ryo-suggest 0.1.0

//! SuggestService - ReadOnly interface for concurrent access
//!
//! Provides thread-safe access to suggestions for LLM and UI queries.
//! Uses parking_lot::RwLock for concurrent read access with exclusive writes.

use parking_lot::{MappedRwLockReadGuard, RwLock, RwLockReadGuard};
use rayon::prelude::*;

use ryo_analysis::context::AnalysisContext;
use ryo_analysis::SymbolId;

use crate::allow::AllowStore;
use crate::id::SuggestId;
use crate::store::{GcConfig, StoredSuggestion, SuggestIndex, SuggestStore};
use crate::suggest::{
    LintSeverity, MutationSpec, ParamDef, SafetyLevel, SuggestCategory, SuggestOpportunity,
    SuggestParams, SymbolScope,
};
use crate::suggest_registry::SuggestRegistry;
use crate::trigger::{AcChanges, PendingChanges, SuggestStrategy, SuggestTrigger};

/// Information about a parameterized suggestion.
///
/// Used by LLMs to discover available generation patterns
/// and their parameter schemas.
#[derive(Debug, Clone)]
pub struct ParameterizedSuggestInfo {
    /// Suggestion name (rule ID)
    pub name: &'static str,
    /// Human-readable description
    pub description: String,
    /// Category for filtering
    pub category: SuggestCategory,
    /// Parameter schema
    pub param_schema: Vec<ParamDef>,
}

/// Query filter for suggestions
#[derive(Debug, Clone, Default)]
pub struct SuggestQuery {
    /// Filter by category
    pub category: Option<SuggestCategory>,

    /// Filter by safety level (max level to include)
    pub max_safety: Option<SafetyLevel>,

    /// Filter by minimum confidence
    pub min_confidence: Option<f32>,

    /// Filter by target symbols (any of these)
    pub target_symbols: Option<Vec<SymbolId>>,

    /// Limit results
    pub limit: Option<usize>,
}

impl SuggestQuery {
    /// Create an empty query (matches all)
    pub fn all() -> Self {
        Self::default()
    }

    /// Filter by category
    pub fn with_category(mut self, category: SuggestCategory) -> Self {
        self.category = Some(category);
        self
    }

    /// Filter by maximum safety level
    pub fn with_max_safety(mut self, safety: SafetyLevel) -> Self {
        self.max_safety = Some(safety);
        self
    }

    /// Filter by minimum confidence
    pub fn with_min_confidence(mut self, confidence: f32) -> Self {
        self.min_confidence = Some(confidence);
        self
    }

    /// Filter by target symbols
    pub fn with_targets(mut self, symbols: Vec<SymbolId>) -> Self {
        self.target_symbols = Some(symbols);
        self
    }

    /// Limit number of results
    pub fn with_limit(mut self, limit: usize) -> Self {
        self.limit = Some(limit);
        self
    }

    /// Check if a suggestion matches this query
    fn matches(&self, stored: &StoredSuggestion, registry: &SuggestRegistry) -> bool {
        // Category filter
        if let Some(cat) = self.category {
            if let Some(suggest) = registry.get(stored.suggest_idx) {
                if suggest.category() != cat {
                    return false;
                }
            }
        }

        // Safety filter
        if let Some(max_safety) = self.max_safety {
            if stored.safety > max_safety {
                return false;
            }
        }

        // Confidence filter
        if let Some(min_conf) = self.min_confidence {
            if stored.opportunity.confidence < min_conf {
                return false;
            }
        }

        // Target symbol filter
        if let Some(ref targets) = self.target_symbols {
            let has_match = stored
                .opportunity
                .targets
                .iter()
                .any(|t| targets.contains(t));
            if !has_match {
                return false;
            }
        }

        true
    }
}

/// View of a suggestion returned by queries
#[derive(Debug)]
pub struct SuggestView<'a> {
    /// The suggestion ID
    pub id: SuggestId,

    /// The stored suggestion data
    pub stored: &'a StoredSuggestion,

    /// Pattern name
    pub pattern_name: &'static str,

    /// Pattern category
    pub category: SuggestCategory,
}

/// Thread-safe service for accessing suggestions
///
/// Provides read-only queries for LLM and UI consumers.
/// Write operations go through SuggestEngine (not this service).
pub struct SuggestService {
    /// Thread-safe store access
    store: RwLock<SuggestStore>,

    /// Pattern registry (immutable after initialization)
    registry: SuggestRegistry,

