oxirs-fuseki 0.3.2

//! Optimizer, cache, dedup, compressor, and join-strategy implementations.
//!
//! Split out of the original `bind_values_enhanced` module (Round 32 refactor).
//! Contains the supporting `impl`s for [`ExpressionEvaluator`],
//! [`AdvancedBindOptimizer`], [`AdvancedValuesOptimizer`], [`ValueSetManager`],
//! [`ExpressionCache`], [`TypeCoercionRules`], [`ExpressionSimplifier`],
//! [`ConstantFolder`], [`CommonSubexpressionEliminator`], [`ValueDeduplicator`],
//! [`ValueCompressor`], [`ValueIndexBuilder`], [`JoinStrategySelector`], and
//! [`MemoryManager`].

use crate::error::{FusekiError, FusekiResult};
use std::collections::{HashMap, HashSet};
use std::sync::Arc;
use tokio::sync::RwLock;
use tracing::warn;

use crate::bind_values_enhanced_types::{
    AdvancedBindOptimizer, AdvancedValuesOptimizer, ArgPattern, BindOptimizationRule, CoercionRule,
    CommonSubexpressionEliminator, CompressionAlgorithm, CompressionDictionary, CompressionLevel,
    ConstantFolder, DedupStrategy, EvictionPolicy, ExpressionCache, ExpressionDAG,
    ExpressionEvaluator, ExpressionFunction, ExpressionPattern, ExpressionSimplifier,
    ExpressionTransformation, HashAlgorithm, IndexType, JoinCondition, JoinCostModel, JoinStrategy,
    JoinStrategySelector, JoinStrategyType, LruTracker, MemoryManager, OptimizationCondition,
    TypeCoercionRules, ValueCompressor, ValueDeduplicator, ValueIndexBuilder, ValueSet,
    ValueSetManager, ValueSetMetadata, ValueType, ValuesClause, ValuesOptimizationStrategy,
};

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

impl ExpressionEvaluator {
    pub fn new() -> Self {
        let mut functions = HashMap::new();

        // Register built-in functions
        functions.insert("CONCAT".to_string(), ExpressionFunction::Concat);
        functions.insert("SUBSTR".to_string(), ExpressionFunction::Substr);
        functions.insert("STRLEN".to_string(), ExpressionFunction::StrLen);
        functions.insert("UCASE".to_string(), ExpressionFunction::UCase);
        functions.insert("LCASE".to_string(), ExpressionFunction::LCase);
        functions.insert("NOW".to_string(), ExpressionFunction::Now);
        functions.insert("MD5".to_string(), ExpressionFunction::MD5);
        functions.insert("SHA256".to_string(), ExpressionFunction::SHA256);

        Self {
            functions,
            custom_functions: HashMap::new(),
            type_coercion: TypeCoercionRules::default(),
        }
    }

    pub fn evaluate(
        &self,
        _expression: &str,
        _bindings: &[HashMap<String, serde_json::Value>],
    ) -> FusekiResult<serde_json::Value> {
        // Simplified evaluation
        // In a real implementation, this would parse and evaluate the expression

        // For now, return a mock result
        Ok(serde_json::json!("evaluated_result"))
    }
}

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

impl AdvancedBindOptimizer {
    pub fn new() -> Self {
        Self {
            optimization_rules: Self::create_default_rules(),
            simplifier: ExpressionSimplifier::new(),
            constant_folder: ConstantFolder::new(),
            cse: CommonSubexpressionEliminator::new(),
        }
    }

    fn create_default_rules() -> Vec<BindOptimizationRule> {
        vec![
            // Constant folding rules
            BindOptimizationRule {
                name: "constant_concat".to_string(),
                pattern: ExpressionPattern::FunctionCall {
                    function: "CONCAT".to_string(),
                    args: vec![ArgPattern::Constant, ArgPattern::Constant],
                },
                transformation: ExpressionTransformation::Simplify("folded".to_string()),
                conditions: vec![OptimizationCondition::IsConstant],
                priority: 10,
            },
            // String optimization rules
            BindOptimizationRule {
                name: "strlen_constant".to_string(),
                pattern: ExpressionPattern::FunctionCall {
                    function: "STRLEN".to_string(),
                    args: vec![ArgPattern::Constant],
                },
                transformation: ExpressionTransformation::Simplify("length".to_string()),
                conditions: vec![],
                priority: 9,
            },
        ]
    }

    pub fn optimize_expression(&self, expr: &str) -> FusekiResult<String> {
        let mut optimized = expr.to_string();

        // Apply optimization rules
        for rule in &self.optimization_rules {
            if self.matches_pattern(&optimized, &rule.pattern) {
                optimized = self.apply_transformation(&optimized, &rule.transformation)?;
            }
        }

        // Simplify
        optimized = self.simplifier.simplify(&optimized)?;

        // Fold constants
        optimized = self.constant_folder.fold(&optimized)?;

        // Eliminate common subexpressions
        optimized = self.cse.eliminate(&optimized)?;

