//! The Clawmates §15 MCP "door": the single gated egress a tool-free ZeroClaw
//! agent uses to act on the world.
//!
//! Agents have **no native outbound tools**; their only actuator is this MCP
//! server (`POST /mcp`, JSON-RPC 2.0, protocol `2024-11-05`). The door keeps the
//! parts that make capability *governed* — the agent never holds a credential
//! (broker-executed tools reveal secrets only inside the broker), every action
//! is journaled to the append-only audit log, and a central policy decides each
//! call — but the **human approver is replaced by an automated policy/governor**
//! ("agents control their destiny"). The default policy is allow-all, so agents
//! are autonomous out of the gate; recipient allowlists, spend caps, taint
//! blocks, or a governor agent plug into [`policy_decide`].
//!
//! v1 exposes `email_send` (runtime-executed → `outbox`, observable, no external
//! creds). Broker-backed tools (e.g. `slack_post`) are the next increment — they
//! additionally need the approval→grant chain the broker consumes.

use axum::extract::State;
use axum::http::header::AUTHORIZATION;
use axum::http::HeaderMap;
use axum::Json;
use serde::Deserialize;
use serde_json::{json, Value};

use crate::AppState;

/// MCP protocol version the ZeroClaw client negotiates.
const MCP_PROTOCOL_VERSION: &str = "2024-11-05";

/// Tools the door exposes, as `(mcp_name, internal_registry_name)`. The agent
/// sees `clawmates__<mcp_name>`; ZeroClaw strips the prefix and calls us with
/// `<mcp_name>`. We keep MCP names underscore-only (some models choke on dots).
const EXPOSED_TOOLS: &[(&str, &str)] = &[
    ("email_send", "email.send"),
    ("slack_post", "slack.post"),
    ("delegate", "delegate"),
];

fn internal_name(mcp_name: &str) -> Option<&'static str> {
    EXPOSED_TOOLS
        .iter()
        .find(|(m, _)| *m == mcp_name)
        .map(|(_, i)| *i)
}

/// A JSON-RPC 2.0 request frame.
#[derive(Deserialize)]
pub struct JsonRpcReq {
    #[allow(dead_code)]
    jsonrpc: Option<String>,
    #[serde(default)]
    id: Option<Value>,
    method: String,
    #[serde(default)]
    params: Option<Value>,
}

fn ok(id: Option<Value>, result: Value) -> Json<Value> {
    Json(json!({ "jsonrpc": "2.0", "id": id, "result": result }))
}

fn err(id: Option<Value>, code: i64, message: &str) -> Json<Value> {
    Json(json!({ "jsonrpc": "2.0", "id": id, "error": { "code": code, "message": message } }))
}

/// A tool-call result in MCP shape (the agent reads `content`; `isError`
/// distinguishes a refused/failed call from a successful one).
fn tool_result(id: Option<Value>, is_error: bool, text: String) -> Json<Value> {
    ok(
        id,
        json!({ "isError": is_error, "content": [{ "type": "text", "text": text }] }),
    )
}

/// Door policy decision. The human is removed: this is where autonomy is
/// governed (or not).
enum PolicyOutcome {
    Approve,
    Deny(String),
}

/// Decides each door call in place of a human. The human is removed; autonomy
/// is *governed* (not ungoverned) by, in order:
///   1. a kill switch (`CLAWMATES_DOOR_POLICY=deny`) — halt all egress, no redeploy;
///   2. a per-workspace hourly rate cap (`CLAWMATES_DOOR_RATE_LIMIT`, counts
///      executed door actions in the audit log);
///   3. an email recipient-domain allowlist (`CLAWMATES_DOOR_EMAIL_ALLOW`);
///   4. a governor hook (extension point) — a deterministic rule set or a
///      governor agent can veto here.
///
/// Default (no env set) = allow-all → agents fully autonomous.
async fn policy_decide(
    state: &AppState,
    workspace: cm_domain::WorkspaceId,
    mcp_tool: &str,
    category: Option<cm_domain::GatedCategory>,
    args: &Value,
) -> PolicyOutcome {
    // 1. Kill switch.
    if std::env::var("CLAWMATES_DOOR_POLICY").as_deref() == Ok("deny") {
        return PolicyOutcome::Deny("door policy is set to deny (kill switch active)".into());
    }

