akar-main 0.1.12

use akar_common::error::ProcessorError;
use akar_common::types::Value;
use akar_common::vector::DataChunk;
use akar_parser::ast::Expression;
use akar_processor::processor::{StandaloneCallFn, StandaloneCallHandler, StandaloneCallRegistry};
use std::sync::Arc;

use crate::connection::utils::{ast_constant_to_value, rows_to_datachunk, value_to_csv_string};
use crate::database::Database;

/// Callback for executing an arbitrary Cypher query string.
pub type QueryFn = Arc<dyn Fn(&str) -> Result<crate::query_result::QueryResult, String> + Send + Sync>;

pub struct DbStandaloneCallHandler {
    database: Arc<Database>,
    registry: StandaloneCallRegistry,
}

impl DbStandaloneCallHandler {
    pub fn new(database: Arc<Database>) -> Self {
        Self::with_query_executor(database, None)
    }

    pub fn with_query_executor(database: Arc<Database>, query_fn: Option<QueryFn>) -> Self {
        let mut registry = StandaloneCallRegistry::new();
        registry.register(Arc::new(ShowTablesHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(TableInfoHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(ShowFunctionsHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(ShowIndexesHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(ShowSequencesHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(ShowMacrosHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(ShowConnectionHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(DbVersionHandler));
        registry.register(Arc::new(CatalogVersionHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(CurrentSettingHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(StatsInfoHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(StorageInfoHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(ShowAttachedDatabasesHandler));
        registry.register(Arc::new(BmInfoHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(FileInfoHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(FreeSpaceInfoHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(DiskSizeInfoHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(StorageVersionHandler));
        registry.register(Arc::new(ShowLoadedExtensionsHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(ShowOfficialExtensionsHandler));
        registry.register(Arc::new(ClearWarningsHandler));
        registry.register(Arc::new(ShowWarningsHandler));
        registry.register(Arc::new(ShowProjectedGraphsHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(ProjectedGraphInfoHandler {
            database: database.clone(),
        }));
        registry.register(Arc::new(DropProjectedGraphHandler {
            database: database.clone(),
        }));
        if let Some(qf) = query_fn {
            registry.register(Arc::new(ExportCsvHandler { query_fn: qf.clone() }));
            registry.register(Arc::new(ExportParquetHandler { query_fn: qf }));
        }
        Self { database, registry }
    }
}

fn eval_ast_expr_to_value(expr: &Expression) -> Value {
    match expr {
        Expression::Constant(c) => ast_constant_to_value(c),
        _ => Value::Null,
    }
}

fn extract_arg_string(args: &[Expression], idx: usize) -> Result<String, String> {
    if idx >= args.len() {
        return Err(format!("Missing argument at index {} ({} provided)", idx, args.len()));
    }
    match &args[idx] {
        Expression::Constant(c) => match c {
            akar_parser::ast::Constant::String(s) => Ok(s.clone()),
            _ => Err(format!("Argument {} expected a string literal, got {:?}", idx, c)),
        },
        other => Err(format!(
            "Argument {} expected a constant expression, got: {:?}",
            idx, other
        )),
    }
}

impl StandaloneCallHandler for DbStandaloneCallHandler {
    fn execute_call(&self, name: &str, args: &[Expression]) -> Result<Vec<DataChunk>, ProcessorError> {
        if let Some(handler) = self.registry.get(name) {
            let result_rows = handler.execute(args)?;
            return Self::format_result(result_rows);
        }

        let args_vals: Vec<Value> = args.iter().map(eval_ast_expr_to_value).collect();
        let graph = akar_processor::processor::CatalogGraphSource::new(Some(&self.database.table_catalog()));
        let registry = self
            .database
            .function_registry
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        match registry.execute_table_function(name, &args_vals, Some(&graph)) {
            Ok(rows) => Self::format_result(rows),
            Err(original_err) => {
                let known_calls = [
                    "show_tables",
                    "table_info",
                    "show_functions",
                    "show_indexes",
                    "show_sequences",
                    "show_macros",
                    "show_connection",
                    "db_version",
                    "catalog_version",
                    "current_setting",
                    "stats_info",
                    "storage_info",
                    "show_attached_databases",
                    "bm_info",
                    "file_info",
                    "free_space_info",
                    "disk_size_info",
                    "storage_version",
                    "show_loaded_extensions",
                    "show_official_extensions",
                    "clear_warnings",
                    "show_warnings",
                    "show_projected_graphs",
                    "projected_graph_info",
                    "drop_projected_graph",
                    "export_csv",
                    "export_parquet",
                ];
                let lower = name.to_lowercase();
                let suggestion = known_calls
                    .iter()
                    .find(|k| k.contains(&lower) || lower.contains(**k))
                    .map(|k| format!(" Did you mean CALL {}()?", k))
                    .unwrap_or_default();
                Err(ProcessorError::Execution(format!(
                    "CALL '{}' failed: {}.{}",
                    name, original_err, suggestion
                )))
            }
        }
    }
}

