//! Query planner for optimization.

use crate::types::Result;

/// Query planner for execution optimization.
pub struct QueryPlanner;

impl QueryPlanner {
    /// Generate query execution plan.
    ///
    /// # Arguments
    ///
    /// * `sql` - SQL query
    ///
    /// # Returns
    ///
    /// Execution plan with estimated cost
    ///
    /// # Errors
    ///
    /// Returns `DatabaseError::QueryError` if planning fails
    pub fn plan(sql: &str) -> Result<ExecutionPlan> {
        todo!("Implement QueryPlanner::plan")
    }
}

/// Query execution plan.
#[derive(Debug, Clone)]
pub struct ExecutionPlan {
    /// Plan steps
    pub steps: Vec<PlanStep>,
    /// Estimated cost
    pub estimated_cost: f64,
}

/// Individual plan step.
#[derive(Debug, Clone)]
pub enum PlanStep {
    /// Table scan
    Scan { table: String },
    /// Index lookup
    IndexLookup { field: String, value: String },
    /// Vector search
    VectorSearch { query: Vec<f32>, k: usize },
    /// Filter with predicate
    Filter { predicate: String },
}
