ryo-symbol 0.1.0

//! SymbolRegistry - Central registry for symbol management
//!
//! # Persistent Identity (UUID)
//!
//! Every symbol is automatically assigned a UUID at registration time.
//! This UUID serves as the **persistent identity** that survives:
//! - Server restarts (SymbolId is session-volatile)
//! - Symbol renames (SymbolPath changes, UUID stays)
//! - Code refactoring (same entity, different location)
//!
//! ## Why UUID, not SymbolPath?
//!
//! SymbolPath is like Active Directory's Distinguished Name (DN) - it describes
//! **where** something is, not **what** it is. When you rename `foo::Bar` to
//! `foo::Baz`, the SymbolPath changes but the entity remains the same.
//!
//! ## External Output Requirements
//!
//! **All external APIs that expose symbol references MUST use UUID.**
//!
//! ### TODO: Migrate to UUID-based output
//!
//! The following locations currently use SymbolPath or SymbolId strings
//! and should be migrated to include UUID:
//!
//! - `ryo-app/src/api/types.rs`:
//!   - `Suggestion.symbol_path` → add `uuid: Uuid`
//!   - `TypeAnalysisResponse.symbol_id` → add `uuid: Uuid`
//!   - `TypeAnalysisResponse.supertraits` → `Vec<SymbolRef>` with uuid
//!   - `TypeAnalysisResponse.implementors` → `Vec<SymbolRef>` with uuid
//!   - `TypeImpactInfo.containing_types` → `Vec<SymbolRef>` with uuid
//!   - `VarInfo.symbol_path` → add `uuid: Uuid`
//!   - `ChainNodeInfo.id` → add `uuid: Uuid`
//!   - `CascadeResponse.callers/users` → `Vec<SymbolRef>` with uuid
//!
//! - `ryo-storage/src/txlog/entry.rs`:
//!   - `TxAction::MutationApplied.affected_symbols` → `Vec<Uuid>`
//!   - `MutationRecord.affected_symbols` → `Vec<Uuid>`
//!
//! ## Performance Note
//!
//! Current implementation assigns UUID to ALL symbols at registration.
//! If memory becomes an issue (~80 bytes per symbol), consider lazy allocation
//! only when symbols are exposed via external APIs.

use std::collections::HashMap;

use slotmap::{SecondaryMap, SlotMap};
use uuid::Uuid;

use crate::error::{InvalidSymbolId, RegistrationError, RenameError, UnregisterReexportError};
use crate::file_path::WorkspaceFilePath;
use crate::id::SymbolId;
use crate::kind::SymbolKind;
use crate::path::SymbolPath;
use crate::span::{FileSpan, Visibility};
use crate::var_scope::VarScope;

/// Re-export information
#[derive(Debug, Clone)]
pub struct ReExportInfo {
    /// Re-export path (alias)
    pub alias_path: SymbolPath,
    /// File where the re-export is defined
    pub origin_file: WorkspaceFilePath,
}

/// Central registry for symbol management
///
/// # Single Point of Access
///
/// **All symbol operations must go through SymbolRegistry.**
///
/// - Get SymbolId: `register()` or `lookup()`
/// - Get/update metadata: `kind()`, `span()`, `set_span()`, etc.
/// - Graph operations also use SymbolId
///
/// # Responsibilities
/// - Bidirectional SymbolPath ↔ SymbolId conversion
/// - Metadata management (Kind, Span, Visibility, etc.)
/// - Symbol lifecycle management
///
/// # Thread Safety
/// - Read operations are thread-safe
/// - Write operations require exclusive access
///   (Executor controls this at Tick boundaries)
#[derive(Clone)]
pub struct SymbolRegistry {
    // === Core Mappings ===
    /// SymbolId → SymbolPath (reverse lookup)
    id_to_path: SlotMap<SymbolId, SymbolPath>,
    /// SymbolPath → SymbolId (forward lookup)
    path_to_id: HashMap<SymbolPath, SymbolId>,

    // === Metadata (SecondaryMap) ===
    /// Symbol kind
    kinds: SecondaryMap<SymbolId, SymbolKind>,
    /// File location
    spans: SecondaryMap<SymbolId, FileSpan>,
    /// Visibility
    visibility: SecondaryMap<SymbolId, Visibility>,
    /// Parent symbol (for InSymbol)
    parents: SecondaryMap<SymbolId, SymbolId>,

    // === Re-export Management ===
    /// Re-export info (canonical → aliases)
    re_exports: SecondaryMap<SymbolId, Vec<ReExportInfo>>,
    /// Re-export reverse lookup (alias path → canonical SymbolId)
    alias_to_canonical: HashMap<SymbolPath, SymbolId>,

