// SPF Smart Gateway - HTTP API Server Transport
// Copyright 2026 Joseph Stone - All Rights Reserved
//
// HTTP API running alongside stdio MCP server.
// Uses Axum 0.8 with Tower middleware stack and optional TLS (axum-server + rustls).
//
// Routes:
//   POST /mcp/v1  — Full JSON-RPC 2.0 (initialize, tools/list, tools/call)
//   GET  /health   — Health check (no auth)
//   GET  /status   — SPF gateway status
//   GET  /tools    — Tool definitions list
//   GET  /ws       — WebSocket (persistent JSON-RPC, auth on upgrade)
//
// Auth modes:
//   "key"    — X-SPF-Key header (API key)
//   "crypto" — Ed25519 signed requests (X-SPF-Pub, X-SPF-Sig, X-SPF-Time, X-SPF-Nonce)
//   "both"   — Accept either method
//
// Middleware (Tower + axum):
//   TraceLayer — structured request/response logging
//   CatchPanicLayer — handler panics → 500 (never crash server)
//   RequestBodyLimitLayer — 10MB (matches original read_body limit)
//   SetSensitiveRequestHeadersLayer — hide auth headers from logs
//   CompressionLayer — gzip response compression
//   CORS (axum::middleware::from_fn) — browser preflight + response headers
//   Timeout — 30s per request via spawn_blocking + tokio::time::timeout
//
// Threading:
//   serve() is async — runs in caller's tokio runtime (shared with mesh in E7).
//   start() is sync wrapper — creates own runtime (backward compat with mcp.rs).
//
// BLOCK SEC-4: SPF_API_KEY env var override in serve() — process-scoped, not in JSON files

use crate::agent_state::AgentStateDb;
use crate::config::SpfConfig;
use crate::config_db::SpfConfigDb;
use crate::fs::SpfFs;
use crate::mcp;
use crate::session::Session;
use crate::storage::SpfStorage;
use crate::tmp_db::SpfTmpDb;
use ed25519_dalek::{Signature, Verifier, VerifyingKey};
use iroh::Endpoint;
use serde_json::{json, Value};
use sha2::{Sha256, Digest};
use std::collections::{HashMap, HashSet};
use std::sync::{Arc, Mutex};
use std::time::{Duration, Instant};

/// P2: Tracked peer in the mesh.
#[derive(Debug, Clone)]
pub struct MeshPeerStatus {
    pub role: crate::config::AgentRole,
    pub name: String,
    pub last_seen: Instant,
}
use axum::{
    Router,
    middleware,
    routing::{get, post},
    extract::{Request, State, Query, Path, ws::{WebSocketUpgrade, WebSocket, Message}},
    http::{HeaderMap, HeaderName, Method, StatusCode, header},
    response::{IntoResponse, Response},
    body::Body,
    Json,
};
use tower::ServiceBuilder;
use tower_http::{
    trace::TraceLayer,
    limit::RequestBodyLimitLayer,
    catch_panic::CatchPanicLayer,
    sensitive_headers::SetSensitiveRequestHeadersLayer,
    compression::CompressionLayer,
};

const PROTOCOL_VERSION: &str = "2024-11-05";
const TIMESTAMP_WINDOW_SECS: u64 = 30;
const NONCE_EXPIRY_SECS: u64 = 60;

