#!/usr/bin/env python3
"""
SQL Query Strategy

This module implements the SQL query strategy for structured data queries.

Company: eXonware.com
Author: Eng. Muhammad AlShehri
Email: connect@exonware.com
Version: 0.0.1.15
Generation Date: January 2, 2025
"""

import re
from typing import Any, Dict, List, Optional, Union
from .base import AStructuredQueryStrategy
from ...errors import XWNodeTypeError, XWNodeValueError
from ...contracts import QueryMode, QueryTrait
from ...base import XWNodeBase


class SQLStrategy(AStructuredQueryStrategy):
    """
    SQL query strategy for standard SQL operations.
    
    Supports:
    - SELECT, INSERT, UPDATE, DELETE operations
    - JOIN operations
    - Aggregate functions
    - WHERE clauses
    - ORDER BY, GROUP BY, HAVING
    """
    
    def __init__(self, **options):
        super().__init__(**options)
        self._mode = QueryMode.SQL
        self._traits = QueryTrait.STRUCTURED | QueryTrait.ANALYTICAL | QueryTrait.BATCH
    
    def execute(self, query: str, **kwargs) -> Any:
        """Execute SQL query."""
        if not self.validate_query(query):
            raise XWNodeValueError(f"Invalid SQL query: {query}")
        
        query_type = self._get_query_type(query)
        
        if query_type == "SELECT":
            return self._execute_select(query, **kwargs)
        elif query_type == "INSERT":
            return self._execute_insert(query, **kwargs)
        elif query_type == "UPDATE":
            return self._execute_update(query, **kwargs)
        elif query_type == "DELETE":
            return self._execute_delete(query, **kwargs)
        else:
            raise XWNodeValueError(f"Unsupported query type: {query_type}")
    
    def validate_query(self, query: str) -> bool:
        """Validate SQL query syntax."""
        if not query or not isinstance(query, str):
            return False
        
        # Basic SQL validation
        query = query.strip().upper()
        valid_operations = ["SELECT", "INSERT", "UPDATE", "DELETE", "CREATE", "DROP", "ALTER"]
        
        for operation in valid_operations:
            if query.startswith(operation):
                return True
        
        return False
    
    def get_query_plan(self, query: str) -> Dict[str, Any]:
        """Get SQL query execution plan."""
        query_type = self._get_query_type(query)
        
        return {
            "query_type": query_type,
            "operation": query_type,
            "complexity": self._estimate_complexity(query),
            "estimated_cost": self._estimate_cost(query),
            "optimization_hints": self._get_optimization_hints(query)
        }
    
    def select_query(self, table: str, columns: List[str], where_clause: str = None) -> Any:
        """Execute SELECT query."""
        query = f"SELECT {', '.join(columns)} FROM {table}"
        if where_clause:
            query += f" WHERE {where_clause}"
        
        return self.execute(query)
    
    def insert_query(self, table: str, data: Dict[str, Any]) -> Any:
        """Execute INSERT query."""
        columns = list(data.keys())
        values = list(data.values())
        
        query = f"INSERT INTO {table} ({', '.join(columns)}) VALUES ({', '.join(['?' for _ in values])})"
        return self.execute(query, values=values)
    
    def update_query(self, table: str, data: Dict[str, Any], where_clause: str = None) -> Any:
        """Execute UPDATE query."""
        set_clause = ', '.join([f"{k} = ?" for k in data.keys()])
        query = f"UPDATE {table} SET {set_clause}"
        
        if where_clause:
            query += f" WHERE {where_clause}"
        
        return self.execute(query, values=list(data.values()))
    
    def delete_query(self, table: str, where_clause: str = None) -> Any:
        """Execute DELETE query."""
        query = f"DELETE FROM {table}"
        if where_clause:
            query += f" WHERE {where_clause}"
        
        return self.execute(query)
    
    def join_query(self, tables: List[str], join_conditions: List[str]) -> Any:
        """Execute JOIN query."""
        if len(tables) < 2:
            raise XWNodeValueError("JOIN requires at least 2 tables")
        
        query = f"SELECT * FROM {tables[0]}"
        for i, table in enumerate(tables[1:], 1):
            if i <= len(join_conditions):
                query += f" JOIN {table} ON {join_conditions[i-1]}"
            else:
                query += f" CROSS JOIN {table}"
        
        return self.execute(query)
    
    def aggregate_query(self, table: str, functions: List[str], group_by: List[str] = None) -> Any:
        """Execute aggregate query."""
        query = f"SELECT {', '.join(functions)} FROM {table}"
        if group_by:
            query += f" GROUP BY {', '.join(group_by)}"
        
        return self.execute(query)
    