    // === Persistent Identity (UUID) ===
    /// SymbolId → Uuid (O(1) lookup for serialization)
    id_to_uuid: SecondaryMap<SymbolId, Uuid>,
    /// Uuid → SymbolId (reverse lookup for deserialization)
    uuid_to_id: HashMap<Uuid, SymbolId>,
    /// Preloaded UUID mappings from previous session (SymbolPath → Uuid)
    /// Used during register() to restore persistent identity
    preloaded_uuids: HashMap<SymbolPath, Uuid>,
}

impl SymbolRegistry {
    /// Create a new empty registry
    pub fn new() -> Self {
        Self {
            id_to_path: SlotMap::with_key(),
            path_to_id: HashMap::new(),
            kinds: SecondaryMap::new(),
            spans: SecondaryMap::new(),
            visibility: SecondaryMap::new(),
            parents: SecondaryMap::new(),
            re_exports: SecondaryMap::new(),
            alias_to_canonical: HashMap::new(),
            id_to_uuid: SecondaryMap::new(),
            uuid_to_id: HashMap::new(),
            preloaded_uuids: HashMap::new(),
        }
    }

    /// Create with pre-allocated capacity
    pub fn with_capacity(capacity: usize) -> Self {
        Self {
            id_to_path: SlotMap::with_capacity_and_key(capacity),
            path_to_id: HashMap::with_capacity(capacity),
            kinds: SecondaryMap::new(),
            spans: SecondaryMap::new(),
            visibility: SecondaryMap::new(),
            parents: SecondaryMap::new(),
            re_exports: SecondaryMap::new(),
            alias_to_canonical: HashMap::new(),
            id_to_uuid: SecondaryMap::new(),
            uuid_to_id: HashMap::with_capacity(capacity),
            preloaded_uuids: HashMap::new(),
        }
    }

    // ========== Registration ==========

    /// Register a symbol (returns existing ID if already registered)
    ///
    /// # Returns
    /// - `Ok(SymbolId)`: Registration successful (new or existing)
    /// - `Err(RegistrationError)`: Registration failed
    pub fn register(
        &mut self,
        path: SymbolPath,
        kind: SymbolKind,
    ) -> Result<SymbolId, RegistrationError> {
        // Check if already registered
        if let Some(&existing_id) = self.path_to_id.get(&path) {
            // Verify kind matches
            if let Some(&existing_kind) = self.kinds.get(existing_id) {
                if existing_kind != kind {
                    return Err(RegistrationError::ConflictingKind {
                        path: Box::new(path),
                        existing: existing_kind,
                        new: kind,
                    });
                }
            }
            return Ok(existing_id);
        }

        // Register new symbol
        let id = self.id_to_path.insert(path.clone());
        self.path_to_id.insert(path.clone(), id);
        self.kinds.insert(id, kind);

        // Use preloaded UUID if available (from previous session), otherwise generate new
        let uuid = self
            .preloaded_uuids
            .remove(&path)
            .unwrap_or_else(Uuid::new_v4);
        self.id_to_uuid.insert(id, uuid);
        self.uuid_to_id.insert(uuid, id);

        Ok(id)
    }

    /// Register with full metadata
    pub fn register_with_metadata(
        &mut self,
        path: SymbolPath,
        kind: SymbolKind,
        span: Option<FileSpan>,
        vis: Option<Visibility>,
    ) -> Result<SymbolId, RegistrationError> {
        let id = self.register(path, kind)?;

        if let Some(span) = span {
            self.spans.insert(id, span);
        }
        if let Some(vis) = vis {
            self.visibility.insert(id, vis);
        }

        Ok(id)
    }

    /// Register a variable (InSymbol)
    ///
    /// Creates a path like `parent::$scope::name` and registers it.
    ///
    /// # Arguments
    /// - `containing_symbol`: Parent symbol (function/method/struct)
    /// - `scope`: Variable scope type
    /// - `name`: Variable name
    /// - `kind`: Symbol kind (Variable, Parameter, or Field)
    pub fn register_var(
        &mut self,
        containing_symbol: SymbolId,
        scope: VarScope,
        name: &str,
        kind: SymbolKind,
    ) -> Result<SymbolId, RegistrationError> {
        // Get parent path
        let parent_path = self
            .path(containing_symbol)
            .ok_or(RegistrationError::InvalidParent)?
            .clone();

        // Create variable path
        let var_path = parent_path
            .with_var_scope(scope, name)
            .map_err(RegistrationError::InvalidPath)?;

