feat(privacy-filter): add heartbeat-level privacy filtering engine

aw-datastore/Cargo.toml

@@ -19,3 +19,4 @@ log = "0.4"
 
 aw-models = { path = "../aw-models" }
 aw-transform = { path = "../aw-transform" }
+regex = "1"

aw-datastore/src/lib.rs

@@ -17,6 +17,7 @@ macro_rules! json_map {
 
 mod datastore;
 mod legacy_import;
+mod privacy_filter;
 mod worker;
 
 pub use self::datastore::DatastoreInstance;

aw-datastore/src/privacy_filter.rs

@@ -0,0 +1,338 @@
+use std::sync::OnceLock;
+
+use serde::{Deserialize, Serialize};
+use serde_json::map::Map;
+use serde_json::Value;
+
+use aw_models::Event;
+
+/// Action to take when a rule matches an event.
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum PrivacyFilterAction {
+    /// Drop the entire event from storage
+    Drop,
+    /// Redact a specific field's value with a replacement
+    Redact,
+}
+
+/// A single privacy filter rule.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PrivacyFilterRule {
+    /// If true, this rule is active
+    pub enabled: bool,
+    /// Only apply to buckets whose ID starts with this prefix (e.g. "aw-watcher-window")
+    pub bucket_prefix: Option<String>,
+    /// Dotted path to the event data field to check (e.g. "title")
+    pub field: Option<String>,
+    /// Regex pattern to match against the field value
+    pub pattern: String,
+    /// What to do when matched
+    pub action: PrivacyFilterAction,
+    /// Replacement text for the redact action
+    pub replacement: Option<String>,
+    /// Pre-compiled regex, populated lazily on first match. Not serialized.
+    #[serde(skip)]
+    regex_cache: OnceLock<Option<regex::Regex>>,
+}
+
+impl PartialEq for PrivacyFilterRule {
+    fn eq(&self, other: &Self) -> bool {
+        self.enabled == other.enabled
+            && self.bucket_prefix == other.bucket_prefix
+            && self.field == other.field
+            && self.pattern == other.pattern
+            && self.action == other.action
+            && self.replacement == other.replacement
+    }
+}
+
+impl PrivacyFilterRule {
+    /// Check if this rule matches a given event in a given bucket.
+    pub fn matches(&self, bucket_id: &str, event: &Event) -> bool {
+        if !self.enabled {
+            return false;
+        }
+
+        // Check bucket prefix if specified
+        if let Some(ref prefix) = self.bucket_prefix {
+            if !bucket_id.starts_with(prefix) {
+                return false;
+            }
+        }
+
+        // Check field pattern if specified
+        if let Some(ref field_path) = self.field {
+            let field_value = resolve_field(&event.data, field_path);
+            match field_value {
+                Some(Value::String(s)) => {
+                    // Compile the regex once and cache it for subsequent calls.
+                    let re = self
+                        .regex_cache
+                        .get_or_init(|| regex::Regex::new(&self.pattern).ok());
+                    re.as_ref().map(|re| re.is_match(s)).unwrap_or(false)
+                }
+                Some(_) | None => false,
+            }
+        } else {
+            true
+        }
+    }
+
+    /// Apply this rule's action to an event.
+    /// Returns None if dropped, Some(event) if kept (possibly redacted).
+    pub fn apply<'a>(&self, event: &'a mut Event) -> Option<&'a mut Event> {
+        match self.action {
+            PrivacyFilterAction::Drop => None,
+            PrivacyFilterAction::Redact => {
+                if let Some(ref replacement) = self.replacement {
+                    if let Some(ref field_path) = self.field {
+                        set_field(
+                            &mut event.data,
+                            field_path,
+                            Value::String(replacement.clone()),
+                        );
+                    }
+                }
+                Some(event)
+            }
+        }
+    }
+}
+
+/// Engine that holds and applies privacy filter rules.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PrivacyFilterEngine {
+    rules: Vec<PrivacyFilterRule>,
+}
+
+impl PrivacyFilterEngine {
