threecrate-io 0.8.0

//! Unified IO registry for format-agnostic reading and writing
//! 
//! This module provides a registry-based approach to IO operations,
//! allowing downstream crates to work with any supported format
//! without knowing the specific implementation details.

use threecrate_core::{PointCloud, TriangleMesh, Result, Point3f};
use std::path::Path;
use std::collections::HashMap;

/// Trait for reading point clouds from files
pub trait PointCloudReader: Send + Sync {
    /// Read a point cloud from the given path
    fn read_point_cloud(&self, path: &Path) -> Result<PointCloud<Point3f>>;
    
    /// Check if this reader can handle the given file by examining its header
    fn can_read(&self, path: &Path) -> bool;
    
    /// Get the format name this reader handles
    fn format_name(&self) -> &'static str;
}

/// Trait for writing point clouds to files
pub trait PointCloudWriter: Send + Sync {
    /// Write a point cloud to the given path
    fn write_point_cloud(&self, cloud: &PointCloud<Point3f>, path: &Path) -> Result<()>;
    
    /// Get the format name this writer handles
    fn format_name(&self) -> &'static str;
}

/// Trait for reading meshes from files
pub trait MeshReader: Send + Sync {
    /// Read a mesh from the given path
    fn read_mesh(&self, path: &Path) -> Result<TriangleMesh>;
    
    /// Check if this reader can handle the given file by examining its header
    fn can_read(&self, path: &Path) -> bool;
    
    /// Get the format name this reader handles
    fn format_name(&self) -> &'static str;
}

/// Trait for writing meshes to files
pub trait MeshWriter: Send + Sync {
    /// Write a mesh to the given path
    fn write_mesh(&self, mesh: &TriangleMesh, path: &Path) -> Result<()>;
    
    /// Get the format name this writer handles
    fn format_name(&self) -> &'static str;
}

/// Format handler that can read and write both point clouds and meshes
pub trait FormatHandler: PointCloudReader + PointCloudWriter + MeshReader + MeshWriter + Send + Sync {
    /// Get the file extensions this handler supports
    fn supported_extensions(&self) -> &[&'static str];
    
    /// Get the magic bytes/header signature for format detection
    fn magic_bytes(&self) -> &[u8];
}

/// IO registry that manages format handlers and provides unified access
pub struct IoRegistry {
    point_cloud_readers: HashMap<String, Box<dyn PointCloudReader>>,
    point_cloud_writers: HashMap<String, Box<dyn PointCloudWriter>>,
    mesh_readers: HashMap<String, Box<dyn MeshReader>>,
    mesh_writers: HashMap<String, Box<dyn MeshWriter>>,
    #[allow(dead_code)] // Reserved for future use
    format_handlers: HashMap<String, Box<dyn FormatHandler>>,
}

impl IoRegistry {
    /// Create a new empty IO registry
    pub fn new() -> Self {
        Self {
            point_cloud_readers: HashMap::new(),
            point_cloud_writers: HashMap::new(),
            mesh_readers: HashMap::new(),
            mesh_writers: HashMap::new(),
            format_handlers: HashMap::new(),
        }
    }
    
    /// Register a point cloud reader for a specific format
    pub fn register_point_cloud_handler(&mut self, format: &str, handler: Box<dyn PointCloudReader>) {
        self.point_cloud_readers.insert(format.to_lowercase(), handler);
    }
    
    /// Register a point cloud writer for a specific format
    pub fn register_point_cloud_writer(&mut self, format: &str, handler: Box<dyn PointCloudWriter>) {
        self.point_cloud_writers.insert(format.to_lowercase(), handler);
    }
    
    /// Register a mesh reader for a specific format
    pub fn register_mesh_handler(&mut self, format: &str, handler: Box<dyn MeshReader>) {
        self.mesh_readers.insert(format.to_lowercase(), handler);
    }
    
    /// Register a mesh writer for a specific format
    pub fn register_mesh_writer(&mut self, format: &str, handler: Box<dyn MeshWriter>) {
        self.mesh_writers.insert(format.to_lowercase(), handler);
    }
    
    /// Register a complete format handler
    pub fn register_format_handler(&mut self, handler: Box<dyn FormatHandler>) {
        // For now, we'll skip the automatic registration of format handlers
        // since cloning trait objects is complex. Users can register each
        // capability separately using the specific register_* methods.
        let _handler = handler; // Suppress unused variable warning
    }
    
    /// Read a point cloud, auto-detecting the format
    pub fn read_point_cloud(&self, path: &Path, format_hint: &str) -> Result<PointCloud<Point3f>> {
        // First try the format hint
        if let Some(reader) = self.point_cloud_readers.get(&format_hint.to_lowercase()) {
            if reader.can_read(path) {
                return reader.read_point_cloud(path);
            }
        }
        