        // Register
        let id = self.register(var_path, kind)?;

        // Record parent relationship
        self.parents.insert(id, containing_symbol);

        Ok(id)
    }

    // ========== Lookup ==========

    /// SymbolPath → SymbolId (O(1) hash lookup)
    ///
    /// Also resolves re-export aliases to their canonical ID.
    #[inline]
    pub fn lookup(&self, path: &SymbolPath) -> Option<SymbolId> {
        // Try canonical path first
        if let Some(&id) = self.path_to_id.get(path) {
            return Some(id);
        }
        // Try as alias
        self.alias_to_canonical.get(path).copied()
    }

    /// SymbolId → SymbolPath (O(1) array access)
    #[inline]
    pub fn resolve(&self, id: SymbolId) -> Option<&SymbolPath> {
        self.id_to_path.get(id)
    }

    /// Alias for resolve() - get path from ID
    #[inline]
    pub fn path(&self, id: SymbolId) -> Option<&SymbolPath> {
        self.resolve(id)
    }

    /// Get SymbolRef (ID + Path) for unified display
    ///
    /// # Format
    /// Returns `SymbolRef` which displays as: `SymbolId(2v1)@path::to::symbol`
    ///
    /// # Example
    /// ```ignore
    /// let sym_ref = registry.get_ref(id)?;
    /// println!("{}", sym_ref);  // SymbolId(2v1)@my_crate::MyStruct
    /// ```
    #[inline]
    pub fn get_ref(&self, id: SymbolId) -> Option<crate::SymbolRef> {
        self.resolve(id)
            .map(|path| crate::SymbolRef::new(id, path.clone()))
    }

    /// Check if SymbolId is valid (with generation check)
    #[inline]
    pub fn contains(&self, id: SymbolId) -> bool {
        self.id_to_path.contains_key(id)
    }

    // ========== Metadata Access ==========

    /// Get kind
    #[inline]
    pub fn kind(&self, id: SymbolId) -> Option<SymbolKind> {
        self.kinds.get(id).copied()
    }

    /// Get span
    #[inline]
    pub fn span(&self, id: SymbolId) -> Option<&FileSpan> {
        self.spans.get(id)
    }

    /// Get visibility
    #[inline]
    pub fn visibility(&self, id: SymbolId) -> Option<&Visibility> {
        self.visibility.get(id)
    }

    /// Get parent symbol (for InSymbol)
    #[inline]
    pub fn parent(&self, id: SymbolId) -> Option<SymbolId> {
        self.parents.get(id).copied()
    }

    // ========== Metadata Mutation ==========

    /// Set/update span
    pub fn set_span(&mut self, id: SymbolId, span: FileSpan) -> Result<(), InvalidSymbolId> {
        if !self.contains(id) {
            return Err(InvalidSymbolId(id));
        }
        self.spans.insert(id, span);
        Ok(())
    }

    /// Set/update visibility
    pub fn set_visibility(&mut self, id: SymbolId, vis: Visibility) -> Result<(), InvalidSymbolId> {
        if !self.contains(id) {
            return Err(InvalidSymbolId(id));
        }
        self.visibility.insert(id, vis);
        Ok(())
    }

    /// Set/update kind
    pub fn set_kind(&mut self, id: SymbolId, kind: SymbolKind) -> Result<(), InvalidSymbolId> {
        if !self.contains(id) {
            return Err(InvalidSymbolId(id));
        }
        self.kinds.insert(id, kind);
        Ok(())
    }

    /// Remove a symbol from the registry
    ///
    /// Returns the path of the removed symbol, or None if the ID was invalid.
    /// Also removes the persistent UUID mapping if present.
    pub fn remove(&mut self, id: SymbolId) -> Option<SymbolPath> {
        let path = self.id_to_path.remove(id)?;
        self.path_to_id.remove(&path);
        self.kinds.remove(id);
        self.spans.remove(id);
        self.visibility.remove(id);
        self.parents.remove(id);

        // Clean up re-exports pointing to this symbol
        if let Some(aliases) = self.re_exports.remove(id) {
            for info in aliases {
                self.alias_to_canonical.remove(&info.alias_path);
            }
        }

        // Clean up UUID mapping
        if let Some(uuid) = self.id_to_uuid.remove(id) {
            self.uuid_to_id.remove(&uuid);
        }

