpc.id)),
        "tools/list" => match handle_tools_list(&state, rpc.id.clone()).await {
            Ok(resp) => to_json_response(resp),
            Err(e) => to_json_response(JsonRpcResponse::error(rpc.id, -32603, e)),
        },
        "tools/call" => {
            let tool_name = rpc
                .params
                .get("name")
                .and_then(|v| v.as_str())
                .unwrap_or("");

            if GATEWAY_TOOLS.contains(&tool_name) {
                to_json_response(
                    handle_gateway_tool(tool_name, &rpc.params, &state, rpc.id.clone()).await,
                )
            } else {
                proxy_and_respond(&state, &bytes, rpc.id).await
            }
        }
        _ => proxy_and_respond(&state, &bytes, rpc.id).await,
    }
}

/// Proxy a request to the active project and format the response.
async fn proxy_and_respond(state: &GatewayState, bytes: &[u8], id: Option<Value>) -> Response {
    let url = match state.active_url().await {
        Ok(u) => u,
        Err(e) => {
            return to_json_response(JsonRpcResponse::error(id, -32603, e.to_string()));
        }
    };
    match gateway::io::proxy_mcp_call(&state.client, &url, bytes).await {
        Ok(resp_body) => Response::builder()
            .status(StatusCode::OK)
            .header("Content-Type", "application/json")
            .body(Body::from(resp_body)),
        Err(e) => to_json_response(JsonRpcResponse::error(
            id,
            -32603,
            format!("proxy error: {e}"),
        )),
    }
}

/// GET handler — method not allowed.
#[handler]
pub async fn gateway_mcp_get_handler() -> Response {
    Response::builder()
        .status(StatusCode::METHOD_NOT_ALLOWED)
        .body(Body::empty())
}

// ── Protocol handlers ───────────────────────────────────────────────────────

fn handle_initialize(id: Option<Value>) -> JsonRpcResponse {
    JsonRpcResponse::success(
        id,
        json!({
            "protocolVersion": "2025-03-26",
            "capabilities": { "tools": {} },
            "serverInfo": {
                "name": "huskies-gateway",
                "version": "1.0.0"
            }
        }),
    )
}

/// Fetch tools/list from the active project and merge in gateway tools.
async fn handle_tools_list(
    state: &GatewayState,
    id: Option<Value>,
) -> Result<JsonRpcResponse, String> {
    let url = state.active_url().await.map_err(|e| e.to_string())?;

    let resp_json = gateway::io::fetch_tools_list(&state.client, &url).await?;

    let mut tools: Vec<Value> = resp_json
        .get("result")
        .and_then(|r| r.get("tools"))
        .and_then(|t| t.as_array())
        .cloned()
        .unwrap_or_default();

    let mut all_tools = gateway_tool_definitions();
    all_tools.append(&mut tools);

    Ok(JsonRpcResponse::success(id, json!({ "tools": all_tools })))
}

// ── Gateway tool dispatch ──────────────────────────────────────────────��────

/// Dispatch a gateway-specific tool call.
async fn handle_gateway_tool(
    tool_name: &str,
    params: &Value,
    state: &GatewayState,
    id: Option<Value>,
) -> JsonRpcResponse {
    match tool_name {
        "switch_project" => handle_switch_project_tool(params, state, id).await,
        "gateway_status" => handle_gateway_status_tool(state, id).await,
        "gateway_health" => handle_gateway_health_tool(state, id).await,
        "init_project" => handle_init_project_tool(params, state, id).await,
        "aggregate_pipeline_status" => handle_aggregate_pipeline_status_tool(state, id).await,
        _ => JsonRpcResponse::error(id, -32601, format!("Unknown gateway tool: {tool_name}")),
    }
}

async fn handle_switch_project_tool(
    params: &Value,
    state: &GatewayState,
    id: Option<Value>,
) -> JsonRpcResponse {
    let project = params
        .get("arguments")
        .and_then(|a| a.get("project"))
        .or_else(|| params.get("project"))
        .and_then(|v| v.as_str())
        .unwrap_or("");

