//! Ontology vocabulary extraction from authority corpus.
//!
//! Extracts concept vocabulary from corpus assertions to constrain
//! LLM output to paths that match authority subjects.

use serde::Deserialize;
use stemedb_core::types::{Assertion, ObjectValue};

/// A concept from the authority corpus.
#[derive(Debug, Clone)]
pub struct AuthorityConcept {
    /// Full subject path (e.g., "owasp://rate_limit/enabled")
    pub subject: String,
    /// Leaf key for matching (e.g., "rate_limit/enabled")
    pub leaf_path: String,
    /// Valid predicate (e.g., "enabled")
    pub predicate: String,
    /// Expected value type
    pub value_type: ValueType,
    /// Example value for LLM context
    pub example_value: String,
    /// Description for LLM context
    pub description: String,
}

/// Value type for a concept.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ValueType {
    /// Boolean value (true/false).
    Boolean,
    /// Text string value.
    Text,
    /// Numeric value.
    Number,
}

impl ValueType {
    /// Convert to string for prompt.
    pub fn as_str(&self) -> &'static str {
        match self {
            ValueType::Boolean => "boolean",
            ValueType::Text => "text",
            ValueType::Number => "number",
        }
    }
}

/// Helper to extract description from source_metadata JSON.
#[derive(Debug, Deserialize)]
struct SourceMetadata {
    description: Option<String>,
}

/// Vocabulary extracted from authority corpus.
pub struct OntologyVocabulary {
    /// List of authority concepts for constraining LLM output.
    pub concepts: Vec<AuthorityConcept>,
}

impl OntologyVocabulary {
    /// Build vocabulary from corpus assertions.
    pub fn from_assertions(assertions: &[Assertion]) -> Self {
        let concepts = assertions.iter().filter_map(Self::assertion_to_concept).collect();

        Self { concepts }
    }

    /// Convert an assertion to an AuthorityConcept.
    fn assertion_to_concept(assertion: &Assertion) -> Option<AuthorityConcept> {
        let leaf_path = Self::extract_leaf_path(&assertion.subject)?;

        let (value_type, example_value) = match &assertion.object {
            ObjectValue::Boolean(b) => (ValueType::Boolean, b.to_string()),
            ObjectValue::Text(t) => (ValueType::Text, t.clone()),
            ObjectValue::Number(n) => (ValueType::Number, n.to_string()),
            ObjectValue::Reference(r) => (ValueType::Text, r.clone()),
        };

        // Extract description from source_metadata if available
        let description = assertion
            .source_metadata
            .as_ref()
            .and_then(|meta| serde_json::from_slice::<SourceMetadata>(meta).ok())
            .and_then(|m| m.description)
            .unwrap_or_else(|| format!("{} {}", assertion.subject, assertion.predicate));

        Some(AuthorityConcept {
            subject: assertion.subject.clone(),
            leaf_path,
            predicate: assertion.predicate.clone(),
            value_type,
            example_value,
            description,
        })
    }

    /// Extract the leaf path from a subject.
    ///
    /// For `rfc://5246/tls/cert_verification`, returns `tls/cert_verification`.
    /// For `owasp://rate_limit/enabled`, returns `rate_limit/enabled`.
    fn extract_leaf_path(subject: &str) -> Option<String> {
        // Split on "://" to separate scheme from path
        let path = subject.find("://").map(|i| &subject[i + 3..]).unwrap_or(subject);

        // Get last two non-empty segments
        let mut segments: Vec<&str> = path.split('/').filter(|s| !s.is_empty()).collect();

        if segments.len() < 2 {
            return None;
        }

        // Take last 2 segments
        let len = segments.len();
        segments.drain(..len - 2);
        Some(segments.join("/"))
    }

    /// Format concepts as a markdown table for prompt injection.
    pub fn to_prompt_section(&self) -> String {
        let mut lines = Vec::with_capacity(self.concepts.len() + 3);

        lines.push("| Concept Path | Predicate | Value Type | Example | Description |".to_string());
        lines.push("|--------------|-----------|------------|---------|-------------|".to_string());

        for concept in &self.concepts {
            // Truncate description for table readability
            let desc = if concept.description.len() > 60 {
                format!("{}...", &concept.description[..57])
            } else {
                concept.description.clone()
            };

            lines.push(format!(
                "| {} | {} | {} | {} | {} |",
                concept.leaf_path,
                concept.predicate,
                concept.value_type.as_str(),
                concept.example_value,
                desc
            ));
        }

        lines.join("\n")
    }

    /// Find a concept by leaf path.
    pub fn find_by_leaf(&self, leaf_path: &str) -> Option<&AuthorityConcept> {
        self.concepts.iter().find(|c| c.leaf_path == leaf_path)
    }

    /// Find a concept by leaf path AND predicate.
    ///
    /// This is more precise than `find_by_leaf` when multiple predicates
    /// are defined for the same subject path (e.g., auth/bypass with
    /// debug_mode and header_based predicates).
    pub fn find_by_leaf_and_predicate(
        &self,
        leaf_path: &str,
        predicate: &str,
    ) -> Option<&AuthorityConcept> {
        self.concepts.iter().find(|c| c.leaf_path == leaf_path && c.predicate == predicate)
    }

