cloudillo-core 0.8.18

// SPDX-FileCopyrightText: Szilárd Hajba
// SPDX-License-Identifier: LGPL-3.0-or-later

//! Attribute-Based Access Control (ABAC) system for Cloudillo
//!
//! Implements classic ABAC with 4-object model:
//! - Subject: Authenticated user (AuthCtx)
//! - Action: Operation being performed (string like "file:read")
//! - Object: Resource being accessed (implements AttrSet trait)
//! - Environment: Context (time, etc.)

use crate::prelude::*;
use cloudillo_types::auth_adapter::AuthCtx;
use cloudillo_types::types::AccessLevel;
use std::collections::HashMap;

/// Visibility levels for resources (files, actions, profile fields)
///
/// Stored as single char in database:
/// - None/NULL = Direct (most restrictive, owner + explicit audience only)
/// - 'P' = Public (anyone, including unauthenticated)
/// - 'V' = Verified (any authenticated user from any federated instance)
/// - '2' = 2nd degree (friend of friend, reserved for future voucher token system)
/// - 'F' = Follower (authenticated user who follows the owner)
/// - 'C' = Connected (authenticated user who is connected/mutual with owner)
///
/// Hierarchy (from most permissive to most restrictive):
/// Public > Verified > 2nd Degree > Follower > Connected > Direct
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, PartialOrd, Ord)]
pub enum VisibilityLevel {
	/// Anyone can access, including unauthenticated users
	Public,
	/// Any authenticated user from any federated instance
	Verified,
	/// Friend of friend (2nd degree connection) - reserved for voucher token system
	SecondDegree,
	/// Authenticated user who follows the owner
	Follower,
	/// Authenticated user who is connected (mutual) with owner
	Connected,
	/// Readable by any active subscriber of the action's container (group members).
	/// Owner/tenant pass the base check; subscribers pass via the audience bridge.
	Subscribed,
	/// Most restrictive - only owner and explicit audience
	#[default]
	Direct,
}

impl VisibilityLevel {
	/// Parse from database char value
	pub fn from_char(c: Option<char>) -> Self {
		match c {
			Some('P') => Self::Public,
			Some('V') => Self::Verified,
			Some('2') => Self::SecondDegree,
			Some('F') => Self::Follower,
			Some('C') => Self::Connected,
			Some('S') => Self::Subscribed,
			// NULL or unknown = Direct (most restrictive, secure by default)
			None | Some(_) => Self::Direct,
		}
	}

	/// Convert to database char value (inverse of from_char)
	pub fn to_char(&self) -> Option<char> {
		match self {
			Self::Public => Some('P'),
			Self::Verified => Some('V'),
			Self::SecondDegree => Some('2'),
			Self::Follower => Some('F'),
			Self::Connected => Some('C'),
			Self::Subscribed => Some('S'),
			Self::Direct => None,
		}
	}

	/// Convert to string for attribute lookup
	pub fn as_str(&self) -> &'static str {
		match self {
			Self::Public => "public",
			Self::Verified => "verified",
			Self::SecondDegree => "second_degree",
			Self::Follower => "follower",
			Self::Connected => "connected",
			Self::Subscribed => "subscribed",
			Self::Direct => "direct",
		}
	}
}

/// Subject's access level to a resource based on their relationship with the owner
///
/// Used to determine if a subject meets the visibility requirements.
/// Higher levels grant access to more restrictive visibility settings.
///
/// Hierarchy: Owner > Connected > Follower > SecondDegree > Verified > Public > None
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, PartialOrd, Ord)]
pub enum SubjectAccessLevel {
	/// No authentication or relationship
	#[default]
	None,
	/// Unauthenticated but public access requested
	Public,
	/// Authenticated user (has valid JWT from any federated instance)
	Verified,
	/// Has voucher token proving 2nd degree connection (future)
	SecondDegree,
	/// Follows the resource owner
	Follower,
	/// Connected (mutual) with resource owner
	Connected,
	/// Is the resource owner
	Owner,
}

impl SubjectAccessLevel {
	/// Check if this access level can view content with given visibility
	pub fn can_access(self, visibility: VisibilityLevel) -> bool {
		match visibility {
			VisibilityLevel::Public => true, // Everyone can access public
			VisibilityLevel::Verified => self >= Self::Verified,
			VisibilityLevel::SecondDegree => self >= Self::SecondDegree,
			VisibilityLevel::Follower => self >= Self::Follower,
			VisibilityLevel::Connected => self >= Self::Connected,
			// Both admit only owner/tenant here; subscribers/explicit-audience readers
			// pass via the audience bridge in `can_view_item`.
			VisibilityLevel::Subscribed | VisibilityLevel::Direct => self >= Self::Owner,
		}
	}

