little-durable-objects 0.1.13

use anyhow::{Result, ensure};
use serde::{Deserialize, Serialize};
use serde_json::Value;

use crate::{actor::ActorSocketEffect, actor_state::ActorStorageKey};

const MAX_NAMESPACE_ID_BYTES: usize = 96;
const MAX_ACTOR_TYPE_BYTES: usize = 48;
const MAX_ACTOR_ID_BYTES: usize = 128;
const MAX_METHOD_BYTES: usize = 128;

/// The authenticated tenant boundary shared by a collection of actors.
#[derive(Clone, Debug)]
pub struct ActorScope {
    pub namespace_id: String,
}

impl ActorScope {
    pub fn validate(&self) -> Result<()> {
        validate_component("namespace ID", &self.namespace_id, MAX_NAMESPACE_ID_BYTES)
    }

    pub fn contains(&self, actor: &ActorKey) -> bool {
        actor.namespace_id == self.namespace_id
    }
}

/// The namespace-scoped identity of one actor instance.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub struct ActorKey {
    pub namespace_id: String,
    pub actor_type: String,
    pub actor_id: String,
}

impl ActorKey {
    pub fn validate(&self) -> Result<()> {
        validate_component("namespace ID", &self.namespace_id, MAX_NAMESPACE_ID_BYTES)?;
        validate_component("actor type", &self.actor_type, MAX_ACTOR_TYPE_BYTES)?;
        validate_component("actor ID", &self.actor_id, MAX_ACTOR_ID_BYTES)?;
        self.storage_key().validate()
    }

    /// Stable, readable identity used for coordination records.
    pub fn storage_key(&self) -> ActorStorageKey {
        ActorStorageKey::new(format!(
            "object.v1.{}.{}.{}",
            self.namespace_id, self.actor_type, self.actor_id
        ))
    }
}

#[derive(Clone, Debug, PartialEq)]
pub struct ActorInvocation {
    /// Correlation ID for this caller attempt. It is not an idempotency key.
    pub request_id: String,
    pub actor: ActorKey,
    pub method: String,
    pub args: Vec<Value>,
}

impl ActorInvocation {
    pub fn validate(&self) -> Result<()> {
        ensure!(!self.request_id.is_empty(), "request ID must not be empty");
        ensure!(
            self.request_id.len() <= 255,
            "request ID must be at most 255 bytes"
        );
        self.actor.validate()?;
        validate_component("actor method", &self.method, MAX_METHOD_BYTES)?;
        Ok(())
    }
}

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct ActorInvocationFailure {
    pub code: String,
    pub message: String,
}

impl ActorInvocationFailure {
    pub(crate) fn outcome_unknown_after_execution() -> Self {
        Self {
            code: "outcome_unknown".into(),
            message: "actor execution completed, but its durable publication outcome could not be confirmed".into(),
        }
    }
}

#[derive(Clone, Debug, PartialEq)]
pub enum ActorExecutionResult {
    Completed {
        result: Value,
        effects: Vec<ActorSocketEffect>,
    },
    Failed {
        failure: ActorInvocationFailure,
    },
    Reroute,
    HostUnavailable,
}

fn validate_component(name: &str, value: &str, max_bytes: usize) -> Result<()> {
    ensure!(!value.is_empty(), "{name} must not be empty");
    ensure!(
        value.len() <= max_bytes,
        "{name} must be at most {max_bytes} bytes"
    );
    ensure!(
        value
            .bytes()
            .all(|byte| byte.is_ascii_alphanumeric() || matches!(byte, b'-' | b'_' | b'.')),
        "{name} may contain only ASCII letters, digits, '.', '-', and '_'"
    );
    Ok(())
}

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

    #[test]
    fn maps_a_tenant_scoped_actor_to_one_safe_object_id() {
        let key = ActorKey {
            namespace_id: "namespace-1".into(),
            actor_type: "counter".into(),
            actor_id: "customer.123".into(),
        };

        key.validate().expect("actor key");
        assert_eq!(
            key.storage_key().as_str(),
            "object.v1.namespace-1.counter.customer.123"
        );
    }

    #[test]
    fn rejects_components_that_can_reshape_storage_paths() {
        let mut key = ActorKey {
            namespace_id: "namespace-1".into(),
            actor_type: "counter".into(),
            actor_id: "../other".into(),
        };
        assert!(key.validate().is_err());

        key.actor_id = "valid".into();
        key.actor_type = "counter/type".into();
        assert!(key.validate().is_err());
    }
}