        Ok(optimized)
    }

    fn matches_pattern(&self, _expr: &str, _pattern: &ExpressionPattern) -> bool {
        // Pattern matching implementation
        true
    }

    fn apply_transformation(
        &self,
        expr: &str,
        _transformation: &ExpressionTransformation,
    ) -> FusekiResult<String> {
        // Transformation implementation
        Ok(expr.to_string())
    }
}

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

impl AdvancedValuesOptimizer {
    pub fn new() -> Self {
        Self {
            strategies: Self::create_default_strategies(),
            deduplicator: ValueDeduplicator::new(),
            compressor: ValueCompressor::new(),
            index_builder: ValueIndexBuilder::new(),
        }
    }

    fn create_default_strategies() -> Vec<ValuesOptimizationStrategy> {
        vec![
            ValuesOptimizationStrategy::HashJoin { threshold: 1000 },
            ValuesOptimizationStrategy::IndexBuild {
                index_type: IndexType::Hash,
            },
            ValuesOptimizationStrategy::Compress {
                algorithm: CompressionAlgorithm::Dictionary,
            },
        ]
    }

    pub fn optimize(&self, clause: &ValuesClause) -> FusekiResult<ValuesClause> {
        let mut optimized = clause.clone();

        // Deduplicate values
        optimized = self.deduplicator.deduplicate(optimized)?;

        // Apply optimization strategies
        for strategy in &self.strategies {
            if self.should_apply_strategy(&optimized, strategy) {
                optimized = self.apply_strategy(optimized, strategy)?;
            }
        }

        Ok(optimized)
    }

    fn should_apply_strategy(
        &self,
        clause: &ValuesClause,
        strategy: &ValuesOptimizationStrategy,
    ) -> bool {
        match strategy {
            ValuesOptimizationStrategy::HashJoin { threshold } => clause.rows.len() > *threshold,
            _ => true,
        }
    }

    fn apply_strategy(
        &self,
        clause: ValuesClause,
        _strategy: &ValuesOptimizationStrategy,
    ) -> FusekiResult<ValuesClause> {
        // Strategy application
        Ok(clause)
    }
}

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

impl ValueSetManager {
    pub fn new() -> Self {
        Self {
            value_sets: Arc::new(RwLock::new(HashMap::new())),
            metadata: Arc::new(RwLock::new(HashMap::new())),
            memory_manager: MemoryManager::new(),
        }
    }

    pub async fn store_value_set(&self, value_set: ValueSet) -> FusekiResult<String> {
        let id = value_set.id.clone();
        let size_bytes = serde_json::to_vec(&value_set.values)?.len();

        // Check memory limits
        self.memory_manager.check_and_evict(size_bytes).await?;

        // Store value set
        self.value_sets
            .write()
            .await
            .insert(id.clone(), value_set.clone());

        // Store metadata
        let metadata = ValueSetMetadata {
            created_at: chrono::Utc::now(),
            last_accessed: chrono::Utc::now(),
            access_count: 1,
            size_bytes,
            cardinality: value_set.values.len(),
            selectivity: 1.0,
        };

        self.metadata.write().await.insert(id.clone(), metadata);

        Ok(id)
    }

    pub async fn get_value_set(&self, id: &str) -> FusekiResult<ValueSet> {
        let sets = self.value_sets.read().await;

        sets.get(id)
            .cloned()
            .ok_or_else(|| FusekiError::internal(format!("Value set not found: {id}")))
    }
}

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

impl ExpressionCache {
    pub fn new() -> Self {
        Self {
            cache: HashMap::new(),
            max_size: 1000,
            lru_tracker: LruTracker {
                access_order: Vec::new(),
                access_times: HashMap::new(),
            },
        }
    }

    pub fn evict_lru(&mut self) {
        if let Some(oldest_key) = self.lru_tracker.access_order.first().cloned() {
            self.cache.remove(&oldest_key);
            self.lru_tracker.access_order.remove(0);
            self.lru_tracker.access_times.remove(&oldest_key);
        }
    }
}

impl Default for TypeCoercionRules {
    fn default() -> Self {
        let mut rules = HashMap::new();
        let mut implicit_coercions = HashSet::new();

        // Integer to Decimal
        implicit_coercions.insert((ValueType::Integer, ValueType::Decimal));

        // String to URI
        rules.insert(
            (ValueType::String, ValueType::Uri),
            CoercionRule {
                from_type: ValueType::String,
                to_type: ValueType::Uri,
                coercion_fn: "str_to_uri".to_string(),
                is_safe: false,
            },
        );

        Self {
            rules,
            implicit_coercions,
        }
    }
}

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

impl ExpressionSimplifier {
    pub fn new() -> Self {
        Self {
            simplification_rules: Vec::new(),
            algebra_rules: Vec::new(),
        }
    }

    pub fn simplify(&self, expr: &str) -> FusekiResult<String> {
        // Simplification logic
        Ok(expr.to_string())
    }
}

