// src-tauri/src/extension/database/executor.rs

use crate::crdt::hlc::HlcService;
use crate::crdt::transformer::CrdtTransformer;
use crate::crdt::trigger;
use crate::database::core::{convert_value_ref_to_json, parse_sql_statements};
use crate::database::error::DatabaseError;
use rusqlite::{params_from_iter, types::Value as SqliteValue, ToSql, Transaction};
use serde_json::Value as JsonValue;
use sqlparser::ast::Statement;
use std::collections::HashSet;

/// SQL-Executor OHNE Berechtigungsprüfung - für interne Nutzung
pub struct SqlExecutor;

impl SqlExecutor {
    /// Führt ein SQL Statement OHNE RETURNING aus (mit CRDT)
    /// Returns: modified_schema_tables
    pub fn execute_internal_typed(
        tx: &Transaction,
        hlc_service: &HlcService,
        sql: &str,
        params: &[&dyn ToSql],
    ) -> Result<HashSet<String>, DatabaseError> {
        let mut ast_vec = parse_sql_statements(sql)?;

        if ast_vec.len() != 1 {
            return Err(DatabaseError::ExecutionError {
                sql: sql.to_string(),
                reason: "execute_internal_typed should only receive a single SQL statement"
                    .to_string(),
                table: None,
            });
        }

        let mut statement = ast_vec.pop().unwrap();

        let transformer = CrdtTransformer::new();
        let hlc_timestamp =
            hlc_service
                .new_timestamp_and_persist(tx)
                .map_err(|e| DatabaseError::HlcError {
                    reason: e.to_string(),
                })?;

        let mut modified_schema_tables = HashSet::new();
        if let Some(table_name) = transformer.transform_execute_statement_with_table_info(
            &mut statement,
            &hlc_timestamp,
        )? {
            modified_schema_tables.insert(table_name);
        }

        let sql_str = statement.to_string();
        eprintln!("DEBUG: Transformed execute SQL: {sql_str}");

        // Führe Statement aus
        tx.execute(&sql_str, params)
            .map_err(|e| DatabaseError::ExecutionError {
                sql: sql_str.clone(),
                table: None,
                reason: format!("Execute failed: {e}"),
            })?;

        // Trigger-Logik für CREATE TABLE
        if let Statement::CreateTable(create_table_details) = statement {
            let raw_name = create_table_details.name.to_string();
            // Remove quotes from table name
            let table_name_str = raw_name
                .trim_matches('"')
                .trim_matches('`')
                .to_string();
            eprintln!("DEBUG: Setting up triggers for table: {table_name_str}");
            trigger::setup_triggers_for_table(tx, &table_name_str, false)?;
        }

        Ok(modified_schema_tables)
    }

    /// Führt ein SQL Statement MIT RETURNING aus (mit CRDT)
    /// Returns: (modified_schema_tables, returning_results)
    pub fn query_internal_typed(
        tx: &Transaction,
        hlc_service: &HlcService,
        sql: &str,
        params: &[&dyn ToSql],
    ) -> Result<(HashSet<String>, Vec<Vec<JsonValue>>), DatabaseError> {
        let mut ast_vec = parse_sql_statements(sql)?;

        if ast_vec.len() != 1 {
            return Err(DatabaseError::ExecutionError {
                sql: sql.to_string(),
                reason: "query_internal_typed should only receive a single SQL statement"
                    .to_string(),
                table: None,
            });
        }

        let mut statement = ast_vec.pop().unwrap();

        let transformer = CrdtTransformer::new();
        let hlc_timestamp =
            hlc_service
                .new_timestamp_and_persist(tx)
                .map_err(|e| DatabaseError::HlcError {
                    reason: e.to_string(),
                })?;

        let mut modified_schema_tables = HashSet::new();
        if let Some(table_name) = transformer.transform_execute_statement_with_table_info(
            &mut statement,
            &hlc_timestamp,
        )? {
            modified_schema_tables.insert(table_name);
        }

        let sql_str = statement.to_string();
        eprintln!("DEBUG: Transformed SQL (with RETURNING): {sql_str}");

        // Prepare und query ausführen
        let mut stmt = tx
            .prepare(&sql_str)
            .map_err(|e| DatabaseError::ExecutionError {
                sql: sql_str.clone(),
                table: None,
                reason: e.to_string(),
            })?;

        let column_names: Vec<String> = stmt
            .column_names()
            .into_iter()
            .map(|s| s.to_string())
            .collect();
        let num_columns = column_names.len();

        let mut rows = stmt
            .query(params_from_iter(params.iter()))
            .map_err(|e| DatabaseError::ExecutionError {
                sql: sql_str.clone(),
                table: None,
                reason: e.to_string(),
            })?;

        let mut result_vec: Vec<Vec<JsonValue>> = Vec::new();