impl DbStandaloneCallHandler {
    fn format_result(result_rows: Vec<Vec<Value>>) -> Result<Vec<DataChunk>, ProcessorError> {
        if result_rows.is_empty() {
            Ok(vec![])
        } else {
            let num_cols = result_rows[0].len();
            let col_names_strings = (0..num_cols).map(|i| format!("col_{}", i)).collect::<Vec<_>>();
            let col_names = col_names_strings.iter().map(|s| s.as_str()).collect::<Vec<_>>();
            Ok(vec![rows_to_datachunk(result_rows, &col_names)?])
        }
    }
}

struct ShowTablesHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ShowTablesHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let catalog = self
            .database
            .catalog
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let entries: Vec<Vec<Value>> = catalog
            .all_entries()
            .map(|e| {
                let kind = match e {
                    akar_catalog::CatalogEntry::NodeTable(_) => "NODE",
                    akar_catalog::CatalogEntry::RelTable(_) => "REL",
                    akar_catalog::CatalogEntry::Sequence(_) => "SEQUENCE",
                    akar_catalog::CatalogEntry::Macro(_) => "MACRO",
                    akar_catalog::CatalogEntry::VectorIndex(_) => "VECTOR_INDEX",
                    akar_catalog::CatalogEntry::Foreign(_) => "FOREIGN",
                };
                vec![Value::String(e.name().to_string()), Value::String(kind.to_string())]
            })
            .collect();
        Ok(entries)
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_tables", "show tables", "list_tables", "list tables", "tables"]
    }
}

struct TableInfoHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for TableInfoHandler {
    fn execute(&self, args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let table_name = extract_arg_string(args, 0)?;
        let cat = self
            .database
            .catalog
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let entry = cat
            .get_entry_by_name(&table_name)
            .ok_or_else(|| format!("Table '{table_name}' not found"))?;
        let columns = entry.columns();
        let rows: Vec<Vec<Value>> = columns
            .iter()
            .map(|col| {
                vec![
                    Value::String(table_name.clone()),
                    Value::String(col.name.clone()),
                    Value::String(format!("{:?}", col.logical_type)),
                    Value::String(if col.is_primary_key { "NO" } else { "YES" }.into()),
                ]
            })
            .collect();
        Ok(rows)
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["table_info"]
    }
}

struct ShowFunctionsHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ShowFunctionsHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let registry = self
            .database
            .function_registry
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let funcs = registry.list_all();
        Ok(funcs
            .into_iter()
            .map(|(name, kind)| vec![Value::String(name), Value::String(kind)])
            .collect())
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_functions"]
    }
}

struct ShowIndexesHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ShowIndexesHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let cat = self
            .database
            .catalog
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let indexes = cat.indexes();
        Ok(indexes
            .into_iter()
            .map(|(name, table, kind, col)| {
                vec![
                    Value::String(name),
                    Value::String(table),
                    Value::String(kind),
                    Value::String(col),
                ]
            })
            .collect())
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_indexes"]
    }
}

struct ShowSequencesHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ShowSequencesHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let cat = self
            .database
            .catalog
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let seqs = cat.sequences();
        Ok(seqs
            .into_iter()
            .map(|s| vec![Value::String(s.name.clone()), Value::Int64(s.curr_val())])
            .collect())
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_sequences"]
    }
}

struct ShowMacrosHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ShowMacrosHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let cat = self
            .database
            .catalog
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let macros = cat.macros();
        Ok(macros
            .into_iter()
            .map(|m| {
                vec![
                    Value::String(m.name.clone()),
                    Value::String(
                        m.default_args
                            .iter()
                            .map(|(k, v)| format!("{k}={v}"))
                            .collect::<Vec<_>>()
                            .join(", "),
                    ),
                ]
            })
            .collect())
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_macros"]
    }
}