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

impl ConstantFolder {
    pub fn new() -> Self {
        Self {
            folding_rules: HashMap::new(),
            partial_evaluation: true,
        }
    }

    pub fn fold(&self, expr: &str) -> FusekiResult<String> {
        // Constant folding logic for CONCAT function
        if expr.starts_with("CONCAT(") && expr.ends_with(")") {
            let inner = &expr[7..expr.len() - 1]; // Remove CONCAT( and )

            // Check if all arguments are string literals
            let args: Vec<&str> = inner.split(", ").collect();
            let mut all_literals = true;
            let mut result_parts = Vec::new();

            for arg in &args {
                let trimmed = arg.trim();
                if trimmed.starts_with('"') && trimmed.ends_with('"') && trimmed.len() >= 2 {
                    // Remove quotes and store the string content
                    result_parts.push(&trimmed[1..trimmed.len() - 1]);
                } else {
                    all_literals = false;
                    break;
                }
            }

            if all_literals && !result_parts.is_empty() {
                // Fold the constants into a single string literal
                let folded_result = result_parts.join("");
                return Ok(format!("\"{folded_result}\""));
            }
        }

        // For other expressions or non-foldable CONCAT, return unchanged
        Ok(expr.to_string())
    }
}

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

impl CommonSubexpressionEliminator {
    pub fn new() -> Self {
        Self {
            expression_dag: ExpressionDAG {
                nodes: HashMap::new(),
                edges: HashMap::new(),
                roots: HashSet::new(),
            },
            sharing_threshold: 2,
        }
    }

    pub fn eliminate(&self, expr: &str) -> FusekiResult<String> {
        // CSE logic
        Ok(expr.to_string())
    }
}

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

impl ValueDeduplicator {
    pub fn new() -> Self {
        Self {
            dedup_strategy: DedupStrategy::Exact,
            hash_algorithm: HashAlgorithm::XXHash,
        }
    }

    pub fn deduplicate(&self, clause: ValuesClause) -> FusekiResult<ValuesClause> {
        // Deduplication logic
        Ok(clause)
    }
}

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

impl ValueCompressor {
    pub fn new() -> Self {
        Self {
            compression_level: CompressionLevel::Balanced,
            dictionary: Arc::new(RwLock::new(CompressionDictionary {
                string_dict: HashMap::new(),
                uri_dict: HashMap::new(),
                reverse_dict: HashMap::new(),
                next_id: 1,
            })),
        }
    }
}

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

impl ValueIndexBuilder {
    pub fn new() -> Self {
        Self {
            index_types: vec![IndexType::Hash],
            build_threshold: 1000,
        }
    }
}

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

impl JoinStrategySelector {
    pub fn new() -> Self {
        Self {
            strategies: Self::create_default_strategies(),
            cost_model: JoinCostModel {
                cpu_cost_per_comparison: 1.0,
                memory_cost_per_entry: 0.1,
                io_cost_per_block: 10.0,
            },
        }
    }

    fn create_default_strategies() -> Vec<JoinStrategy> {
        vec![
            JoinStrategy {
                name: "nested_loop".to_string(),
                strategy_type: JoinStrategyType::NestedLoop,
                applicable_conditions: vec![JoinCondition::SizeThreshold { min: 0, max: 100 }],
                estimated_cost: 100.0,
            },
            JoinStrategy {
                name: "hash_join".to_string(),
                strategy_type: JoinStrategyType::HashJoin,
                applicable_conditions: vec![JoinCondition::SizeThreshold {
                    min: 100,
                    max: 10000,
                }],
                estimated_cost: 50.0,
            },
        ]
    }

    pub fn select_strategy(
        &self,
        clause: &ValuesClause,
        bindings: &[HashMap<String, serde_json::Value>],
    ) -> FusekiResult<JoinStrategy> {
        // Select best strategy based on sizes
        let values_size = clause.rows.len();
        let bindings_size = bindings.len();

        for strategy in &self.strategies {
            if self.strategy_applicable(strategy, values_size, bindings_size) {
                return Ok(strategy.clone());
            }
        }

        // Default to nested loop
        Ok(self.strategies[0].clone())
    }

    fn strategy_applicable(
        &self,
        strategy: &JoinStrategy,
        values_size: usize,
        _bindings_size: usize,
    ) -> bool {
        for condition in &strategy.applicable_conditions {
            if let JoinCondition::SizeThreshold { min, max } = condition {
                if values_size < *min || values_size > *max {
                    return false;
                }
            }
        }
        true
    }
}

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

impl MemoryManager {
    pub fn new() -> Self {
        Self {
            max_memory_mb: 100,
            current_usage_bytes: Arc::new(RwLock::new(0)),
            eviction_policy: EvictionPolicy::LRU,
        }
    }

    pub async fn check_and_evict(&self, required_bytes: usize) -> FusekiResult<()> {
        let current = *self.current_usage_bytes.read().await;
        let max_bytes = self.max_memory_mb * 1024 * 1024;

        if current + required_bytes > max_bytes {
            // Implement eviction logic
            warn!("Memory limit reached, eviction needed");
        }

        *self.current_usage_bytes.write().await += required_bytes;
        Ok(())
    }
}