    match gateway::switch_project(state, project).await {
        Ok(url) => JsonRpcResponse::success(
            id,
            json!({
                "content": [{
                    "type": "text",
                    "text": format!("Switched to project '{project}' ({url})")
                }]
            }),
        ),
        Err(e) => JsonRpcResponse::error(id, -32602, e.to_string()),
    }
}

async fn handle_gateway_status_tool(state: &GatewayState, id: Option<Value>) -> JsonRpcResponse {
    let active = state.active_project.read().await.clone();
    let url = match state.active_url().await {
        Ok(u) => u,
        Err(e) => return JsonRpcResponse::error(id.clone(), -32603, e.to_string()),
    };

    match gateway::io::fetch_pipeline_status_for_project(&state.client, &url).await {
        Ok(upstream) => {
            let pipeline = upstream.get("result").cloned().unwrap_or(json!(null));
            JsonRpcResponse::success(
                id,
                json!({
                    "content": [{
                        "type": "text",
                        "text": format!(
                            "Pipeline status for '{active}':\n{}",
                            serde_json::to_string_pretty(&pipeline).unwrap_or_default()
                        )
                    }]
                }),
            )
        }
        Err(e) => JsonRpcResponse::error(id, -32603, e),
    }
}

async fn handle_gateway_health_tool(state: &GatewayState, id: Option<Value>) -> JsonRpcResponse {
    let mut results = BTreeMap::new();

    let project_entries: Vec<(String, String)> = state
        .projects
        .read()
        .await
        .iter()
        .map(|(n, e)| (n.clone(), e.url.clone()))
        .collect();
    for (name, url) in &project_entries {
        let status = match gateway::io::check_project_health(&state.client, url).await {
            Ok(true) => "healthy".to_string(),
            Ok(false) => "unhealthy".to_string(),
            Err(e) => e,
        };
        results.insert(name.clone(), status);
    }

    let active = state.active_project.read().await.clone();
    JsonRpcResponse::success(
        id,
        json!({
            "content": [{
                "type": "text",
                "text": format!(
                    "Health check (active: '{active}'):\n{}",
                    results.iter()
                        .map(|(name, status)| format!("  {name}: {status}"))
                        .collect::<Vec<_>>()
                        .join("\n")
                )
            }]
        }),
    )
}

async fn handle_init_project_tool(
    params: &Value,
    state: &GatewayState,
    id: Option<Value>,
) -> JsonRpcResponse {
    let args = params.get("arguments").unwrap_or(params);

    let path_str = args.get("path").and_then(|v| v.as_str()).unwrap_or("");
    let name = args.get("name").and_then(|v| v.as_str());
    let url = args.get("url").and_then(|v| v.as_str());

    match gateway::init_project(state, path_str, name, url).await {
        Ok(registered_name) => {
            let next_steps = if let Some(ref n) = registered_name {
                format!(
                    "Project registered as '{n}' in projects.toml.\n\
                     Next steps:\n\
                     1. Start a huskies server at '{path_str}' \
                        (e.g. `huskies {path_str}` or via Docker).\n\
                     2. Call switch_project with name='{n}' to make it active.\n\
                     3. Call wizard_status to begin the setup wizard."
                )
            } else {
                format!(
                    "Next steps:\n\
                     1. Start a huskies server at '{path_str}' \
                        (e.g. `huskies {path_str}` or via Docker).\n\
                     2. Register the project: call init_project again with name and url \
                        parameters, or add it to projects.toml manually.\n\
                     3. Call switch_project and then wizard_status to begin the setup wizard.\n\n\
                     Note: wizard_* MCP tools require a running huskies server for the project."
                )
            };