    /// Evaluation strategy
    strategy: SuggestStrategy,

    /// Pending changes tracker
    pending: RwLock<PendingChanges>,

    /// GC configuration
    gc_config: GcConfig,
}

impl SuggestService {
    /// Create a new service with the given registry
    pub fn new(registry: SuggestRegistry) -> Self {
        Self {
            store: RwLock::new(SuggestStore::new()),
            registry,
            strategy: SuggestStrategy::default(),
            pending: RwLock::new(PendingChanges::new()),
            gc_config: GcConfig::default(),
        }
    }

    /// Create a service with custom strategy
    pub fn with_strategy(registry: SuggestRegistry, strategy: SuggestStrategy) -> Self {
        Self {
            store: RwLock::new(SuggestStore::new()),
            registry,
            strategy,
            pending: RwLock::new(PendingChanges::new()),
            gc_config: GcConfig::default(),
        }
    }

    /// Create a service with custom GC configuration
    pub fn with_gc_config(registry: SuggestRegistry, gc_config: GcConfig) -> Self {
        Self {
            store: RwLock::new(SuggestStore::new()),
            registry,
            strategy: SuggestStrategy::default(),
            pending: RwLock::new(PendingChanges::new()),
            gc_config,
        }
    }

    // ========== Read Operations (concurrent safe) ==========

    /// Get a suggestion by ID
    ///
    /// Returns a mapped guard that holds the read lock while providing
    /// access to the stored suggestion.
    pub fn get(&self, id: SuggestId) -> Option<MappedRwLockReadGuard<'_, StoredSuggestion>> {
        let guard = self.store.read();
        RwLockReadGuard::try_map(guard, |store| store.get(id)).ok()
    }

    /// Check if a suggestion ID is still valid
    pub fn is_valid(&self, id: SuggestId) -> bool {
        self.store.read().is_valid(id)
    }

    /// Query suggestions with filter
    pub fn query(&self, query: &SuggestQuery) -> Vec<(SuggestId, SuggestCategory, SafetyLevel)> {
        let store = self.store.read();

        let mut results: Vec<_> = store
            .iter()
            .filter(|(_, stored)| query.matches(stored, &self.registry))
            .map(|(id, stored)| {
                let category = self
                    .registry
                    .get(stored.suggest_idx)
                    .map(|s| s.category())
                    .unwrap_or(SuggestCategory::Refactor);
                (id, category, stored.safety)
            })
            .collect();

        // Apply limit
        if let Some(limit) = query.limit {
            results.truncate(limit);
        }

        results
    }

    /// Get all suggestions for auto-application (safety=Auto)
    pub fn auto_applicable(&self) -> Vec<SuggestId> {
        self.query(&SuggestQuery::all().with_max_safety(SafetyLevel::Auto))
            .into_iter()
            .map(|(id, _, _)| id)
            .collect()
    }

    /// Get suggestions by category
    pub fn by_category(&self, category: SuggestCategory) -> Vec<SuggestId> {
        self.query(&SuggestQuery::all().with_category(category))
            .into_iter()
            .map(|(id, _, _)| id)
            .collect()
    }

    /// Get suggestion count
    pub fn count(&self) -> usize {
        self.store.read().len()
    }

    /// Check if there are any suggestions
    pub fn is_empty(&self) -> bool {
        self.count() == 0
    }

    /// Get pattern names for a suggestion
    pub fn pattern_name(&self, id: SuggestId) -> Option<&'static str> {
        let store = self.store.read();
        let stored = store.get(id)?;
        self.registry.get(stored.suggest_idx).map(|s| s.name())
    }

    /// Get rule ID for a suggestion (e.g., "RL021").
    /// Returns None for non-pattern-based suggestions.
    pub fn rule_id(&self, id: SuggestId) -> Option<&str> {
        let store = self.store.read();
        let stored = store.get(id)?;
        self.registry
            .get(stored.suggest_idx)
            .and_then(|s| s.rule_id())
    }

    /// Get registry access (for pattern lookup)
    pub fn registry(&self) -> &SuggestRegistry {
        &self.registry
    }