	/// Return the visibility level chars this access level can see.
	/// Returns `None` for Owner (sees everything including NULL/Direct).
	/// Used to push visibility filtering into SQL for correct pagination.
	pub fn visible_levels(self) -> Option<&'static [char]> {
		match self {
			Self::None | Self::Public => Some(&['P']),
			Self::Verified => Some(&['P', 'V']),
			Self::SecondDegree => Some(&['P', 'V', '2']),
			Self::Follower => Some(&['P', 'V', '2', 'F']),
			Self::Connected => Some(&['P', 'V', '2', 'F', 'C']),
			Self::Owner => None,
		}
	}
}

/// The one relationship ladder, shared so the endpoints that list and the
/// endpoint that searches cannot drift apart.
///
/// Callers compute the four inputs themselves, because *how* you become the
/// owner or a real authenticated caller differs by endpoint — `GET /api/search`
/// demotes every scoped caller to `Public` before asking (a file scope is handed
/// to an untrusted app and carries no ambient authority), while `GET /api/files`
/// resolves a scope through its own share lookup. What must never differ is the
/// ordering below.
///
/// [`can_view_item`] carries a third copy of the ladder with a different
/// signature: it folds the item owner into the owner test and an
/// `is_authenticated` flag into `is_real_auth`.
// Four bools on purpose: they are the ladder's rungs, and a struct would put a
// name between each caller and the ordering this function exists to fix in one
// place. Both call sites pass them in the order the doc above states.
#[allow(clippy::fn_params_excessive_bools)]
pub fn relationship_level(
	is_owner: bool,
	connected: bool,
	following: bool,
	is_real_auth: bool,
) -> SubjectAccessLevel {
	if is_owner {
		SubjectAccessLevel::Owner
	} else if connected {
		SubjectAccessLevel::Connected
	} else if following {
		SubjectAccessLevel::Follower
	} else if is_real_auth {
		SubjectAccessLevel::Verified
	} else {
		SubjectAccessLevel::Public
	}
}

/// Context for checking whether a subject can view an item
pub struct ViewCheckContext<'a> {
	pub subject_id_tag: &'a str,
	pub is_authenticated: bool,
	pub item_owner_id_tag: &'a str,
	pub tenant_id_tag: &'a str,
	pub visibility: Option<char>,
	pub subject_following_owner: bool,
	pub subject_connected_to_owner: bool,
	pub audience_tags: Option<&'a [&'a str]>,
}

/// Check if subject can view an item based on visibility and relationship
///
/// This is a standalone function for use in list filtering where we don't
/// have full ABAC context. It evaluates visibility rules directly.
pub fn can_view_item(ctx: &ViewCheckContext<'_>) -> bool {
	let visibility = VisibilityLevel::from_char(ctx.visibility);

	// Determine subject's access level
	// Note: "guest" id_tag is used for unauthenticated users - treat as Public
	let is_real_auth =
		ctx.is_authenticated && !ctx.subject_id_tag.is_empty() && ctx.subject_id_tag != "guest";
	let is_tenant = ctx.subject_id_tag == ctx.tenant_id_tag;
	let access_level = if ctx.subject_id_tag == ctx.item_owner_id_tag || is_tenant {
		SubjectAccessLevel::Owner // Tenant has same access as owner
	} else if ctx.subject_connected_to_owner {
		SubjectAccessLevel::Connected
	} else if ctx.subject_following_owner {
		SubjectAccessLevel::Follower
	} else if is_real_auth {
		SubjectAccessLevel::Verified
	} else {
		SubjectAccessLevel::Public
	};

	// Check basic access
	if access_level.can_access(visibility) {
		return true;
	}