    def _get_query_type(self, query: str) -> str:
        """Extract query type from SQL query."""
        query = query.strip().upper()
        for operation in ["SELECT", "INSERT", "UPDATE", "DELETE", "CREATE", "DROP", "ALTER"]:
            if query.startswith(operation):
                return operation
        return "UNKNOWN"
    
    def _execute_select(self, query: str, **kwargs) -> Any:
        """Execute SELECT query."""
        # Placeholder implementation
        return {"result": "SELECT executed", "query": query}
    
    def _execute_insert(self, query: str, **kwargs) -> Any:
        """Execute INSERT query."""
        # Placeholder implementation
        return {"result": "INSERT executed", "query": query}
    
    def _execute_update(self, query: str, **kwargs) -> Any:
        """Execute UPDATE query."""
        # Placeholder implementation
        return {"result": "UPDATE executed", "query": query}
    
    def _execute_delete(self, query: str, **kwargs) -> Any:
        """Execute DELETE query."""
        # Placeholder implementation
        return {"result": "DELETE executed", "query": query}
    
    def _estimate_complexity(self, query: str) -> str:
        """Estimate query complexity."""
        query = query.upper()
        if "JOIN" in query:
            return "HIGH"
        elif "GROUP BY" in query or "ORDER BY" in query:
            return "MEDIUM"
        else:
            return "LOW"
    
    def _estimate_cost(self, query: str) -> int:
        """Estimate query cost."""
        complexity = self._estimate_complexity(query)
        if complexity == "HIGH":
            return 100
        elif complexity == "MEDIUM":
            return 50
        else:
            return 10
    
    def _get_optimization_hints(self, query: str) -> List[str]:
        """Get query optimization hints."""
        hints = []
        query = query.upper()
        
        if "SELECT *" in query:
            hints.append("Consider specifying columns instead of using *")
        if "WHERE" not in query and "SELECT" in query:
            hints.append("Consider adding WHERE clause to limit results")
        if "ORDER BY" in query:
            hints.append("Consider adding index on ORDER BY columns")
        
        return hints
    
    def to_actions_tree(self, sql_query: str) -> XWNodeBase:
        """Convert SQL query to XWQuery Script actions tree."""
        from .xwquery_strategy import XWQueryScriptStrategy
        
        # Parse SQL into XWQuery Script actions
        script_strategy = XWQueryScriptStrategy()
        
        # Map SQL constructs to XWQuery actions:
        # SELECT -> SELECT action
        # FROM -> FROM action  
        # WHERE -> WHERE action
        # JOIN -> JOIN action (with nested conditions)
        # Subqueries -> nested SELECT actions
        # etc.
        
        # For now, create a basic actions tree
        actions = {
            "root": {
                "type": "PROGRAM",
                "statements": [
                    {
                        "type": "SELECT",
                        "id": "sql_action_1",
                        "content": sql_query,
                        "line_number": 1,
                        "timestamp": "2025-01-02T00:00:00",
                        "children": []
                    }
                ],
                "comments": [],
                "metadata": {
                    "version": "1.0",
                    "created": "2025-01-02T00:00:00",
                    "source_format": "SQL"
                }
            }
        }
        
        return XWNodeBase.from_native(actions)
    
    def from_actions_tree(self, actions_tree: XWNodeBase) -> str:
        """Convert XWQuery Script actions tree to SQL query."""
        from .xwquery_strategy import XWQueryScriptStrategy
        
        script_strategy = XWQueryScriptStrategy(actions_tree)
        return script_strategy.to_format("SQL")
    
    def can_handle(self, query_string: str) -> bool:
        """Check if this strategy can handle the given query string."""
        return self.validate_query(query_string)
    
    def get_supported_operations(self) -> List[str]:
        """Get list of supported query operations."""
        return [
            "SELECT", "INSERT", "UPDATE", "DELETE", "CREATE", "DROP", "ALTER",
            "JOIN", "UNION", "GROUP BY", "ORDER BY", "HAVING", "WHERE",
            "WITH", "CASE", "WINDOW", "PARTITION BY", "OVER"
        ]
    
    def estimate_complexity(self, query_string: str) -> Dict[str, Any]:
        """Estimate query complexity and resource requirements."""
        complexity = self._estimate_complexity(query_string)
        cost = self._estimate_cost(query_string)
        
        return {
            "complexity_level": complexity,
            "estimated_cost": cost,
            "has_joins": "JOIN" in query_string.upper(),
            "has_subqueries": "SELECT" in query_string.upper().replace("SELECT", "", 1),
            "has_aggregates": any(func in query_string.upper() for func in ["SUM", "COUNT", "AVG", "MIN", "MAX"]),
            "has_window_functions": "OVER" in query_string.upper(),
            "query_length": len(query_string),
            "estimated_memory": "high" if complexity == "HIGH" else "medium" if complexity == "MEDIUM" else "low"
        }