    // ========== MutationSpec Generation ==========

    /// Generate MutationSpecs for a suggestion
    ///
    /// Takes AnalysisContext to resolve types and generate accurate specs.
    pub fn to_mutation_specs(
        &self,
        id: SuggestId,
        ctx: &AnalysisContext,
    ) -> Option<Vec<MutationSpec>> {
        let store = self.store.read();
        let stored = store.get(id)?;
        let suggest = self.registry.get(stored.suggest_idx)?;

        suggest.to_mutation_specs(ctx, &stored.opportunity).ok()
    }

    // ========== Parameterized Generation ==========

    /// Generate suggestions with external parameters.
    ///
    /// This method enables code generation from patterns with user-provided
    /// parameters. For example, generating `OrderAPI` from an API pattern
    /// with `{ "name": "Order" }`.
    ///
    /// # Arguments
    /// * `ctx` - Analysis context for code graph queries
    /// * `rule_id` - Rule ID of the parameterized suggestion (e.g., "api-pattern")
    /// * `params` - User-provided parameters (e.g., `{ "name": "Order" }`)
    ///
    /// # Returns
    /// * `Some(opportunities)` - Generated opportunities if rule exists and accepts params
    /// * `None` - If rule not found or doesn't accept params
    ///
    /// # Example
    /// ```ignore
    /// let params = [("name".to_string(), "Order".to_string())].into_iter().collect();
    /// let opps = service.generate_with_params(&ctx, "api-pattern", &params);
    /// ```
    pub fn generate_with_params(
        &self,
        ctx: &AnalysisContext,
        rule_id: &str,
        params: &SuggestParams,
    ) -> Option<Vec<SuggestOpportunity>> {
        let (_, suggest) = self.registry.get_by_name(rule_id)?;

        if !suggest.accepts_params() {
            return None;
        }

        Some(suggest.detect_with_params(ctx, &[], params))
    }

    /// Generate suggestions and store them.
    ///
    /// Like `generate_with_params`, but also stores the generated opportunities
    /// in the service for later retrieval and application.
    ///
    /// Returns the number of suggestions stored.
    pub fn generate_and_store(
        &self,
        ctx: &AnalysisContext,
        rule_id: &str,
        params: &SuggestParams,
    ) -> usize {
        let Some((idx, suggest)) = self.registry.get_by_name(rule_id) else {
            return 0;
        };

        if !suggest.accepts_params() {
            return 0;
        }

        let opportunities = suggest.detect_with_params(ctx, &[], params);
        let mut count = 0;

        for opportunity in opportunities {
            let stored = StoredSuggestion::new(
                opportunity,
                idx,
                suggest.safety_level(),
                suggest.priority_weight(),
            );
            if self.insert(stored).is_some() {
                count += 1;
            }
        }

        count
    }

    /// List all parameterized suggestions with their schemas.
    ///
    /// Returns suggestions that accept external parameters, along with
    /// their parameter schemas. Useful for LLMs to discover available
    /// generation patterns.
    pub fn list_parameterized(&self) -> Vec<ParameterizedSuggestInfo> {
        self.registry
            .iter()
            .filter_map(|(_, suggest)| {
                if suggest.accepts_params() {
                    Some(ParameterizedSuggestInfo {
                        name: suggest.name(),
                        description: suggest.description().to_string(),
                        category: suggest.category(),
                        param_schema: suggest.param_schema(),
                    })
                } else {
                    None
                }
            })
            .collect()
    }

    // ========== Write Operations (exclusive access) ==========

    /// Record changes and check if evaluation should trigger
    pub fn record_changes(&self, trigger: SuggestTrigger) -> bool {
        let mut pending = self.pending.write();

        // Accumulate changes
        if let Some(changes) = trigger.changes() {
            pending.record_goal(changes.clone());
        }

        // Check if we should evaluate
        self.strategy.should_evaluate(&trigger, &pending)
    }

    /// Take pending changes (for evaluation)
    pub fn take_pending(&self) -> (usize, AcChanges) {
        self.pending.write().take()
    }

    /// Insert a new suggestion (write operation).
    ///
    /// Returns `None` if an active suggestion with the same identity
    /// (pattern + opportunity_id) already exists.
    pub fn insert(&self, suggestion: StoredSuggestion) -> Option<SuggestId> {
        self.store.write().insert(suggestion)
    }

    /// Close a suggestion (write operation)
    pub fn close(&self, id: SuggestId, reason: impl Into<String>) -> bool {
        self.store.write().close(id, reason)
    }

    /// Invalidate suggestions for a modified symbol
    pub fn invalidate_for_symbol(&self, symbol: &SymbolId) {
        self.store.write().invalidate_for_symbol(symbol);
    }