	// Direct and Subscribed also check explicit audience. For Subscribed,
	// `filter.rs` injects the reader into `audience_tags` when they hold an active
	// SUBS to the container (group membership).
	if (visibility == VisibilityLevel::Direct || visibility == VisibilityLevel::Subscribed)
		&& let Some(tags) = ctx.audience_tags
	{
		return tags.contains(&ctx.subject_id_tag);
	}

	false
}

// Re-export AttrSet from cloudillo-types (canonical definition)
pub use cloudillo_types::abac::AttrSet;

/// True iff `auth` carries the site-admin (SADM) role.
///
/// Single source of truth for the role-name string; callers must not
/// compare role strings inline.
pub fn is_admin(auth: &AuthCtx) -> bool {
	auth.roles.iter().any(|r| r.as_ref() == "SADM")
}

/// Environment attributes (environmental context)
#[derive(Debug, Clone)]
pub struct Environment {
	pub time: Timestamp,
	// Future: ip_address, user_agent, etc.
}

impl Environment {
	pub fn new() -> Self {
		Self { time: Timestamp::now() }
	}
}

impl Default for Environment {
	fn default() -> Self {
		Self::new()
	}
}

/// Policy rule condition
#[derive(Debug, Clone)]
pub struct Condition {
	pub attribute: String,
	pub operator: Operator,
	pub value: serde_json::Value,
}

#[derive(Debug, Clone, Copy)]
pub enum Operator {
	Equals,
	NotEquals,
	Contains,
	NotContains,
	GreaterThan,
	LessThan,
	In,      // Subject attr in object list
	HasRole, // Subject has specific role
}

impl Condition {
	/// Evaluate condition against subject, action, object, environment
	pub fn evaluate(
		&self,
		subject: &AuthCtx,
		action: &str,
		object: &dyn AttrSet,
		_environment: &Environment,
	) -> bool {
		// First, try to get value from object
		if let Some(obj_val) = object.get(&self.attribute) {
			return self.compare_value(obj_val);
		}

		// Then try subject attributes
		match self.attribute.as_str() {
			"subject.id_tag" => self.compare_value(&subject.id_tag),
			"subject.tn_id" => self.compare_value(&subject.tn_id.0.to_string()),
			"subject.roles" | "role.admin" | "role.moderator" | "role.member" => {
				// Special handling for role checks
				if let Operator::HasRole = self.operator
					&& let Some(role) = self.value.as_str()
				{
					return subject.roles.iter().any(|r| r.as_ref() == role);
				}
				// For dotted notation like "role.admin"
				if self.attribute.starts_with("role.") {
					let role_name = &self.attribute[5..];
					return subject.roles.iter().any(|r| r.as_ref() == role_name);
				}
				false
			}
			"action" => self.compare_value(action),
			_ => false,
		}
	}

	fn compare_value(&self, actual: &str) -> bool {
		match self.operator {
			Operator::Equals => self.value.as_str() == Some(actual),
			Operator::NotEquals => self.value.as_str() != Some(actual),
			Operator::Contains => {
				if let Some(needle) = self.value.as_str() {
					actual.contains(needle)
				} else {
					false
				}
			}
			Operator::NotContains => {
				if let Some(needle) = self.value.as_str() {
					!actual.contains(needle)
				} else {
					true
				}
			}
			Operator::GreaterThan => {
				if let (Some(threshold), Ok(val)) = (self.value.as_f64(), actual.parse::<f64>()) {
					val > threshold
				} else {
					false
				}
			}
			Operator::LessThan => {
				if let (Some(threshold), Ok(val)) = (self.value.as_f64(), actual.parse::<f64>()) {
					val < threshold
				} else {
					false
				}
			}
			Operator::In | Operator::HasRole => false,
		}
	}
}

/// Policy rule
#[derive(Debug, Clone)]
pub struct PolicyRule {
	pub name: String,
	pub conditions: Vec<Condition>,
	pub effect: Effect,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Effect {
	Allow,
	Deny,
}

impl PolicyRule {
	/// Evaluate rule against subject, action, object, environment
	pub fn evaluate(
		&self,
		subject: &AuthCtx,
		action: &str,
		object: &dyn AttrSet,
		environment: &Environment,
	) -> Option<Effect> {
		// All conditions must match for rule to apply
		let all_match = self
			.conditions
			.iter()
			.all(|cond| cond.evaluate(subject, action, object, environment));

		if all_match { Some(self.effect) } else { None }
	}
}

/// ABAC Policy (collection of rules)
#[derive(Debug, Clone)]
pub struct Policy {
	pub name: String,
	pub rules: Vec<PolicyRule>,
}

impl Policy {
	/// Evaluate policy - returns Effect if any rule matches
	pub fn evaluate(
		&self,
		subject: &AuthCtx,
		action: &str,
		object: &dyn AttrSet,
		environment: &Environment,
	) -> Option<Effect> {
		for rule in &self.rules {
			if let Some(effect) = rule.evaluate(subject, action, object, environment) {
				return Some(effect);
			}
		}
		None
	}
}