+    pub fn new(rules: Vec<PrivacyFilterRule>) -> Self {
+        PrivacyFilterEngine { rules }
+    }
+
+    /// Example rules for common sensitive data patterns.
+    /// Not applied automatically — use `new()` with these rules to opt in.
+    pub fn with_defaults() -> Self {
+        let rules = vec![
+            PrivacyFilterRule {
+                enabled: true,
+                bucket_prefix: Some("aw-watcher-window".to_string()),
+                field: Some("title".to_string()),
+                pattern: r"(?i)(private browsing|incognito)".to_string(),
+                action: PrivacyFilterAction::Drop,
+                replacement: None,
+                regex_cache: OnceLock::new(),
+            },
+            PrivacyFilterRule {
+                enabled: true,
+                bucket_prefix: Some("aw-watcher-window".to_string()),
+                field: Some("title".to_string()),
+                pattern: r"(?i).*banking.*".to_string(),
+                action: PrivacyFilterAction::Redact,
+                replacement: Some("REDACTED".to_string()),
+                regex_cache: OnceLock::new(),
+            },
+        ];
+        PrivacyFilterEngine { rules }
+    }
+
+    /// Parse rules from a JSON string (as stored in settings).
+    pub fn from_json(json_str: &str) -> Result<Self, String> {
+        let rules: Vec<PrivacyFilterRule> = serde_json::from_str(json_str)
+            .map_err(|e| format!("Failed to parse privacy filter rules: {e}"))?;
+        Ok(PrivacyFilterEngine { rules })
+    }
+
+    /// Serialize rules to JSON string.
+    pub fn to_json(&self) -> Result<String, String> {
+        serde_json::to_string(&self.rules)
+            .map_err(|e| format!("Failed to serialize privacy filter rules: {e}"))
+    }
+
+    /// Filter a single event for a given bucket.
+    /// Applies all matching rules. Returns None if dropped, Some (possibly redacted) event if kept.
+    pub fn filter_event(&self, bucket_id: &str, event: Event) -> Option<Event> {
+        let mut event = event;
+        for rule in &self.rules {
+            if rule.matches(bucket_id, &event) {
+                match rule.apply(&mut event) {
+                    Some(_) => {}        // Redacted — continue applying other rules
+                    None => return None, // Dropped
+                }
+            }
+        }
+        Some(event)
+    }
+
+    /// Filter a batch of events for a given bucket.
+    pub fn filter_events(&self, bucket_id: &str, events: Vec<Event>) -> Vec<Event> {
+        events
+            .into_iter()
+            .filter_map(|e| self.filter_event(bucket_id, e))
+            .collect()
+    }
+}
+
+/// Resolve a dotted field path (e.g. "title", "data.url") from a serde_json Map.
+fn resolve_field<'a>(data: &'a Map<String, Value>, path: &str) -> Option<&'a Value> {
+    let parts: Vec<&str> = path.split('.').collect();
+    let mut current: &Map<String, Value> = data;
+    for (i, part) in parts.iter().enumerate() {
+        let val = current.get(*part)?;
+        if i == parts.len() - 1 {
+            return Some(val);
+        }
+        match val {
+            Value::Object(map) => current = map,
+            _ => return None,
+        }
+    }
+    None
+}
+
+/// Set a field value at a dotted path in a serde_json Map.
+fn set_field(data: &mut Map<String, Value>, path: &str, value: Value) {
+    let parts: Vec<&str> = path.split('.').collect();
+    let mut current: &mut Map<String, Value> = data;
+    for (i, part) in parts.iter().enumerate() {
+        if i == parts.len() - 1 {
+            current.insert(part.to_string(), value);
+            return;
+        }
+        current = match current
+            .entry(part.to_string())
+            .or_insert_with(|| Value::Object(Map::new()))
+            .as_object_mut()
+        {
+            Some(m) => m,
+            None => return, // intermediate segment is not an object — skip silently
+        };
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chrono::Utc;
+    use serde_json::json;
+
+    fn test_event(title: &str) -> Event {
+        Event {
+            id: None,