            JsonRpcResponse::success(
                id,
                json!({
                    "content": [{
                        "type": "text",
                        "text": format!("Successfully initialised huskies project at '{path_str}'.\n\n{next_steps}")
                    }]
                }),
            )
        }
        Err(e) => {
            let code = match &e {
                gateway::Error::Config(_) => -32602,
                gateway::Error::DuplicateToken(_) => -32602,
                _ => -32603,
            };
            JsonRpcResponse::error(id, code, e.to_string())
        }
    }
}

async fn handle_aggregate_pipeline_status_tool(
    state: &GatewayState,
    id: Option<Value>,
) -> JsonRpcResponse {
    let project_urls: BTreeMap<String, String> = state
        .projects
        .read()
        .await
        .iter()
        .map(|(name, entry)| (name.clone(), entry.url.clone()))
        .collect();

    let statuses =
        gateway::io::fetch_all_project_pipeline_statuses(&project_urls, &state.client).await;
    let active = state.active_project.read().await.clone();

    JsonRpcResponse::success(
        id,
        json!({
            "content": [{
                "type": "text",
                "text": format!(
                    "Aggregate pipeline status (active: '{active}'):\n{}",
                    serde_json::to_string_pretty(&statuses).unwrap_or_default()
                )
            }],
            "projects": statuses,
            "active": active,
        }),
    )
}

// ── Agent REST handlers ─────────────────────────────────────────────────────

/// `GET /gateway/mode` — returns `{"mode":"gateway"}`.
#[handler]
pub async fn gateway_mode_handler() -> Response {
    let body = json!({ "mode": "gateway" });
    Response::builder()
        .status(StatusCode::OK)
        .header("Content-Type", "application/json")
        .body(Body::from(serde_json::to_vec(&body).unwrap_or_default()))
}

/// `POST /gateway/tokens` — generate a one-time join token.
#[handler]
pub async fn gateway_generate_token_handler(state: Data<&Arc<GatewayState>>) -> Response {
    let token = gateway::generate_join_token(&state).await;
    let body = json!({ "token": token });
    Response::builder()
        .status(StatusCode::OK)
        .header("Content-Type", "application/json")
        .body(Body::from(serde_json::to_vec(&body).unwrap_or_default()))
}

/// Request body sent by a build agent when registering with the gateway.
#[derive(Deserialize)]
struct RegisterAgentRequest {
    token: String,
    label: String,
    address: String,
}

/// `POST /gateway/register` — build agent presents its join token and registers.
#[handler]
pub async fn gateway_register_agent_handler(
    body: Body,
    state: Data<&Arc<GatewayState>>,
) -> Response {
    let bytes = match body.into_bytes().await {
        Ok(b) => b,
        Err(_) => {
            return Response::builder()
                .status(StatusCode::BAD_REQUEST)
                .body(Body::from("could not read request body"));
        }
    };

    let req: RegisterAgentRequest = match serde_json::from_slice(&bytes) {
        Ok(r) => r,
        Err(_) => {
            return Response::builder()
                .status(StatusCode::BAD_REQUEST)
                .body(Body::from("invalid JSON body"));
        }
    };

    match gateway::register_agent(&state, &req.token, req.label, req.address).await {
        Ok(agent) => {
            let body = serde_json::to_vec(&agent).unwrap_or_default();
            Response::builder()
                .status(StatusCode::OK)
                .header("Content-Type", "application/json")
                .body(Body::from(body))
        }
        Err(_) => Response::builder()
            .status(StatusCode::UNAUTHORIZED)
            .body(Body::from("invalid or already-used join token")),
    }
}

/// `GET /gateway/agents` — list all registered build agents.
#[handler]
pub async fn gateway_list_agents_handler(state: Data<&Arc<GatewayState>>) -> Response {
    let agents = state.joined_agents.read().await.clone();
    let body = serde_json::to_vec(&agents).unwrap_or_default();
    Response::builder()
        .status(StatusCode::OK)
        .header("Content-Type", "application/json")
        .body(Body::from(body))
}