/// Profile-level policy configuration (TOP + BOTTOM)
#[derive(Debug, Clone)]
pub struct ProfilePolicy {
	pub tn_id: TnId,
	pub top_policy: Policy,    // Maximum permissions (constraints)
	pub bottom_policy: Policy, // Minimum permissions (guarantees)
}

/// Collection-level policy configuration
///
/// Used for CREATE operations where no specific object exists yet.
/// Evaluates permissions based on subject attributes only.
///
/// Example: User wants to upload a file
///   - Can evaluate "can user create files?" without the file existing
///   - Checks: quota_remaining > 0, role == "creator", !banned, email_verified
#[derive(Debug, Clone)]
pub struct CollectionPolicy {
	pub resource_type: String, // "files", "actions", "profiles"
	pub action: String,        // "create", "list"
	pub top_policy: Policy,    // Denials/constraints
	pub bottom_policy: Policy, // Guarantees
}

/// Main permission checker
pub struct PermissionChecker {
	profile_policies: HashMap<TnId, ProfilePolicy>,
	collection_policies: HashMap<String, CollectionPolicy>, // key: "resource:action"
}

impl PermissionChecker {
	pub fn new() -> Self {
		Self { profile_policies: HashMap::new(), collection_policies: HashMap::new() }
	}

	/// Load profile policy for tenant (called during bootstrap)
	pub fn load_policy(&mut self, policy: ProfilePolicy) {
		self.profile_policies.insert(policy.tn_id, policy);
	}

	/// Load collection policy for resource type + action
	pub fn load_collection_policy(&mut self, policy: CollectionPolicy) {
		let key = format!("{}:{}", policy.resource_type, policy.action);
		self.collection_policies.insert(key, policy);
	}

	/// Get collection policy for resource type and action
	pub fn get_collection_policy(
		&self,
		resource_type: &str,
		action: &str,
	) -> Option<&CollectionPolicy> {
		let key = format!("{}:{}", resource_type, action);
		self.collection_policies.get(&key)
	}

	/// Core permission check function
	pub fn has_permission(
		&self,
		subject: &AuthCtx,
		action: &str,
		object: &dyn AttrSet,
		environment: &Environment,
	) -> bool {
		// Step 1: Check TOP policy (constraints)
		if let Some(profile_policy) = self.profile_policies.get(&subject.tn_id) {
			if let Some(Effect::Deny) =
				profile_policy.top_policy.evaluate(subject, action, object, environment)
			{
				info!("TOP policy denied: tn_id={}, action={}", subject.tn_id.0, action);
				return false;
			}

			// Step 2: Check BOTTOM policy (guarantees)
			if let Some(Effect::Allow) =
				profile_policy.bottom_policy.evaluate(subject, action, object, environment)
			{
				info!("BOTTOM policy allowed: tn_id={}, action={}", subject.tn_id.0, action);
				return true;
			}
		}

		// Step 3: Default permission rules (ownership, visibility, etc.)
		self.check_default_rules(subject, action, object, environment)
	}

	/// Default permission rules (when policies don't match)
	fn check_default_rules(
		&self,
		subject: &AuthCtx,
		action: &str,
		object: &dyn AttrSet,
		_environment: &Environment,
	) -> bool {
		use tracing::debug;

		// Leader override - leaders can do everything
		if subject.roles.iter().any(|r| r.as_ref() == "leader") {
			debug!(subject = %subject.id_tag, action = action, "Leader role allows access");
			return true;
		}

		// Parse action into resource:operation
		let parts: Vec<&str> = action.split(':').collect();
		if parts.len() != 2 {
			debug!(subject = %subject.id_tag, action = action, "Invalid action format (expected resource:operation)");
			return false;
		}
		let operation = parts[1];