        // Try to detect format by header signature
        if let Some(detected_format) = self.detect_format_by_header(path) {
            if let Some(reader) = self.point_cloud_readers.get(&detected_format) {
                return reader.read_point_cloud(path);
            }
        }
        
        // Fall back to extension-based detection
        if let Some(reader) = self.point_cloud_readers.get(&format_hint.to_lowercase()) {
            return reader.read_point_cloud(path);
        }
        
        Err(threecrate_core::Error::UnsupportedFormat(
            format!("No point cloud reader found for format: {}", format_hint)
        ))
    }
    
    /// Read a mesh, auto-detecting the format
    pub fn read_mesh(&self, path: &Path, format_hint: &str) -> Result<TriangleMesh> {
        // First try the format hint
        if let Some(reader) = self.mesh_readers.get(&format_hint.to_lowercase()) {
            if reader.can_read(path) {
                return reader.read_mesh(path);
            }
        }
        
        // Try to detect format by header signature
        if let Some(detected_format) = self.detect_format_by_header(path) {
            if let Some(reader) = self.mesh_readers.get(&detected_format) {
                return reader.read_mesh(path);
            }
        }
        
        // Fall back to extension-based detection
        if let Some(reader) = self.mesh_readers.get(&format_hint.to_lowercase()) {
            return reader.read_mesh(path);
        }
        
        Err(threecrate_core::Error::UnsupportedFormat(
            format!("No mesh reader found for format: {}", format_hint)
        ))
    }
    
    /// Write a point cloud, auto-detecting the format
    pub fn write_point_cloud(&self, cloud: &PointCloud<Point3f>, path: &Path, format_hint: &str) -> Result<()> {
        if let Some(writer) = self.point_cloud_writers.get(&format_hint.to_lowercase()) {
            return writer.write_point_cloud(cloud, path);
        }
        
        Err(threecrate_core::Error::UnsupportedFormat(
            format!("No point cloud writer found for format: {}", format_hint)
        ))
    }
    
    /// Write a mesh, auto-detecting the format
    pub fn write_mesh(&self, mesh: &TriangleMesh, path: &Path, format_hint: &str) -> Result<()> {
        if let Some(writer) = self.mesh_writers.get(&format_hint.to_lowercase()) {
            return writer.write_mesh(mesh, path);
        }
        
        Err(threecrate_core::Error::UnsupportedFormat(
            format!("No mesh writer found for format: {}", format_hint)
        ))
    }
    
    /// Detect file format by examining the header/magic bytes
    fn detect_format_by_header(&self, path: &Path) -> Option<String> {
        use std::fs::File;
        use std::io::Read;
        
        let mut file = match File::open(path) {
            Ok(file) => file,
            Err(_) => return None,
        };
        
        let mut header = [0u8; 16];
        if let Ok(bytes_read) = file.read(&mut header) {
            if bytes_read < 4 {
                return None;
            }
            
            // Check magic bytes for various formats
            if header.starts_with(b"ply") {
                return Some("ply".to_string());
            } else if header.starts_with(b"#") || header.starts_with(b"v ") {
                // Check if it's an OBJ file by looking for vertex definitions
                let mut file = File::open(path).ok()?;
                let mut content = String::new();
                if file.read_to_string(&mut content).is_ok() {
                    if content.lines().any(|line| line.trim().starts_with("v ")) {
                        return Some("obj".to_string());
                    }
                }
            } else if header.starts_with(b"LASF") {
                return Some("las".to_string());
            } else if header.starts_with(b"# .PCD") {
                return Some("pcd".to_string());
            } else if header.starts_with(b"ASTM-E57") {
                return Some("e57".to_string());
            }
        }
        
        None
    }
    
    /// Get a list of supported formats for point clouds
    pub fn supported_point_cloud_formats(&self) -> Vec<String> {
        self.point_cloud_readers.keys().cloned().collect()
    }
    
    /// Get a list of supported formats for meshes
    pub fn supported_mesh_formats(&self) -> Vec<String> {
        self.mesh_readers.keys().cloned().collect()
    }
    
    /// Check if a format is supported for reading point clouds
    pub fn supports_point_cloud_reading(&self, format: &str) -> bool {
        self.point_cloud_readers.contains_key(&format.to_lowercase())
    }
    
    /// Check if a format is supported for writing point clouds
    pub fn supports_point_cloud_writing(&self, format: &str) -> bool {
        self.point_cloud_writers.contains_key(&format.to_lowercase())
    }
    
    /// Check if a format is supported for reading meshes
    pub fn supports_mesh_reading(&self, format: &str) -> bool {
        self.mesh_readers.contains_key(&format.to_lowercase())
    }
    
    /// Check if a format is supported for writing meshes
    pub fn supports_mesh_writing(&self, format: &str) -> bool {
        self.mesh_writers.contains_key(&format.to_lowercase())
    }
}

impl Default for IoRegistry {
    fn default() -> Self {
        Self::new()
    }
}

// Note: FormatHandler cloning has been removed for simplicity.
// Users should register format handlers using the specific register_* methods.