/// `DELETE /gateway/agents/:id` — remove a registered build agent.
#[handler]
pub async fn gateway_remove_agent_handler(
    PoemPath(id): PoemPath<String>,
    state: Data<&Arc<GatewayState>>,
) -> Response {
    if gateway::remove_agent(&state, &id).await {
        Response::builder()
            .status(StatusCode::NO_CONTENT)
            .body(Body::empty())
    } else {
        Response::builder()
            .status(StatusCode::NOT_FOUND)
            .body(Body::from("agent not found"))
    }
}

/// Request body for assigning an agent to a project.
#[derive(Deserialize)]
struct AssignAgentRequest {
    project: Option<String>,
}

/// `POST /gateway/agents/:id/assign` — assign or unassign an agent to a project.
#[handler]
pub async fn gateway_assign_agent_handler(
    PoemPath(id): PoemPath<String>,
    body: Json<AssignAgentRequest>,
    state: Data<&Arc<GatewayState>>,
) -> Response {
    match gateway::assign_agent(&state, &id, body.0.project).await {
        Ok(agent) => {
            let body = serde_json::to_vec(&agent).unwrap_or_default();
            Response::builder()
                .status(StatusCode::OK)
                .header("Content-Type", "application/json")
                .body(Body::from(body))
        }
        Err(gateway::Error::ProjectNotFound(msg)) => Response::builder()
            .status(StatusCode::BAD_REQUEST)
            .body(Body::from(msg)),
        Err(_) => Response::builder()
            .status(StatusCode::NOT_FOUND)
            .body(Body::from("agent not found")),
    }
}

/// `POST /gateway/agents/:id/heartbeat` — update an agent's last-seen timestamp.
#[handler]
pub async fn gateway_heartbeat_handler(
    PoemPath(id): PoemPath<String>,
    state: Data<&Arc<GatewayState>>,
) -> Response {
    if gateway::heartbeat_agent(&state, &id).await {
        Response::builder()
            .status(StatusCode::NO_CONTENT)
            .body(Body::empty())
    } else {
        Response::builder()
            .status(StatusCode::NOT_FOUND)
            .body(Body::from("agent not found"))
    }
}

// ── Event-push WebSocket handler ────────────────────────────────────────────

/// Query parameters accepted on the `/gateway/events/push` WebSocket upgrade.
#[derive(Deserialize)]
struct EventPushQueryParams {
    /// One-time join token generated by `POST /gateway/tokens`.
    token: Option<String>,
    /// The project name this node represents (e.g. `"huskies"`).
    project: Option<String>,
}

/// `GET /gateway/events/push` — WebSocket endpoint for project nodes to push
/// [`StatusEvent`] frames to the gateway.
///
/// # Authentication
///
/// The connecting node must supply a valid one-time join token via the `token`
/// query parameter, obtained from `POST /gateway/tokens`.  The token is
/// consumed on the first successful upgrade — the connection itself is then
/// kept open indefinitely.
///
/// # Protocol
///
/// Each message from the project node must be a JSON-encoded
/// [`crate::service::events::StoredEvent`].  The gateway fan-outs the event
/// (tagged with the project name) to all current local subscribers.
///
/// The server does not send data back; clients should treat any close frame
/// as a signal to reconnect with exponential back-off (see docs/gateway-protocol.html).
///
/// # Reconnect-with-backoff
///
/// Project nodes MUST reconnect on disconnect.  Recommended policy:
///
/// - Initial retry delay: **1 s**
/// - Back-off multiplier: **2×** per attempt
/// - Max delay cap: **60 s**
/// - Jitter: add ±10 % to the delay to avoid thundering herds
#[handler]
pub async fn gateway_event_push_handler(
    ws: WebSocket,
    state: Data<&Arc<GatewayState>>,
    Query(params): Query<EventPushQueryParams>,
) -> poem::Response {
    // ── Authentication (pre-upgrade) ─────────────────────────────────────
    let token = match params.token {
        Some(t) if !t.is_empty() => t,
        _ => {
            return poem::Response::builder()
                .status(StatusCode::UNAUTHORIZED)
                .body("token query parameter required");
        }
    };

    let project = match params.project {
        Some(p) if !p.is_empty() => p,
        _ => {
            return poem::Response::builder()
                .status(StatusCode::BAD_REQUEST)
                .body("project query parameter required");
        }
    };

