//! M3.6.5 — Query Levels and Floor: Multi-tier query filtering
//!
//! Allows queries to filter results by level (L0/L1/L2 vs R),
//! set floor thresholds, and control which tiers contribute to responses.

use serde::{Deserialize, Serialize};

/// Query filtering parameters
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QueryLevels {
    /// Include L0/L1/L2 evidence? (default: true)
    pub include_evidence: bool,

    /// Include R (reference) docs? (default: true)
    pub include_reference: bool,

    /// Minimum relevance score (0.0-1.0) to include a result
    pub floor: f32,

    /// Specific levels to include (empty = all)
    pub level_filter: Vec<String>,  // ["L1", "L2"] or empty for all
}

impl Default for QueryLevels {
    fn default() -> Self {
        Self {
            include_evidence: true,
            include_reference: false,  // R opt-in only
            floor: 0.0,
            level_filter: vec![],
        }
    }
}

impl QueryLevels {
    /// Create evidence-only filter (R excluded by default)
    pub fn evidence_only() -> Self {
        Self {
            include_evidence: true,
            include_reference: false,
            floor: 0.0,
            level_filter: vec![],
        }
    }

    /// Create reference-only filter
    pub fn reference_only() -> Self {
        Self {
            include_evidence: false,
            include_reference: true,
            floor: 0.0,
            level_filter: vec!["R".to_string()],
        }
    }

    /// Create hybrid (both evidence and reference)
    pub fn hybrid(floor: f32) -> Self {
        Self {
            include_evidence: true,
            include_reference: true,
            floor,
            level_filter: vec![],
        }
    }

    /// Check if a result should be included
    pub fn should_include(&self, level: &str, score: f32) -> bool {
        // Check floor threshold first
        if score < self.floor {
            return false;
        }

        // Check level filter
        if !self.level_filter.is_empty() {
            if !self.level_filter.contains(&level.to_string()) {
                return false;
            }
        }

        // Check evidence/reference flags
        if level == "R" {
            return self.include_reference;
        } else if level.starts_with("L") {
            return self.include_evidence;
        }

        false
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_default_levels() {
        let levels = QueryLevels::default();
        assert!(levels.include_evidence);
        assert!(!levels.include_reference);
    }

    #[test]
    fn test_evidence_only_filter() {
        let levels = QueryLevels::evidence_only();
        assert!(levels.should_include("L1", 0.9));
        assert!(levels.should_include("L2", 0.7));
        assert!(!levels.should_include("R", 0.99));
    }

    #[test]
    fn test_reference_only_filter() {
        let levels = QueryLevels::reference_only();
        assert!(!levels.should_include("L1", 0.9));
        assert!(levels.should_include("R", 0.5));
    }

    #[test]
    fn test_hybrid_filter() {
        let levels = QueryLevels::hybrid(0.6);
        assert!(levels.should_include("L1", 0.8));
        assert!(levels.should_include("R", 0.7));
        assert!(!levels.should_include("L0", 0.5));  // Below floor
    }

    #[test]
    fn test_floor_threshold() {
        let levels = QueryLevels {
            include_evidence: true,
            include_reference: true,
            floor: 0.75,
            level_filter: vec![],
        };

        assert!(levels.should_include("L1", 0.80));
        assert!(!levels.should_include("L1", 0.70));
    }

    #[test]
    fn test_level_filter_specific() {
        let levels = QueryLevels {
            include_evidence: true,
            include_reference: true,
            floor: 0.0,
            level_filter: vec!["L1".to_string(), "L2".to_string()],
        };

        assert!(levels.should_include("L1", 0.5));
        assert!(levels.should_include("L2", 0.5));
        assert!(!levels.should_include("L0", 0.9));  // Filtered out
    }

    #[test]
    fn test_r_opt_in() {
        // R should require explicit opt-in
        let default_levels = QueryLevels::default();
        assert!(!default_levels.should_include("R", 1.0));

        let with_r = QueryLevels::hybrid(0.0);
        assert!(with_r.should_include("R", 1.0));
    }
}