openlatch-client 0.0.1

//! Envelope module — core data types for event wrapping, agent identification, and verdict responses.
//!
//! This is a leaf module with zero internal dependencies. Every event flowing through the daemon
//! gets wrapped in an [`EventEnvelope`]. The types here are consumed by daemon handlers, the
//! privacy filter, and the logging module.

use serde::{Deserialize, Serialize};

/// Closed enumeration of supported agent platforms.
///
/// This enum is non-negotiable per the envelope format spec. Unknown agent types must be rejected
/// at deserialization. Adding a new agent requires updating this enum and bumping the minor version.
///
/// Serializes to kebab-case (e.g. `ClaudeCode` → `"claude-code"`).
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
#[serde(rename_all = "kebab-case")]
pub enum AgentType {
    ClaudeCode,
    Cursor,
    Windsurf,
    GithubCopilot,
    CodexCli,
    GeminiCli,
    Cline,
    // SECURITY: Closed enum — unknown agent types are rejected at deserialization (OL-1001).
    // Manual rename needed: kebab-case would produce "open-claw" but the spec requires "openclaw".
    #[serde(rename = "openclaw")]
    OpenClaw,
}

/// Hook event type — identifies which agent lifecycle event triggered this envelope.
///
/// Serializes to snake_case (e.g. `PreToolUse` → `"pre_tool_use"`).
#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq)]
#[serde(rename_all = "snake_case")]
pub enum HookEventType {
    PreToolUse,
    UserPromptSubmit,
    Stop,
}

/// Verdict returned to the agent hook.
///
/// In M1, only `Allow` and `Approve` are used. `Deny` is defined for schema completeness
/// but is never returned by M1 handlers.
///
/// Serializes to lowercase (e.g. `Allow` → `"allow"`).
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
#[serde(rename_all = "lowercase")]
pub enum Verdict {
    Allow,
    Approve,
    /// Defined for schema completeness — not used in M1.
    Deny,
}

/// Complete event envelope wrapping a raw agent hook event with cross-cutting metadata.
///
/// All fields correspond to EVNT-02 requirements. Optional fields are omitted from JSON
/// when `None` to keep payloads compact.
///
/// # Examples
///
/// ```rust
/// use openlatch_client::envelope::{EventEnvelope, AgentType, HookEventType, Verdict,
///     new_event_id, current_timestamp, os_string, arch_string};
///
/// let envelope = EventEnvelope {
///     schema_version: "1.0".to_string(),
///     id: new_event_id(),
///     timestamp: current_timestamp(),
///     event_type: HookEventType::PreToolUse,
///     session_id: "session-abc".to_string(),
///     tool_name: Some("bash".to_string()),
///     tool_input: None,
///     user_prompt: None,
///     reason: None,
///     verdict: Verdict::Allow,
///     latency_ms: 3,
///     agent_platform: AgentType::ClaudeCode,
///     agent_version: None,
///     os: os_string().to_string(),
///     arch: arch_string().to_string(),
///     client_version: env!("CARGO_PKG_VERSION").to_string(),
/// };
/// ```
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
#[serde(rename_all = "snake_case")]
pub struct EventEnvelope {
    pub schema_version: String,
    pub id: String,
    pub timestamp: String,
    pub event_type: HookEventType,
    pub session_id: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub tool_name: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub tool_input: Option<serde_json::Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub user_prompt: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reason: Option<String>,
    pub verdict: Verdict,
    pub latency_ms: u64,
    pub agent_platform: AgentType,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub agent_version: Option<String>,
    pub os: String,
    pub arch: String,
    pub client_version: String,
}

/// Verdict response returned to the agent hook after processing.
///
/// Mirrors the cloud response schema. Optional fields are omitted when `None`.
/// Use the [`VerdictResponse::allow`] and [`VerdictResponse::approve`] constructors for M1.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
#[serde(rename_all = "snake_case")]
pub struct VerdictResponse {
    pub schema_version: String,
    pub verdict: Verdict,
    pub event_id: String,
    pub latency_ms: f64,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reason: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub severity: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub threat_category: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub rule_id: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub details_url: Option<String>,
}

impl VerdictResponse {
    /// Constructs an `allow` verdict response for PreToolUse and UserPromptSubmit events.
    pub fn allow(event_id: String, latency_ms: f64) -> Self {
        Self {
            schema_version: "1.0".to_string(),
            verdict: Verdict::Allow,
            event_id,
            latency_ms,
            reason: None,
            severity: None,
            threat_category: None,
            rule_id: None,
            details_url: None,
        }
    }