    // Validate and consume the one-time token.
    {
        let mut tokens = state.pending_tokens.write().await;
        if !tokens.contains_key(&token) {
            return poem::Response::builder()
                .status(StatusCode::UNAUTHORIZED)
                .body("invalid or already-used join token");
        }
        tokens.remove(&token);
    }

    // ── WebSocket upgrade ────────────────────────────────────────────────
    use poem::IntoResponse as _;
    let state = Arc::clone(&state);
    ws.on_upgrade(move |socket| async move {
        let (_, mut stream) = socket.split();

        crate::slog!(
            "[gateway] Project node '{}' connected to event-push endpoint",
            project
        );

        while let Some(msg) = stream.next().await {
            let text = match msg {
                Ok(WsMessage::Text(t)) => t,
                Ok(WsMessage::Close(_)) | Err(_) => break,
                _ => continue,
            };

            match serde_json::from_str::<crate::service::events::StoredEvent>(&text) {
                Ok(event) => {
                    gateway::broadcast_status_event(&state, project.clone(), event);
                }
                Err(e) => {
                    crate::slog!(
                        "[gateway] event-push: invalid frame from '{}': {e}",
                        project
                    );
                }
            }
        }

        crate::slog!(
            "[gateway] Project node '{}' disconnected from event-push endpoint",
            project
        );
    })
    .into_response()
}

// ── Health handler ──────────────────────────────────────────────────────────

/// HTTP GET `/health` handler for the gateway.
#[handler]
pub async fn gateway_health_handler(state: Data<&Arc<GatewayState>>) -> Response {
    let (all_healthy, statuses) = gateway::health_check_all(&state).await;

    let body = json!({
        "status": if all_healthy { "ok" } else { "degraded" },
        "projects": statuses,
    });

    let status = if all_healthy {
        StatusCode::OK
    } else {
        StatusCode::SERVICE_UNAVAILABLE
    };
    Response::builder()
        .status(status)
        .header("Content-Type", "application/json")
        .body(Body::from(serde_json::to_vec(&body).unwrap_or_default()))
}

// ── Gateway Web UI ──────────────────────────────────────────────────────────

/// `GET /api/gateway` — returns the list of registered projects and the active project.
#[handler]
pub async fn gateway_api_handler(state: Data<&Arc<GatewayState>>) -> Response {
    let active = state.active_project.read().await.clone();
    let projects: Vec<Value> = state
        .projects
        .read()
        .await
        .iter()
        .map(|(name, entry)| {
            json!({
                "name": name,
                "url": entry.url,
            })
        })
        .collect();

    let body = json!({ "active": active, "projects": projects });
    Response::builder()
        .status(StatusCode::OK)
        .header("Content-Type", "application/json")
        .body(Body::from(serde_json::to_vec(&body).unwrap_or_default()))
}

/// Request body for `POST /api/gateway/switch`.
#[derive(Deserialize)]
struct SwitchRequest {
    project: String,
}

/// `POST /api/gateway/switch` — switch the active project.
#[handler]
pub async fn gateway_switch_handler(
    state: Data<&Arc<GatewayState>>,
    body: Json<SwitchRequest>,
) -> Response {
    match gateway::switch_project(&state, &body.project).await {
        Ok(_) => {
            let body_val = json!({ "ok": true });
            Response::builder()
                .status(StatusCode::OK)
                .header("Content-Type", "application/json")
                .body(Body::from(
                    serde_json::to_vec(&body_val).unwrap_or_default(),
                ))
        }
        Err(e) => {
            let body_val = json!({ "ok": false, "error": e.to_string() });
            Response::builder()
                .status(StatusCode::BAD_REQUEST)
                .header("Content-Type", "application/json")
                .body(Body::from(
                    serde_json::to_vec(&body_val).unwrap_or_default(),
                ))
        }
    }
}