/// Shared server state — used by all transports (stdio, HTTP, mesh).
/// Wrapped in Arc for thread-safe sharing.
pub struct ServerState {
    pub config: SpfConfig,
    pub config_db: Option<SpfConfigDb>,
    pub session: Mutex<Session>,
    pub storage: SpfStorage,
    pub tmp_db: Option<SpfTmpDb>,
    pub agent_db: Option<AgentStateDb>,
    pub fs_db: Option<SpfFs>,
    pub pub_key_hex: String,
    pub trusted_keys: HashSet<String>,
    pub auth_mode: String,
    pub nonce_cache: Mutex<HashMap<String, Instant>>,
    pub listeners: Vec<Box<dyn crate::dispatch::DispatchListener>>,
    /// Mesh endpoint handle for outbound peer calls (None if mesh disabled)
    pub mesh_tx: Option<std::sync::mpsc::Sender<crate::mesh::MeshRequest>>,
    /// Peer info with addresses for direct mesh connections
    pub peers: HashMap<String, crate::identity::PeerInfo>,
    /// Transformer runtime state — None if transformer disabled or not yet loaded
    pub transformer: Option<std::sync::Arc<std::sync::RwLock<crate::transformer_tools::TransformerState>>>,
    /// Transformer configuration — loaded from LIVE/CONFIG/transformer.json
    pub transformer_config: crate::config::TransformerConfig,
    /// Pipeline state for task orchestration
    pub pipeline: std::sync::Arc<std::sync::Mutex<crate::pipeline::PipelineState>>,
    /// Ed25519 signing key — needed for I-4 peer API key derivation
    pub signing_key: ed25519_dalek::SigningKey,
    /// Network pool configuration — role (NetAdmin/Worker), pool size, peer list
    pub network_config: crate::config::NetworkConfig,
    /// Live pool state — None on Worker nodes, Some(Arc<PoolState>) on NetAdmin
    pub pool_state: Option<std::sync::Arc<crate::network::PoolState>>,
    /// Reverse proxy browser session — ProxyEngine + mpsc channel ends
    pub browser: std::sync::Mutex<crate::browser::BrowserSession>,
    /// WsBrowserChannels produced by BrowserSession::connect(), consumed by /ws/browser handler
    pub ws_browser_channels: std::sync::Mutex<Option<crate::browser::WsBrowserChannels>>,
    /// HTTP server port — injected into proxied pages as WebSocket target port
    pub http_port: u16,
    /// P2: Tracked mesh peers — pubkey → MeshPeerStatus
    pub tracked_peers: Mutex<HashMap<String, MeshPeerStatus>>,
    /// P5: Orchestrator state — Some only on orchestrator nodes
    pub orchestrator_state: Mutex<Option<Arc<std::sync::Mutex<crate::orchestrator::OrchestratorState>>>>,
    /// DS: Iroh QUIC endpoint — stored by mesh on startup, used by MCP for direct duplex calls
    pub endpoint: Mutex<Option<Endpoint>>,
    /// DS: Tokio runtime handle — bridges sync MCP thread to async mesh I/O
    pub tokio_handle: Mutex<Option<tokio::runtime::Handle>>,
}

/// P5: Helper — get tracked peer count without full state reference (for tool access).
pub fn tracked_peer_count(state: &Arc<ServerState>) -> usize {
    state.tracked_peers.lock().unwrap().len()
}

/// Application state for Axum handlers — wraps ServerState + API key.
/// Clone is required by Axum's State extractor.
#[derive(Clone)]
struct AppState {
    inner: Arc<ServerState>,
    api_key: String,
}

// ============================================================================
// AUTH — Dual mode: API key + Ed25519 crypto
// ============================================================================

/// Extract a header value by name from Axum HeaderMap.
/// HeaderMap keys are case-insensitive by spec.
fn extract_header(headers: &HeaderMap, name: &str) -> Option<String> {
    headers.get(name)
        .and_then(|v| v.to_str().ok())
        .map(|s| s.to_string())
}

/// Dual-mode auth check. Tries API key first, then crypto.
/// Returns true if request is authenticated.
fn check_auth(headers: &HeaderMap, method_str: &str, path: &str,
              body: &str, api_key: &str, state: &ServerState) -> bool {
    let mode = state.auth_mode.as_str();

    // Try API key auth
    if mode == "key" || mode == "both" {
        if let Some(key) = extract_header(headers, "x-spf-key") {
            return key == api_key;
        }
    }

    // Try crypto auth
    if mode == "crypto" || mode == "both" {
        if let (Some(pub_hex), Some(sig_hex), Some(time_str), Some(nonce)) = (
            extract_header(headers, "x-spf-pub"),
            extract_header(headers, "x-spf-sig"),
            extract_header(headers, "x-spf-time"),
            extract_header(headers, "x-spf-nonce"),
        ) {
            return verify_crypto_auth(
                &pub_hex, &sig_hex, &time_str, &nonce,
                method_str, path, body,
                &state.trusted_keys, &state.nonce_cache,
            );
        }
    }

    // I-4 FIX: Try peer-derived key auth (mesh↔HTTP bridge)
    if mode == "both" || mode == "key" {
        if let Some(peer_key_header) = extract_header(headers, "x-spf-peer-key") {
            if let Some(peer_pub) = extract_header(headers, "x-spf-peer-pub") {
                // Verify the peer is trusted before attempting derivation
                if state.trusted_keys.contains(&peer_pub) {
                    let expected = crate::identity::derive_peer_api_key(
                        &state.signing_key, &peer_pub
                    );
                    if let Some(expected_key) = expected {
                        if peer_key_header == expected_key {
                            return true;
                        }
                    }
                }
            }
        }
    }

    false
}

/// Verify Ed25519 crypto authentication with replay prevention.
fn verify_crypto_auth(pub_hex: &str, sig_hex: &str, time_str: &str, nonce: &str,
                      method: &str, path: &str, body: &str,
                      trusted_keys: &HashSet<String>,
                      nonce_cache: &Mutex<HashMap<String, Instant>>) -> bool {
    // 1. Check public key is in trusted keys
    if !trusted_keys.contains(pub_hex) {
        return false;
    }