    /// Remove suggestions for a deleted symbol
    pub fn remove_for_symbol(&self, symbol: &SymbolId) {
        self.store.write().remove_for_symbol(symbol);
    }

    /// Run garbage collection
    pub fn gc(&self, valid_symbols: impl Fn(&SymbolId) -> bool) {
        self.store.write().gc(&self.gc_config, &valid_symbols);
    }

    /// Clear all suggestions
    pub fn clear(&self) {
        self.store.write().clear();
    }

    // ========== Detection (batch operation) ==========

    /// Detect suggestions for given symbols using registered patterns.
    ///
    /// This is the main entry point for suggestion detection.
    /// Automatically filters out suggestions for symbols with `@spec:allow(...)` directives.
    ///
    /// Returns the number of new suggestions found.
    pub fn detect(&self, ctx: &AnalysisContext, symbols: &[SymbolId]) -> usize {
        // Build allow store from context (extracts @spec:allow directives)
        let allow_store = AllowStore::from_context(ctx);
        self.detect_with_allow(ctx, symbols, &allow_store)
    }

    /// Detect suggestions with custom AllowStore.
    ///
    /// Use this when you want to reuse an AllowStore across multiple detect calls
    /// or when you have a pre-built AllowStore.
    pub fn detect_with_allow(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        allow_store: &AllowStore,
    ) -> usize {
        let mut count = 0;

        for (idx, suggest) in self.registry.iter() {
            let rule_id = suggest.rule_id();
            let opportunities = suggest.detect(ctx, symbols);

            for opportunity in opportunities {
                // Check if this opportunity should be skipped due to @spec:allow
                if let Some(rule_id) = rule_id {
                    if allow_store.is_allowed_for_symbols(ctx, &opportunity.targets, rule_id) {
                        continue; // Skip allowed suggestions
                    }
                }

                let stored = StoredSuggestion::new(
                    opportunity,
                    idx,
                    suggest.safety_level(),
                    suggest.priority_weight(),
                );
                if self.insert(stored).is_some() {
                    count += 1;
                }
            }
        }

        count
    }

    /// Detect suggestions with rule filter.
    ///
    /// The `is_rule_enabled` closure takes (rule_id, file_path) to check if a rule should be processed.
    /// Rules returning `false` are skipped. This enables project and module-level rule configuration.
    pub fn detect_with_rule_filter<F>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        is_rule_enabled: F,
    ) -> usize
    where
        F: Fn(&str, &str) -> bool,
    {
        let allow_store = AllowStore::from_context(ctx);
        self.detect_with_allow_and_rule_filter(ctx, symbols, &allow_store, is_rule_enabled)
    }

    /// Detect suggestions with custom AllowStore and rule filter.
    ///
    /// Combines symbol-level allow directives with project/module-level rule filtering.
    /// The `is_rule_enabled` closure takes (rule_id, file_path) to support module configs.
    pub fn detect_with_allow_and_rule_filter<F>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        allow_store: &AllowStore,
        is_rule_enabled: F,
    ) -> usize
    where
        F: Fn(&str, &str) -> bool,
    {
        self.detect_with_config(ctx, symbols, allow_store, is_rule_enabled, |_| None)
    }

    /// Detect suggestions with full configuration support.
    ///
    /// This is the most complete variant that supports:
    /// - Custom AllowStore for symbol-level @spec:allow directives
    /// - Rule filter closure for project-level rule configuration
    /// - Severity override closure for per-rule severity changes
    ///
    /// The `severity_override` closure takes a rule_id and returns an optional
    /// new severity. If None, the default severity is used.
    ///
    /// The `is_rule_enabled` closure takes (rule_id, file_path) to support
    /// module-level rule configuration.
    pub fn detect_with_config<F, S>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        allow_store: &AllowStore,
        is_rule_enabled: F,
        severity_override: S,
    ) -> usize
    where
        F: Fn(&str, &str) -> bool,
        S: Fn(&str) -> Option<LintSeverity>,
    {
        self.detect_with_config_and_scope(
            ctx,
            symbols,
            allow_store,
            is_rule_enabled,
            severity_override,
            &[],
        )
    }