    /// Constructs an `approve` verdict response for Stop events.
    pub fn approve(event_id: String, latency_ms: f64) -> Self {
        Self {
            schema_version: "1.0".to_string(),
            verdict: Verdict::Approve,
            event_id,
            latency_ms,
            reason: None,
            severity: None,
            threat_category: None,
            rule_id: None,
            details_url: None,
        }
    }
}

/// Generates a new UUIDv7 event ID.
///
/// UUIDv7 IDs encode a millisecond-precision Unix timestamp in the most significant bits,
/// making them monotonically ordered when compared lexicographically. This satisfies EVNT-01.
pub fn new_event_id() -> String {
    format!("evt_{}", uuid::Uuid::now_v7())
}

/// Returns the current UTC timestamp as an RFC 3339 string with Z suffix.
///
/// Example output: `"2026-04-07T12:00:00Z"`
///
/// # PERFORMANCE: Pure in-memory — no I/O, no allocation beyond the returned String.
pub fn current_timestamp() -> String {
    chrono::Utc::now().to_rfc3339_opts(chrono::SecondsFormat::Secs, true)
}

/// Returns the current OS name as reported by the Rust standard library.
///
/// Examples: `"linux"`, `"macos"`, `"windows"`
pub fn os_string() -> &'static str {
    std::env::consts::OS
}

/// Returns the current CPU architecture as reported by the Rust standard library.
///
/// Examples: `"x86_64"`, `"aarch64"`
pub fn arch_string() -> &'static str {
    std::env::consts::ARCH
}

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

    fn make_test_envelope() -> EventEnvelope {
        EventEnvelope {
            schema_version: "1.0".to_string(),
            id: new_event_id(),
            timestamp: current_timestamp(),
            event_type: HookEventType::PreToolUse,
            session_id: "test-session-123".to_string(),
            tool_name: Some("bash".to_string()),
            tool_input: Some(serde_json::json!({"command": "ls -la"})),
            user_prompt: None,
            reason: None,
            verdict: Verdict::Allow,
            latency_ms: 3,
            agent_platform: AgentType::ClaudeCode,
            agent_version: None,
            os: os_string().to_string(),
            arch: arch_string().to_string(),
            client_version: env!("CARGO_PKG_VERSION").to_string(),
        }
    }

    #[test]
    fn test_event_envelope_serializes_all_required_fields() {
        let envelope = make_test_envelope();
        let json = serde_json::to_value(&envelope).expect("serialization must succeed");

        // All required fields must be present
        assert!(
            json.get("schema_version").is_some(),
            "missing schema_version"
        );
        assert!(json.get("id").is_some(), "missing id");
        assert!(json.get("timestamp").is_some(), "missing timestamp");
        assert!(json.get("event_type").is_some(), "missing event_type");
        assert!(json.get("session_id").is_some(), "missing session_id");
        assert!(json.get("verdict").is_some(), "missing verdict");
        assert!(json.get("latency_ms").is_some(), "missing latency_ms");
        assert!(
            json.get("agent_platform").is_some(),
            "missing agent_platform"
        );
        assert!(json.get("os").is_some(), "missing os");
        assert!(json.get("arch").is_some(), "missing arch");
        assert!(
            json.get("client_version").is_some(),
            "missing client_version"
        );
    }

    #[test]
    fn test_agent_type_claude_code_serializes_to_kebab_case() {
        let agent_type = AgentType::ClaudeCode;
        let json = serde_json::to_string(&agent_type).expect("serialization must succeed");
        assert_eq!(json, "\"claude-code\"");
    }

    #[test]
    fn test_all_8_agent_types_serialize_correctly() {
        let cases = [
            (AgentType::ClaudeCode, "claude-code"),
            (AgentType::Cursor, "cursor"),
            (AgentType::Windsurf, "windsurf"),
            (AgentType::GithubCopilot, "github-copilot"),
            (AgentType::CodexCli, "codex-cli"),
            (AgentType::GeminiCli, "gemini-cli"),
            (AgentType::Cline, "cline"),
            (AgentType::OpenClaw, "openclaw"),
        ];

        for (agent, expected) in cases {
            let json = serde_json::to_string(&agent).expect("serialization must succeed");
            assert_eq!(
                json,
                format!("\"{}\"", expected),
                "wrong serialization for {:?}",
                agent
            );
        }
    }