// ── Project management API ──────────────────────────────────────────────────

/// Request body for adding a new project.
#[derive(Deserialize)]
struct AddProjectRequest {
    name: String,
    url: String,
}

/// `POST /api/gateway/projects` — add a new project.
#[handler]
pub async fn gateway_add_project_handler(
    state: Data<&Arc<GatewayState>>,
    body: Json<AddProjectRequest>,
) -> Response {
    match gateway::add_project(&state, &body.name, &body.url).await {
        Ok(()) => {
            let name = body.0.name.trim().to_string();
            let url = body.0.url.trim().to_string();
            let body_val = json!({ "name": name, "url": url });
            Response::builder()
                .status(StatusCode::OK)
                .header("Content-Type", "application/json")
                .body(Body::from(
                    serde_json::to_vec(&body_val).unwrap_or_default(),
                ))
        }
        Err(gateway::Error::DuplicateToken(_)) => Response::builder()
            .status(StatusCode::CONFLICT)
            .body(Body::from(format!(
                "project '{}' already exists",
                body.0.name.trim()
            ))),
        Err(e) => Response::builder()
            .status(StatusCode::BAD_REQUEST)
            .body(Body::from(e.to_string())),
    }
}

/// `DELETE /api/gateway/projects/:name` — remove a project.
#[handler]
pub async fn gateway_remove_project_handler(
    PoemPath(name): PoemPath<String>,
    state: Data<&Arc<GatewayState>>,
) -> Response {
    match gateway::remove_project(&state, &name).await {
        Ok(()) => Response::builder()
            .status(StatusCode::NO_CONTENT)
            .body(Body::empty()),
        Err(gateway::Error::ProjectNotFound(msg)) => Response::builder()
            .status(StatusCode::NOT_FOUND)
            .body(Body::from(msg)),
        Err(e) => Response::builder()
            .status(StatusCode::BAD_REQUEST)
            .body(Body::from(e.to_string())),
    }
}

// ── Bot configuration API ───────────────────────────────────────────────────

/// Request/response body for the bot configuration API.
#[derive(Deserialize, Serialize, Default)]
pub(crate) struct BotConfigPayload {
    transport: String,
    homeserver: Option<String>,
    username: Option<String>,
    password: Option<String>,
    slack_bot_token: Option<String>,
    slack_signing_secret: Option<String>,
}

/// `GET /api/gateway/bot-config` — return current bot.toml fields as JSON.
#[handler]
pub async fn gateway_bot_config_get_handler(state: Data<&Arc<GatewayState>>) -> Response {
    let fields = gateway::io::read_bot_config_raw(&state.config_dir);
    let payload = BotConfigPayload {
        transport: fields.transport,
        homeserver: fields.homeserver,
        username: fields.username,
        password: fields.password,
        slack_bot_token: fields.slack_bot_token,
        slack_signing_secret: fields.slack_signing_secret,
    };
    Response::builder()
        .status(StatusCode::OK)
        .header("Content-Type", "application/json")
        .body(Body::from(serde_json::to_vec(&payload).unwrap_or_default()))
}

/// `POST /api/gateway/bot-config` — write new bot.toml and restart the bot.
#[handler]
pub async fn gateway_bot_config_save_handler(
    state: Data<&Arc<GatewayState>>,
    body: Json<BotConfigPayload>,
) -> Response {
    let content = gateway::config::serialize_bot_config(
        &body.transport,
        body.homeserver.as_deref(),
        body.username.as_deref(),
        body.password.as_deref(),
        body.slack_bot_token.as_deref(),
        body.slack_signing_secret.as_deref(),
    );

    match gateway::save_bot_config_and_restart(&state, &content).await {
        Ok(()) => {
            let ok = json!({ "ok": true });
            Response::builder()
                .status(StatusCode::OK)
                .header("Content-Type", "application/json")
                .body(Body::from(serde_json::to_vec(&ok).unwrap_or_default()))
        }
        Err(e) => {
            let err = json!({ "ok": false, "error": e.to_string() });
            Response::builder()
                .status(StatusCode::INTERNAL_SERVER_ERROR)
                .header("Content-Type", "application/json")
                .body(Body::from(serde_json::to_vec(&err).unwrap_or_default()))
        }
    }
}