    // 2. Per-workspace hourly rate cap (counts executed door actions).
    if let Some(cap) = std::env::var("CLAWMATES_DOOR_RATE_LIMIT")
        .ok()
        .and_then(|v| v.parse::<i64>().ok())
    {
        let used: i64 = sqlx::query_scalar(
            "SELECT count(*) FROM audit_log
             WHERE workspace_id = $1 AND event_type = 'door.executed'
               AND created_at > now() - interval '1 hour'",
        )
        .bind(workspace.as_uuid())
        .fetch_one(&state.pool)
        .await
        .unwrap_or(0);
        if used >= cap {
            return PolicyOutcome::Deny(format!(
                "hourly rate limit reached ({used}/{cap} door actions this hour)"
            ));
        }
    }

    // 3. Email recipient-domain allowlist.
    if mcp_tool == "email_send" {
        if let Ok(allow) = std::env::var("CLAWMATES_DOOR_EMAIL_ALLOW") {
            let to = args.get("to").and_then(|v| v.as_str()).unwrap_or("");
            let domain = to.rsplit('@').next().unwrap_or("").to_ascii_lowercase();
            let permitted = allow
                .split(',')
                .map(|d| d.trim().to_ascii_lowercase())
                .any(|d| !d.is_empty() && d == domain);
            if !permitted {
                return PolicyOutcome::Deny(format!(
                    "recipient domain {domain:?} is not in CLAWMATES_DOOR_EMAIL_ALLOW"
                ));
            }
        }
    }

    // 4. Governor agent: when CLAWMATES_DOOR_GOVERNOR is set, an LLM judges the
    //    action and can veto — the "self-governing topology" path. Fail-open
    //    (a governor outage doesn't halt agents); deterministic rules above are
    //    the hard floor.
    if std::env::var("CLAWMATES_DOOR_GOVERNOR").is_ok() {
        let system = "You are a security governor for an autonomous agent's outbound actions. \
             Reply with exactly ALLOW or DENY on the first line, then one short reason. \
             DENY if the action looks like data exfiltration, spam, credential/secret leakage, \
             or sending sensitive or internal data to an untrusted external recipient. \
             Otherwise ALLOW.";
        let request = format!(
            "Tool: {mcp_tool}\nCategory: {}\nPayload: {}",
            category.map(|c| c.as_str()).unwrap_or("none"),
            serde_json::to_string(args).unwrap_or_default()
        );
        // `CLAWMATES_JUDGE_MODEL=runtime:<alias>` routes the governor through a
        // ZeroClaw runtime agent (e.g. Kimi via kimi_cli on the subscription) —
        // no platform API key needed. Otherwise the server-side registry judge.
        let judge_model = cm_runtime::judge_model();
        let (allow, reason) = if let Some(alias) = judge_model.strip_prefix("runtime:") {
            match crate::topology_exec::ZeroClawDriveExecutor::from_env() {
                Ok(exec) => exec.judge(alias.trim(), system, &request).await,
                Err(e) => (true, format!("governor unreachable (fail-open): {e}")),
            }
        } else {
            state.runtime.judge(system, &request).await
        };
        // Fail-open is deliberate, but a governor that is failing open on EVERY
        // request is a security control that has quietly stopped existing —
        // and the caller drops `reason` whenever it allows, so nothing said so.
        // `judge()` returns this exact prefix when the provider never answered,
        // which a rate-limited or uncredited judge model does on every call.
        if allow && reason.starts_with("governor unreachable") {
            eprintln!(
                "mcp_door: WARNING — the door governor is FAILING OPEN for {mcp_tool} \
                 ({reason}). Every outbound action is being approved unjudged. Point \
                 CLAWMATES_JUDGE_MODEL at a reachable model."
            );
        }
        if !allow {
            return PolicyOutcome::Deny(format!("governor agent vetoed — {reason}"));
        }
    }