    /// Detect suggestions with full configuration and scope filtering.
    ///
    /// Extends `detect_with_config` with scope-based filtering.
    /// Each opportunity is tagged with its `SymbolScope` (Lib/Bin/Test)
    /// based on symbol context. If `scope_filter` is non-empty, only
    /// opportunities matching one of the specified scopes are stored.
    pub fn detect_with_config_and_scope<F, S>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        allow_store: &AllowStore,
        is_rule_enabled: F,
        severity_override: S,
        scope_filter: &[SymbolScope],
    ) -> usize
    where
        F: Fn(&str, &str) -> bool,
        S: Fn(&str) -> Option<LintSeverity>,
    {
        let mut count = 0;

        // Pre-compute binary crate names once for scope resolution
        let binary_crates = SymbolScope::binary_crate_names(ctx);

        for (idx, suggest) in self.registry.iter() {
            let rule_id = suggest.rule_id();

            let opportunities = suggest.detect(ctx, symbols);

            for opportunity in opportunities {
                // Check module-level and project-level rule filter
                if let Some(rule_id) = rule_id {
                    let file_path = &opportunity.location.file;
                    if !is_rule_enabled(rule_id, file_path) {
                        continue;
                    }
                }

                // Check symbol-level @spec:allow
                if let Some(rule_id) = rule_id {
                    if allow_store.is_allowed_for_symbols(ctx, &opportunity.targets, rule_id) {
                        continue;
                    }
                }

                // Resolve scope from primary target symbol
                let scope = opportunity
                    .primary_target()
                    .map(|sid| SymbolScope::resolve(ctx, sid, &binary_crates))
                    .unwrap_or_default();

                // Apply CLI scope filter (empty = allow all)
                if !scope_filter.is_empty() && !scope_filter.contains(&scope) {
                    continue;
                }

                // Apply suggest-level scope constraint (e.g., Safety rules → lib+bin only)
                let target_scopes = suggest.target_scopes();
                if !target_scopes.is_empty() && !target_scopes.contains(&scope) {
                    continue;
                }

                // Tag opportunity with resolved scope
                let opportunity = opportunity.with_scope(scope);

                // Apply severity override if configured
                let opportunity = if let Some(rule_id) = rule_id {
                    if let Some(new_severity) = severity_override(rule_id) {
                        opportunity.with_severity_override(new_severity)
                    } else {
                        opportunity
                    }
                } else {
                    opportunity
                };

                // Determine safety level:
                // - For Lint context, use lint_severity (which may be overridden)
                // - For other contexts, use the pattern's default safety_level
                let safety = opportunity
                    .lint_severity()
                    .map(SafetyLevel::from)
                    .unwrap_or_else(|| suggest.safety_level());

                let stored =
                    StoredSuggestion::new(opportunity, idx, safety, suggest.priority_weight());
                if self.insert(stored).is_some() {
                    count += 1;
                }
            }
        }

        count
    }

    /// Detect suggestions for specific patterns only.
    ///
    /// Automatically filters out suggestions for symbols with `@spec:allow(...)` directives.
    pub fn detect_patterns(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        pattern_names: &[&str],
    ) -> usize {
        let allow_store = AllowStore::from_context(ctx);
        self.detect_patterns_with_allow(ctx, symbols, pattern_names, &allow_store)
    }

    /// Detect suggestions for specific patterns with custom AllowStore.
    pub fn detect_patterns_with_allow(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        pattern_names: &[&str],
        allow_store: &AllowStore,
    ) -> usize {
        let mut count = 0;

        for name in pattern_names {
            if let Some((idx, suggest)) = self.registry.get_by_name(name) {
                let rule_id = suggest.rule_id();
                let opportunities = suggest.detect(ctx, symbols);

                for opportunity in opportunities {
                    // Check if this opportunity should be skipped due to @spec:allow
                    if let Some(rule_id) = rule_id {
                        if allow_store.is_allowed_for_symbols(ctx, &opportunity.targets, rule_id) {
                            continue;
                        }
                    }

                    let stored = StoredSuggestion::new(
                        opportunity,
                        idx,
                        suggest.safety_level(),
                        suggest.priority_weight(),
                    );
                    if self.insert(stored).is_some() {
                        count += 1;
                    }
                }
            }
        }

        count
    }

    /// Detect suggestions with pre-check filter.
    ///
    /// The `precheck` callback is called for each opportunity with:
    /// - The opportunity itself
    /// - The generated MutationSpecs
    ///
    /// Only opportunities where `precheck` returns `true` are stored.
    /// This enables scan-time verification to ensure Apply will succeed.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let count = service.detect_with_precheck(ctx, symbols, |opp, specs, ctx| {
    ///     // Run GraphVerifier on specs
    ///     verify_specs(specs, ctx)
    /// });
    /// ```
    pub fn detect_with_precheck<F>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        precheck: F,
    ) -> DetectWithPrecheckResult
    where
        F: Fn(&SuggestOpportunity, &[MutationSpec], &AnalysisContext) -> bool,
    {
        let allow_store = AllowStore::from_context(ctx);
        self.detect_with_precheck_and_allow(ctx, symbols, &allow_store, precheck)
    }