    // 2. Check timestamp within window
    let timestamp: u64 = match time_str.parse() {
        Ok(t) => t,
        Err(_) => return false,
    };
    let now = std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .unwrap_or_default()
        .as_secs();
    if now.abs_diff(timestamp) > TIMESTAMP_WINDOW_SECS {
        return false;
    }

    // 3. Check nonce uniqueness (and clean expired entries)
    {
        let mut cache = nonce_cache.lock().unwrap();
        let instant_now = Instant::now();
        cache.retain(|_, t| instant_now.duration_since(*t).as_secs() < NONCE_EXPIRY_SECS);
        if cache.contains_key(nonce) {
            return false; // replay detected
        }
        cache.insert(nonce.to_string(), instant_now);
    }

    // 4. Build canonical signing string
    let body_hash = hex::encode(Sha256::digest(body.as_bytes()));
    let canonical = format!("{}\n{}\n{}\n{}\n{}", method, path, body_hash, time_str, nonce);

    // 5. Decode public key
    let pub_bytes: [u8; 32] = match hex::decode(pub_hex) {
        Ok(b) if b.len() == 32 => match b.try_into() {
            Ok(arr) => arr,
            Err(_) => return false,
        },
        _ => return false,
    };
    let verifying_key = match VerifyingKey::from_bytes(&pub_bytes) {
        Ok(vk) => vk,
        Err(_) => return false,
    };

    // 6. Decode signature
    let sig_bytes: [u8; 64] = match hex::decode(sig_hex) {
        Ok(b) if b.len() == 64 => match b.try_into() {
            Ok(arr) => arr,
            Err(_) => return false,
        },
        _ => return false,
    };
    let signature = Signature::from_bytes(&sig_bytes);

    // 7. Verify signature over canonical string
    verifying_key.verify(canonical.as_bytes(), &signature).is_ok()
}

// ============================================================================
// RESPONSE HELPERS
// ============================================================================

/// Standard 401 response for failed auth
fn unauthorized() -> Response {
    (StatusCode::UNAUTHORIZED, Json(json!({
        "jsonrpc": "2.0",
        "id": null,
        "error": {"code": -32000, "message": "Unauthorized: invalid or missing authentication"}
    }))).into_response()
}

// ============================================================================
// JSON-RPC 2.0 HANDLER — shared by POST /mcp/v1 and WebSocket
// ============================================================================

/// Process a JSON-RPC 2.0 message. Returns (status_code, response_value).
/// Sync function — call from async via tokio::task::block_in_place().
fn handle_jsonrpc(body: &str, state: &Arc<ServerState>) -> (StatusCode, Value) {
    if body.is_empty() {
        return (StatusCode::BAD_REQUEST, json!({
            "jsonrpc": "2.0", "id": null,
            "error": {"code": -32700, "message": "Parse error: empty body"}
        }));
    }

    let msg: Value = match serde_json::from_str(body) {
        Ok(v) => v,
        Err(_) => {
            return (StatusCode::BAD_REQUEST, json!({
                "jsonrpc": "2.0", "id": null,
                "error": {"code": -32700, "message": "Parse error: invalid JSON"}
            }));
        }
    };

    let method = msg["method"].as_str().unwrap_or("");
    let id = &msg["id"];
    let params = &msg["params"];

    match method {
        "initialize" => {
            (StatusCode::OK, json!({
                "jsonrpc": "2.0",
                "id": id,
                "result": {
                    "protocolVersion": PROTOCOL_VERSION,
                    "capabilities": { "tools": {} },
                    "serverInfo": {
                        "name": "spf-smart-gate",
                        "version": env!("CARGO_PKG_VERSION"),
                    }
                }
            }))
        }

        "tools/list" => {
            (StatusCode::OK, json!({
                "jsonrpc": "2.0",
                "id": id,
                "result": { "tools": mcp::tool_definitions() }
            }))
        }

        "tools/call" => {
            let name = params["name"].as_str().unwrap_or("");
            let args = params.get("arguments").cloned().unwrap_or(json!({}));

            // Route through Unified Dispatch — same gate as stdio and mesh
            let resp = crate::dispatch::call(state, crate::dispatch::Source::Http, name, &args);
            (StatusCode::OK, json!({
                "jsonrpc": "2.0",
                "id": id,
                "result": { "content": [resp.result] }
            }))
        }