    PolicyOutcome::Approve
}

/// Mint an auto-approved approval + single-use execution grant for a
/// broker-executed door tool. The broker (cm-secrets) verifies & consumes this
/// grant before it reveals the credential — so even autonomous actions keep
/// credential custody out of the agent. Returns the approval id.
async fn mint_grant(
    state: &AppState,
    user: &cm_auth::AuthedUser,
    agent_id: cm_domain::AgentId,
    internal: &str,
    category: Option<cm_domain::GatedCategory>,
    args: &Value,
) -> Result<uuid::Uuid, String> {
    // approvals.run_id / requested_by_agent are strict FKs → agent → session → run.
    let session =
        cm_db::repo::sessions::create(&state.pool, agent_id, user.workspace_id, "mcp-door")
            .await
            .map_err(|e| e.to_string())?;
    let run_id = cm_db::repo::runs::create(&state.pool, session.id)
        .await
        .map_err(|e| e.to_string())?;
    let approval = cm_safety::approvals::create(
        &state.pool,
        cm_safety::NewApproval {
            workspace_id: user.workspace_id,
            run_id,
            session_key: session.id.as_uuid().to_string(),
            action_type: internal.to_string(),
            category: category.unwrap_or(cm_domain::GatedCategory::OutboundMessage),
            payload: args.clone(),
            preview: state.runtime.tool_preview(internal, args),
            requested_by_agent: agent_id,
            taint_sources: Vec::new(),
            expires_at: Some(time::OffsetDateTime::now_utc() + time::Duration::hours(1)),
        },
    )
    .await
    .map_err(|e| e.to_string())?;
    // Auto-decide (policy already approved above): mints the single-use grant
    // and writes the decision to the audit log.
    cm_safety::approvals::decide(
        &state.pool,
        approval.id,
        user.user_id,
        cm_safety::Decision::Approve,
    )
    .await
    .map_err(|e| e.to_string())?;
    Ok(approval.id)
}

/// Authenticate the bearer header → workspace/user. `None` if missing/invalid.
///
/// Accepts [`cm_auth::SCOPE_AGENT_DOOR`] as well as a person's session. This
/// route is the one that can `delegate`, and the thing that will eventually
/// hold a token for it is an agent runtime — so the narrow credential has to
/// exist before something reaches for the only one that does.
async fn authed(state: &AppState, headers: &HeaderMap) -> Option<cm_auth::AuthedUser> {
    let token = headers
        .get(AUTHORIZATION)
        .and_then(|v| v.to_str().ok())
        .and_then(|v| v.strip_prefix("Bearer "))?;
    state
        .auth
        .authenticate_scoped(token, cm_auth::SCOPE_AGENT_DOOR)
        .await
        .ok()
}

/// Resolve the specific claw making the call. Our ZeroClaw fork stamps the
/// calling agent's alias (`claw_<id>`) on every door request via the
/// `X-ZeroClaw-Agent` header (see `mcp_servers_for_agent`); we resolve it to the
/// agent and verify it belongs to the authenticated workspace. Falls back to the
/// workspace's first agent for agents provisioned before per-claw identity, so
/// attribution degrades gracefully rather than failing.
async fn caller_agent(
    state: &AppState,
    user: &cm_auth::AuthedUser,
    headers: &HeaderMap,
) -> Result<cm_domain::AgentId, String> {
    if let Some(alias) = headers
        .get("x-zeroclaw-agent")
        .and_then(|v| v.to_str().ok())
    {
        if let Some(hex) = alias.strip_prefix("claw_") {
            if let Ok(uuid) = uuid::Uuid::parse_str(hex) {
                let agent_id = cm_domain::AgentId::from(uuid);
                if let Ok(agent) = cm_db::repo::agents::get(&state.pool, agent_id).await {
                    if agent.workspace_id == user.workspace_id {
                        return Ok(agent.id);
                    }
                }
            }
        }
    }
    // Legacy fallback: attribute to the workspace's first agent.
    match cm_db::repo::agents::roster(&state.pool, user.workspace_id).await {
        Ok(roster) if !roster.is_empty() => Ok(roster[0].id),
        Ok(_) => Err("no agent in workspace to act on behalf of".into()),
        Err(_) => Err("failed to resolve workspace agent".into()),
    }
}