/// `GET /api/gateway/pipeline` — fetch pipeline status from all registered projects.
#[handler]
pub async fn gateway_all_pipeline_handler(state: Data<&Arc<GatewayState>>) -> Response {
    let project_urls: BTreeMap<String, String> = state
        .projects
        .read()
        .await
        .iter()
        .map(|(n, e)| (n.clone(), e.url.clone()))
        .collect();

    let results =
        gateway::io::fetch_all_project_pipeline_statuses(&project_urls, &state.client).await;

    let active = state.active_project.read().await.clone();
    let body = json!({ "active": active, "projects": results });
    Response::builder()
        .status(StatusCode::OK)
        .header("Content-Type", "application/json")
        .body(Body::from(serde_json::to_vec(&body).unwrap_or_default()))
}

// ── Bot config page ─────────────────────────────────────────────────────────

/// Self-contained HTML page for bot configuration.
const GATEWAY_BOT_CONFIG_HTML: &str = r#"<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Bot Configuration &#x2014; Huskies Gateway</title>
<style>
  *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
  body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: #0f172a;
    color: #e2e8f0;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
  }
  .card {
    background: #1e293b;
    border: 1px solid #334155;
    border-radius: 12px;
    padding: 2rem;
    width: 100%;
    max-width: 520px;
    box-shadow: 0 4px 24px rgba(0,0,0,0.4);
  }
  .header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
  }
  .back {
    color: #64748b;
    text-decoration: none;
    font-size: 0.85rem;
    margin-right: auto;
  }
  .back:hover { color: #94a3b8; }
  .logo { font-size: 1.5rem; }
  h1 { font-size: 1.2rem; font-weight: 600; color: #f8fafc; }
  .field { margin-bottom: 1rem; }
  label {
    display: block;
    font-size: 0.75rem;
    font-weight: 500;
    color: #94a3b8;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.4rem;
  }
  input, select {
    width: 100%;
    padding: 0.625rem 0.875rem;
    background: #0f172a;
    border: 1px solid #334155;
    border-radius: 8px;
    color: #f1f5f9;
    font-size: 0.9rem;
  }
  input:focus, select:focus { outline: none; border-color: #6366f1; box-shadow: 0 0 0 2px rgba(99,102,241,0.25); }
  select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2394a3b8' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.875rem center;
    padding-right: 2.5rem;
  }
  .section { margin-top: 1rem; }
  .divider {
    border: none;
    border-top: 1px solid #334155;
    margin: 1.25rem 0;
  }
  button {
    width: 100%;
    padding: 0.75rem;
    background: #6366f1;
    border: none;
    border-radius: 8px;
    color: #fff;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    margin-top: 1.25rem;
  }
  button:hover { background: #4f46e5; }
  button:disabled { background: #334155; color: #64748b; cursor: not-allowed; }
  .status { margin-top: 0.875rem; font-size: 0.8rem; color: #64748b; min-height: 1.25rem; }
  .status.ok { color: #4ade80; }
  .status.err { color: #f87171; }
</style>
</head>
<body>
<div class="card">
  <div class="header">
    <a href="/" class="back">&#x2190; Gateway</a>
    <span class="logo">&#x1F916;</span>
    <h1>Bot Configuration</h1>
  </div>
  <div class="field">
    <label for="transport">Transport</label>
    <select id="transport" onchange="onTransportChange(this.value)">
      <option value="matrix">Matrix</option>
      <option value="slack">Slack</option>
    </select>
  </div>
  <hr class="divider">
  <div id="matrix-fields" class="section">
    <div class="field">
      <label for="homeserver">Homeserver URL</label>
      <input type="text" id="homeserver" placeholder="https://matrix.example.com">