        "ping" => (StatusCode::OK, json!({"jsonrpc": "2.0", "id": id, "result": {}})),

        _ => (StatusCode::BAD_REQUEST, json!({
            "jsonrpc": "2.0",
            "id": id,
            "error": {"code": -32601, "message": format!("Unknown method: {}", method)}
        })),
    }
}

// ============================================================================
// CORS MIDDLEWARE — browser clients (ecommerce, web dashboards)
// ============================================================================

/// CORS middleware via axum::middleware::from_fn.
/// tower_http::CorsLayer requires ResBody: Default (same issue as TimeoutLayer),
/// so we handle CORS manually — zero body type constraints.
async fn cors_middleware(request: Request, next: middleware::Next) -> Response {
    // Preflight: browsers send OPTIONS before the real request
    if request.method() == Method::OPTIONS {
        return Response::builder()
            .status(StatusCode::OK)
            .header("access-control-allow-origin", "*")
            .header("access-control-allow-methods", "GET, POST, OPTIONS")
            .header("access-control-allow-headers",
                "content-type, authorization, x-spf-key, x-spf-sig, x-spf-pub, x-spf-time, x-spf-nonce")
            .header("access-control-max-age", "3600")
            .body(axum::body::Body::empty())
            .unwrap();
    }

    let mut response = next.run(request).await;
    let headers = response.headers_mut();
    headers.insert("access-control-allow-origin", "*".parse().unwrap());
    headers.insert("access-control-allow-methods", "GET, POST, OPTIONS".parse().unwrap());
    headers.insert("access-control-allow-headers",
        "content-type, authorization, x-spf-key, x-spf-sig, x-spf-pub, x-spf-time, x-spf-nonce".parse().unwrap());
    response
}

// ============================================================================
// ROUTE HANDLERS
// ============================================================================

/// GET /health — no auth required (health checks, load balancers)
async fn health_handler(State(app): State<AppState>) -> Response {
    let session = app.inner.session.lock().unwrap();
    let action_count = session.action_count;
    drop(session);

    Json(json!({
        "status": "ok",
        "version": env!("CARGO_PKG_VERSION"),
        "actions": action_count,
    })).into_response()
}

/// GET /status — requires auth
async fn status_handler(
    State(app): State<AppState>,
    headers: HeaderMap,
) -> Response {
    if !check_auth(&headers, "GET", "/status", "", &app.api_key, &app.inner) {
        return unauthorized();
    }

    let session = app.inner.session.lock().unwrap();
    let summary = session.status_summary();
    drop(session);

    Json(json!({
        "version": env!("CARGO_PKG_VERSION"),
        "mode": format!("{:?}", app.inner.config.enforce_mode),
        "session": summary,
    })).into_response()
}

/// GET /tools — requires auth
async fn tools_handler(
    State(app): State<AppState>,
    headers: HeaderMap,
) -> Response {
    if !check_auth(&headers, "GET", "/tools", "", &app.api_key, &app.inner) {
        return unauthorized();
    }

    Json(json!({
        "tools": mcp::tool_definitions()
    })).into_response()
}

/// POST /mcp/v1 — JSON-RPC 2.0 protocol handler, requires auth.
/// Body extracted as String for crypto auth signature verification.
/// 30s timeout via spawn_blocking + tokio::time::timeout.
async fn mcp_handler(
    State(app): State<AppState>,
    headers: HeaderMap,
    body: String,
) -> Response {
    if !check_auth(&headers, "POST", "/mcp/v1", &body, &app.api_key, &app.inner) {
        return unauthorized();
    }

    let state = app.inner.clone();
    let result = tokio::time::timeout(
        Duration::from_secs(30),
        tokio::task::spawn_blocking(move || handle_jsonrpc(&body, &state)),
    ).await;

    match result {
        Ok(Ok((status, json))) => (status, Json(json)).into_response(),
        Ok(Err(_)) => (StatusCode::INTERNAL_SERVER_ERROR, Json(json!({
            "jsonrpc": "2.0", "id": null,
            "error": {"code": -32603, "message": "Internal error"}
        }))).into_response(),
        Err(_) => (StatusCode::REQUEST_TIMEOUT, Json(json!({
            "jsonrpc": "2.0", "id": null,
            "error": {"code": -32000, "message": "Request timeout (30s)"}
        }))).into_response(),
    }
}

// ============================================================================
// WEBSOCKET — persistent JSON-RPC connection (E5)
// ============================================================================

/// GET /ws — WebSocket upgrade, requires auth on the HTTP upgrade request.
/// Once upgraded, the connection is authenticated for its lifetime.
async fn ws_handler(
    State(app): State<AppState>,
    headers: HeaderMap,
    ws: WebSocketUpgrade,
) -> Response {
    if !check_auth(&headers, "GET", "/ws", "", &app.api_key, &app.inner) {
        return unauthorized();
    }

    let state = app.inner.clone();
    ws.on_upgrade(move |socket| handle_ws(socket, state))
}

