ggen-domain 5.1.3

//! Extract ontology schema from RDF/OWL files
//!
//! This module handles:
//! - Loading ontology files (TTL, RDF/XML, N-Triples, JSON-LD)
//! - Parsing RDF graphs
//! - Extracting classes, properties, relationships via SPARQL
//! - Transforming to intermediate schema format
//! - Caching extracted schemas

use ggen_core::ontology_pack::OntologySchema;
use ggen_utils::error::{Error, Result};
use std::path::PathBuf;

/// Input for ontology extraction
#[derive(Debug, Clone)]
pub struct ExtractInput {
    /// Path to ontology file (TTL, RDF/XML, etc.)
    pub ontology_file: PathBuf,

    /// Namespace to extract (if None, extract all)
    pub namespace: Option<String>,

    /// Output path for extracted schema JSON
    pub output_path: Option<PathBuf>,
}

/// Output from ontology extraction
#[derive(Debug, Clone, serde::Serialize)]
pub struct ExtractOutput {
    /// Extracted schema
    pub schema: OntologySchema,

    /// Output file path (if saved)
    pub output_file: Option<PathBuf>,

    /// Extraction statistics
    pub stats: ExtractionStats,
}

/// Statistics about extraction
#[derive(Debug, Clone, serde::Serialize)]
pub struct ExtractionStats {
    /// Number of classes found
    pub classes_found: usize,

    /// Number of properties found
    pub properties_found: usize,

    /// Number of relationships found
    pub relationships_found: usize,

    /// Time taken in milliseconds
    pub extraction_time_ms: u64,
}

/// Execute ontology extraction
///
/// # Example
///
/// ```rust,no_run
/// use ggen_domain::ontology::extract::{execute_extract, ExtractInput};
/// use std::path::PathBuf;
///
/// #[tokio::main]
/// async fn main() -> Result<(), Box<dyn std::error::Error>> {
///     let input = ExtractInput {
///         ontology_file: PathBuf::from("schema-org.ttl"),
///         namespace: Some("https://schema.org/".to_string()),
///         output_path: Some(PathBuf::from("schema-org.json")),
///     };
///
///     let output = execute_extract(&input).await?;
///     println!("Found {} classes", output.stats.classes_found);
///     Ok(())
/// }
/// ```
pub async fn execute_extract(input: &ExtractInput) -> Result<ExtractOutput> {
    let start_time = std::time::Instant::now();

    // 1. Validate input file exists
    if !input.ontology_file.exists() {
        return Err(Error::new(&format!(
            "Ontology file not found: {}",
            input.ontology_file.display()
        )));
    }

    // 2. Load ontology file into RDF graph
    let _file_content = tokio::fs::read_to_string(&input.ontology_file).await?;

    // 3. Parse based on file extension (or content detection)
    let namespace = input.namespace.as_deref().unwrap_or("http://example.org#");

    // Note: RDF parsing to be implemented
    // For now, return a simple schema structure
    let schema = OntologySchema {
        namespace: namespace.to_string(),
        classes: vec![],
        properties: vec![],
        relationships: vec![],
        prefixes: Default::default(),
    };

    // 4. Save to output file if specified
    let output_file = if let Some(output_path) = &input.output_path {
        let json = serde_json::to_string_pretty(&schema)?;
        tokio::fs::write(output_path, json).await?;
        Some(output_path.clone())
    } else {
        None
    };

    let elapsed = start_time.elapsed();
    let stats = ExtractionStats {
        classes_found: schema.classes.len(),
        properties_found: schema.properties.len(),
        relationships_found: schema.relationships.len(),
        extraction_time_ms: elapsed.as_millis() as u64,
    };

    Ok(ExtractOutput {
        schema,
        output_file,
        stats,
    })
}

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

    #[tokio::test]
    async fn test_extract_missing_file() {
        let input = ExtractInput {
            ontology_file: PathBuf::from("/nonexistent/ontology.ttl"),
            namespace: None,
            output_path: None,
        };

        let result = execute_extract(&input).await;
        assert!(result.is_err());
    }
}