struct ShowConnectionHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ShowConnectionHandler {
    fn execute(&self, args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let table_name = extract_arg_string(args, 0)?;
        let cat = self
            .database
            .catalog
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let info = cat
            .connection_info(&table_name)
            .ok_or_else(|| format!("Table '{table_name}' not found"))?;
        Ok(vec![info])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_connection"]
    }
}

struct DbVersionHandler;

impl StandaloneCallFn for DbVersionHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let version = env!("CARGO_PKG_VERSION");
        Ok(vec![vec![Value::String(version.to_string())]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["db_version"]
    }
}

struct CatalogVersionHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for CatalogVersionHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let cat = self
            .database
            .catalog
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let ver = cat.version();
        Ok(vec![vec![Value::Int64(ver as i64)]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["catalog_version"]
    }
}

struct CurrentSettingHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for CurrentSettingHandler {
    fn execute(&self, args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let key = extract_arg_string(args, 0).unwrap_or_else(|_| String::new());
        let (k, v) = match key.to_lowercase().as_str() {
            "spill_threshold" => ("spill_threshold", self.database.effective_spill_threshold().to_string()),
            "checkpoint_threshold" => (
                "checkpoint_threshold",
                self.database.config.checkpoint_threshold.to_string(),
            ),
            "buffer_pool_size" => ("buffer_pool_size", self.database.config.buffer_pool_size.to_string()),
            "max_num_threads" => ("max_num_threads", self.database.config.max_num_threads.to_string()),
            "concurrent_writes" => (
                "concurrent_writes",
                // Read the live runtime toggle (SET concurrent_writes) rather
                // than the static config so current_setting stays in sync (P52.50).
                self.database.transaction_manager.allow_concurrent_writes().to_string(),
            ),
            "read_only" => ("read_only", self.database.config.read_only.to_string()),
            _ => (key.as_str(), "UNKNOWN".to_string()),
        };
        Ok(vec![vec![Value::String(k.to_string()), Value::String(v)]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["current_setting"]
    }
}

struct StatsInfoHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for StatsInfoHandler {
    fn execute(&self, args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let table_name = extract_arg_string(args, 0)?;
        let (row_count, storage_size) = {
            let cat = self
                .database
                .catalog
                .lock()
                .map_err(|e| format!("Lock poisoned: {e}"))?;
            let table_id = cat
                .get_table_id(&table_name)
                .ok_or_else(|| format!("Table '{table_name}' not found"))?;
            let stats = self
                .database
                .stats_store
                .lock()
                .map_err(|e| format!("Lock poisoned: {e}"))?;
            stats.table_stats_by_id(table_id)
        };
        Ok(vec![vec![
            Value::String(table_name),
            Value::Int64(row_count as i64),
            Value::String(crate::connection::utils::format_storage_size(storage_size)),
        ]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["stats_info"]
    }
}

struct StorageInfoHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for StorageInfoHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let sm = &self.database.storage_manager;
        let info = sm.storage_info();
        Ok(vec![vec![
            Value::String(info.db_path),
            Value::Int64(info.page_size as i64),
            Value::Int64(info.total_pages as i64),
            Value::Int64(info.free_pages as i64),
        ]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["storage_info"]
    }
}

struct ShowAttachedDatabasesHandler;

impl StandaloneCallFn for ShowAttachedDatabasesHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        Ok(vec![vec![
            Value::String("main".to_string()),
            Value::String("local".to_string()),
        ]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_attached_databases"]
    }
}

struct BmInfoHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for BmInfoHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let bm = &self.database.storage_manager;
        let info = bm.buffer_info();
        Ok(vec![vec![
            Value::String("buffer_pool".to_string()),
            Value::Int64(info.total_memory as i64),
            Value::Int64(info.used_memory as i64),
            Value::Int64(info.num_pinned as i64),
        ]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["bm_info"]
    }
}

struct FileInfoHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for FileInfoHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let sm = &self.database.storage_manager;
        let info = sm.file_info();
        Ok(vec![vec![
            Value::Int64(info.total_file_size as i64),
            Value::Int64(info.num_data_pages as i64),
            Value::Int64(info.wal_size as i64),
        ]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["file_info"]
    }
}