		// Ownership check for modify operations
		if matches!(operation, "update" | "delete" | "write") {
			if let Some(owner) = object.get("owner_id_tag")
				&& owner == subject.id_tag.as_ref()
			{
				debug!(subject = %subject.id_tag, action = action, owner = owner, "Owner access allowed for modify operation");
				return true;
			}
			// Pre-computed access level (community roles, FSHR shares, scoped tokens). Ordering
			// comes from `AccessLevel` itself; an unrecognized name parses to `None` and denies.
			if let Some(al) = object.get("access_level")
				&& AccessLevel::from_str_name(al).is_some_and(AccessLevel::can_write)
			{
				debug!(subject = %subject.id_tag, action = action, "Write access level allows modify operation");
				return true;
			}
			debug!(subject = %subject.id_tag, action = action, "Denied: not owner and no write access level");
			return false;
		}

		// Visibility check for read operations
		if matches!(operation, "read") {
			// Explicit access grants (FSHR file shares, scoped tokens), same `AccessLevel`
			// ordering as the modify branch above.
			if let Some(al) = object.get("access_level")
				&& AccessLevel::from_str_name(al).is_some_and(AccessLevel::can_read)
			{
				return true;
			}
			return self.check_visibility(subject, object);
		}

		// Create operations - check quota/limits in future
		if operation == "create" {
			debug!(subject = %subject.id_tag, action = action, "Create operation allowed");
			return true; // Allow for now
		}

		// Admin operations (e.g. `profile:admin`) — community moderators and above
		// pass the gate. Leaders were already allowed by the override at the top of
		// this function; this admits moderators so they can manage lower-ranked
		// members. The finer-grained target-rank and field-level rules (a moderator
		// may only re-role members strictly below them, never rename or change
		// status) are enforced in the handler — see `patch_profile_admin`'s
		// role-hierarchy guard in `cloudillo-profile/src/update.rs`.
		if operation == "admin" {
			use crate::roles::{MODERATOR_LEVEL, highest_role_level};
			if highest_role_level(&subject.roles) >= MODERATOR_LEVEL {
				debug!(subject = %subject.id_tag, action = action, "Moderator+ role allows admin operation");
				return true;
			}
			debug!(subject = %subject.id_tag, action = action, "Denied: admin operation requires moderator+");
			return false;
		}

		// Default deny
		debug!(subject = %subject.id_tag, action = action, "Default deny: no matching rules");
		false
	}

	/// Check visibility-based access using the new VisibilityLevel enum
	///
	/// Determines subject's access level and checks against resource visibility.
	/// Supports both char-based visibility (from DB) and string-based (legacy).
	#[expect(clippy::unused_self, reason = "method may use self in future policy checks")]
	fn check_visibility(&self, subject: &AuthCtx, object: &dyn AttrSet) -> bool {
		use tracing::debug;

		// Parse visibility from object attributes
		// Try char-based first (from "visibility_char"), then fall back to string
		let visibility = if let Some(vis_char) = object.get("visibility_char") {
			VisibilityLevel::from_char(vis_char.chars().next())
		} else if let Some(vis_str) = object.get("visibility") {
			match vis_str {
				"public" | "P" => VisibilityLevel::Public,
				"verified" | "V" => VisibilityLevel::Verified,
				"second_degree" | "2" => VisibilityLevel::SecondDegree,
				"follower" | "F" => VisibilityLevel::Follower,
				"connected" | "C" => VisibilityLevel::Connected,
				// "direct" or unknown = Direct (secure by default)
				_ => VisibilityLevel::Direct,
			}
		} else {
			VisibilityLevel::Direct // No visibility = Direct (most restrictive)
		};

		// Determine subject's access level based on relationship with resource
		let is_owner = object.get("owner_id_tag") == Some(subject.id_tag.as_ref());
		let is_issuer = object.get("issuer_id_tag") == Some(subject.id_tag.as_ref());
		let is_connected = object.get("connected") == Some("true");
		let is_follower = object.get("following") == Some("true");
		let in_audience = object.contains("audience_tag", subject.id_tag.as_ref());