#[cfg(test)]
mod tests {
    use super::*;
    use threecrate_core::Point3f;
    use std::fs;
    
    // Mock implementations for testing
    struct MockPlyHandler;
    
    impl PointCloudReader for MockPlyHandler {
        fn read_point_cloud(&self, _path: &Path) -> Result<PointCloud<Point3f>> {
            let mut cloud = PointCloud::new();
            cloud.push(Point3f::new(0.0, 0.0, 0.0));
            Ok(cloud)
        }
        
        fn can_read(&self, _path: &Path) -> bool {
            true
        }
        
        fn format_name(&self) -> &'static str {
            "ply"
        }
    }
    
    impl PointCloudWriter for MockPlyHandler {
        fn write_point_cloud(&self, _cloud: &PointCloud<Point3f>, _path: &Path) -> Result<()> {
            Ok(())
        }
        
        fn format_name(&self) -> &'static str {
            "ply"
        }
    }
    
    impl MeshReader for MockPlyHandler {
        fn read_mesh(&self, _path: &Path) -> Result<TriangleMesh> {
            let vertices = vec![Point3f::new(0.0, 0.0, 0.0)];
            let faces = vec![];
            Ok(TriangleMesh::from_vertices_and_faces(vertices, faces))
        }
        
        fn can_read(&self, _path: &Path) -> bool {
            true
        }
        
        fn format_name(&self) -> &'static str {
            "ply"
        }
    }
    
    impl MeshWriter for MockPlyHandler {
        fn write_mesh(&self, _mesh: &TriangleMesh, _path: &Path) -> Result<()> {
            Ok(())
        }
        
        fn format_name(&self) -> &'static str {
            "ply"
        }
    }
    
    impl FormatHandler for MockPlyHandler {
        fn supported_extensions(&self) -> &[&'static str] {
            &["ply"]
        }
        
        fn magic_bytes(&self) -> &[u8] {
            b"ply"
        }
    }
    
    impl Clone for MockPlyHandler {
        fn clone(&self) -> Self {
            Self
        }
    }
    
    #[test]
    fn test_registry_registration() {
        let mut registry = IoRegistry::new();
        
        // Register handlers
        registry.register_point_cloud_handler("ply", Box::new(MockPlyHandler));
        registry.register_mesh_handler("ply", Box::new(MockPlyHandler));
        registry.register_point_cloud_writer("ply", Box::new(MockPlyHandler));
        registry.register_mesh_writer("ply", Box::new(MockPlyHandler));
        
        // Check support
        assert!(registry.supports_point_cloud_reading("ply"));
        assert!(registry.supports_mesh_reading("ply"));
        assert!(registry.supports_point_cloud_writing("ply"));
        assert!(registry.supports_mesh_writing("ply"));
        
        // Check unsupported formats
        assert!(!registry.supports_point_cloud_reading("obj"));
        assert!(!registry.supports_mesh_reading("xyz"));
    }
    
    #[test]
    fn test_format_detection() {
        let mut registry = IoRegistry::new();
        registry.register_point_cloud_handler("ply", Box::new(MockPlyHandler));
        registry.register_mesh_handler("ply", Box::new(MockPlyHandler));
        
        // Create a test PLY file
        let temp_file = "test_detection.ply";
        let ply_content = "ply\nformat ascii 1.0\nelement vertex 1\nproperty float x\nproperty float y\nproperty float z\nend_header\n0.0 0.0 0.0\n";
        fs::write(temp_file, ply_content).unwrap();
        
        // Test reading with format detection
        let cloud = registry.read_point_cloud(Path::new(temp_file), "ply").unwrap();
        assert_eq!(cloud.len(), 1);
        
        let mesh = registry.read_mesh(Path::new(temp_file), "ply").unwrap();
        assert_eq!(mesh.vertex_count(), 1);
        
        // Cleanup
        let _ = fs::remove_file(temp_file);
    }
    
    #[test]
    fn test_unsupported_format() {
        let registry = IoRegistry::new();
        
        let result = registry.read_point_cloud(Path::new("test.xyz"), "xyz");
        assert!(result.is_err());
        
        let result = registry.read_mesh(Path::new("test.xyz"), "xyz");
        assert!(result.is_err());
    }
    
    #[test]
    fn test_supported_formats_list() {
        let mut registry = IoRegistry::new();
        registry.register_point_cloud_handler("ply", Box::new(MockPlyHandler));
        registry.register_mesh_handler("obj", Box::new(MockPlyHandler));
        
        let pc_formats = registry.supported_point_cloud_formats();
        let mesh_formats = registry.supported_mesh_formats();
        
        assert!(pc_formats.contains(&"ply".to_string()));
        assert!(mesh_formats.contains(&"obj".to_string()));
    }
}