struct FreeSpaceInfoHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for FreeSpaceInfoHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let sm = &self.database.storage_manager;
        let info = sm.fsm_info();
        Ok(vec![vec![
            Value::Int64(info.total_free_pages as i64),
            Value::Int64(info.num_entries as i64),
        ]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["free_space_info"]
    }
}

struct DiskSizeInfoHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for DiskSizeInfoHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let sm = &self.database.storage_manager;
        let info = sm.file_info();
        Ok(vec![vec![
            Value::Int64(info.total_file_size as i64),
            Value::Int64(info.num_data_pages as i64),
            Value::Int64(info.wal_size as i64),
        ]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["disk_size_info"]
    }
}

struct StorageVersionHandler;

impl StandaloneCallFn for StorageVersionHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        Ok(vec![vec![Value::String(
            akar_storage::version_info::STORAGE_VERSION.to_string(),
        )]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["storage_version"]
    }
}

struct ShowLoadedExtensionsHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ShowLoadedExtensionsHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let reg = self
            .database
            .extension_registry
            .lock()
            .map_err(|e| format!("Lock poisoned: {e}"))?;
        let names: Vec<Vec<Value>> = reg.names().iter().map(|n| vec![Value::String(n.clone())]).collect();
        Ok(names)
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_loaded_extensions"]
    }
}

struct ShowOfficialExtensionsHandler;

impl StandaloneCallFn for ShowOfficialExtensionsHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        Ok(vec![
            vec![Value::String("json".into()), Value::String("JSON functions".into())],
            vec![Value::String("fts".into()), Value::String("Full-Text Search".into())],
            vec![
                Value::String("vector".into()),
                Value::String("Vector similarity search".into()),
            ],
            vec![
                Value::String("httpfs".into()),
                Value::String("HTTP/S3 file access".into()),
            ],
            vec![
                Value::String("duckdb".into()),
                Value::String("DuckDB integration".into()),
            ],
            vec![
                Value::String("sqlite".into()),
                Value::String("SQLite integration".into()),
            ],
            vec![
                Value::String("postgres".into()),
                Value::String("PostgreSQL integration".into()),
            ],
            vec![
                Value::String("delta".into()),
                Value::String("Delta Lake integration".into()),
            ],
            vec![
                Value::String("iceberg".into()),
                Value::String("Apache Iceberg integration".into()),
            ],
            vec![
                Value::String("azure".into()),
                Value::String("Azure Blob Storage".into()),
            ],
            vec![
                Value::String("unity_catalog".into()),
                Value::String("Unity Catalog integration".into()),
            ],
            vec![Value::String("neo4j".into()), Value::String("Neo4j integration".into())],
            vec![Value::String("llm".into()), Value::String("LLM integration".into())],
            vec![Value::String("algo".into()), Value::String("Graph algorithms".into())],
        ])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_official_extensions"]
    }
}

struct ClearWarningsHandler;

impl StandaloneCallFn for ClearWarningsHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        Ok(vec![vec![Value::String("Warnings cleared".into())]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["clear_warnings"]
    }
}

struct ShowWarningsHandler;

impl StandaloneCallFn for ShowWarningsHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        Ok(vec![])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_warnings"]
    }
}

// ==================== Export CSV / Parquet handlers ====================
// Wraps COPY TO as CALL functions: export_csv / export_parquet
// Usage:  CALL export_csv('file.csv', 'MATCH (n) RETURN n');
//         CALL export_parquet('file.parquet', 'MATCH (n) RETURN n');

struct ExportCsvHandler {
    query_fn: QueryFn,
}

impl StandaloneCallFn for ExportCsvHandler {
    fn execute(&self, args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let file_path = extract_arg_string(args, 0)?;
        let query_string = extract_arg_string(args, 1)?;
        let result = (self.query_fn)(&query_string)?;

        let path = std::path::Path::new(&file_path);
        let mut w = csv::WriterBuilder::new()
            .has_headers(true)
            .from_path(path)
            .map_err(|e| format!("Cannot create CSV file '{}': {}", file_path, e))?;