+            timestamp: Utc::now(),
+            duration: chrono::Duration::seconds(1),
+            data: json_map! {"title": json!(title), "app": json!("Firefox")},
+        }
+    }
+
+    #[test]
+    fn test_drop_incognito_window() {
+        let engine = PrivacyFilterEngine::with_defaults();
+        let event = test_event("Private Browsing - Mozilla Firefox");
+        let rule = &engine.rules[0];
+        assert!(rule.matches("aw-watcher-window", &event));
+    }
+
+    #[test]
+    fn test_allow_normal_window() {
+        let engine = PrivacyFilterEngine::with_defaults();
+        let event = test_event("GitHub - Mozilla Firefox");
+        let rule = &engine.rules[0];
+        assert!(!rule.matches("aw-watcher-window", &event));
+    }
+
+    #[test]
+    fn test_redact_banking() {
+        let engine = PrivacyFilterEngine::with_defaults();
+        let mut event = test_event("Online Banking - My Account Balance");
+        let rule = &engine.rules[1];
+        assert!(rule.matches("aw-watcher-window", &event));
+        let result = rule.apply(&mut event);
+        assert!(result.is_some());
+        assert_eq!(
+            result.unwrap().data.get("title").unwrap().as_str().unwrap(),
+            "REDACTED"
+        );
+    }
+
+    #[test]
+    fn test_bucket_scoping() {
+        let rule = PrivacyFilterRule {
+            enabled: true,
+            bucket_prefix: Some("aw-watcher-window".to_string()),
+            field: Some("title".to_string()),
+            pattern: r"(?i)(private browsing|incognito)".to_string(),
+            action: PrivacyFilterAction::Drop,
+            replacement: None,
+            regex_cache: OnceLock::new(),
+        };
+        let event = test_event("Private Browsing - Mozilla Firefox");
+        assert!(rule.matches("aw-watcher-window", &event));
+        assert!(!rule.matches("aw-watcher-afk", &event));
+    }
+
+    #[test]
+    fn test_disabled_rule() {
+        let rule = PrivacyFilterRule {
+            enabled: false,
+            bucket_prefix: Some("aw-watcher-window".to_string()),
+            field: Some("title".to_string()),
+            pattern: ".*".to_string(),
+            action: PrivacyFilterAction::Drop,
+            replacement: None,
+            regex_cache: OnceLock::new(),
+        };
+        let event = test_event("Anything at all");
+        assert!(!rule.matches("aw-watcher-window", &event));
+    }
+
+    #[test]
+    fn test_invalid_regex_no_panic() {
+        let rule = PrivacyFilterRule {
+            enabled: true,
+            bucket_prefix: Some("aw-watcher-window".to_string()),
+            field: Some("title".to_string()),
+            pattern: r"[invalid".to_string(),
+            action: PrivacyFilterAction::Drop,
+            replacement: None,
+            regex_cache: OnceLock::new(),
+        };
+        let event = test_event("test");
+        assert!(!rule.matches("aw-watcher-window", &event));
+    }
+
+    #[test]
+    fn test_set_field_no_panic_on_non_object_intermediate() {
+        let mut data = serde_json::Map::new();
+        data.insert(
+            "title".to_string(),
+            Value::String("flat string".to_string()),
+        );
+        // "title" is a string, not an object — setting "title.nested" should not panic
+        set_field(
+            &mut data,
+            "title.nested",
+            Value::String("value".to_string()),
+        );
+        // title should remain unchanged
+        assert_eq!(data.get("title").unwrap().as_str().unwrap(), "flat string");
+    }
+
+    #[test]
+    fn test_drop_action() {
+        let rule = PrivacyFilterRule {
+            enabled: true,
+            bucket_prefix: None,
+            field: Some("title".to_string()),
+            pattern: ".*".to_string(),
+            action: PrivacyFilterAction::Drop,
+            replacement: None,
+            regex_cache: OnceLock::new(),
+        };
+        let mut event = test_event("anything");
+        assert!(rule.matches("any-bucket", &event));
+        let result = rule.apply(&mut event);
+        assert!(result.is_none(), "Drop action should return None");
+    }
+}