elasticctl-api 0.1.3

//! Deterministic rule forms.
//!
//! `canonical` is what `pull` writes: volatile fields removed and keys sorted.
//! `comparable` is what `diff` compares: `canonical` plus server defaults.
//! They remain separate so `pull` does not write defaults the author omitted.

use crate::model::{Rule, VOLATILE_FIELDS, server_defaults};
use serde_json::{Map, Value};

/// Remove the server-owned fields that change on every write.
pub fn strip_volatile(rule: &mut Rule) {
    let map = rule.as_map_mut();
    for field in VOLATILE_FIELDS {
        map.remove(field);
    }
}

/// Add fields the server fills on create without overwriting explicit values.
pub fn fill_defaults(rule: &mut Rule) {
    let map = rule.as_map_mut();
    for (k, v) in server_defaults() {
        map.entry(k).or_insert(v);
    }
}

/// Recursively sort object keys for deterministic output.
///
/// `serde_json::Map` currently uses `BTreeMap`, but `preserve_order` makes it
/// retain insertion order. Rebuild the map so output order does not depend on
/// a transitive feature.
fn sort_value(value: &Value) -> Value {
    match value {
        Value::Object(m) => {
            let mut keys: Vec<&String> = m.keys().collect();
            keys.sort();
            let mut out = Map::new();
            for k in keys {
                out.insert(k.clone(), sort_value(&m[k]));
            }
            Value::Object(out)
        }
        // Array order is meaningful for tags, index patterns, and threat
        // mappings, so preserve it.
        Value::Array(a) => Value::Array(a.iter().map(sort_value).collect()),
        other => other.clone(),
    }
}

/// The on-disk form.
pub fn canonical(rule: &Rule) -> Rule {
    let mut out = rule.clone();
    strip_volatile(&mut out);
    let sorted = sort_value(&Value::Object(out.as_map().clone()));
    Rule::from_value(sorted).expect("rule_id survives normalization")
}

/// The comparison form.
pub fn comparable(rule: &Rule) -> Rule {
    let mut out = rule.clone();
    strip_volatile(&mut out);
    fill_defaults(&mut out);
    let sorted = sort_value(&Value::Object(out.as_map().clone()));
    Rule::from_value(sorted).expect("rule_id survives normalization")
}

/// Sort rules for stable file output and diff reports. Rules with unreadable
/// `rule_id` values sort last.
pub fn sort_rules(rules: &mut [Rule]) {
    rules.sort_by(|a, b| {
        let (x, y) = (
            a.rule_id().unwrap_or("\u{7f}"),
            b.rule_id().unwrap_or("\u{7f}"),
        );
        x.cmp(y)
    });
}

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

    fn pulled() -> Rule {
        // A rule returned by the API.
        Rule::from_value(json!({
            "rule_id": "abc", "name": "a rule", "type": "query", "risk_score": 21,
            "id": "6b796e42-99fa-4296-8dc1-a693dd455dd0",
            "created_at": "2026-08-12T17:49:01.682Z", "created_by": "key-id",
            "updated_at": "2026-08-12T17:49:01.682Z", "updated_by": "key-id",
            "revision": 0, "version": 1,
            "execution_summary": {"last_execution": {"date": "2026-08-13T03:00:20.804Z"}},
            "max_signals": 100, "to": "now"
        }))
        .unwrap()
    }

    fn hand_authored() -> Rule {
        // A hand-authored rule has no volatile fields or defaults.
        Rule::from_value(json!({
            "rule_id": "abc", "name": "a rule", "type": "query", "risk_score": 21
        }))
        .unwrap()
    }

    #[test]
    fn strip_volatile_removes_all_eight_measured_fields() {
        let mut r = pulled();
        strip_volatile(&mut r);
        for f in VOLATILE_FIELDS {
            assert!(!r.as_map().contains_key(f), "{f} should have been stripped");
        }
        assert_eq!(r.rule_id().unwrap(), "abc", "identity must survive");
        assert_eq!(
            r.as_map()["max_signals"],
            json!(100),
            "non-volatile fields stay"
        );
    }

    #[test]
    fn strip_volatile_is_idempotent() {
        let mut once = pulled();
        strip_volatile(&mut once);
        let mut twice = once.clone();
        strip_volatile(&mut twice);
        assert_eq!(once, twice);
    }

    #[test]
    fn fill_defaults_adds_only_absent_fields() {
        let mut r = hand_authored();
        fill_defaults(&mut r);
        assert_eq!(r.as_map()["max_signals"], json!(100));
        assert_eq!(r.as_map()["to"], json!("now"));
        assert_eq!(
            r.as_map()["risk_score"],
            json!(21),
            "an author's value is never replaced"
        );
    }

    #[test]
    fn fill_defaults_never_overwrites_an_explicit_value() {
        let mut r = Rule::from_value(json!({"rule_id": "abc", "max_signals": 5000})).unwrap();
        fill_defaults(&mut r);
        assert_eq!(r.as_map()["max_signals"], json!(5000));
    }