    /// Detect suggestions with pre-check filter and custom AllowStore.
    pub fn detect_with_precheck_and_allow<F>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        allow_store: &AllowStore,
        precheck: F,
    ) -> DetectWithPrecheckResult
    where
        F: Fn(&SuggestOpportunity, &[MutationSpec], &AnalysisContext) -> bool,
    {
        let mut result = DetectWithPrecheckResult::default();

        for (idx, suggest) in self.registry.iter() {
            let rule_id = suggest.rule_id();
            let opportunities = suggest.detect(ctx, symbols);

            for opportunity in opportunities {
                // Check if this opportunity should be skipped due to @spec:allow
                if let Some(rule_id) = rule_id {
                    if allow_store.is_allowed_for_symbols(ctx, &opportunity.targets, rule_id) {
                        continue; // Skip allowed suggestions
                    }
                }

                // Generate MutationSpecs for pre-check
                let specs = match suggest.to_mutation_specs(ctx, &opportunity) {
                    Ok(s) => s,
                    Err(_) => {
                        result.skipped_no_specs += 1;
                        continue;
                    }
                };

                if specs.is_empty() {
                    result.skipped_no_specs += 1;
                    continue;
                }

                // Run pre-check
                if precheck(&opportunity, &specs, ctx) {
                    let stored = StoredSuggestion::new(
                        opportunity,
                        idx,
                        suggest.safety_level(),
                        suggest.priority_weight(),
                    );
                    if self.insert(stored).is_some() {
                        result.passed += 1;
                    }
                } else {
                    result.failed_precheck += 1;
                }
            }
        }

        result
    }

    /// Detect suggestions with parallel pre-check execution.
    ///
    /// This method parallelizes the expensive precheck phase using rayon:
    /// 1. Phase 1 (sequential): Detect all opportunities and generate specs
    /// 2. Phase 2 (parallel): Run precheck on each candidate
    /// 3. Phase 3 (sequential): Insert passed suggestions
    ///
    /// This significantly reduces wall-clock time when precheck involves
    /// expensive operations like fork_clone() (~100ms each).
    ///
    /// # Example
    ///
    /// ```ignore
    /// let result = service.detect_with_parallel_precheck(ctx, symbols, |opp, specs, ctx| {
    ///     // This closure runs in parallel - must be Sync
    ///     let mut forked = ctx.fork_clone();
    ///     executor.execute_v2(&blueprint, &mut forked).success
    /// });
    /// ```
    pub fn detect_with_parallel_precheck<F>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        precheck: F,
    ) -> DetectWithPrecheckResult
    where
        F: Fn(&SuggestOpportunity, &[MutationSpec], &AnalysisContext) -> bool + Sync,
    {
        self.detect_with_parallel_precheck_limited(ctx, symbols, None, precheck)
    }

    /// Detect suggestions with parallel pre-check and optional limit.
    ///
    /// When `limit` is Some(N), only the top N candidates by priority are checked.
    /// Candidates are sorted by priority (confidence * safety_weight) before precheck.
    pub fn detect_with_parallel_precheck_limited<F>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        limit: Option<usize>,
        precheck: F,
    ) -> DetectWithPrecheckResult
    where
        F: Fn(&SuggestOpportunity, &[MutationSpec], &AnalysisContext) -> bool + Sync,
    {
        let allow_store = AllowStore::from_context(ctx);
        self.detect_with_parallel_precheck_and_allow_limited(
            ctx,
            symbols,
            &allow_store,
            limit,
            precheck,
        )
    }

    /// Detect suggestions with parallel pre-check, custom AllowStore, and optional limit.
    pub fn detect_with_parallel_precheck_and_allow<F>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        allow_store: &AllowStore,
        precheck: F,
    ) -> DetectWithPrecheckResult
    where
        F: Fn(&SuggestOpportunity, &[MutationSpec], &AnalysisContext) -> bool + Sync,
    {
        self.detect_with_parallel_precheck_and_allow_limited(
            ctx,
            symbols,
            allow_store,
            None,
            precheck,
        )
    }