/// WebSocket message loop — each text message is a JSON-RPC request.
/// Same dispatch path as POST /mcp/v1 but persistent connection.
async fn handle_ws(mut socket: WebSocket, state: Arc<ServerState>) {
    eprintln!("[SPF-WS] Client connected");

    while let Some(Ok(msg)) = socket.recv().await {
        match msg {
            Message::Text(text) => {
                let state_ref = state.clone();
                let result = tokio::time::timeout(
                    Duration::from_secs(30),
                    tokio::task::spawn_blocking(move || handle_jsonrpc(&text, &state_ref)),
                ).await;

                let resp_json = match result {
                    Ok(Ok((_, json))) => json,
                    Ok(Err(_)) => json!({"jsonrpc": "2.0", "id": null,
                        "error": {"code": -32603, "message": "Internal error"}}),
                    Err(_) => json!({"jsonrpc": "2.0", "id": null,
                        "error": {"code": -32000, "message": "Request timeout (30s)"}}),
                };
                let resp = serde_json::to_string(&resp_json).unwrap_or_default();
                if socket.send(Message::Text(resp.into())).await.is_err() {
                    break;
                }
            }
            Message::Ping(data) => {
                if socket.send(Message::Pong(data)).await.is_err() {
                    break;
                }
            }
            Message::Close(_) => break,
            _ => {}
        }
    }

    eprintln!("[SPF-WS] Client disconnected");
}

// ============================================================================
// HTTP SERVER
// ============================================================================

/// Scan for an available port starting at preferred.
/// Tries preferred..=preferred+1000. Returns first port that binds.
/// Logs if non-preferred port selected.
fn find_available_port(bind: &str, preferred: u16) -> u16 {
    let range_end = preferred.saturating_add(1000);
    for port in preferred..=range_end {
        let addr = format!("{}:{}", bind, port);
        match std::net::TcpListener::bind(&addr) {
            Ok(listener) => {
                drop(listener);
                if port != preferred {
                    eprintln!(
                        "[SPF] Port {} in use — auto-selected port {}",
                        preferred, port
                    );
                }
                return port;
            }
            Err(_) => continue,
        }
    }
    eprintln!(
        "[SPF] WARNING: No port available in {}..={}, falling back to {}",
        preferred, range_end, preferred
    );
    preferred
}

// ============================================================================
// WB-2d: REVERSE PROXY HANDLERS — /proxy, /proxy/asset, /ws/browser
// No auth: served to local browser (localhost only, no external exposure).
// ============================================================================

/// GET /proxy?url=... — Fetch target URL, inject CONTROL_JS, serve to browser.
async fn proxy_handler(
    State(app): State<AppState>,
    Query(params): Query<HashMap<String, String>>,
) -> Response {
    let url = match params.get("url") {
        Some(u) if !u.is_empty() => u.clone(),
        _ => return (StatusCode::BAD_REQUEST, "Missing url parameter").into_response(),
    };
    if let Err(e) = crate::web::validate_url(&url) {
        return (StatusCode::BAD_REQUEST, e).into_response();
    }
    let ws_port = app.inner.http_port;
    let state = app.inner.clone();
    match tokio::task::spawn_blocking(move || {
        state.browser.lock().unwrap().proxy_page(&url, ws_port)
    }).await {
        Ok(Ok(page)) => Response::builder()
            .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
            .body(Body::from(page.html))
            .unwrap_or_else(|_| StatusCode::INTERNAL_SERVER_ERROR.into_response()),
        Ok(Err(e)) => (StatusCode::BAD_GATEWAY, format!("Proxy error: {}", e)).into_response(),
        Err(_) => StatusCode::INTERNAL_SERVER_ERROR.into_response(),
    }
}

/// GET /proxy/asset?url=... — Fetch and passthrough a page asset (CSS/JS/image).
async fn proxy_asset_handler(
    State(app): State<AppState>,
    Query(params): Query<HashMap<String, String>>,
) -> Response {
    let url = match params.get("url") {
        Some(u) if !u.is_empty() => u.clone(),
        _ => return (StatusCode::BAD_REQUEST, "Missing url parameter").into_response(),
    };
    if let Err(e) = crate::web::validate_url(&url) {
        return (StatusCode::BAD_REQUEST, e).into_response();
    }
    let state = app.inner.clone();
    match tokio::task::spawn_blocking(move || {
        state.browser.lock().unwrap().proxy_asset(&url)
    }).await {
        Ok(Ok(asset)) => Response::builder()
            .header(header::CONTENT_TYPE, asset.content_type)
            .body(Body::from(asset.data))
            .unwrap_or_else(|_| StatusCode::INTERNAL_SERVER_ERROR.into_response()),
        Ok(Err(e)) => (StatusCode::BAD_GATEWAY, format!("Asset error: {}", e)).into_response(),
        Err(_) => StatusCode::INTERNAL_SERVER_ERROR.into_response(),
    }
}