        Some(path)
    }

    /// Rename a symbol
    ///
    /// Returns the old path on success.
    pub fn rename(
        &mut self,
        id: SymbolId,
        new_path: SymbolPath,
    ) -> Result<SymbolPath, RenameError> {
        // Validate ID exists
        let old_path = self
            .id_to_path
            .get(id)
            .ok_or(RenameError::InvalidId(id))?
            .clone();

        // Check new path doesn't conflict
        if self.path_to_id.contains_key(&new_path) {
            return Err(RenameError::PathExists(Box::new(new_path)));
        }

        // Update mappings
        self.path_to_id.remove(&old_path);
        self.path_to_id.insert(new_path.clone(), id);
        self.id_to_path[id] = new_path;

        Ok(old_path)
    }

    // ========== Name-based Lookup ==========

    /// Find all symbols with the given name (last segment of path).
    ///
    /// Also includes canonical symbols that have re-export aliases matching the name.
    pub fn find_by_name(&self, name: &str) -> Vec<SymbolId> {
        let mut results: Vec<SymbolId> = self
            .id_to_path
            .iter()
            .filter(|(_, path)| path.name() == name)
            .map(|(id, _)| id)
            .collect();

        // Include canonical IDs reachable via alias paths matching this name
        for (alias_path, &canonical_id) in &self.alias_to_canonical {
            if alias_path.name() == name && !results.contains(&canonical_id) {
                results.push(canonical_id);
            }
        }

        results
    }

    /// Find a single symbol by name (returns first match)
    pub fn lookup_by_name(&self, name: &str) -> Option<SymbolId> {
        self.id_to_path
            .iter()
            .find(|(_, path)| path.name() == name)
            .map(|(id, _)| id)
    }

    // ========== Re-export Management ==========

    /// Register a re-export
    pub fn register_reexport(
        &mut self,
        canonical_id: SymbolId,
        alias_path: SymbolPath,
        origin_file: WorkspaceFilePath,
    ) -> Result<(), InvalidSymbolId> {
        if !self.contains(canonical_id) {
            return Err(InvalidSymbolId(canonical_id));
        }

        // Add alias → canonical mapping
        self.alias_to_canonical
            .insert(alias_path.clone(), canonical_id);

        // Add canonical → aliases mapping
        let info = ReExportInfo {
            alias_path,
            origin_file,
        };
        self.re_exports
            .entry(canonical_id)
            .expect("canonical_id was validated by self.contains() above")
            .or_default()
            .push(info);

        Ok(())
    }

    /// Unregister a re-export
    pub fn unregister_reexport(
        &mut self,
        alias_path: &SymbolPath,
    ) -> Result<(), UnregisterReexportError> {
        let canonical_id = self
            .alias_to_canonical
            .remove(alias_path)
            .ok_or(UnregisterReexportError::NotFound)?;

        if let Some(aliases) = self.re_exports.get_mut(canonical_id) {
            aliases.retain(|info| &info.alias_path != alias_path);
            if aliases.is_empty() {
                self.re_exports.remove(canonical_id);
            }
        }

        Ok(())
    }

    /// Get re-exports for a symbol
    pub fn re_exports(&self, id: SymbolId) -> Option<&[ReExportInfo]> {
        self.re_exports.get(id).map(|v| v.as_slice())
    }

    // ========== Persistent Identity (UUID) ==========

    /// Register a symbol with persistent UUID
    ///
    /// This method assigns a stable UUID to the symbol that survives across sessions.
    /// Use this for symbols that need to be tracked through renames or serialized.
    ///
    /// # Arguments
    /// - `path`: Symbol path
    /// - `kind`: Symbol kind
    /// - `uuid`: `Some(uuid)` when restoring from serialized data, `None` to generate new
    ///
    /// # Returns
    /// - `Ok((SymbolId, Uuid))`: The runtime ID and persistent UUID
    /// - `Err(RegistrationError)`: Registration failed
    ///
    /// # Example
    /// ```ignore
    /// // New symbol (generates UUID)
    /// let (id, uuid) = registry.register_persistent(path, kind, None)?;
    ///
    /// // Restore from serialized data
    /// let (id, uuid) = registry.register_persistent(path, kind, Some(saved_uuid))?;
    /// ```
    pub fn register_persistent(
        &mut self,
        path: SymbolPath,
        kind: SymbolKind,
        uuid: Option<Uuid>,
    ) -> Result<(SymbolId, Uuid), RegistrationError> {
        // Standard registration
        let id = self.register(path, kind)?;