    /// Detect suggestions with parallel pre-check, custom AllowStore, and optional limit.
    pub fn detect_with_parallel_precheck_and_allow_limited<F>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        allow_store: &AllowStore,
        limit: Option<usize>,
        precheck: F,
    ) -> DetectWithPrecheckResult
    where
        F: Fn(&SuggestOpportunity, &[MutationSpec], &AnalysisContext) -> bool + Sync,
    {
        self.detect_with_parallel_precheck_full(
            ctx,
            symbols,
            allow_store,
            limit,
            |_| true,
            precheck,
        )
    }

    /// Detect suggestions with parallel pre-check, rule filter, and optional limit.
    ///
    /// This is the most complete variant that supports:
    /// - Custom AllowStore for symbol-level @spec:allow directives
    /// - Rule filter closure for project-level rule configuration
    /// - Optional limit on candidates to check
    /// - Parallel precheck execution
    pub fn detect_with_parallel_precheck_and_rule_filter<F, R>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        limit: Option<usize>,
        is_rule_enabled: R,
        precheck: F,
    ) -> DetectWithPrecheckResult
    where
        F: Fn(&SuggestOpportunity, &[MutationSpec], &AnalysisContext) -> bool + Sync,
        R: Fn(&str) -> bool,
    {
        let allow_store = AllowStore::from_context(ctx);
        self.detect_with_parallel_precheck_full(
            ctx,
            symbols,
            &allow_store,
            limit,
            is_rule_enabled,
            precheck,
        )
    }

    /// Full-featured parallel precheck detection with all options.
    ///
    /// This is the internal implementation that other parallel precheck methods delegate to.
    pub fn detect_with_parallel_precheck_full<F, R>(
        &self,
        ctx: &AnalysisContext,
        symbols: &[SymbolId],
        allow_store: &AllowStore,
        limit: Option<usize>,
        is_rule_enabled: R,
        precheck: F,
    ) -> DetectWithPrecheckResult
    where
        F: Fn(&SuggestOpportunity, &[MutationSpec], &AnalysisContext) -> bool + Sync,
        R: Fn(&str) -> bool,
    {
        // Phase 1: Collect all candidates (sequential, lightweight)
        // Each candidate contains: (opportunity, specs, suggest_idx, safety_level, priority)
        let mut candidates: Vec<(
            SuggestOpportunity,
            Vec<MutationSpec>,
            SuggestIndex,
            SafetyLevel,
            u8,
        )> = Vec::new();
        let mut skipped_no_specs = 0;

        for (idx, suggest) in self.registry.iter() {
            let rule_id = suggest.rule_id();

            // Check project-level rule filter first (skip entire pattern if disabled)
            if let Some(rule_id) = rule_id {
                if !is_rule_enabled(rule_id) {
                    continue;
                }
            }

            let opportunities = suggest.detect(ctx, symbols);

            for opportunity in opportunities {
                // Check symbol-level @spec:allow
                if let Some(rule_id) = rule_id {
                    if allow_store.is_allowed_for_symbols(ctx, &opportunity.targets, rule_id) {
                        continue;
                    }
                }

                // Generate MutationSpecs
                let specs = match suggest.to_mutation_specs(ctx, &opportunity) {
                    Ok(s) => s,
                    Err(_) => {
                        skipped_no_specs += 1;
                        continue;
                    }
                };

                if specs.is_empty() {
                    skipped_no_specs += 1;
                    continue;
                }

                let safety = suggest.safety_level();
                let priority = crate::suggest::compute_priority(
                    opportunity.confidence,
                    safety,
                    suggest.priority_weight(),
                );
                candidates.push((opportunity, specs, idx, safety, priority));
            }
        }

        // Phase 1.5: Sort by priority (descending) and limit if requested
        candidates.sort_by_key(|b| std::cmp::Reverse(b.4)); // Higher priority first
        let total_candidates = candidates.len();
        let skipped_by_limit = if let Some(limit) = limit {
            if candidates.len() > limit {
                let skipped = candidates.len() - limit;
                candidates.truncate(limit);
                skipped
            } else {
                0
            }
        } else {
            0
        };