/// GET /ws/browser — WebSocket endpoint for browser control JS.
/// Bridges std::sync::mpsc channels (BrowserSession) ↔ WebSocket (browser JS).
async fn ws_browser_handler(
    ws: WebSocketUpgrade,
    State(app): State<AppState>,
) -> impl IntoResponse {
    ws.on_upgrade(move |socket| async move {
        // Take channels — only one WS browser session at a time
        let channels = app.inner.ws_browser_channels.lock()
            .ok()
            .and_then(|mut g| g.take());
        if let Some(channels) = channels {
            handle_browser_ws(socket, channels).await;
        }
        // No channels = no active session, close immediately
    })
}

/// Bridge mpsc channels to WebSocket — command relay between BrowserSession and browser JS.
async fn handle_browser_ws(
    mut socket: WebSocket,
    channels: crate::browser::WsBrowserChannels,
) {
    loop {
        // Forward any pending commands from BrowserSession → browser JS
        while let Ok(cmd) = channels.cmd_rx.try_recv() {
            if socket.send(Message::Text(cmd.into())).await.is_err() {
                return;
            }
        }
        // Wait up to 50ms for a message from browser JS (polling rate)
        match tokio::time::timeout(
            std::time::Duration::from_millis(50),
            socket.recv(),
        ).await {
            Ok(Some(Ok(Message::Text(text)))) => {
                if channels.resp_tx.send(text.to_string()).is_err() {
                    return; // BrowserSession dropped — session over
                }
            }
            Ok(Some(Ok(Message::Close(_)))) | Ok(Some(Err(_))) | Ok(None) => return,
            _ => {} // Binary/ping/pong/timeout — continue polling
        }
    }
}

// ============================================================================
// CH-2 + CH-3: CHANNEL HUB — WebSocket + HTTP API routes
// ============================================================================

/// GET /ws/channel/:id — WebSocket upgrade for channel communication.
/// Auth required on upgrade. Peer identified by X-SPF-Pub header (or query param fallback).
/// Once upgraded, the connection is a full-duplex push channel.
async fn ws_channel_handler(
    State(app): State<AppState>,
    Path(channel_id): Path<String>,
    headers: HeaderMap,
    Query(params): Query<HashMap<String, String>>,
    ws: WebSocketUpgrade,
) -> Response {
    if !check_auth(&headers, "GET", &format!("/ws/channel/{}", channel_id), "", &app.api_key, &app.inner) {
        return unauthorized();
    }

    // Identify the connecting agent — prefer header, fallback to query param
    let peer_key = extract_header(&headers, "x-spf-pub")
        .or_else(|| params.get("key").cloned())
        .unwrap_or_else(|| "anonymous".to_string());
    let peer_name = extract_header(&headers, "x-spf-name")
        .or_else(|| params.get("name").cloned())
        .unwrap_or_else(|| peer_key[..8.min(peer_key.len())].to_string());

    ws.on_upgrade(move |socket| {
        crate::channel::handle_channel_ws(socket, channel_id, peer_key, peer_name)
    })
}

/// POST /api/channel/create — Create a new channel.
/// Body: { "name": "ops", "key": "abc...", "display_name": "ALPHA" }
async fn api_channel_create(
    State(app): State<AppState>,
    headers: HeaderMap,
    Json(body): Json<Value>,
) -> Response {
    if !check_auth(&headers, "POST", "/api/channel/create", "", &app.api_key, &app.inner) {
        return unauthorized();
    }
    let name = body["name"].as_str().unwrap_or("unnamed");
    let key = body["key"].as_str().unwrap_or(&app.inner.pub_key_hex);
    let display_name = body["display_name"].as_str().unwrap_or("Agent");
    Json(crate::channel::api_create_channel(name, key, display_name)).into_response()
}

/// POST /api/channel/join — Join an existing channel.
/// Body: { "channel_id": "ch-1", "key": "abc...", "name": "BRAVO" }
async fn api_channel_join(
    State(app): State<AppState>,
    headers: HeaderMap,
    Json(body): Json<Value>,
) -> Response {
    if !check_auth(&headers, "POST", "/api/channel/join", "", &app.api_key, &app.inner) {
        return unauthorized();
    }
    let channel_id = body["channel_id"].as_str().unwrap_or("");
    let key = body["key"].as_str().unwrap_or(&app.inner.pub_key_hex);
    let name = body["name"].as_str().unwrap_or("Agent");
    Json(crate::channel::api_join_channel(channel_id, key, name)).into_response()
}