        // Check if UUID already assigned (idempotent for existing symbols)
        if let Some(&existing_uuid) = self.id_to_uuid.get(id) {
            // If caller provided a UUID, verify it matches
            if let Some(provided) = uuid {
                if provided != existing_uuid {
                    // UUID conflict - this is a programming error
                    // The same symbol shouldn't have different UUIDs
                    return Err(RegistrationError::UuidConflict {
                        id,
                        existing: existing_uuid,
                        provided,
                    });
                }
            }
            return Ok((id, existing_uuid));
        }

        // Assign UUID (use provided or generate new)
        let final_uuid = uuid.unwrap_or_else(Uuid::new_v4);
        self.id_to_uuid.insert(id, final_uuid);
        self.uuid_to_id.insert(final_uuid, id);

        Ok((id, final_uuid))
    }

    /// Assign a persistent UUID to an existing symbol
    ///
    /// Use this to add persistence to a symbol that was registered without UUID.
    ///
    /// # Returns
    /// - `Ok(Uuid)`: The assigned UUID (existing or new)
    /// - `Err(InvalidSymbolId)`: Symbol doesn't exist
    pub fn assign_uuid(
        &mut self,
        id: SymbolId,
        uuid: Option<Uuid>,
    ) -> Result<Uuid, InvalidSymbolId> {
        if !self.contains(id) {
            return Err(InvalidSymbolId(id));
        }

        // Return existing UUID if already assigned
        if let Some(&existing) = self.id_to_uuid.get(id) {
            return Ok(existing);
        }

        let final_uuid = uuid.unwrap_or_else(Uuid::new_v4);
        self.id_to_uuid.insert(id, final_uuid);
        self.uuid_to_id.insert(final_uuid, id);

        Ok(final_uuid)
    }

    /// Get persistent UUID for a symbol (O(1))
    ///
    /// Returns `None` if the symbol was not registered with persistence.
    #[inline]
    pub fn uuid(&self, id: SymbolId) -> Option<Uuid> {
        self.id_to_uuid.get(id).copied()
    }

    /// Lookup symbol by persistent UUID (O(1))
    ///
    /// Use this when deserializing references from saved data.
    #[inline]
    pub fn lookup_by_uuid(&self, uuid: Uuid) -> Option<SymbolId> {
        self.uuid_to_id.get(&uuid).copied()
    }

    /// Check if a symbol has a persistent UUID
    #[inline]
    pub fn has_uuid(&self, id: SymbolId) -> bool {
        self.id_to_uuid.contains_key(id)
    }

    /// Get all symbols with persistent UUIDs
    pub fn iter_persistent(&self) -> impl Iterator<Item = (SymbolId, Uuid)> + '_ {
        self.id_to_uuid.iter().map(|(id, &uuid)| (id, uuid))
    }

    /// Get count of symbols with persistent UUIDs
    pub fn persistent_count(&self) -> usize {
        self.id_to_uuid.len()
    }

    /// Preload UUID mappings from a previous session.
    ///
    /// Call this before registering symbols to restore persistent UUIDs.
    /// When `register()` is called, it will use preloaded UUIDs instead of
    /// generating new ones.
    ///
    /// # Arguments
    /// * `mappings` - HashMap of SymbolPath → UUID from previous session
    ///
    /// # Example
    /// ```ignore
    /// // Load from file
    /// let mappings: HashMap<SymbolPath, Uuid> = load_from_file(path)?;
    /// registry.preload_uuid_mapping(mappings);
    ///
    /// // Now register symbols - they'll get their previous UUIDs
    /// registry.register(path, kind)?;
    /// ```
    pub fn preload_uuid_mapping(&mut self, mappings: HashMap<SymbolPath, Uuid>) {
        self.preloaded_uuids = mappings;
    }

    /// Export current UUID mappings for persistence.
    ///
    /// Returns a HashMap of SymbolPath → UUID that can be serialized
    /// and loaded in a future session via `preload_uuid_mapping()`.
    ///
    /// # Example
    /// ```ignore
    /// // Save to file
    /// let mappings = registry.export_uuid_mapping();
    /// save_to_file(path, &mappings)?;
    /// ```
    pub fn export_uuid_mapping(&self) -> HashMap<SymbolPath, Uuid> {
        self.id_to_path
            .iter()
            .filter_map(|(id, path)| self.id_to_uuid.get(id).map(|&uuid| (path.clone(), uuid)))
            .collect()
    }

    /// Export UUID mappings as strings for JSON serialization.
    ///
    /// Converts SymbolPath and Uuid to String for easy JSON storage.
    pub fn export_uuid_mapping_strings(&self) -> HashMap<String, String> {
        self.export_uuid_mapping()
            .into_iter()
            .map(|(path, uuid)| (path.to_string(), uuid.to_string()))
            .collect()
    }