		// Calculate subject's effective access level
		// Note: "guest" id_tag is used for unauthenticated users - treat as Public
		let is_authenticated = !subject.id_tag.is_empty() && subject.id_tag.as_ref() != "guest";
		let access_level = if is_owner || is_issuer {
			SubjectAccessLevel::Owner
		} else if is_connected {
			SubjectAccessLevel::Connected
		} else if is_follower {
			SubjectAccessLevel::Follower
		} else if is_authenticated {
			// Authenticated user without specific relationship
			SubjectAccessLevel::Verified
		} else {
			SubjectAccessLevel::Public
		};

		// Check if access level meets visibility requirement
		let allowed = access_level.can_access(visibility);

		// For Direct visibility, also check explicit audience
		let allowed =
			if visibility == VisibilityLevel::Direct { allowed || in_audience } else { allowed };

		debug!(
			subject = %subject.id_tag,
			visibility = ?visibility,
			access_level = ?access_level,
			is_owner = is_owner,
			is_issuer = is_issuer,
			is_connected = is_connected,
			is_follower = is_follower,
			in_audience = in_audience,
			allowed = allowed,
			"Visibility check"
		);

		allowed
	}

	/// Evaluate collection policy (for CREATE operations)
	///
	/// Collection policies check subject attributes without an object existing.
	/// Used for operations like "can user upload files?" or "can user create posts?"
	pub fn has_collection_permission(
		&self,
		subject: &AuthCtx,
		subject_attrs: &dyn AttrSet,
		resource_type: &str,
		action: &str,
		environment: &Environment,
	) -> bool {
		use tracing::debug;

		// Get collection policy
		let Some(policy) = self.get_collection_policy(resource_type, action) else {
			// No policy defined → allow by default
			debug!(
				subject = %subject.id_tag,
				resource_type = resource_type,
				action = action,
				"No collection policy found - allowing by default"
			);
			return true;
		};

		// Step 1: Check TOP policy (denials/constraints)
		if let Some(Effect::Deny) =
			policy.top_policy.evaluate(subject, action, subject_attrs, environment)
		{
			debug!(
				subject = %subject.id_tag,
				resource_type = resource_type,
				action = action,
				"Collection TOP policy denied"
			);
			return false;
		}

		// Step 2: Check BOTTOM policy (guarantees)
		if let Some(Effect::Allow) =
			policy.bottom_policy.evaluate(subject, action, subject_attrs, environment)
		{
			debug!(
				subject = %subject.id_tag,
				resource_type = resource_type,
				action = action,
				"Collection BOTTOM policy allowed"
			);
			return true;
		}

		// Step 3: Default deny (no policies matched)
		debug!(
			subject = %subject.id_tag,
			resource_type = resource_type,
			action = action,
			"No matching collection policies - default deny"
		);
		false
	}
}

impl Default for PermissionChecker {
	fn default() -> Self {
		Self::new()
	}
}

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

	#[test]
	fn test_environment_creation() {
		let env = Environment::new();
		assert!(env.time.0 > 0);
	}

	#[test]
	fn test_permission_checker_creation() {
		let checker = PermissionChecker::new();
		assert_eq!(checker.profile_policies.len(), 0);
	}

	/// Only the pre-computed `access_level`, no owner — so only the access-level branch can allow
	/// anything.
	struct AccessLevelObject(&'static str);

	impl AttrSet for AccessLevelObject {
		fn get(&self, key: &str) -> Option<&str> {
			match key {
				"access_level" => Some(self.0),
				_ => None,
			}
		}

		fn get_list(&self, _key: &str) -> Option<Vec<&str>> {
			None
		}
	}

	fn plain_subject() -> AuthCtx {
		AuthCtx {
			tn_id: TnId(1),
			id_tag: "alice.example.com".into(),
			roles: Box::new([]),
			scope: None,
			anonymous: false,
		}
	}

	#[test]
	fn admin_access_level_allows_read_and_update() {
		// The owner resolves to `AccessLevel::Admin`, so "admin" must satisfy both the modify and
		// the read branch.
		let checker = PermissionChecker::new();
		let subject = plain_subject();
		let env = Environment::new();
		let object = AccessLevelObject("admin");

		assert!(checker.has_permission(&subject, "file:read", &object, &env));
		assert!(checker.has_permission(&subject, "file:update", &object, &env));
		assert!(checker.has_permission(&subject, "file:delete", &object, &env));