    #[test]
    fn test_event_envelope_id_has_evt_prefix_and_valid_uuid_v7() {
        let id = new_event_id();
        assert!(
            id.starts_with("evt_"),
            "ID must start with evt_ prefix: {}",
            id
        );
        let uuid_part = id.strip_prefix("evt_").unwrap();
        let parsed = uuid::Uuid::parse_str(uuid_part).expect("ID must contain a valid UUID");
        // UUIDv7 has version nibble = 7 in the 7th byte (bits 12-15)
        assert_eq!(parsed.get_version_num(), 7, "UUID version must be 7");
    }

    #[test]
    fn test_consecutive_event_ids_are_monotonically_ordered() {
        let id1 = new_event_id();
        // Small sleep not needed — UUIDv7 uses sub-millisecond monotonic counter
        let id2 = new_event_id();
        assert!(
            id1 <= id2,
            "UUIDv7 IDs must be monotonically ordered: {} <= {}",
            id1,
            id2
        );
    }

    #[test]
    fn test_timestamp_ends_with_z_suffix() {
        let ts = current_timestamp();
        assert!(
            ts.ends_with('Z'),
            "Timestamp must end with 'Z' for UTC: {}",
            ts
        );
    }

    #[test]
    fn test_verdict_response_serializes_optional_fields_omitted_when_none() {
        let resp = VerdictResponse::allow("evt-001".to_string(), 5.0);
        let json = serde_json::to_value(&resp).expect("serialization must succeed");

        // Optional fields must NOT appear when None
        assert!(
            json.get("reason").is_none(),
            "reason should be omitted when None"
        );
        assert!(
            json.get("severity").is_none(),
            "severity should be omitted when None"
        );
        assert!(
            json.get("threat_category").is_none(),
            "threat_category should be omitted when None"
        );
        assert!(
            json.get("rule_id").is_none(),
            "rule_id should be omitted when None"
        );
        assert!(
            json.get("details_url").is_none(),
            "details_url should be omitted when None"
        );

        // Required fields must still be present
        assert_eq!(json["schema_version"], "1.0");
        assert_eq!(json["event_id"], "evt-001");
        assert_eq!(json["latency_ms"], 5.0);
    }

    #[test]
    fn test_verdict_allow_serializes_to_allow() {
        let verdict = Verdict::Allow;
        let json = serde_json::to_string(&verdict).expect("serialization must succeed");
        assert_eq!(json, "\"allow\"");
    }

    #[test]
    fn test_verdict_approve_serializes_to_approve() {
        let verdict = Verdict::Approve;
        let json = serde_json::to_string(&verdict).expect("serialization must succeed");
        assert_eq!(json, "\"approve\"");
    }

    #[test]
    fn test_hook_event_type_pre_tool_use_serializes_to_snake_case() {
        let event_type = HookEventType::PreToolUse;
        let json = serde_json::to_string(&event_type).expect("serialization must succeed");
        assert_eq!(json, "\"pre_tool_use\"");
    }

    #[test]
    fn test_event_envelope_round_trips_through_serde_json() {
        let original = make_test_envelope();
        let serialized = serde_json::to_string(&original).expect("serialization must succeed");
        let deserialized: EventEnvelope =
            serde_json::from_str(&serialized).expect("deserialization must succeed");
        assert_eq!(original, deserialized);
    }

    #[test]
    fn test_client_version_matches_cargo_pkg_version() {
        let envelope = make_test_envelope();
        assert_eq!(envelope.client_version, env!("CARGO_PKG_VERSION"));
    }

    #[test]
    fn test_user_prompt_serialized_when_present_omitted_when_none() {
        let mut envelope = make_test_envelope();

        // When None, field should be absent from JSON
        let json = serde_json::to_value(&envelope).unwrap();
        assert!(
            json.get("user_prompt").is_none(),
            "user_prompt should be omitted when None"
        );

        // When Some, field should be present
        envelope.user_prompt = Some("tell me about Rust".to_string());
        let json = serde_json::to_value(&envelope).unwrap();
        assert_eq!(json["user_prompt"], "tell me about Rust");
    }

    #[test]
    fn test_reason_serialized_when_present_omitted_when_none() {
        let mut envelope = make_test_envelope();

        // When None, field should be absent from JSON
        let json = serde_json::to_value(&envelope).unwrap();
        assert!(
            json.get("reason").is_none(),
            "reason should be omitted when None"
        );

        // When Some, field should be present
        envelope.reason = Some("end_turn".to_string());
        let json = serde_json::to_value(&envelope).unwrap();
        assert_eq!(json["reason"], "end_turn");
    }

    #[test]
    fn test_schema_version_serializes_as_string() {
        let envelope = make_test_envelope();
        let json = serde_json::to_value(&envelope).unwrap();
        assert_eq!(
            json["schema_version"], "1.0",
            "schema_version must be string \"1.0\""
        );
    }
}