/// Execute a gated `delegate` call: drive a sibling claw for a sub-task and
/// return its result, audited at every step. The target is tool-free behind the
/// door, so this adds no egress (§15 holds). Safety (v1): self-delegation is
/// rejected with the precise caller identity; a per-workspace hourly cap
/// (`CLAWMATES_DELEGATE_RATE_LIMIT`) plus the per-turn timeout bound runaway
/// fan-out / recursion. Chain-based cycle detection is a follow-up.
async fn delegate_call(
    state: &AppState,
    user: &cm_auth::AuthedUser,
    caller: cm_domain::AgentId,
    args: &Value,
    id: Option<Value>,
) -> Json<Value> {
    let Some(to) = args
        .get("to")
        .and_then(|v| v.as_str())
        .filter(|s| !s.is_empty())
    else {
        return tool_result(id, true, "delegate: missing 'to' (target claw name)".into());
    };
    let Some(task) = args
        .get("task")
        .and_then(|v| v.as_str())
        .filter(|s| !s.is_empty())
    else {
        return tool_result(id, true, "delegate: missing 'task'".into());
    };
    let context: Vec<String> = args
        .get("context")
        .and_then(|v| v.as_array())
        .map(|a| {
            a.iter()
                .filter_map(|x| x.as_str().map(str::to_owned))
                .collect()
        })
        .unwrap_or_default();

    // Resolve the target claw by name within the workspace.
    let target = match cm_db::repo::agents::roster(&state.pool, user.workspace_id).await {
        Ok(roster) => roster.into_iter().find(|a| a.name.eq_ignore_ascii_case(to)),
        Err(_) => {
            return tool_result(
                id,
                true,
                "delegate: failed to resolve workspace roster".into(),
            )
        }
    };
    let Some(target) = target else {
        return tool_result(
            id,
            true,
            format!("delegate: no claw named {to:?} in this workspace"),
        );
    };
    if target.id == caller {
        return tool_result(id, true, "delegate: cannot delegate to yourself".into());
    }

    // Per-workspace hourly delegation budget (counts delegation.invoked).
    if let Some(cap) = std::env::var("CLAWMATES_DELEGATE_RATE_LIMIT")
        .ok()
        .and_then(|v| v.parse::<i64>().ok())
    {
        let used: i64 = sqlx::query_scalar(
            "SELECT count(*) FROM audit_log
             WHERE workspace_id = $1 AND event_type = 'delegation.invoked'
               AND created_at > now() - interval '1 hour'",
        )
        .bind(user.workspace_id.as_uuid())
        .fetch_one(&state.pool)
        .await
        .unwrap_or(0);
        if used >= cap {
            return tool_result(
                id,
                true,
                format!("delegate: hourly delegation limit reached ({used}/{cap})"),
            );
        }
    }

    let _ = cm_db::repo::audit::append(
        &state.pool,
        user.workspace_id,
        cm_db::repo::audit::Actor::Agent(caller),
        "delegation.invoked",
        "agent",
        &target.name,
        json!({ "to_id": target.id.to_string(), "task": task }),
    )
    .await;