		// Levels below admin are unaffected.
		let writer = AccessLevelObject("write");
		assert!(checker.has_permission(&subject, "file:read", &writer, &env));
		assert!(checker.has_permission(&subject, "file:update", &writer, &env));
		let reader = AccessLevelObject("read");
		assert!(checker.has_permission(&subject, "file:read", &reader, &env));
		assert!(!checker.has_permission(&subject, "file:update", &reader, &env));

		// A string outside the `AccessLevel::as_str` vocabulary must not read as authority.
		let bogus = AccessLevelObject("bogus");
		assert!(!checker.has_permission(&subject, "file:read", &bogus, &env));
		assert!(!checker.has_permission(&subject, "file:update", &bogus, &env));
		// ...and "none" is a recognized level that still grants nothing.
		let none = AccessLevelObject("none");
		assert!(!checker.has_permission(&subject, "file:read", &none, &env));
		assert!(!checker.has_permission(&subject, "file:update", &none, &env));
	}

	#[test]
	fn test_subscribed_level_char_roundtrip() {
		assert_eq!(VisibilityLevel::from_char(Some('S')), VisibilityLevel::Subscribed);
		assert_eq!(VisibilityLevel::Subscribed.to_char(), Some('S'));
		assert_eq!(VisibilityLevel::Subscribed.as_str(), "subscribed");
	}

	#[test]
	fn test_subscribed_can_access_base_check() {
		// Only owner/tenant pass the base check; everyone else must go through the
		// audience/subscription bridge in `can_view_item`.
		assert!(SubjectAccessLevel::Owner.can_access(VisibilityLevel::Subscribed));
		assert!(!SubjectAccessLevel::Connected.can_access(VisibilityLevel::Subscribed));
		assert!(!SubjectAccessLevel::Follower.can_access(VisibilityLevel::Subscribed));
		assert!(!SubjectAccessLevel::Verified.can_access(VisibilityLevel::Subscribed));
		assert!(!SubjectAccessLevel::Public.can_access(VisibilityLevel::Subscribed));
	}

	#[test]
	fn test_subscribed_view_via_audience_bridge() {
		// A member injected into audience_tags (by filter.rs) can view a Subscribed row
		// issued by a co-member, despite having no follow/connect relationship.
		let member = "alice.example.com";
		let ctx = ViewCheckContext {
			subject_id_tag: member,
			is_authenticated: true,
			item_owner_id_tag: "bob.example.com", // a different member
			tenant_id_tag: "home.example.com",
			visibility: Some('S'),
			subject_following_owner: false,
			subject_connected_to_owner: false,
			audience_tags: Some(&[member]),
		};
		assert!(can_view_item(&ctx));
	}

	#[test]
	fn test_subscribed_denied_when_not_member() {
		// A non-member (not in audience_tags) cannot view a Subscribed row.
		let ctx = ViewCheckContext {
			subject_id_tag: "carol.example.com",
			is_authenticated: true,
			item_owner_id_tag: "bob.example.com",
			tenant_id_tag: "home.example.com",
			visibility: Some('S'),
			subject_following_owner: false,
			subject_connected_to_owner: false,
			audience_tags: Some(&[]),
		};
		assert!(!can_view_item(&ctx));
	}

	#[test]
	fn test_subscribed_owner_and_tenant_shortcut() {
		// The issuer views their own Subscribed row without the audience bridge.
		let ctx = ViewCheckContext {
			subject_id_tag: "bob.example.com",
			is_authenticated: true,
			item_owner_id_tag: "bob.example.com",
			tenant_id_tag: "home.example.com",
			visibility: Some('S'),
			subject_following_owner: false,
			subject_connected_to_owner: false,
			audience_tags: Some(&[]),
		};
		assert!(can_view_item(&ctx));

		// The node tenant reads any Subscribed row hosted on their own node.
		let ctx_tenant = ViewCheckContext {
			subject_id_tag: "home.example.com",
			is_authenticated: true,
			item_owner_id_tag: "bob.example.com",
			tenant_id_tag: "home.example.com",
			visibility: Some('S'),
			subject_following_owner: false,
			subject_connected_to_owner: false,
			audience_tags: Some(&[]),
		};
		assert!(can_view_item(&ctx_tenant));
	}
}