    #[test]
    fn canonical_sorts_keys_so_output_is_deterministic() {
        let a = Rule::from_value(json!({"rule_id": "x", "zeta": 1, "alpha": 2})).unwrap();
        let b = Rule::from_value(json!({"rule_id": "x", "alpha": 2, "zeta": 1})).unwrap();
        let (ca, cb) = (canonical(&a), canonical(&b));
        assert_eq!(ca, cb, "key order must not affect the canonical form");
        let keys: Vec<&String> = ca.as_map().keys().collect();
        let mut sorted = keys.clone();
        sorted.sort();
        assert_eq!(keys, sorted);
    }

    #[test]
    fn canonical_sorts_nested_object_keys_too() {
        let r = Rule::from_value(json!({
            "rule_id": "x", "rule_source": {"zeta": 1, "alpha": 2}
        }))
        .unwrap();
        let c = canonical(&r);
        let nested = c.as_map()["rule_source"].as_object().unwrap();
        let keys: Vec<&String> = nested.keys().collect();
        assert_eq!(keys, vec!["alpha", "zeta"]);
    }

    #[test]
    fn canonical_does_not_invent_defaults() {
        let c = canonical(&hand_authored());
        assert!(
            !c.as_map().contains_key("max_signals"),
            "pull must not bloat files"
        );
    }

    // The state engine relies on this property.
    #[test]
    fn a_pulled_rule_and_its_hand_authored_equivalent_compare_equal() {
        assert_eq!(
            comparable(&pulled()),
            comparable(&hand_authored()),
            "a sparse local file must not read as drift against its remote counterpart"
        );
    }

    #[test]
    fn a_real_difference_still_compares_unequal() {
        let mut changed = hand_authored();
        changed.as_map_mut().insert("risk_score".into(), json!(99));
        assert_ne!(comparable(&pulled()), comparable(&changed));
    }

    #[test]
    fn sort_rules_orders_by_rule_id() {
        let mk = |id: &str| Rule::from_value(json!({"rule_id": id})).unwrap();
        let mut rules = vec![mk("c"), mk("a"), mk("b")];
        sort_rules(&mut rules);
        let ids: Vec<&str> = rules.iter().map(|r| r.rule_id().unwrap()).collect();
        assert_eq!(ids, vec!["a", "b", "c"]);
    }

    #[test]
    fn array_order_is_preserved_not_sorted() {
        let r = Rule::from_value(json!({
            "rule_id": "x",
            "tags": ["zebra", "alpha", "middle"],
            "index": ["logs-b-*", "logs-a-*"],
            "threat": [{"z": 1}, {"a": 2}]
        }))
        .unwrap();
        let c = canonical(&r);
        let tags = c.as_map()["tags"].as_array().unwrap();
        let tag_strs: Vec<&str> = tags.iter().filter_map(|v| v.as_str()).collect();
        assert_eq!(
            tag_strs,
            vec!["zebra", "alpha", "middle"],
            "tag order must be preserved"
        );
        let index = c.as_map()["index"].as_array().unwrap();
        let index_strs: Vec<&str> = index.iter().filter_map(|v| v.as_str()).collect();
        assert_eq!(
            index_strs,
            vec!["logs-b-*", "logs-a-*"],
            "index order must be preserved"
        );
        let threat = c.as_map()["threat"].as_array().unwrap();
        let first_key = threat[0].as_object().unwrap().keys().next().unwrap();
        assert_eq!(
            first_key, "z",
            "array element order preserved, keys sorted within"
        );
    }

    #[test]
    fn sort_rules_puts_unreadable_rule_id_last_without_panicking() {
        // Transparent `Deserialize` can create this; `from_value` rejects it.
        let bad: Rule = serde_json::from_value(json!({"rule_id": 123})).unwrap();
        let good_c = Rule::from_value(json!({"rule_id": "c"})).unwrap();
        let good_a = Rule::from_value(json!({"rule_id": "a"})).unwrap();
        let mut rules = vec![good_c, bad, good_a];
        sort_rules(&mut rules);
        assert_eq!(rules[0].rule_id().unwrap(), "a");
        assert_eq!(rules[1].rule_id().unwrap(), "c");
        assert!(rules[2].rule_id().is_err(), "unreadable id sorts last");
    }

    #[test]
    fn canonical_is_idempotent() {
        let r = Rule::from_value(json!({
            "rule_id": "x", "tags": ["z", "a"], "nested": {"z": 1, "a": 2}
        }))
        .unwrap();
        let once = canonical(&r);
        let twice = canonical(&once);
        assert_eq!(once, twice);
    }

    #[test]
    fn comparable_is_idempotent() {
        let r = Rule::from_value(json!({
            "rule_id": "x", "name": "test", "type": "query", "risk_score": 10
        }))
        .unwrap();
        let once = comparable(&r);
        let twice = comparable(&once);
        assert_eq!(once, twice);
    }
}