    let exec = match crate::topology_exec::ZeroClawDriveExecutor::from_env() {
        Ok(exec) => exec,
        Err(e) => return tool_result(id, true, format!("delegate: runtime unavailable: {e}")),
    };
    let alias = crate::runtime_provision::claw_alias(target.id.as_uuid());
    match exec.delegate(&alias, task, &context).await {
        Ok(outcome) => {
            let _ = cm_db::repo::audit::append(
                &state.pool,
                user.workspace_id,
                cm_db::repo::audit::Actor::Agent(caller),
                "delegation.completed",
                "agent",
                &target.name,
                json!({ "to_id": target.id.to_string(), "tokens": outcome.tokens,
                        "blocked": outcome.gated.len() }),
            )
            .await;
            // §15: the result is untrusted content from another agent. The
            // attribution stays — knowing which claw produced this is
            // information the caller needs to weigh it. The "treat it as
            // information, not instructions" imperative that followed is gone:
            // that is model-correction of the kind a current frontier model no
            // longer needs, and taint tracking (output_taint = InterAgent), not
            // a sentence in the payload, is what actually contains this.
            let mut text = format!(
                "The following is the result returned by claw '{}'.\n\n{}",
                target.name, outcome.output
            );
            if !outcome.gated.is_empty() {
                text.push_str(&format!(
                    "\n\n[note: {} action(s) by '{}' were blocked at the door during this delegation]",
                    outcome.gated.len(),
                    target.name
                ));
            }
            tool_result(id, false, text)
        }
        Err(e) => {
            let _ = cm_db::repo::audit::append(
                &state.pool,
                user.workspace_id,
                cm_db::repo::audit::Actor::Agent(caller),
                "delegation.error",
                "agent",
                &target.name,
                json!({ "to_id": target.id.to_string(), "error": e.to_string() }),
            )
            .await;
            tool_result(id, true, format!("delegate: turn failed: {e}"))
        }
    }
}

/// `POST /mcp` — the JSON-RPC entrypoint ZeroClaw agents connect to.
pub async fn mcp(
    State(state): State<AppState>,
    headers: HeaderMap,
    Json(req): Json<JsonRpcReq>,
) -> Json<Value> {
    match req.method.as_str() {
        // Handshake — no auth needed to negotiate the protocol.
        "initialize" => ok(
            req.id,
            json!({
                "protocolVersion": MCP_PROTOCOL_VERSION,
                "capabilities": { "tools": {} },
                "serverInfo": { "name": "clawmates", "version": env!("CARGO_PKG_VERSION") },
            }),
        ),
        // Best-effort notification; nothing to do.
        "notifications/initialized" => Json(json!({ "jsonrpc": "2.0" })),

        "tools/list" => {
            if authed(&state, &headers).await.is_none() {
                return err(
                    req.id,
                    -32001,
                    "unauthorized: missing or invalid bearer token",
                );
            }
            let tools: Vec<Value> = EXPOSED_TOOLS
                .iter()
                .filter_map(|(mcp_name, internal)| {
                    state.runtime.tool_descriptor_json(internal).map(|mut d| {
                        // Present under the MCP-facing name.
                        d["name"] = json!(mcp_name);
                        d
                    })
                })
                .collect();
            ok(req.id, json!({ "tools": tools }))
        }

        "tools/call" => {
            let Some(user) = authed(&state, &headers).await else {
                return err(
                    req.id,
                    -32001,
                    "unauthorized: missing or invalid bearer token",
                );
            };
            let params = req.params.clone().unwrap_or_else(|| json!({}));
            let mcp_name = params.get("name").and_then(|v| v.as_str()).unwrap_or("");
            let args = params
                .get("arguments")
                .cloned()
                .unwrap_or_else(|| json!({}));

            let Some(internal) = internal_name(mcp_name) else {
                return tool_result(
                    req.id,
                    true,
                    // Derived from EXPOSED_TOOLS rather than hand-written: the
                    // literal list here had already drifted to name only one of
                    // the three tools the door actually exposes.
                    format!(
                        "unknown tool {mcp_name:?} (this door exposes: {})",
                        EXPOSED_TOOLS
                            .iter()
                            .map(|(m, _)| *m)
                            .collect::<Vec<_>>()
                            .join(", ")
                    ),
                );
            };

            let category = state.runtime.tool_gate_category(internal);