/// POST /api/channel/leave — Leave a channel.
/// Body: { "channel_id": "ch-1", "key": "abc..." }
async fn api_channel_leave(
    State(app): State<AppState>,
    headers: HeaderMap,
    Json(body): Json<Value>,
) -> Response {
    if !check_auth(&headers, "POST", "/api/channel/leave", "", &app.api_key, &app.inner) {
        return unauthorized();
    }
    let channel_id = body["channel_id"].as_str().unwrap_or("");
    let key = body["key"].as_str().unwrap_or(&app.inner.pub_key_hex);
    Json(crate::channel::api_leave_channel(channel_id, key)).into_response()
}

/// POST /api/channel/send — Send a message to a channel.
/// Body: { "channel_id": "ch-1", "key": "abc...", "name": "ALPHA", "text": "hello", "msg_type": "text" }
async fn api_channel_send(
    State(app): State<AppState>,
    headers: HeaderMap,
    Json(body): Json<Value>,
) -> Response {
    if !check_auth(&headers, "POST", "/api/channel/send", "", &app.api_key, &app.inner) {
        return unauthorized();
    }
    let channel_id = body["channel_id"].as_str().unwrap_or("");
    let key = body["key"].as_str().unwrap_or(&app.inner.pub_key_hex);
    let name = body["name"].as_str().unwrap_or("Agent");
    let text = body["text"].as_str().unwrap_or("");
    let msg_type = match body["msg_type"].as_str() {
        Some("tool_result") => crate::channel::MessageType::ToolResult,
        Some("system") => crate::channel::MessageType::System,
        _ => crate::channel::MessageType::Text,
    };
    Json(crate::channel::api_send_message(channel_id, key, name, text, msg_type)).into_response()
}

/// GET /api/channel/list — List all channels.
async fn api_channel_list(
    State(app): State<AppState>,
    headers: HeaderMap,
) -> Response {
    if !check_auth(&headers, "GET", "/api/channel/list", "", &app.api_key, &app.inner) {
        return unauthorized();
    }
    Json(crate::channel::api_list_channels()).into_response()
}

/// GET /api/channel/:id/history — Get message history for a channel.
async fn api_channel_history(
    State(app): State<AppState>,
    Path(channel_id): Path<String>,
    headers: HeaderMap,
    Query(params): Query<HashMap<String, String>>,
) -> Response {
    if !check_auth(&headers, "GET", &format!("/api/channel/{}/history", channel_id), "", &app.api_key, &app.inner) {
        return unauthorized();
    }
    let limit: usize = params.get("limit")
        .and_then(|l| l.parse().ok())
        .unwrap_or(50);
    Json(crate::channel::api_channel_history(&channel_id, limit)).into_response()
}

/// Build the Axum Router with all routes and middleware.
fn build_router(app_state: AppState) -> Router {
    // Tower middleware stack — applied to ALL routes
    // TimeoutLayer removed: requires ResBody: Default which axum::body::Body doesn't impl.
    // Timeout protection provided by tokio task isolation + SPF gate rate limiting.
    // CompressionLayer applied on Router (outside stack) to avoid body type conflicts.
    let middleware_stack = ServiceBuilder::new()
        // 1. Structured request/response tracing (outermost)
        .layer(TraceLayer::new_for_http())
        // 2. Hide auth headers from trace output
        .layer(SetSensitiveRequestHeadersLayer::new([
            HeaderName::from_static("x-spf-key"),
            HeaderName::from_static("x-spf-sig"),
        ]))
        // 3. 10MB body limit (matches original read_body limit)
        .layer(RequestBodyLimitLayer::new(10 * 1024 * 1024))
        // 4. Convert handler panics to 500 (innermost — uses ResponseForPanic, not Default)
        .layer(CatchPanicLayer::new());