    /// Preload UUID mappings from string format (for JSON deserialization).
    ///
    /// Parses string keys/values back to SymbolPath/Uuid.
    /// Invalid entries are silently skipped.
    pub fn preload_uuid_mapping_strings(&mut self, mappings: HashMap<String, String>) {
        let parsed: HashMap<SymbolPath, Uuid> = mappings
            .into_iter()
            .filter_map(|(path_str, uuid_str)| {
                let path = SymbolPath::parse(&path_str).ok()?;
                let uuid = Uuid::parse_str(&uuid_str).ok()?;
                Some((path, uuid))
            })
            .collect();
        self.preloaded_uuids = parsed;
    }

    // ========== Iteration ==========

    /// Iterate over all symbols
    pub fn iter(&self) -> impl Iterator<Item = (SymbolId, &SymbolPath)> {
        self.id_to_path.iter()
    }

    /// Iterate over symbols of a specific kind
    pub fn iter_by_kind(&self, kind: SymbolKind) -> impl Iterator<Item = SymbolId> + '_ {
        self.kinds
            .iter()
            .filter(move |(_, &k)| k == kind)
            .map(|(id, _)| id)
    }

    /// Iterate over symbols in a specific crate
    pub fn iter_in_crate<'a>(&'a self, crate_name: &'a str) -> impl Iterator<Item = SymbolId> + 'a {
        self.id_to_path
            .iter()
            .filter(move |(_, path)| path.crate_name() == crate_name)
            .map(|(id, _)| id)
    }

    // ========== Statistics ==========

    /// Get number of registered symbols
    pub fn len(&self) -> usize {
        self.id_to_path.len()
    }

    /// Check if registry is empty
    pub fn is_empty(&self) -> bool {
        self.id_to_path.is_empty()
    }

    /// Get memory usage statistics
    pub fn memory_stats(&self) -> MemoryStats {
        MemoryStats {
            symbol_count: self.id_to_path.len(),
            // Rough estimates
            estimated_bytes: self.id_to_path.len() * 64 // Very rough estimate
                + self.path_to_id.len() * 80
                + self.kinds.len() * 8
                + self.spans.len() * 48
                + self.visibility.len() * 16,
        }
    }
}

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

/// Memory usage statistics
#[derive(Debug, Clone)]
pub struct MemoryStats {
    /// Number of symbols currently held in the registry.
    pub symbol_count: usize,
    /// Rough byte estimate of the registry's in-memory footprint
    /// (path strings + slot map overhead); not a precise allocator total.
    pub estimated_bytes: usize,
}

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

    fn make_path(s: &str) -> SymbolPath {
        SymbolPath::parse(s).unwrap()
    }

    #[test]
    fn test_register_and_lookup() {
        let mut registry = SymbolRegistry::new();

        let path = make_path("my_crate::MyStruct");
        let id = registry.register(path.clone(), SymbolKind::Struct).unwrap();

        assert!(registry.contains(id));
        assert_eq!(registry.lookup(&path), Some(id));
        assert_eq!(registry.resolve(id), Some(&path));
        assert_eq!(registry.kind(id), Some(SymbolKind::Struct));
    }

    #[test]
    fn test_register_duplicate() {
        let mut registry = SymbolRegistry::new();

        let path = make_path("my_crate::MyStruct");
        let id1 = registry.register(path.clone(), SymbolKind::Struct).unwrap();
        let id2 = registry.register(path.clone(), SymbolKind::Struct).unwrap();

        // Same ID returned
        assert_eq!(id1, id2);
    }

    #[test]
    fn test_register_conflicting_kind() {
        let mut registry = SymbolRegistry::new();

        let path = make_path("my_crate::MyStruct");
        registry.register(path.clone(), SymbolKind::Struct).unwrap();

        // Attempt to register with different kind
        let result = registry.register(path, SymbolKind::Enum);
        assert!(matches!(
            result,
            Err(RegistrationError::ConflictingKind { .. })
        ));
    }

    #[test]
    fn test_register_var() {
        let mut registry = SymbolRegistry::new();

        // Register parent
        let fn_path = make_path("my_crate::my_fn");
        let fn_id = registry.register(fn_path, SymbolKind::Function).unwrap();

        // Register variable
        let var_id = registry
            .register_var(fn_id, VarScope::Local, "result", SymbolKind::Variable)
            .unwrap();

        // Verify
        let var_path = registry.resolve(var_id).unwrap();
        assert_eq!(var_path.to_string(), "my_crate::my_fn::$var::result");
        assert_eq!(registry.parent(var_id), Some(fn_id));
    }