        // Phase 2: Run precheck in parallel (expensive, CPU-bound)
        // Each task gets its own forked context via the precheck closure
        let precheck_results: Vec<Option<StoredSuggestion>> = candidates
            .into_par_iter()
            .map(|(opportunity, specs, suggest_idx, safety, priority)| {
                if precheck(&opportunity, &specs, ctx) {
                    let mut stored = StoredSuggestion::new_with_priority(
                        opportunity,
                        suggest_idx,
                        safety,
                        priority,
                    );
                    stored.precheck_status = crate::store::PrecheckStatus::Passed;
                    Some(stored)
                } else {
                    None
                }
            })
            .collect();

        // Phase 3: Insert passed suggestions (sequential, needs write lock)
        let mut passed = 0;
        let mut failed_precheck = 0;

        for result in precheck_results {
            match result {
                Some(stored) => {
                    if self.insert(stored).is_some() {
                        passed += 1;
                    }
                }
                None => {
                    failed_precheck += 1;
                }
            }
        }

        DetectWithPrecheckResult {
            passed,
            failed_precheck,
            skipped_no_specs,
            skipped_by_limit,
            total_candidates,
        }
    }
}

/// Result of detection with pre-check.
#[derive(Debug, Clone, Default)]
pub struct DetectWithPrecheckResult {
    /// Number of suggestions that passed pre-check and were stored
    pub passed: usize,
    /// Number of suggestions that failed pre-check
    pub failed_precheck: usize,
    /// Number of suggestions skipped due to no MutationSpecs generated
    pub skipped_no_specs: usize,
    /// Number of suggestions skipped due to limit
    pub skipped_by_limit: usize,
    /// Total candidates before limiting (for logging)
    pub total_candidates: usize,
}

impl DetectWithPrecheckResult {
    /// Total suggestions detected (before pre-check filtering)
    pub fn total_detected(&self) -> usize {
        self.passed + self.failed_precheck + self.skipped_no_specs
    }

    /// Number of suggestions that were prechecked
    pub fn prechecked(&self) -> usize {
        self.passed + self.failed_precheck
    }
}

/// Statistics about service state
#[derive(Debug, Clone, Default)]
pub struct SuggestStats {
    /// Total active suggestions
    pub active_count: usize,

    /// Suggestions by category
    pub by_category: std::collections::HashMap<SuggestCategory, usize>,

    /// Suggestions by safety level
    pub by_safety: std::collections::HashMap<SafetyLevel, usize>,

    /// Number of registered patterns
    pub pattern_count: usize,
}

impl SuggestService {
    /// Get statistics about current state
    pub fn stats(&self) -> SuggestStats {
        let mut stats = SuggestStats {
            pattern_count: self.registry.len(),
            ..SuggestStats::default()
        };

        let store = self.store.read();

        for (_, stored) in store.iter() {
            stats.active_count += 1;

            // Count by category
            if let Some(suggest) = self.registry.get(stored.suggest_idx) {
                *stats.by_category.entry(suggest.category()).or_default() += 1;
            }

            // Count by safety
            *stats.by_safety.entry(stored.safety).or_default() += 1;
        }

        stats
    }

    /// Take the store contents, leaving an empty store.
    ///
    /// Used for preserving suggestions across API reload.
    pub fn take_store(&self) -> SuggestStore {
        std::mem::take(&mut *self.store.write())
    }

    /// Restore store contents from a previous backup.
    ///
    /// Used for preserving suggestions across API reload.
    pub fn restore_store(&self, store: SuggestStore) {
        *self.store.write() = store;
    }
}

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

    #[test]
    fn test_suggest_query_builder() {
        let query = SuggestQuery::all()
            .with_category(SuggestCategory::Derive)
            .with_max_safety(SafetyLevel::Confirm)
            .with_min_confidence(0.8)
            .with_limit(10);

        assert_eq!(query.category, Some(SuggestCategory::Derive));
        assert_eq!(query.max_safety, Some(SafetyLevel::Confirm));
        assert_eq!(query.min_confidence, Some(0.8));
        assert_eq!(query.limit, Some(10));
    }

    #[test]
    fn test_service_new() {
        let registry = SuggestRegistry::new();
        let service = SuggestService::new(registry);

        assert!(service.is_empty());
        assert_eq!(service.count(), 0);
    }

    #[test]
    fn test_service_with_strategy() {
        let registry = SuggestRegistry::new();
        let strategy = SuggestStrategy::high_perf();
        let service = SuggestService::with_strategy(registry, strategy);

        assert!(service.is_empty());
    }
}