        // Lese alle RETURNING Zeilen
        while let Some(row) = rows.next().map_err(|e| DatabaseError::ExecutionError {
            sql: sql_str.clone(),
            table: None,
            reason: e.to_string(),
        })? {
            let mut row_values: Vec<JsonValue> = Vec::new();
            for i in 0..num_columns {
                let value_ref = row.get_ref(i).map_err(|e| DatabaseError::ExecutionError {
                    sql: sql_str.clone(),
                    table: None,
                    reason: e.to_string(),
                })?;
                let json_value = convert_value_ref_to_json(value_ref)?;
                row_values.push(json_value);
            }
            result_vec.push(row_values);
        }

        // Trigger-Logik für CREATE TABLE
        if let Statement::CreateTable(create_table_details) = statement {
            let raw_name = create_table_details.name.to_string();
            // Remove quotes from table name
            let table_name_str = raw_name
                .trim_matches('"')
                .trim_matches('`')
                .to_string();
            eprintln!("DEBUG: Setting up triggers for table (RETURNING): {table_name_str}");
            trigger::setup_triggers_for_table(tx, &table_name_str, false)?;
        }

        Ok((modified_schema_tables, result_vec))
    }

    /// Führt ein einzelnes SQL Statement OHNE Typinformationen aus (JSON params)
    pub fn execute_internal(
        tx: &Transaction,
        hlc_service: &HlcService,
        sql: &str,
        params: &[JsonValue],
    ) -> Result<HashSet<String>, DatabaseError> {
        let sql_params: Vec<SqliteValue> = params
            .iter()
            .map(crate::database::core::ValueConverter::json_to_rusqlite_value)
            .collect::<Result<Vec<_>, _>>()?;
        let param_refs: Vec<&dyn ToSql> = sql_params.iter().map(|p| p as &dyn ToSql).collect();
        Self::execute_internal_typed(tx, hlc_service, sql, &param_refs)
    }

    /// Query-Variante (mit RETURNING) OHNE Typinformationen (JSON params)
    pub fn query_internal(
        tx: &Transaction,
        hlc_service: &HlcService,
        sql: &str,
        params: &[JsonValue],
    ) -> Result<(HashSet<String>, Vec<Vec<JsonValue>>), DatabaseError> {
        let sql_params: Vec<SqliteValue> = params
            .iter()
            .map(crate::database::core::ValueConverter::json_to_rusqlite_value)
            .collect::<Result<Vec<_>, _>>()?;
        let param_refs: Vec<&dyn ToSql> = sql_params.iter().map(|p| p as &dyn ToSql).collect();
        Self::query_internal_typed(tx, hlc_service, sql, &param_refs)
    }

    /// Führt mehrere SQL Statements als Batch aus
    pub fn execute_batch_internal(
        tx: &Transaction,
        hlc_service: &HlcService,
        sqls: &[String],
        params: &[Vec<JsonValue>],
    ) -> Result<HashSet<String>, DatabaseError> {
        if sqls.len() != params.len() {
            return Err(DatabaseError::ExecutionError {
                sql: format!("{} statements but {} param sets", sqls.len(), params.len()),
                reason: "Statement count and parameter count mismatch".to_string(),
                table: None,
            });
        }

        let mut all_modified_tables = HashSet::new();

        for (sql, param_set) in sqls.iter().zip(params.iter()) {
            let modified_tables = Self::execute_internal(tx, hlc_service, sql, param_set)?;
            all_modified_tables.extend(modified_tables);
        }

        Ok(all_modified_tables)
    }

    /// Query für SELECT-Statements (read-only, kein CRDT nötig außer Filter)
    pub fn query_select(
        conn: &rusqlite::Connection,
        sql: &str,
        params: &[JsonValue],
    ) -> Result<Vec<Vec<JsonValue>>, DatabaseError> {
        let mut ast_vec = parse_sql_statements(sql)?;

        if ast_vec.len() != 1 {
            return Err(DatabaseError::ExecutionError {
                sql: sql.to_string(),
                reason: "query_select should only receive a single SELECT statement".to_string(),
                table: None,
            });
        }

        // Hard Delete: Keine SELECT-Transformation mehr nötig
        let stmt_to_execute = ast_vec.pop().unwrap();
        let transformed_sql = stmt_to_execute.to_string();

        eprintln!("DEBUG: SELECT (no transformation): {transformed_sql}");

        // Convert JSON params to SQLite values
        let sql_params: Vec<SqliteValue> = params
            .iter()
            .map(crate::database::core::ValueConverter::json_to_rusqlite_value)
            .collect::<Result<Vec<_>, _>>()?;

        let mut prepared_stmt = conn.prepare(&transformed_sql)?;

        let num_columns = prepared_stmt.column_count();

        let param_refs: Vec<&dyn ToSql> = sql_params.iter().map(|p| p as &dyn ToSql).collect();

        let mut rows = prepared_stmt.query(params_from_iter(param_refs.iter()))?;

        let mut result: Vec<Vec<JsonValue>> = Vec::new();
        while let Some(row) = rows.next()? {
            let mut row_values: Vec<JsonValue> = Vec::new();
            for i in 0..num_columns {
                let value_ref = row.get_ref(i)?;
                let json_value = convert_value_ref_to_json(value_ref)?;
                row_values.push(json_value);
            }
            result.push(row_values);
        }

        Ok(result)
    }
}