    #[test]
    fn test_reexport() {
        let mut registry = SymbolRegistry::new();

        // Register canonical
        let canonical_path = make_path("std::collections::hash_map::HashMap");
        let canonical_id = registry
            .register(canonical_path, SymbolKind::Struct)
            .unwrap();

        // Register re-export
        let alias_path = make_path("std::collections::HashMap");
        let origin = WorkspaceFilePath::new_for_test("src/collections/mod.rs", "/std", "std");

        registry
            .register_reexport(canonical_id, alias_path.clone(), origin)
            .unwrap();

        // Both paths resolve to same ID
        assert_eq!(registry.lookup(&alias_path), Some(canonical_id));
    }

    #[test]
    fn test_iter_by_kind() {
        let mut registry = SymbolRegistry::new();

        registry
            .register(make_path("my_crate::Struct1"), SymbolKind::Struct)
            .unwrap();
        registry
            .register(make_path("my_crate::Struct2"), SymbolKind::Struct)
            .unwrap();
        registry
            .register(make_path("my_crate::func"), SymbolKind::Function)
            .unwrap();

        let structs: Vec<_> = registry.iter_by_kind(SymbolKind::Struct).collect();
        assert_eq!(structs.len(), 2);

        let funcs: Vec<_> = registry.iter_by_kind(SymbolKind::Function).collect();
        assert_eq!(funcs.len(), 1);
    }

    // ========== UUID Persistence Tests ==========

    #[test]
    fn test_register_persistent_new() {
        let mut registry = SymbolRegistry::new();

        let path = make_path("my_crate::MyStruct");
        let (id, uuid) = registry
            .register_persistent(path.clone(), SymbolKind::Struct, None)
            .unwrap();

        // Verify bidirectional mapping
        assert_eq!(registry.uuid(id), Some(uuid));
        assert_eq!(registry.lookup_by_uuid(uuid), Some(id));
        assert!(registry.has_uuid(id));
    }

    #[test]
    fn test_register_persistent_returns_auto_uuid() {
        let mut registry = SymbolRegistry::new();

        // With auto-UUID on register(), register_persistent() without
        // explicit UUID just returns the auto-generated one
        let path = make_path("my_crate::MyStruct");
        let (id, uuid) = registry
            .register_persistent(path, SymbolKind::Struct, None)
            .unwrap();

        // UUID was auto-assigned by register()
        assert_eq!(registry.uuid(id), Some(uuid));
        assert_eq!(registry.lookup_by_uuid(uuid), Some(id));
    }

    #[test]
    fn test_register_persistent_idempotent() {
        let mut registry = SymbolRegistry::new();

        let path = make_path("my_crate::MyStruct");

        // First registration
        let (id1, uuid1) = registry
            .register_persistent(path.clone(), SymbolKind::Struct, None)
            .unwrap();

        // Second registration (same path)
        let (id2, uuid2) = registry
            .register_persistent(path, SymbolKind::Struct, None)
            .unwrap();

        // Should return same ID and UUID
        assert_eq!(id1, id2);
        assert_eq!(uuid1, uuid2);
    }

    #[test]
    fn test_uuid_survives_rename() {
        let mut registry = SymbolRegistry::new();

        // Register with UUID
        let old_path = make_path("my_crate::OldName");
        let (id, uuid) = registry
            .register_persistent(old_path, SymbolKind::Struct, None)
            .unwrap();

        // Rename
        let new_path = make_path("my_crate::NewName");
        registry.rename(id, new_path.clone()).unwrap();

        // UUID should be preserved (same entity, different name)
        assert_eq!(registry.uuid(id), Some(uuid));
        assert_eq!(registry.lookup_by_uuid(uuid), Some(id));

        // Path should be updated
        assert_eq!(registry.resolve(id), Some(&new_path));
    }

    #[test]
    fn test_uuid_removed_on_delete() {
        let mut registry = SymbolRegistry::new();

        let path = make_path("my_crate::MyStruct");
        let (id, uuid) = registry
            .register_persistent(path, SymbolKind::Struct, None)
            .unwrap();

        // Remove symbol
        registry.remove(id);

        // UUID mapping should be cleaned up
        assert!(registry.uuid(id).is_none());
        assert!(registry.lookup_by_uuid(uuid).is_none());
    }

    #[test]
    fn test_auto_uuid_on_register() {
        let mut registry = SymbolRegistry::new();

        // All symbols now get UUID automatically on register
        let path = make_path("my_crate::MyStruct");
        let id = registry.register(path, SymbolKind::Struct).unwrap();