    /// Find a concept by leaf path with fuzzy matching.
    ///
    /// Returns the best match if similarity is above the threshold.
    pub fn fuzzy_match(&self, leaf_path: &str, threshold: f32) -> Option<&AuthorityConcept> {
        let mut best_match: Option<(&AuthorityConcept, f32)> = None;

        for concept in &self.concepts {
            let similarity = Self::path_similarity(&concept.leaf_path, leaf_path);
            if similarity >= threshold {
                if let Some((_, best_score)) = best_match {
                    if similarity > best_score {
                        best_match = Some((concept, similarity));
                    }
                } else {
                    best_match = Some((concept, similarity));
                }
            }
        }

        best_match.map(|(c, _)| c)
    }

    /// Calculate similarity between two paths.
    ///
    /// Uses segment-based matching:
    /// - Exact match: 1.0
    /// - Same final segment: 0.7
    /// - Contains same words: 0.5
    fn path_similarity(a: &str, b: &str) -> f32 {
        if a == b {
            return 1.0;
        }

        let a_lower = a.to_lowercase();
        let b_lower = b.to_lowercase();

        if a_lower == b_lower {
            return 0.95;
        }

        // Check final segment match
        let a_final = a_lower.rsplit('/').next().unwrap_or(&a_lower);
        let b_final = b_lower.rsplit('/').next().unwrap_or(&b_lower);

        if a_final == b_final {
            return 0.7;
        }

        // Check word overlap
        let a_words: Vec<&str> = a_lower.split(['/', '_']).collect();
        let b_words: Vec<&str> = b_lower.split(['/', '_']).collect();

        let mut matches = 0;
        for a_word in &a_words {
            if b_words.contains(a_word) {
                matches += 1;
            }
        }

        if matches > 0 {
            let max_words = a_words.len().max(b_words.len()) as f32;
            return (matches as f32) / max_words * 0.5;
        }

        0.0
    }

    /// Get all unique leaf paths as a simple list for the prompt.
    pub fn leaf_paths(&self) -> Vec<&str> {
        self.concepts.iter().map(|c| c.leaf_path.as_str()).collect()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use stemedb_core::types::{HlcTimestamp, LifecycleStage, SourceClass};

    fn make_test_assertion(subject: &str, predicate: &str, value: ObjectValue) -> Assertion {
        let source_metadata = serde_json::json!({
            "description": "Test description",
            "source": "test",
        });

        Assertion {
            subject: subject.to_string(),
            predicate: predicate.to_string(),
            object: value,
            parent_hash: None,
            source_hash: [0u8; 32],
            source_class: SourceClass::Clinical,
            visual_hash: None,
            epoch: None,
            source_metadata: serde_json::to_vec(&source_metadata).ok(),
            lifecycle: LifecycleStage::Approved,
            signatures: vec![],
            confidence: 1.0,
            timestamp: 0,
            hlc_timestamp: HlcTimestamp::default(),
            vector: None,
        }
    }

    #[test]
    fn test_extract_leaf_path() {
        assert_eq!(
            OntologyVocabulary::extract_leaf_path("rfc://5246/tls/cert_verification"),
            Some("tls/cert_verification".to_string())
        );

        assert_eq!(
            OntologyVocabulary::extract_leaf_path("owasp://rate_limit/enabled"),
            Some("rate_limit/enabled".to_string())
        );

        assert_eq!(
            OntologyVocabulary::extract_leaf_path("owasp://injection/db/query/construction"),
            Some("query/construction".to_string())
        );
    }

    #[test]
    fn test_from_assertions() {
        let assertions = vec![
            make_test_assertion(
                "rfc://5246/tls/cert_verification",
                "enabled",
                ObjectValue::Boolean(true),
            ),
            make_test_assertion(
                "owasp://rate_limit/enabled",
                "enabled",
                ObjectValue::Boolean(true),
            ),
        ];

        let vocab = OntologyVocabulary::from_assertions(&assertions);

        assert_eq!(vocab.concepts.len(), 2);
        assert!(vocab.find_by_leaf("tls/cert_verification").is_some());
        assert!(vocab.find_by_leaf("rate_limit/enabled").is_some());
    }

    #[test]
    fn test_fuzzy_match() {
        let assertions = vec![make_test_assertion(
            "owasp://rate_limit/enabled",
            "enabled",
            ObjectValue::Boolean(true),
        )];

        let vocab = OntologyVocabulary::from_assertions(&assertions);

        // Exact match
        let exact = vocab.fuzzy_match("rate_limit/enabled", 0.5);
        assert!(exact.is_some());
        assert_eq!(exact.map(|c| c.leaf_path.as_str()), Some("rate_limit/enabled"));

        // Similar match - same final segment should score 0.7
        let fuzzy = vocab.fuzzy_match("api/enabled", 0.6);
        assert!(fuzzy.is_some());
        assert_eq!(fuzzy.map(|c| c.leaf_path.as_str()), Some("rate_limit/enabled"));

        // No match
        let no_match = vocab.fuzzy_match("completely_different", 0.5);
        assert!(no_match.is_none());
    }

    #[test]
    fn test_to_prompt_section() {
        let assertions = vec![make_test_assertion(
            "owasp://rate_limit/enabled",
            "enabled",
            ObjectValue::Boolean(true),
        )];

        let vocab = OntologyVocabulary::from_assertions(&assertions);
        let section = vocab.to_prompt_section();

        assert!(section.contains("rate_limit/enabled"));
        assert!(section.contains("enabled"));
        assert!(section.contains("boolean"));
    }

    #[test]
    fn test_path_similarity() {
        // Exact match
        assert_eq!(OntologyVocabulary::path_similarity("a/b", "a/b"), 1.0);

        // Case insensitive
        assert!(OntologyVocabulary::path_similarity("A/B", "a/b") > 0.9);

        // Same final segment
        assert!(
            OntologyVocabulary::path_similarity("x/cert_verification", "y/cert_verification") > 0.6
        );

        // No match
        assert_eq!(OntologyVocabulary::path_similarity("a/b", "x/y"), 0.0);
    }
}