    </div>
    <div class="field">
      <label for="username">Bot Username</label>
      <input type="text" id="username" placeholder="@bot:example.com">
    </div>
    <div class="field">
      <label for="password">Password</label>
      <input type="password" id="password" placeholder="&#x2022;&#x2022;&#x2022;&#x2022;&#x2022;&#x2022;&#x2022;&#x2022;">
    </div>
  </div>
  <div id="slack-fields" class="section" style="display:none">
    <div class="field">
      <label for="slack-bot-token">Bot Token</label>
      <input type="password" id="slack-bot-token" placeholder="xoxb-&#x2026;">
    </div>
    <div class="field">
      <label for="slack-signing-secret">App / Signing Secret</label>
      <input type="password" id="slack-signing-secret" placeholder="Your signing secret">
    </div>
  </div>
  <button id="save-btn" onclick="save()">Save &amp; Restart Bot</button>
  <div id="status" class="status"></div>
</div>
<script>
function onTransportChange(v) {
  document.getElementById('matrix-fields').style.display = v === 'matrix' ? '' : 'none';
  document.getElementById('slack-fields').style.display = v === 'slack' ? '' : 'none';
}
async function loadConfig() {
  try {
    const r = await fetch('/api/gateway/bot-config');
    const d = await r.json();
    document.getElementById('transport').value = d.transport || 'matrix';
    onTransportChange(d.transport || 'matrix');
    document.getElementById('homeserver').value = d.homeserver || '';
    document.getElementById('username').value = d.username || '';
    document.getElementById('password').value = d.password || '';
    document.getElementById('slack-bot-token').value = d.slack_bot_token || '';
    document.getElementById('slack-signing-secret').value = d.slack_signing_secret || '';
  } catch(e) {
    document.getElementById('status').textContent = 'Failed to load config: ' + e;
    document.getElementById('status').className = 'status err';
  }
}
async function save() {
  const btn = document.getElementById('save-btn');
  const statusEl = document.getElementById('status');
  btn.disabled = true;
  btn.textContent = 'Saving\u2026';
  statusEl.className = 'status';
  statusEl.textContent = '';
  const transport = document.getElementById('transport').value;
  const payload = { transport };
  if (transport === 'matrix') {
    payload.homeserver = document.getElementById('homeserver').value;
    payload.username = document.getElementById('username').value;
    payload.password = document.getElementById('password').value;
  } else {
    payload.slack_bot_token = document.getElementById('slack-bot-token').value;
    payload.slack_signing_secret = document.getElementById('slack-signing-secret').value;
  }
  try {
    const r = await fetch('/api/gateway/bot-config', {
      method: 'POST',
      headers: {'Content-Type': 'application/json'},
      body: JSON.stringify(payload)
    });
    const d = await r.json();
    if (d.ok) {
      statusEl.className = 'status ok';
      statusEl.textContent = 'Saved \u2014 bot restarted with new credentials.';
    } else {
      statusEl.className = 'status err';
      statusEl.textContent = d.error || 'Save failed';
    }
  } catch(e) {
    statusEl.className = 'status err';
    statusEl.textContent = 'Error: ' + e;
  }
  btn.disabled = false;
  btn.textContent = 'Save & Restart Bot';
}
loadConfig();
</script>
</body>
</html>
"#;

/// Serve the bot configuration HTML page at `GET /bot-config`.
#[handler]
pub async fn gateway_bot_config_page_handler() -> Response {
    Response::builder()
        .status(StatusCode::OK)
        .header("Content-Type", "text/html; charset=utf-8")
        .body(Body::from(GATEWAY_BOT_CONFIG_HTML))
}