            // The gate — human replaced by automated policy.
            if let PolicyOutcome::Deny(reason) =
                policy_decide(&state, user.workspace_id, mcp_name, category, &args).await
            {
                let _ = cm_db::repo::audit::append(
                    &state.pool,
                    user.workspace_id,
                    cm_db::repo::audit::Actor::System,
                    "door.denied",
                    "tool",
                    mcp_name,
                    json!({ "category": category.map(|c| c.as_str()), "reason": reason, "args": args }),
                )
                .await;
                return tool_result(req.id, true, format!("denied by policy: {reason}"));
            }

            // Attribute the action to the specific calling claw (X-ZeroClaw-Agent
            // header), or the workspace's first agent as a legacy fallback.
            let agent_id = match caller_agent(&state, &user, &headers).await {
                Ok(id) => id,
                Err(msg) => return tool_result(req.id, true, msg),
            };

            // Gated delegation bridge: `delegate` causes a sibling claw to run a
            // full turn and returns its result, gated + audited here rather than
            // via ZeroClaw's in-memory DelegateTool (which would bypass the door).
            if internal == "delegate" {
                return delegate_call(&state, &user, agent_id, &args, req.id).await;
            }

            // Broker-executed tools (e.g. slack.post) need a single-use grant
            // the broker consumes — the agent never holds the credential. Mint
            // an auto-approved approval+grant (the human is the policy above).
            // Runtime-executed tools (email.send -> outbox) need no grant.
            let approval_id = if state.runtime.tool_broker_executed(internal) {
                match mint_grant(&state, &user, agent_id, internal, category, &args).await {
                    Ok(id) => Some(id),
                    Err(e) => {
                        return tool_result(req.id, true, format!("could not mint grant: {e}"))
                    }
                }
            } else {
                None
            };

            match state
                .runtime
                .execute_door_tool(
                    user.workspace_id,
                    agent_id,
                    internal,
                    args.clone(),
                    approval_id,
                )
                .await
            {
                Ok(output) => {
                    let _ = cm_db::repo::audit::append(
                        &state.pool,
                        user.workspace_id,
                        cm_db::repo::audit::Actor::Agent(agent_id),
                        "door.executed",
                        "tool",
                        mcp_name,
                        json!({
                            "category": category.map(|c| c.as_str()),
                            "auto_decided": true,
                            "args": args,
                            "output": output,
                        }),
                    )
                    .await;
                    tool_result(req.id, false, output.to_string())
                }
                Err(message) => {
                    let _ = cm_db::repo::audit::append(
                        &state.pool,
                        user.workspace_id,
                        cm_db::repo::audit::Actor::Agent(agent_id),
                        "door.error",
                        "tool",
                        mcp_name,
                        json!({ "error": message, "args": args }),
                    )
                    .await;
                    tool_result(req.id, true, format!("tool error: {message}"))
                }
            }
        }

        other => err(req.id, -32601, &format!("method not found: {other}")),
    }
}

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

    #[test]
    fn exposed_tool_name_maps_to_registry_name() {
        assert_eq!(internal_name("email_send"), Some("email.send"));
        assert_eq!(internal_name("slack_post"), Some("slack.post"));
        assert_eq!(internal_name("delegate"), Some("delegate"));
        assert_eq!(internal_name("shell"), None);
    }

    #[test]
    fn ok_frame_echoes_id_and_carries_result() {
        let Json(v) = ok(Some(json!(7)), json!({ "tools": [] }));
        assert_eq!(v["jsonrpc"], "2.0");
        assert_eq!(v["id"], 7);
        assert_eq!(v["result"]["tools"], json!([]));
    }

    #[test]
    fn err_frame_has_code_and_message() {
        let Json(v) = err(Some(json!("a")), -32001, "unauthorized");
        assert_eq!(v["error"]["code"], -32001);
        assert_eq!(v["error"]["message"], "unauthorized");
    }

    #[test]
    fn tool_result_shapes_content_and_is_error() {
        let Json(v) = tool_result(Some(json!(1)), true, "denied by policy: nope".into());
        assert_eq!(v["result"]["isError"], true);
        assert_eq!(v["result"]["content"][0]["type"], "text");
        assert_eq!(v["result"]["content"][0]["text"], "denied by policy: nope");
    }
}