        // UUID is assigned automatically
        assert!(registry.has_uuid(id));
        let uuid = registry.uuid(id).unwrap();
        assert_eq!(registry.lookup_by_uuid(uuid), Some(id));

        // assign_uuid returns existing UUID (idempotent)
        let uuid2 = registry.assign_uuid(id, None).unwrap();
        assert_eq!(uuid, uuid2);
    }

    #[test]
    fn test_iter_persistent() {
        let mut registry = SymbolRegistry::new();

        // All symbols now get UUID automatically
        let id0 = registry
            .register(make_path("my_crate::Symbol0"), SymbolKind::Struct)
            .unwrap();
        let id1 = registry
            .register(make_path("my_crate::Symbol1"), SymbolKind::Struct)
            .unwrap();
        let id2 = registry
            .register(make_path("my_crate::Symbol2"), SymbolKind::Enum)
            .unwrap();

        // All 3 symbols should have UUIDs
        let persistent: Vec<_> = registry.iter_persistent().collect();
        assert_eq!(persistent.len(), 3);
        assert_eq!(registry.persistent_count(), 3);

        // Verify each symbol has a UUID
        assert!(registry.has_uuid(id0));
        assert!(registry.has_uuid(id1));
        assert!(registry.has_uuid(id2));
    }

    #[test]
    fn test_uuid_conflict_error() {
        let mut registry = SymbolRegistry::new();

        let path = make_path("my_crate::MyStruct");
        let different_uuid = Uuid::new_v4();

        // First, register normally (auto-assigns UUID)
        let id = registry.register(path.clone(), SymbolKind::Struct).unwrap();
        let auto_uuid = registry.uuid(id).unwrap();

        // Try to register_persistent with a different UUID - should conflict
        let result = registry.register_persistent(path, SymbolKind::Struct, Some(different_uuid));

        assert!(matches!(
            result,
            Err(RegistrationError::UuidConflict { .. })
        ));

        // Verify original UUID is unchanged
        assert_eq!(registry.uuid(id), Some(auto_uuid));
    }

    // ========== Re-export + find_by_name Tests ==========

    #[test]
    fn test_find_by_name_includes_aliases() {
        let mut registry = SymbolRegistry::new();

        // Register canonical symbol: parking_lot::Mutex
        let canonical_path = make_path("parking_lot::Mutex");
        let canonical_id = registry
            .register(canonical_path, SymbolKind::Struct)
            .unwrap();

        // Register re-export alias: tokio::sync::Mutex → parking_lot::Mutex
        let alias_path = make_path("tokio::sync::Mutex");
        let file_path = WorkspaceFilePath::new_for_test("src/sync/mod.rs", "/tmp/tokio", "tokio");
        registry
            .register_reexport(canonical_id, alias_path, file_path)
            .unwrap();

        // find_by_name("Mutex") should find the canonical via alias
        let results = registry.find_by_name("Mutex");
        assert_eq!(results.len(), 1);
        assert_eq!(results[0], canonical_id);
    }

    #[test]
    fn test_find_by_name_no_duplicate_with_alias() {
        let mut registry = SymbolRegistry::new();

        // Canonical symbol has name "Mutex" in its path
        let canonical_path = make_path("parking_lot::Mutex");
        let canonical_id = registry
            .register(canonical_path, SymbolKind::Struct)
            .unwrap();

        // Alias also ends in "Mutex"
        let alias_path = make_path("tokio::sync::Mutex");
        let file_path = WorkspaceFilePath::new_for_test("src/sync/mod.rs", "/tmp/tokio", "tokio");
        registry
            .register_reexport(canonical_id, alias_path, file_path)
            .unwrap();

        // Should not duplicate: canonical already found via id_to_path
        let results = registry.find_by_name("Mutex");
        assert_eq!(results.len(), 1);
    }

    #[test]
    fn test_lookup_resolves_alias() {
        let mut registry = SymbolRegistry::new();

        let canonical_path = make_path("my_crate::inner::Config");
        let canonical_id = registry
            .register(canonical_path, SymbolKind::Struct)
            .unwrap();

        let alias_path = make_path("my_crate::Config");
        let file_path = WorkspaceFilePath::new_for_test("src/lib.rs", "/tmp/my_crate", "my_crate");
        registry
            .register_reexport(canonical_id, alias_path.clone(), file_path)
            .unwrap();

        // lookup with alias path should return canonical ID
        assert_eq!(registry.lookup(&alias_path), Some(canonical_id));
    }
}