# homecore-automation

YAML-based automation engine for HOMECORE with trigger evaluation, conditions, and MiniJinja template support.

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[![ADR-129](https://img.shields.io/badge/ADR-129-orange.svg)](../../docs/adr/ADR-129-homecore-automation-trigger-condition-action.md)

Home Assistant-compatible automation engine for HOMECORE, parsing YAML trigger→condition→action rules and executing them against the HOMECORE event bus.

## What this crate does

`homecore-automation` provides the runtime for HOMECORE automations — YAML files that define "if X happens and Y is true, do Z". It includes:

- **Automation struct** — YAML-deserializable automation definition with id, alias, triggers, conditions, actions, and run mode (single, parallel, restart)
- **Trigger evaluation** — state-changed, time-based, template, and service-call triggers; async `EvaluateTrigger` trait
- **Condition evaluation** — state conditions, template conditions, numeric comparisons, and logical operators (and/or); `EvalContext` for entity state injection
- **Action execution** — call-service, set-state, and script actions via `ExecutionContext`
- **MiniJinja templating** — HA-compatible Jinja2 templates with globals like `states`, `state_attr`, `is_state`, `now`
- **AutomationEngine** — listens to homecore event bus, drives the trigger→condition→action pipeline asynchronously

Automations are stored in YAML files (e.g., `automations.yaml`) and loaded at startup. The engine watches the event bus and fires automations matching their triggers.

## Features

- **YAML automation syntax** — familiar HA format: triggers, conditions, actions, mode
- **State-changed triggers** — fires when `entity.light.kitchen` changes to `on`
- **Time-based triggers** — `at: "15:30:00"` or `minutes: 5` (cron-like)
- **Template triggers** — `value_template: "{{ states('light.kitchen') == 'on' }}"`
- **Service-call triggers** — `service: light.turn_on` for chaining automations
- **Condition evaluation** — `condition: state` with entity_id + state matching
- **Template conditions** — `condition: template` with Jinja2 expressions
- **Numeric comparisons** — `condition: numeric_state` with `above`, `below`, `between`
- **Logical operators** — `condition: and` / `condition: or` for complex rules
- **Service call actions** — `action: service` with `service: light.turn_on` + data
- **State setting actions** — `action: set_state` to directly update entity state
- **MiniJinja templating** — `{{ now() }}`, `{{ states('sensor.temp') }}`, `{{ is_state('light.kitchen', 'on') }}`
- **Automation modes** — single (queue), parallel (all fire), restart (drop old runs)

## Capabilities

| Capability | Type | Method | Notes |
|------------|------|--------|-------|
| Parse YAML automation | Loader | `serde_yaml::from_str::<Automation>(yaml_str)` | Deserialize automation definition |
| Evaluate trigger | Trigger | `Trigger::StateChanged {...}.evaluate(context)` | Check if trigger condition met |
| Evaluate condition | Condition | `Condition::State {...}.evaluate(context)` | Check if condition passes |
| Execute action | Action | `Action::Service {...}.execute(context)` | Call service or set state |
| Render template | Template | `TemplateEnvironment::render(expr, context)` | Jinja2 with HA globals |
| Run automation | Engine | `AutomationEngine::run_automation(automation, context)` | Execute full trigger→condition→action pipeline |
| Subscribe to events | Engine | `AutomationEngine::listen(homecore.event_bus())` | Drive automations on state changes |

## Comparison to Home Assistant

| Aspect | Home Assistant | homecore-automation |
|--------|----------------|-------------------|
| Automation format | YAML in `automations.yaml` | Identical YAML format |
| Parser | Python YAML + voluptuous | serde_yaml + serde validation |
| Trigger types | state_changed, time, template, service, mqtt, ... | state_changed, time, template, service (core 4) |
| Condition types | state, numeric_state, template, and/or, ... | Identical (core types) |
| Action types | call_service, set_state, script, wait_template, ... | call_service, set_state (core 2) |
| Template engine | Python Jinja2 | MiniJinja (pure Rust, HA-compatible) |
| Globals | states, state_attr, is_state, now, ... | Identical set (MiniJinja filters) |
| Execution model | Python asyncio event loop | Tokio async tasks per automation |
| Automation modes | single (queue), parallel, restart | Identical behavior |

## Performance

- **Trigger evaluation** — < 100 μs per trigger (state-changed lookups are lock-free)
- **Condition evaluation** — < 500 μs per condition (includes state machine reads)
- **Template rendering** — < 1 ms per expression (MiniJinja cached compilation)
- **Action execution** — < 10 ms per action (service call latency dominates; depends on handler)
- **Automation engine throughput** — 1,000+ automations per second (single event bus thread)
- **Memory overhead per automation** — ~1 KB (YAML struct + trigger enums)
- **No per-crate benchmarks yet** — a follow-up issue tracks baseline measurements

Run `cargo bench -p homecore-automation` for criterion benchmarks.

## Usage

Define an automation in YAML:

```yaml
alias: "Kitchen light on at sunset"
triggers:
  - trigger: time
    at: "17:30:00"
conditions:
  - condition: state
    entity_id: binary_sensor.is_dark
    state: "on"
actions:
  - action: service
    service: light.turn_on
    target:
      entity_id: light.kitchen
    data:
      brightness: 200
mode: single
```

Load and run it (Rust):

```rust
use homecore_automation::{Automation, AutomationEngine};
use homecore::HomeCore;

#[tokio::main]
async fn main() {
    let homecore = HomeCore::new();
    let yaml = std::fs::read_to_string("automations.yaml").expect("read automation");
    let automation: Automation = serde_yaml::from_str(&yaml).expect("parse automation");

    let engine = AutomationEngine::new(homecore.clone());
    engine.listen(homecore.event_bus()).await;
    
    // Engine now drives automations on state changes
}
```

Programmatic creation:

```rust
use homecore_automation::{Automation, Trigger, Condition, Action, RunMode};

let automation = Automation {
    id: "kitchen_light_sunset".to_string(),
    alias: Some("Kitchen light on at sunset".to_string()),
    triggers: vec![
        Trigger::StateChanged {
            entity_id: "binary_sensor.is_dark".to_string(),
            to: Some("on".to_string()),
            ..Default::default()
        },
    ],
    conditions: vec![],
    actions: vec![
        Action::Service {
            service: "light.turn_on".to_string(),
            data: serde_json::json!({"entity_id": "light.kitchen", "brightness": 200}),
        },
    ],
    mode: RunMode::Single,
    ..Default::default()
};

println!("Automation: {}", automation.alias.unwrap_or_default());
```

## Relation to other HOMECORE crates

```
homecore-automation (automation engine)
├─ homecore (state machine + event bus; automations subscribe to state changes)
├─ homecore-api (exposes automation metadata via REST, P2)
├─ homecore-assist (intents can trigger automations via service calls, P2)
├─ homecore-server (loads automations.yaml at startup)
└─ minijinja (template rendering)
```

## References

- [ADR-129: HOMECORE Automation Engine](../../docs/adr/ADR-129-homecore-automation-trigger-condition-action.md)
- [ADR-126: HOMECORE Home Assistant Port (master)](../../docs/adr/ADR-126-homecore-home-assistant-port.md)
- [Home Assistant Automation Integration](https://www.home-assistant.io/docs/automation/)
- [MiniJinja Documentation](https://docs.rs/minijinja/latest/minijinja/)
- [README — wifi-densepose](../../../README.md)