        if let Some(first_chunk) = result.chunks.first() {
            let header: Vec<String> = if first_chunk.field_names.is_empty() {
                (0..first_chunk.num_fields()).map(|i| format!("column_{}", i)).collect()
            } else {
                first_chunk.field_names.clone()
            };
            if !header.is_empty() {
                w.write_record(&header).map_err(|e| format!("CSV write error: {e}"))?;
            }
        }
        for chunk in &result.chunks {
            for row in 0..chunk.size {
                let row_values: Vec<String> = (0..chunk.fields.len())
                    .map(|col_idx| {
                        chunk
                            .get_value(col_idx, row)
                            .map(|v| value_to_csv_string(&v))
                            .unwrap_or_default()
                    })
                    .collect();
                w.write_record(&row_values)
                    .map_err(|e| format!("CSV write error: {e}"))?;
            }
        }
        w.flush().map_err(|e| format!("CSV flush error: {e}"))?;
        Ok(vec![vec![Value::String(format!(
            "Exported {} rows to '{}'",
            result.num_rows, file_path
        ))]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["export_csv"]
    }
}

struct ExportParquetHandler {
    query_fn: QueryFn,
}

impl StandaloneCallFn for ExportParquetHandler {
    fn execute(&self, args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let file_path = extract_arg_string(args, 0)?;
        let query_string = extract_arg_string(args, 1)?;
        let result = (self.query_fn)(&query_string)?;

        #[cfg(feature = "parquet-export")]
        {
            crate::connection::ddl::write_parquet_to_file(&file_path, &result)
                .map_err(|e| format!("Parquet export error: {e}"))?;
            Ok(vec![vec![Value::String(format!(
                "Exported {} rows to '{}'",
                result.num_rows, file_path
            ))]])
        }
        #[cfg(not(feature = "parquet-export"))]
        {
            let _ = file_path;
            let _ = query_string;
            let _ = result;
            Err("Parquet export requires 'parquet-export' feature. \
                 Build with: cargo build --features parquet-export"
                .into())
        }
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["export_parquet"]
    }
}

// ==================== Projected Graph handlers ====================

struct ShowProjectedGraphsHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ShowProjectedGraphsHandler {
    fn execute(&self, _args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let cat = self.database.catalog.lock().map_err(|e| format!("Lock error: {e}"))?;
        let graphs = cat.projected_graph_entries();
        let rows: Vec<Vec<Value>> = graphs
            .into_iter()
            .map(|g| vec![Value::String(g.name.clone()), Value::String(g.entry_type.clone())])
            .collect();
        Ok(rows)
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["show_projected_graphs"]
    }
}

struct ProjectedGraphInfoHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for ProjectedGraphInfoHandler {
    fn execute(&self, args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let graph_name = extract_arg_string(args, 0)?;
        let cat = self.database.catalog.lock().map_err(|e| format!("Lock error: {e}"))?;
        let info = cat
            .get_projected_graph(&graph_name)
            .ok_or_else(|| format!("Projected graph '{}' not found", graph_name))?;
        match info.entry_type.as_str() {
            "NATIVE" => {
                // NATIVE projected graph: return name, type marker
                Ok(vec![vec![
                    Value::String(info.name.clone()),
                    Value::String("NATIVE".into()),
                    Value::String("Node/rel tables defined at creation".into()),
                ]])
            }
            "CYPHER" => {
                let query = info.cypher_query.clone().unwrap_or_default();
                Ok(vec![vec![
                    Value::String(info.name.clone()),
                    Value::String("CYPHER".into()),
                    Value::String(query),
                ]])
            }
            other => Err(ProcessorError::Execution(format!(
                "Unknown projected graph type: {other}"
            ))),
        }
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["projected_graph_info"]
    }
}

struct DropProjectedGraphHandler {
    database: Arc<Database>,
}

impl StandaloneCallFn for DropProjectedGraphHandler {
    fn execute(&self, args: &[Expression]) -> Result<Vec<Vec<Value>>, ProcessorError> {
        let graph_name = extract_arg_string(args, 0)?;
        let mut cat = self.database.catalog.lock().map_err(|e| format!("Lock error: {e}"))?;
        cat.drop_projected_graph(&graph_name)
            .map_err(|e| ProcessorError::Execution(format!("{e}")))?;
        Ok(vec![vec![Value::String(format!(
            "Projected graph '{}' dropped",
            graph_name
        ))]])
    }

    fn aliases(&self) -> Vec<&'static str> {
        vec!["drop_projected_graph"]
    }
}