    Router::new()
        // Public routes — no auth
        .route("/health", get(health_handler))
        // Protected routes — auth checked in each handler
        .route("/status", get(status_handler))
        .route("/tools", get(tools_handler))
        .route("/mcp/v1", post(mcp_handler))
        // WebSocket — auth on upgrade request
        .route("/ws", get(ws_handler))
        // Reverse proxy browser routes (WB-2d) — no auth, served to local browser
        .route("/proxy", get(proxy_handler))
        .route("/proxy/asset", get(proxy_asset_handler))
        .route("/ws/browser", get(ws_browser_handler))
        // CH-2: Channel WebSocket — full duplex agent communication
        .route("/ws/channel/{id}", get(ws_channel_handler))
        // CH-3: Channel HTTP API — control plane for channel management
        .route("/api/channel/create", post(api_channel_create))
        .route("/api/channel/join", post(api_channel_join))
        .route("/api/channel/leave", post(api_channel_leave))
        .route("/api/channel/send", post(api_channel_send))
        .route("/api/channel/list", get(api_channel_list))
        .route("/api/channel/{id}/history", get(api_channel_history))
        // CORS — browser clients (ecommerce, web dashboards)
        .layer(middleware::from_fn(cors_middleware))
        // Compression outside CatchPanic (CompressionBody doesn't impl Default)
        .layer(CompressionLayer::new())
        // Global middleware (all routes)
        .layer(middleware_stack)
        .with_state(app_state)
}

/// Async HTTP server — runs in caller's tokio runtime.
/// Use this for shared runtime (E7) where mcp.rs spawns HTTP + mesh together.
/// Blocks until server stops or task is cancelled.
///
/// BLOCK SEC-4: SPF_API_KEY env var checked first — process-scoped override.
/// Priority: SPF_API_KEY env > identity-derived key > JSON config fallback.
/// The env var is never written to disk, so AI agents with native Read
/// cannot discover it from config files.
pub async fn serve(
    state: Arc<ServerState>,
    bind: String,
    port: u16,
    api_key: String,
    tls: Option<(Vec<u8>, Vec<u8>)>,
) {
    rustls::crypto::ring::default_provider().install_default().ok();

    // SEC-4: Environment variable override for API key.
    // SPF_API_KEY env var takes priority over identity-derived key.
    // Process-scoped: not readable from JSON config files by AI agents.
    let api_key = match std::env::var("SPF_API_KEY") {
        Ok(env_key) if !env_key.is_empty() => {
            eprintln!("[SPF-HTTP] API key loaded from SPF_API_KEY env var");
            env_key
        }
        _ => api_key, // Fall back to identity-derived key (passed from mcp.rs)
    };

    let port = find_available_port(&bind, port);
    let addr = format!("{}:{}", bind, port);

    let app_state = AppState {
        inner: state,
        api_key,
    };

    let app = build_router(app_state);

    eprintln!("[SPF-HTTP] Listening on {}", addr);

    if let Some((cert_pem, key_pem)) = tls {
        // HTTPS via axum-server + rustls — PEM bytes from rcgen
        let tls_config = axum_server::tls_rustls::RustlsConfig::from_pem(cert_pem, key_pem)
            .await
            .expect("[SPF-HTTP] Failed to load TLS config from PEM");

        let sock_addr: std::net::SocketAddr = addr.parse()
            .expect("[SPF-HTTP] Invalid bind address");

        // Graceful shutdown handle (E6)
        let handle = axum_server::Handle::new();
        let shutdown_handle = handle.clone();
        tokio::spawn(async move {
            tokio::signal::ctrl_c().await.ok();
            eprintln!("[SPF-HTTP] Graceful shutdown initiated (10s timeout)...");
            shutdown_handle.graceful_shutdown(Some(Duration::from_secs(10)));
        });

        axum_server::bind_rustls(sock_addr, tls_config)
            .handle(handle)
            .serve(app.into_make_service())
            .await
            .expect("[SPF-HTTP] HTTPS server failed");
    } else {
        // Plain HTTP via axum::serve
        let listener = tokio::net::TcpListener::bind(&addr)
            .await
            .expect("[SPF-HTTP] Failed to bind TCP");

        // Graceful shutdown (E6)
        axum::serve(listener, app)
            .with_graceful_shutdown(async {
                tokio::signal::ctrl_c().await.ok();
                eprintln!("[SPF-HTTP] Graceful shutdown initiated...");
            })
            .await
            .expect("[SPF-HTTP] HTTP server failed");
    }
}

/// Start HTTP API server — sync wrapper for backward compatibility.
/// Called from spawned thread in mcp::run(). Creates own tokio runtime.
/// Blocks forever (runs in dedicated thread).
///
/// Signature unchanged from tiny_http version — mcp.rs needs zero changes
/// when using this entry point. For shared runtime (E7), use serve() instead.
pub fn start(state: Arc<ServerState>, bind: &str, port: u16, api_key: String, tls: Option<(Vec<u8>, Vec<u8>)>) {
    let bind = bind.to_string();
    let rt = tokio::runtime::Builder::new_multi_thread()
        .worker_threads(2)
        .enable_all()
        .build()
        .expect("[SPF-HTTP] Failed to build tokio runtime");

    rt.block_on(serve(state, bind, port, api_key, tls));
}